Kisspeptin-10 (also referred to as “KP-10”) is a short bioactive peptide fragment of the kisspeptin family, originating from proteolytic processing of a 145-amino acid precursor encoded by the KISS1 gene.^[1] This gene product is believed to undergo sequential cleavage, yielding several functional fragments, including kisspeptin-54, kisspeptin-14, kisspeptin-13, and the decapeptide Kp-10. Among these, Kp-10 corresponds to the C-terminal segment of kisspeptin-54 and appears to have retained full biological activity associated with the peptide family’s function in reproductive signaling pathways.^[2]

Initial characterization of KISS1 positioned it as a gene that has been observed acting as a metastasis suppressor in mammalian research models, particularly in the contexts of malignant melanoma and breast tissue carcinoma.^[1] Its expression profile and tissue-specific activity have since led to growing interest in the neuroendocrine impacts of its peptide products. Kp-10 has been proposed to interact with central regulatory systems involved in reproduction, particularly through its hypothetical impacts on the hypothalamic-pituitary axis.

The KISS1 receptor (KISS1R), also referred to as GPR54, is a G-protein-coupled receptor that binds Kp-10 and other Kisspeptin fragments. This interaction has been proposed as a key upstream regulator of hypothalamic GnRH release, with implications for the modulation of puberty onset and fertility pathways specific to mammals.^[3]

 

Mechanisms of Action

Research suggests that KP-10 may act as an endogenous ligand for GPR54, and this receptor-ligand interaction may initiate intracellular signaling cascades in hypothalamic neurons. These pathways are hypothesized to lead to calcium mobilization, arachidonic acid release, and phosphorylation of extracellular signal-regulated kinases, which may contribute to the depolarization of both Kisspeptin and GnRH neurons.^[4]

Activation of GnRH neurons is central to the release of gonadotropins—follicle-stimulating hormone (FSH) and luteinizing hormone (LH)—from the anterior pituitary. These hormones are considered to regulate mammalian gonad function, and the synthesis of reproductive hormones as observed in murine models in laboratory settings. Studies suggest that deficiencies in this axis, most often observed in conditions such as hypogonadotropic hypogonadism, may be linked to impaired Kisspeptin signaling, highlighting a possible research interest in peptides like KP-10.^[3.]

Experimental findings in less-fertile murine research models suggest that the exogenous introduction of Kisspeptin analogs may stimulate endogenous gonadotropin release, possibly through GnRH-dependent mechanisms. Additionally, sustained exposure or elevated concentrations of KP-10 may be associated with a desensitization response. This type of exposure may suppress further activity along the hypothalamic-pituitary-gonadal (HPG) axis, although this remains under investigation.

The physiological outcomes of KP-10 interaction with GPR54 may vary based on concentration, receptor sensitivity, and developmental stage. Ongoing research continues to explore its regulatory role and expression patterns in both central and peripheral tissues. 

 

Scientific Research and Studies

 

KP-10 (Kisspeptin-10) and the Gonadal Axis

Experimental investigations into delayed reproductive maturation in mammals have included assessments of KP-10 as a potential modulator of the hypothalamic-pituitary-gonadal (HPG) axis. In one such study, researchers investigated whether exposure to KP-10 in preclinical laboratory settings with delayed developmental trajectories might impact luteinizing hormone (LH) secretion dynamics, considered to be a key marker of gonadotropic activation.

The research design involved the introduction of either KP-10 or a reference concentration of gonadotropin-releasing hormone (GnRH) to randomized cohorts of research models. Following an acute phase of hormonal monitoring, all test subjects were subsequently exposed to GnRH over a six-day observation period, allowing for comparative analysis of LH responses.

Data analysis revealed that approximately 47% of the KP-10-exposed group indicated an elevation in LH levels following exposure, suggesting a potential sensitization or activation of GnRH neurons. An additional 6% exhibited a partial or intermediate hormonal response, while the remaining research models showed no measurable change in LH secretion under the experimental conditions.

These findings contribute to ongoing efforts to elucidate the role of Kisspeptin peptides in developmental endocrinology, particularly in research models characterized by disrupted or delayed activation of the HPG axis. Further studies are warranted to clarify receptor sensitivity, neuroendocrine timing, and the interplay between the peptide GnRH axis across different developmental stages.

 

KP-10 (Kisspeptin-10) and Neuroprotection

Emerging data suggests that the deposition of amyloidogenic proteins, including amyloid-beta (Aβ) and alpha-synuclein (α-syn), may contribute to the progressive deterioration of cholinergic neurons within the central nervous system. These protein aggregates are widely regarded as playing a significant role in the pathogenesis of several neurodegenerative disorders due to their ability to disrupt cellular integrity and synaptic transmission. Investigations into the bioactivity of KP-10 (KP-10) have proposed that this decapeptide may interact directly with extracellular Aβ, potentially mitigating its pathological actions through competitive binding or conformational interference.^[6]

Experimental findings have indicated that KP-10 may exhibit a capacity to neutralize or suppress the neurotoxicity associated with Aβ, prion protein (PrP), and islet amyloid polypeptide (IAPP), and that this activity may occur independently of GPR54 or NPFF receptor antagonism. Such receptor-independent actions suggest a physicochemical mode of interaction that does not require canonical signal transduction through known Kisspeptin-binding receptors.

Given the sequence and structural homology between the non-amyloid-β component (NAC) region of α-syn and the C-terminal region of Aβ, researchers have hypothesized that KP-10 may similarly exhibit antagonistic activity against α-syn aggregation. In vitro studies examining cholinergic neuronal models have hypothesized that low nanomolar concentrations of KP-10 are associated with a measurable attenuation of α-syn-induced cytotoxicity, including that mediated by the pathogenic E46K mutation.

Conversely, exposure to supraphysiological levels of KP-10 has been correlated with better-supported cellular detox, suggesting a concentration-dependent biphasic impact.^[7] Molecular dynamics simulations provided further support for this proposed interaction, indicating the formation of stable, energetically favorable complexes between KP-10 and the C-terminal residues of α-syn, which may interfere with oligomerization or fibril formation.

To elucidate the mechanistic relevance of GPR54 signaling in these impacts, cholinergic SH-SY5Y cells overexpressing either wild-type or mutant α-syn were examined following exposure to KP-10 in the presence and absence of the GPR54 antagonist KP-234. Flow cytometric analysis and immunocytochemical evaluation revealed a reduction in apoptotic markers and mitochondrial damage following KP-10 exposure, regardless of whether receptor blockade was present. This observation suggests that KP-10’s neuroprotective impacts may be mediated via receptor-independent mechanisms, possibly through direct protein-protein interactions or membrane-associated pathways.

Further analysis revealed that the introduction of KP-10 led to a marked reduction in α-syn and choline acetyltransferase (ChAT) expression in neurons expressing both wild-type and mutant α-syn constructs. This finding aligns with the hypothesis that KP-10 may interfere with the stability or intracellular accumulation of aggregation-prone proteins, thereby preserving neuronal phenotype and function under proteotoxic stress.

 

Metabolic Dysregulation in Deficient Models

Experimental assessments of KP-10 deficiency have highlighted marked sex-specific alterations in metabolic function. In a comparative murine study, the energetic and glycoregulatory consequences of disrupted KP-10 signaling were evaluated in both male and female murine models.^[8] Female murine models with impaired KP-10 systems exhibited significant support for the growth in mass and the development of more pronounced glucose intolerance. Despite a reduction in caloric intake compared to control females, the KP-10-deficient group exhibited better-supported adiposity, reduced locomotor activity, and mitigated respiratory exchange ratios, indicating impaired metabolic flexibility and energy utilization.

Conversely, male murine models with comparable disruptions in KP-10 signaling displayed no statistically significant differences in overall mass or glucose tolerance when compared to male murine models in the control group. These findings suggest a potentially sex-dependent chromosomal role of KP-10 in modulating metabolic pathways, with the physiology of female murine models appearing particularly sensitive to alterations in KP-10-mediated signaling.

 

KP-10 (Kisspeptin-10) and Caloric Intake Regulation

Kisspeptin-10 (KP-10) has been identified in multiple brain regions of murine models, including the hippocampus, cerebellum, posterior hypothalamus, and septum. Its notable distribution within hypothalamic nuclei implicated in energy homeostasis, particularly the arcuate nucleus (Arc), has led to growing interest in its potential modulatory role in behavioral patterns that involve caloric intake.

To further understand this, a study was conducted to evaluate the impacts of KP-10 exposure on caloric intake in adult male murine models aged 6-8 weeks. The murine models were maintained under standard housing conditions with ad libitum access to a regular murine diet and water.^[9]

Experimental procedures involved the introduction of various concentrations of KP-10 or placebo to two groups: overnight-fasted and fed murine models. In fasted murine models, KP-10 introduction was associated with a suppression of caloric intake during the initial 3- to 12-hour post-observation period. Interestingly, this anorexigenic impact appeared transient. As caloric intake was ramped up by supervising researchers during the subsequent 12- to 16-hour period, the results showed a cumulative intake comparable to that of the research models in the control group. A detailed behavioral analysis revealed that KP-10 exposure led to a reduction in frequency and total duration of time spent consuming calories, accompanied by a concomitant increase in inter-consumption intervals. However, the amount and rate of caloric intake did not appear to differ significantly between the KP-10 and control groups.

To further elucidate the underlying mechanisms, subsequent studies investigated the potential central regulatory impacts of KP-10 on hypothalamic pathways involved in appetite control. In particular, the impacts of KP-10 exposure on gene expression and neurotransmitter dynamics were assessed in Hypo-E22 hypothalamic cell lines. Findings indicated that KP-10 may have exerted a transcriptional impact by upregulating neuropeptide Y (NPY), a potent orexigenic peptide, and concurrently downregulating brain-derived neurotrophic factor (BDNF), which is generally associated with suppression of hunger hormone signaling.

In addition to transcriptional modulation, KP-10 appeared to alter monoaminergic neurotransmission within hypothalamic cells. Exposure to the peptide resulted in reduced intracellular concentrations of dopamine and serotonin (5-hydroxytryptamine; 5-HT), while norepinephrine levels remained relatively unchanged. These alterations were accompanied by support of the respective metabolite-to-neurotransmitter ratios – dihydroxyphenylacetic acid (DOPAC)/dopamine and 5-hydroxyindoleacetic acid (5-HIAA)/serotonin – suggesting better-supported turnover of dopamine and serotonin following KP-10 introduction.

As per researchers:

“this study shows in mice that KP-10 acts centrally to reduce the light phase food intake response to an overnight fast with a delayed onset, whereas the nocturnal food intake is not altered. The reduction in feeding after a fast is achieved through mitigation in meal frequency and is associated with prolonged inter-meal intervals. Such changes in microstructure pattern of feeding are indicative of a stimulatory impact on satiety, which was not related to alterations in gastric emptying of a meal.”

The combination of elevated NPY expression, suppressed BDNF transcription, and diminished serotonergic and dopaminergic signaling suggests a potential role for KP-10 in modulating hypothalamic circuits that regulate behavioral patterns related to caloric intake and energy balance.^[10]

 

KP-10 (Kisspeptin-10) and Behavioral Patterns and Emotional Modulation

A recent investigation aimed to evaluate the impact of KP-10 on limbic system activity, a brain region implicated in behavioral regulation.^[11] Utilizing a combination of neuroimaging modalities and standardized psychometric assessments, the study examined central responses to exogenous KP-10 introduction.

Data obtained from these assessments suggested that KP-10 exposure was associated with better-supported activation within limbic structures, “specifically in response to sexual and couple-bonding stimuli.” Additionally, as per the researchers, “Kisspeptin’s enhancement of limbic brain structures correlated with psychometric measures of reward, drive, mood, and sexual aversion, providing functional significance. In addition, Kisspeptin [exposure] attenuated negative [behavioral patterns].”

These observations suggest a potential neuromodulatory role for KP-10 in neurological processing within the central nervous system, particularly in behavioral regulation.

 

KP-10 (Kisspeptin-10) and Reproductive Hormone Secretion

Another study was conducted to characterize the impacts of KP-10 on gonadotropin release in both male and female murine models.^[11] Following peptide exposure, research models appeared to exhibit a marked elevation in circulating levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), supporting the hypothesized stimulatory role of KP-10 on the hypothalamic–pituitary–gonadal (HPG) axis.

In contrast, baseline levels of FSH and LH in female murine models remained largely unimpacted across the general menstrual cycle. Notably, however, during the preovulatory phase, when gonadotropin sensitivity is heightened, the introduction of KP-10 was correlated with significant support of FSH and LH levels. These findings suggest a phase-dependent modulatory impact of KP-10 on reproductive endocrine activity, potentially mediated by interactions with upstream hypothalamic regulators.

Disclaimer: The products mentioned are not intended for human or animal consumption. Research chemicals are intended solely for laboratory experimentation and/or in-vitro testing. Bodily introduction of any sort is strictly prohibited by law. All purchases are limited to licensed researchers and/or qualified professionals. All information shared in this article is for educational purposes only.

 

References:

1. KISS1 KiSS-1 metastasis suppressor. https://www.ncbi.nlm.nih.gov/gene/3814
2. Mead, E. J., Maguire, J. J., Kuc, R. E., & Davenport, A. P. (2007). Kisspeptin: a multifunctional peptide system with a role in reproduction, cancer, and the cardiovascular system. British journal of pharmacology, 151(8), 1143–1153. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2189831/
3. Hussain, Mehboob A et al. “There is Kisspeptin – And Then There is Kisspeptin.” Trends in endocrinology and metabolism: TEM vol. 26,10 (2015): 564-572. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4587393/
4. Rønnekleiv, O. K., & Kelly, M. J. (2013). Kisspeptin excitation of GnRH neurons. Advances in experimental medicine and biology, 784, 113–131. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4019505/
5. Kristen P. Tolson et.al, Impaired kisspeptin signaling decreases metabolism and promotes glucose intolerance and obesity. The Journal of Clinical Investigation. Published June 17, 2014.
6. Milton NG, Chilumuri A, Rocha-Ferreira E, Nercessian AN, Ashioti M. Kisspeptin prevention of amyloid-β peptide neurotoxicity in vitro. ACS Chem Neurosci. 2012 Sep 19;3(9):706-19. doi: 10.1021/cn300045d. Epub 2012 May 30. PMID: 23019497; PMCID: PMC3447396. https://pmc.ncbi.nlm.nih.gov/articles/PMC3447396/
7. Simon, C., Soga, T., Ahemad, N., Bhuvanendran, S., & Parhar, I. (2022). Kisspeptin-10 (KP-10) Rescues Cholinergic Differentiated SHSY-5Y Cells from α-Synuclein-Induced Toxicity In Vitro. International journal of molecular sciences, 23(9), 5193. https://doi.org/10.3390/ijms23095193
8. Kristen P. Tolson et.al, Impaired kisspeptin signaling decreases metabolism and promotes glucose intolerance and obesity. The Journal of Clinical Investigation. Published June 17, 2014.
9. Stengel, A., Wang, L., Goebel-Stengel, M., & Taché, Y. (2011). Centrally injected kisspeptin reduces food intake by increasing meal intervals in mice. Neuroreport, 22(5), 253–257. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3063509/
10. Orlando G, Leone S, Ferrante C, Chiavaroli A, Mollica A, Stefanucci A, Macedonio G, Dimmito MP, Leporini L, Menghini L, Brunetti L, Recinella L. Impacts of Kisspeptin-10 on Hypothalamic Neuropeptides and Neurotransmitters Involved in Appetite Control. Molecules. 2018 Nov 24;23(12):3071. doi: 10.3390/molecules23123071. PMID: 30477219; PMCID: PMC6321454. https://pmc.ncbi.nlm.nih.gov/articles/PMC6321454/
11. Comninos, A. N., Wall, M. B., Demetriou, L., Shah, A. J., Clarke, S. A., Narayanaswamy, S., Nesbitt, A., Izzi-Engbeaya, C., Prague, J. K., Abbara, A., Ratnasabapathy, R., Salem, V., Nijher, G. M., Jayasena, C. N., Tanner, M., Bassett, P., Mehta, A., Rabiner, E. A., Hönigsperger, C., Silva, M. R., Dhillo, W. S. (2017). Kisspeptin modulates sexual and emotional brain processing in humans. The Journal of clinical investigation, 127(2), 709–719. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5272173/

Recent investigations into growth hormone secretagogues (GHSs), growth hormone-releasing peptides (GHRPs), and analogs of growth hormone (hGH) have pointed to their potential in modulating endogenous hormone regulation. Individually and in combination, these agents may potentially influence physiological processes such as lipid mobilization, muscle composition, circadian rhythm modulation, and various systemic functions, including gastrointestinal and cardiovascular activity.

The Fragment 176-191 & CJC-1295 & Ipamorelin Blend consists of three distinct peptide analogs that have been investigated for their potential modulatory interaction on endogenous growth hormone regulation and systemic metabolism. The blend combines synthetic derivatives of natural signaling molecules, each engineered with the intent to target specific endocrine or metabolic pathways.

Fragment 176-191 is a truncated sequence derived from the carboxyl-terminal region of growth hormone (hGH),^[1] while CJC-1295 is an analog of Growth Hormone-Releasing Hormone (GHRH),^[2] and Ipamorelin is a pentapeptide growth hormone secretagogue (GHS) that appears to mimic ghrelin-like activity.^[3]

Collectively, this peptide blend has been examined in preclinical research for its potential influence on lipolysis, thermogenesis, muscle composition, and hormonal regulation through the hypothalamic-pituitary axis.

Each constituent of the Fragment 176-191 & CJC-1295 & Ipamorelin Blend is designed to interact with distinct, yet biologically interrelated, molecular pathways that appear to converge on hormonal and metabolic regulation. When combined, the peptides may exhibit complementary actions that potentially enhance endocrine signaling and metabolic homeostasis.

 

Overview of Fragment 176-191

This peptide comprises amino acids 176 through 191 of the growth hormone (hGH) molecule, a region identified in research as containing the segment primarily responsible for possible fat-reducing activity.

Unlike full-length hGH, Fragment 176-191 does not appear to affect insulin sensitivity or glucose metabolism directly, but rather may act selectively through beta-3 adrenergic receptors (ADRB3), particularly expressed in white and brown adipose tissue. Activation of ADRB3 is associated with increased intracellular cAMP levels, which in turn may activate protein kinase A (PKA), initiating downstream lipolytic signaling cascades.

Additionally, stimulation of ADRB3 has been implicated in mitochondrial uncoupling and thermogenesis within skeletal muscle cells, a process potentially contributing to increased energy expenditure.^[4] The peptide’s truncated structure appears to maintain bioactivity in lipid metabolism while possibly eliminating other hGH-related effects.

 

Overview of CJC-1295 (Modified GRF 1-29)

CJC-1295 is a tetra-substituted analog of GHRH (1-29), representing the biologically active portion of endogenous GHRH. The inclusion of a Drug Affinity Complex (DAC) is speculated to increase its binding affinity to albumin, thereby significantly extending its half-life and reducing enzymatic degradation in circulation. This stabilization may enable more prolonged interaction with GHRH receptors (GHRH-R) on somatotroph cells within the anterior pituitary.

Upon receptor engagement, a signaling cascade involving cyclic AMP and calcium ion influx may be initiated, which could possibly result in pulsatile secretion of endogenous growth hormone (GH). Research suggests that CJC-1295 may not only elevate GH levels but also enhance Insulin-like Growth Factor 1 (IGF-1) concentrations through hepatic stimulation, with some findings reporting up to a threefold increase in plasma IGF-1.^[5]

These potential actions suggest possible implications in research related to growth hormone axis modulation and systemic anabolism.

 

Overview of Ipamorelin

Ipamorelin is a selective growth hormone secretagogue composed of five amino acids. Structurally and functionally, it appears to mimic the endogenous hormone ghrelin, binding to GHS-R1a (Growth Hormone Secretagogue Receptor 1a) located in the hypothalamus and anterior pituitary.

Upon receptor activation, intracellular calcium mobilization and downstream signaling appear to result in the selective secretion of GH. Notably, unlike earlier GHRPs such as GHRP-6 or Hexarelin, Ipamorelin is characterized by its possible receptor specificity and minimal off-target activity. Studies suggest that the peptide exerts negligible influence on the secretion of adrenocorticotropic hormone (ACTH), prolactin, or cortisol.^[6]

This selective action may make it a suitable candidate for research exploring isolated GH axis stimulation without broad neuroendocrine disruption.

 

Scientific Research and Studies

 

Fragment 176-191, CJC-1295, Ipamorelin Blend and Growth Hormone

Within the Fragment 176-191, CJC-1295, and Ipamorelin peptide blend, distinct mechanisms of action appear to converge on the modulation of growth hormone (GH) signaling. Fragment 176-191, derived from the C-terminal region of hGH, and is designed to emulate the fat-metabolizing potential of the full-length hormone, possibly without affecting systemic GH levels. In contrast, CJC-1295 and Ipamorelin are proposed to stimulate endogenous GH secretion through receptor-mediated pathways in the hypothalamic-pituitary axis.

In early-phase research,^[7] CJC-1295 was evaluated for its potential to increase GH  in certain organism models. In one controlled study, the cohort was divided into control exposure (saline) or CJC-1295 exposed groups. Blood samples collected before and after peptide exposure were reported to indicate a significant rise in circulating GH levels, approximately 7.5 times higher in the peptide group compared to placebo. Notably, this elevation persisted beyond the exposure period, remaining stable for up to seven days post-introduction.

In a separate investigation,^[8] a concentration-escalation design was applied. Research models were exposed to increasing amounts of CJC-1295 appeared to exhibit a concentration-dependent rise in serum GH, with peak levels reaching nearly 10-fold above baseline. The results appeared to emphasize that sustained GHRH stimulation led to prolonged elevations in both GH and IGF-1, suggesting potentially preserved pituitary function.

Ipamorelin, a selective ghrelin mimetic, has also been evaluated for its GH-releasing potential. In one comparative study, a single introduction of the peptide was associated with a dramatic increase in circulating GH, reportedly over 60-fold compared to control groups receiving placebo.^[9] This robust effect, combined with Ipamorelin’s reported receptor selectivity, supports its role as a candidate for further investigation in GH axis modulation.

Together, these findings underscore the differential yet potentially synergistic actions of the peptides in this blend. While Fragment 176-191 may primarily modulate metabolic processes through adrenergic pathways, CJC-1295 and Ipamorelin appear to target GH synthesis and secretion through endocrine mechanisms and appear to collectively contribute to the peptide blend’s proposed research applications.

 

Regenerative and Metabolic Research of Fragment 176-191, CJC-1295 & Ipamorelin Blend

A 2015 preclinical study^[10] evaluated the regenerative implications of Fragment 176-191 in a controlled study involving 32 rabbits. The subjects were systematically divided into four equal groups, each receiving one of the following: saline (placebo), Fragment 176-191, hyaluronic acid (HA), or a combination of both the peptide and HA. Over a 7-week period, all studies were introduced under ultrasound guidance to assess their influence on cartilage preservation.

Upon evaluation, results suggested that the group introduced to the combination blend of Fragment 176-191 and HA appeared to indicate the least degree of cartilage degradation. As per the researchers, the peptide exposure “[appeared to have] enhanced cartilage regeneration, and combined AOD9604 (another name for Fragment 176-191) and HA [appeared] more effective than HA or AOD9604 alone in the collagenase-induced knee OA rabbit model.”

 

Studies on Body Composition: Fat Reduction and Muscle Accrual

Fragment 176-191 has been studied for its potential to promote lipolysis, potentially supporting fat mass reduction. However, the broader blend, which includes CJC-1295 and Ipamorelin, may exert more complex, multi-axis implications in body composition.

Ipamorelin, through its proposed mimetic activity on the ghrelin receptor (GHS-R1a), is thought to stimulate appetite and growth hormone secretion, mechanisms that may contribute to increased body weight. Experimental models suggest that Ipamorelin may be associated with modest gains in both adipose and lean tissue. In one such study utilizing murine subjects, both growth hormone-deficient and growth hormone-intact, Ipamorelin introduction was linked to a roughly 15% increase in total body mass over two weeks. Analysis suggests proportionate enlargement of fat pad weights relative to body size in peptide-exposed groups.

Conversely, CJC-1295 appears to facilitate anabolic changes with a differing trajectory. Research involving GHRH gene knockout mice (GHRHKO), which inherently lack functional growth hormone-releasing hormone, found that CJC-1295 introduction appeared to have supported the normalization of lean body mass. These animals, when exposed to the peptide, reportedly maintained muscle mass levels comparable to wild-type controls while avoiding the excess adiposity observed in control GHRHKO counterparts. Additionally, fat mass measurements in peptide-exposed mice were not elevated, suggesting that CJC-1295 may promote lean tissue development without contributing to fat accumulation.^[11]

Given these differentiated effects, it is plausible that when introduced as a blend, Fragment 176-191 and CJC-1295 might offset the adipogenic potential of Ipamorelin while collectively enhancing hypothetical anabolic outcomes. These combined mechanistic pathways may render this peptide blend a candidate for further inquiry into body recomposition studies.

 

Fragment 176-191 & CJC-1295 & Ipamorelin Blend and Bone Density

The combination of peptides, particularly Ipamorelin, may hold potential for promoting bone mineral content through its proposed activity on lean and muscle mass.

In a controlled study, murine subjects were introduced to Ipamorelin or a placebo, with bone mineral content evaluated in real-time using dual X-ray absorptiometry (DXA) at key sites, including the femur and L6 vertebrae. At the conclusion of the study, femoral bones were further analyzed using mid-diaphyseal peripheral quantitative computed tomography (pQCT) scans to assess structural changes.

The preliminary data from this investigation suggests that Ipamorelin may be associated with an increase in body weight and a possible enhancement in bone mineral content in the tibia and vertebrae, as suggested by DXA results.

As per the researchers, the introduction of these peptides appeared to:

“increase BMC as measured by DXA in vivo. The results of in vitro measurements using pQCT and Archimedes’ principle, in addition to ash weight determinations, show that the increases in cortical and total BMC were due to an increased growth of the bones with increased bone dimensions, whereas the volumetric BMD was unchanged.”^[12]

Disclaimer: The products mentioned are not intended for human or animal consumption. Research chemicals are intended solely for laboratory experimentation and/or in-vitro testing. Bodily introduction of any sort is strictly prohibited by law. All purchases are limited to licensed researchers and/or qualified professionals. All information shared in this article is for educational purposes only.

 

References:

1. National Center for Biotechnology Information (2023). PubChem Substance Record for SID 319360420, 386264-39-7, Source: ToxPlanet. https://pubchem.ncbi.nlm.nih.gov/substance/319360420
2. National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 91976842, CJC1295 Without DAC. https://pubchem.ncbi.nlm.nih.gov/compound/CJC1295-Without-DAC
3. National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 9831659, Ipamorelin. https://pubchem.ncbi.nlm.nih.gov/compound/Ipamorelin
4. Ferrer-Lorente R, Cabot C, Fernández-López JA, Alemany M. Combined effects of oleoyl-estrone and a beta3-adrenergic agonist (CL316,243) on lipid stores of diet-induced overweight male Wistar rats. Life Sci. 2005 Sep 2;77(16):2051-8. doi: 10.1016/j.lfs.2005.04.008. PMID: 15935402. https://pubmed.ncbi.nlm.nih.gov/15935402/
5. Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006 Mar;91(3):799-805. doi: 10.1210/jc.2005-1536. Epub 2005 Dec 13. PMID: 16352683. https://pubmed.ncbi.nlm.nih.gov/16352683/
6. Raun K, Hansen BS, Johansen NL, Thøgersen H, Madsen K, Ankersen M, Andersen PH. Ipamorelin, the first selective growth hormone secretagogue. Eur J Endocrinol. 1998 Nov;139(5):552-61. doi: 10.1530/eje.0.1390552. PMID: 9849822. https://pubmed.ncbi.nlm.nih.gov/9849822/
7. Ionescu M, Frohman LA. Pulsatile growth hormone secretion (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. J Clin Endocrinol Metab. 2006 Dec;91(12):4792-7. Epub 2006 Oct 3. PMID: 17018654. https://pubmed.ncbi.nlm.nih.gov/17018654/
8. Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA. Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. J Clin Endocrinol Metab. 2006 Mar;91(3):799-805. Epub 2005 Dec 13. PMID: 16352683. https://pubmed.ncbi.nlm.nih.gov/16352683/
9. Gobburu, J. V., Agersø, H., Jusko, W. J., & Ynddal, L. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical research, 16(9), 1412–1416. https://doi.org/10.1023/a:1018955126402
10. Kwon DR, Park GY. Effect of Intra-articular Injection of AOD9604 with or without Hyaluronic Acid in Rabbit Osteoarthritis Model. Ann Clin Lab Sci. 2015 Summer;45(4):426-32. PMID: 26275694. https://pubmed.ncbi.nlm.nih.gov/26275694/
11. Alba M, Fintini D, Sagazio A, Lawrence B, Castaigne JP, Frohman LA, Salvatori R. Once-daily administration of CJC-1295, a long-acting growth hormone-releasing hormone (GHRH) analog, normalizes growth in the GHRH knockout mouse. Am J Physiol Endocrinol Metab. 2006 Dec;291(6):E1290-4. doi: 10.1152/ajpendo.00201.2006. Epub 2006 Jul 5. PMID: 16822960. https://pubmed.ncbi.nlm.nih.gov/16822960/
12. Svensson, J., Lall, S., Dickson, S. L., Bengtsson, B. A., Rømer, J., Ahnfelt-Rønne, I., Ohlsson, C., & Jansson, J. O. (2000). The GH secretagogues ipamorelin and GH-releasing peptide-6 increase bone mineral content in adult female rats. The Journal of endocrinology, 165(3), 569–577. https://doi.org/10.1677/joe.0.1650569

Follistatin-344 (FST-344) is an endogenous glycoprotein widely distributed across various tissues. It is classified as an autocrine signaling molecule, meaning that scientists consider it to be synthesized and secreted by cells to bind to their own surface receptors, leading to intracellular modifications.

Research suggests that Follistatin exists primarily in two isoforms, FST-317 and FST-344, with 288 and 315 amino acids, respectively. These isoforms arise through alternative mRNA splicing, resulting in distinct molecular structures.^[1] Among these, FST-344 is regarded as the predominant form, while FST-317 represents a smaller proportion of the total encoded mRNA.

FST-344 consists of three highly conserved domains—FSD1, FSD2, and FSD3—comprising approximately 63 amino acid residues each, with structural conservation maintained in synthetic derivatives.^[2] These domains contain 73–77 amino acid residues, including 10 conserved cysteine residues, which contribute to protein stability and functionality. Due to its diverse regulatory roles, FST-344 has been extensively investigated for its interactions with various members of the Transforming Growth Factor-beta (TGF-β) superfamily.

 

Mechanism of Action

The primary function of FST-344 is hypothesized to involve binding and inhibition of activins, proteins within the TGF-β superfamily that regulate reproductive and cellular processes.^[3] Activins, particularly those secreted by ovarian follicles, enhance the secretion of follicle-stimulating hormone (FSH), and a critical regulator of reproductive physiology. FST-344 has been suggested to mitigate activin-mediated FSH secretion by forming high-affinity inhibitory complexes, thus modulating endocrine function.

FST-344 is believed to be synthesized locally within the pituitary gland, gonads, testes, and ovaries in certain organisms, although it has also been detected in the bloodstream, suggesting potential systemic roles beyond reproductive function. In addition to its interaction with activins, FST-344 is hypothesized to bind to other TGF-β family proteins, including Bone Morphogenetic Proteins (BMPs), which are implicated in bone formation, embryogenesis, and cellular differentiation. However, the precise role of FST-344 in BMP regulation remains an area of ongoing investigation.^[4]

One of the most studied interactions of FST-344 involves Growth Differentiation Factor 8 (GDF8), commonly referred to as myostatin. Myostatin functions as a negative regulator of muscle growth by limiting myocyte proliferation and differentiation. It is proposed that FST-344 binds to myostatin, potentially neutralizing its inhibitory effects and facilitating increased muscle mass. This myostatin inhibition has been widely explored in the context of skeletal muscle physiology, with research suggesting that FST-344-mediated suppression of myostatin might promote muscle hypertrophy. However, the extent of this effect and its underlying mechanisms remain subject to further scientific scrutiny.

Additionally, FST-344 may interact with Growth Differentiation Factor 9 (GDF9), a protein essential for ovarian follicle development. Preliminary findings suggest that FST-344 could play a role in regulating GDF9 activity, though this interaction remains incompletely characterized. Given its broad functional scope, further research is required to elucidate the full spectrum of FST-344’s biological roles, particularly concerning its interactions within the TGF-β superfamily.

 

Scientific Research and Studies

 

FST-344 and Breast Cancer Progression

Studies employing reverse transcription polymerase chain reaction (RT-PCR) analysis have suggested that Follistatin expression may vary in breast cancer models.^[5]

A study examining gene expression datasets in murine models of breast cancer reported that Follistatin was frequently under-expressed in malignant breast cells.^[6] This downregulation is hypothesized to contribute to enhanced cancer cell proliferation, potentially mediated by activin proteins. Given that Follistatin has been proposed to bind and inhibit activins, researchers speculate that restoring Follistatin levels might attenuate activin-induced metastasis and improve overall survival outcomes. However, further investigations are required to elucidate the precise regulatory mechanisms of Follistatin in breast cancer progression.

 

FST-344 and Esophageal Carcinogenesis

Bone morphogenetic proteins (BMPs) have been implicated in the pathological transformation of normal esophageal epithelial cells into malignant phenotypes. Follistatin, hypothesized to exhibit binding affinity for activin and myostatin, is also suggested to interact with BMPs, potentially modulating their activity. By regulating BMP signaling, Follistatin might mitigate excessive cellular proliferation, a hallmark of oncogenic processes. Experimental findings on FST-344 suggest that this peptide may counteract the effects of acid reflux, considered to be a contributor to esophageal tissue inflammation and carcinogenesis. Specifically, Follistatin’s ability to inhibit BMP activity could theoretically interfere with the initiation of malignant transformation, particularly in microenvironments predisposed to chronic inflammation or external stressors such as prolonged acid exposure.^[7]

While preliminary data suggest a possible protective role, further research is necessary to determine the mechanistic pathways underlying this interaction.

 

FST-344 and Skeletal Muscle Modulation

Myostatin, a member of the transforming growth factor-beta (TGF-β) superfamily, is widely recognized for its role in regulating muscle mass by inhibiting muscle cell proliferation and differentiation. As a key regulator of muscle homeostasis, myostatin is primarily synthesized by muscle cells and functions as a negative modulator of excessive muscle growth. FST-344, a glycoprotein that may counteract myostatin activity, has been explored for its potential influence on muscle physiology.

Studies suggest that FST-344 may disrupt myostatin signaling, thereby promoting muscle growth. Based on the study conducted in 1997,^[8] mice subjected to FST-344 exhibited significantly lower myostatin expression. This reduction appeared to correlate with enhanced skeletal muscle mass, with subjects indicating both muscle hypertrophy and hyperplasia, leading to a substantial increase in body mass compared to controls.

Further research has investigated the possibility of endogenously producing FST-344 via mRNA-based delivery systems. In one study, a nanoparticle-mediated mRNA approach was used to stimulate hepatic cells to synthesize and release Follistatin. The results suggested that within 72 hours of peptide exposure, circulating Follistatin levels were elevated, which coincided with a decrease in myostatin and activin A concentrations.^[9]

Activin A, another TGF-β superfamily member, is implicated in various cellular processes, including differentiation, proliferation, and apoptosis. It has been associated with muscle atrophy through its interaction with the activin type IIB receptor (ActRIIB), which appears to activate pathways that promote muscle protein degradation. Research findings suggest that prolonged elevations in Follistatin levels over an eight-week period resulted in a 10% increase in lean muscle mass compared to untreated controls.

Unlike research focused solely on myostatin inhibition—such as studies using anti-myostatin antibodies—Follistatin-344 is hypothesized to exert broader effects by modulating both myostatin and activin A pathways. While myostatin inhibition primarily facilitates muscle hypertrophy, activin A suppression may mitigate additional contributors to muscle loss, including fibrosis and inflammatory responses. This proposed dual mechanism of action may provide a more comprehensive approach to muscle function by enhancing muscle mass while simultaneously improving muscle quality and function, potentially reducing fibrosis-related stiffness and muscle weakness.^[10]

 

FST-344 and Liver Fibrosis

A study was conducted to examine the potential role of Follistatin in mitigating liver fibrosis, specifically focusing on its impact in the early stages of the condition.

In this investigation,^[11] rats were assigned to either a control group or a Follistatin-exposed group for a duration of four weeks. The results suggested that the Follistatin-exposed group exhibited a significant 32% reduction in liver fibrosis compared to the control. Additionally, a substantial decrease in hepatocytic apoptosis—approximately 90%—was observed in the Follistatin-exposed animals, suggesting a protective effect against liver cellular damage.

 

FST-344 and Hair Follicle Growth

FST-344 has been explored for its potential role in promoting tissue regeneration, particularly in relation to hair follicle stimulation and hair growth.

A study^[12] studying the potential of a synthetic Follistatin-based formulation, referred to as Hair Stimulating Complex (HSC), was conducted on research models of hair loss. The study examined 26 models exposed to the peptide over the course of 52 weeks. Histopathological analyses indicated a notable improvement in hair follicle growth within the peptide-exposed group when compared to controls. In addition to promoting hair follicle growth, the peptide-exposed research models indicated an increase in hair thickness and density, with a reported improvement of approximately 13%.

 

FST-344 and Cell Proliferation, Metastasis Regulation

Research investigating the potential of Follistatin on breast cancer suggested an intriguing dual role, wherein Follistatin potentially promotes cell proliferation while simultaneously inhibiting metastasis. This dichotomy appears to extend across various tissues, including the liver, where Follistatin is speculated to play a critical role in hepatocyte proliferation. Studies using rat models suggest that the inactivation of activin, mediated by Follistatin, is considered essential for the initiation of hepatocyte proliferation.^[13]

This observation offers insight into the dual role of Follistatin, which is often linked to increased tumor growth while concurrently limiting tumor invasion and metastasis. It is hypothesized that during cellular growth, an energy trade-off occurs, wherein migratory functions are inhibited to prioritize cellular resources for growth and proliferation. This mechanism may account for the potential of Follistatin in modulating both tumor growth and its dissemination.

 

FST-344 and Insulin Deficiency

Research in murine models suggests that overexpression of FST-344 may significantly impact insulin regulation by increasing the mass of beta-islet cells, which are considered to be responsible for the production of insulin. This enhancement in islet cell mass may result in improved insulin secretion and better regulation of blood glucose levels. In particular, studies have reported that Follistatin exposure in mice may lead to reduced fasting glucose levels and a marked reduction in certain symptoms associated with diabetes.

Per the study reports, the peptide-exposed mice exhibited a substantial improvement in longevity, with their lifespans doubling compared to non-peptide-exposed counterparts. This increase appears to be attributed to the virtual elimination of diabetes-related complications, suggesting that Follistatin may potentially play a critical role in ameliorating the long-term effects of both Type 1 and Type 2 diabetes. By supporting the function of the remaining functional islet cells within the pancreas, Follistatin may offer a potential mode to restore some level of insulin production and function, even in the presence of insulin resistance or autoimmune destruction of beta cells.^[14]

This reported mechanism might provide an alternative to the traditional study of exogenous insulin in diabetes research. Unlike insulin, which only supplements insulin levels, Follistatin’s action is suggested to work within internal physiological controls. By boosting endogenous insulin secretion, it could potentially offer a more natural and finely regulated approach to managing blood sugar levels. As per researchers, the studies suggest “overexpression of FST in the diabetic pancreas preserves β-cell function by promoting β-cell proliferation.”

Disclaimer: The products mentioned are not intended for human or animal consumption. Research chemicals are intended solely for laboratory experimentation and/or in-vitro testing. Bodily introduction of any sort is strictly prohibited by law. All purchases are limited to licensed researchers and/or qualified professionals. All information shared in this article is for educational purposes only.

 

References:

1. FST follistatin [Homo sapiens (human)]. https://www.ncbi.nlm.nih.gov/gene?Db=gene&Cmd=DetailsSearch&Term=10468
2. Shi, L., Resaul, J., Owen, S., Ye, L., & Jiang, W. G. (2016). Clinical and Therapeutic Implications of Follistatin in Solid Tumours. Cancer genomics & proteomics, 13(6), 425–435. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5219916/
3. Rodino-Klapac, L. R., Haidet, A. M., Kota, J., Handy, C., Kaspar, B. K., & Mendell, J. R. (2009). Inhibition of myostatin with emphasis on follistatin as a therapy for muscle disease. Muscle & nerve, 39(3), 283–296. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2717722/
4. Reichel C, Gmeiner G, Thevis M. Detection of black market follistatin 344. Drug Test Anal. 2019 Nov;11(11-12):1675-1697. doi: 10.1002/dta.2741. Erratum in: Drug Test Anal. 2020 Oct;12(10):1522-1533. doi: 10.1002/dta.2882. PMID: 31758732. https://pubmed.ncbi.nlm.nih.gov/31758732/
5. Zabkiewicz C, Resaul J, Hargest R, Jiang WG, Ye L. Increased Expression of Follistatin in Breast Cancer Reduces Invasiveness and Clinically Correlates with Better Survival. Cancer Genomics Proteomics. 2017 Jul-Aug;14(4):241-251. https://pubmed.ncbi.nlm.nih.gov/28647698/
6. Seachrist DD, Sizemore ST, Johnson E, Abdul-Karim FW, Weber Bonk KL, Keri RA. Follistatin is a metastasis suppressor in a mouse model of HER2-positive breast cancer. Breast Cancer Res. 2017 Jun 5;19(1):66. doi: 10.1186/s13058-017-0857-y. PMID: 28583174; PMCID: PMC5460489. https://pubmed.ncbi.nlm.nih.gov/28583174/
7. Lau MC, Ng KY, Wong TL, Tong M, Lee TK, Ming XY, Law S, Lee NP, Cheung AL, Qin YR, Chan KW, Ning W, Guan XY, Ma S. FSTL1 Promotes Metastasis and Chemoresistance in Esophageal Squamous Cell Carcinoma through NFκB-BMP Signaling Cross-talk. Cancer Res. 2017 Nov 1. https://pubmed.ncbi.nlm.nih.gov/28883005/
8. McPherron AC, Lawler AM, Lee SJ. Regulation of skeletal muscle mass in mice by a new TGF-beta superfamily member. Nature. 1997 May 1;387(6628):83-90. https://pubmed.ncbi.nlm.nih.gov/9139826/
9. Schumann C, Nguyen DX, Norgard M, Bortnyak Y, Korzun T, Chan S, Lorenz AS, Moses AS, Albarqi HA, Wong L, Michaelis K, Zhu X, Alani AWG, Taratula OR, Krasnow S, Marks DL, Taratula O. Increasing lean muscle mass in mice via nanoparticle-mediated hepatic delivery of follistatin mRNA. Theranostics 2018; 8(19):5276-5288. doi:10.7150/thno.27847. https://www.thno.org/v08p5276.htm
10. Iskenderian A, Liu N, Deng Q, Huang Y, Shen C, Palmieri K, Crooker R, Lundberg D, Kastrapeli N, Pescatore B, Romashko A, Dumas J, Comeau R, Norton A, Pan J, Rong H, Derakhchan K, Ehmann DE. Myostatin and activin blockade by engineered follistatin results in hypertrophy and improves dystrophic pathology in mdx mouse more than myostatin blockade alone. Skelet Muscle. 2018 Oct 27;8(1):34. https://pubmed.ncbi.nlm.nih.gov/30368252/
11. Patella S, Phillips DJ, Tchongue J, de Kretser DM, Sievert W. Follistatin attenuates early liver fibrosis: effects on hepatic stellate cell activation and hepatocyte apoptosis. Am J Physiol Gastrointest Liver Physiol. 2006 Jan;290(1):G137-44. https://pubmed.ncbi.nlm.nih.gov/16123203/
12. Zimber MP, Ziering C, Zeigler F, Hubka M, Mansbridge JN, Baumgartner M, Hubka K, Kellar R, Perez-Meza D, Sadick N, Naughton GK. Hair regrowth following a Wnt- and follistatin containing treatment: safety and efficacy in a first-in-man phase 1 clinical trial. J Drugs Dermatol. 2011 Nov;10(11):1308-12. https://pubmed.ncbi.nlm.nih.gov/22052313/
13. Ooe H, Chen Q, Kon J, Sasaki K, Miyoshi H, Ichinohe N, Tanimizu N, Mitaka T. Proliferation of rat small hepatocytes requires follistatin expression. J Cell Physiol. 2012 Jun;227(6):2363-70. doi: 10.1002/jcp.22971. PMID: 21826650. https://pubmed.ncbi.nlm.nih.gov/21826650/
14. Zhao C, Qiao C, Tang RH, Jiang J, Li J, Martin CB, Bulaklak K, Li J, Wang DW, Xiao X. Overcoming Insulin Insufficiency by Forced Follistatin Expression in β-cells of db/db Mice. Mol Ther. 2015 May;23(5):866-874. doi: 10.1038/mt.2015.29. Epub 2015 Feb 13. PMID: 25676679; PMCID: PMC4427879. https://pubmed.ncbi.nlm.nih.gov/25676679/

Copper peptides are endogenously occurring complexes formed by binding copper ions (Cu2+) to specific amino acid sequences. Among these, glycyl-L-histidyl-L-lysine (GHK-Cu) is the most extensively studied tripeptide. However, other copper-binding peptides such as DAHK-Cu (Aspartyl-Alanyl-Histidyl-Lysine) and AHK-Cu (Alanine-Histidine-Lysine) have also been identified. These peptides have reportedly been studied for their potential roles in gene expression, tissue remodeling, antioxidant activity, and cellular signaling.

GHK-Cu is a tripeptide complex first isolated from plasma. It is present in various fluid cultures, with a reported decline in concentration associated with cellular aging.^[1] Research suggests that this decline may impact tissue repair and regeneration, as GHK-Cu is implicated in cellular communication and extracellular matrix support.

Beyond GHK-Cu, other copper peptides, such as DAHK-Cu, a tetrapeptide found in albumin, have been investigated for their role in copper transport and redox activity.^[2] Similarly, AHK-Cu has been explored for its potential effects on dermal fibroblast activity and extracellular matrix stability, with emerging data suggesting its involvement in cellular proliferation and hair follicle stimulation.

 

Cooper Peptides: Mechanism of Action

Copper peptides are speculated to function through multiple biochemical pathways, largely mediated by their reputed ability to interact with copper ions and impact cellular processes. GHK-Cu, for example, has been found to modulate gene expression, potentially resetting elements of the genome that may contribute to tissue repair and cellular function.^[1] Studies suggest that GHK-Cu interacts with regulatory genes associated with wound recovery, inflammation reduction, and antioxidant responses.^[3]

Research suggests that GHK-Cu binds to metal ions in the extracellular environment, facilitating their transport and modulating cellular signaling pathways. When introduced into cell cultures at nanomolar concentrations, GHK-Cu has been observed to impact various biological responses, ranging from stimulation of cell growth to induction of cell differentiation.^[3] Furthermore, the peptide appears to have chelating properties, binding copper and iron ions in isolated cellular systems, which may contribute to its reported biological effects.^[1]

DAHK-Cu exhibits distinct biochemical activity compared to GHK-Cu, primarily due to its strong affinity for copper (II) ions, which appears to allow it to participate in redox reactions and potentially regulate oxidative stress within cells. It has been implicated in albumin-mediated copper homeostasis and is thought to play a role in neuroprotection and metabolic regulation.^[2]

Similarly, AHK-Cu has been studied for its role in promoting fibroblast proliferation and extracellular matrix synthesis. Research suggests that AHK-Cu may impact cellular processes by regulating VEGF and TGF-β1 levels, activating fibroblasts and endothelial cells. Fibroblasts produce collagen and elastin, which are essential for epidermal pigmentation, texture, and flexibility, while endothelial cells support blood vessel function.^[4] This activation is suggested to support dermal elasticity, wound recovery, and reduce fine lines and wrinkles.

 

Scientific Research and Studies

 

Cooper Peptides (GHK-Cu): Research and Biological Mechanisms

Investigations into the biological functions of GHK-Cu date back to the 1980s^[5], when its role in tissue repair and regeneration was first explored. As a naturally occurring tripeptide with a high affinity for copper (II) ions, GHK-Cu is believed by researchers to be released at sites of tissue injury, where it is hypothesized to coordinate wound-recovery responses. Experimental studies using dermally wounded rat models demonstrated that extracellular matrix components release GHK upon injury, allowing it to bind circulating copper ions. This complex is thought to upregulate the expression of decorin, considered to be a key regulator of collagen synthesis, extracellular matrix organization, and cellular repair processes. Additionally, decorin may play a critical role in modulating fibrotic responses and may contribute to anti-tumor defense mechanisms.

Subsequent studies in the 2000s^[6] further elucidated the molecular effects of GHK-Cu, demonstrating its ability to support collagen production while simultaneously regulating matrix turnover through the induction of tissue inhibitors of metalloproteinases (TIMP-1 and TIMP-2). These TIMPs inhibit matrix metalloproteinases (MMPs), thereby preserving extracellular matrix integrity and mitigating excessive degradation, processes that are closely linked to cellular aging and wound recovery dynamics.

Other copper-binding peptides, including DAHK-Cu and AHK-Cu, exhibit distinct yet overlapping biological activities. While DAHK-Cu has been associated with antioxidative functions and the regulation of inflammatory responses, AHK-Cu has been implicated in cellular signaling pathways involving vascular endothelial growth factor (VEGF) and transforming growth factor beta-1 (TGF-β1), which facilitates fibroblast activation and endothelial cell function. This regulatory activity supports the synthesis of collagen and elastin, wound recovery, and the integrity of skin structure.

Collectively, these peptides highlight the potential of copper-complexed biomolecules in regenerative and reparative processes.

 

Cooper Peptides: Metastasis Regulation

Research^[1] suggests the potential anticancer effects of GHK-Cu in conjunction with ascorbic acid (vitamin C) on sarcoma cell proliferation. The experimental model consisted of 180 mice with pre-established tumor growths that were exposed to a mixture of GHK-Cu and ascorbic acid. The findings suggested a potential reduction in tumor progression, prompting further analysis of the peptide’s molecular effects.

Subsequent research suggested that GHK-Cu may modulate apoptotic signaling by upregulating caspase activity and associated gene expression pathways. Specifically, the peptide appeared to suppress proliferation in SH-SY5Y neuroblastoma cells and U937 histiocytic lymphoma cells, which serve as established models for studying neural and immune-related malignancies. Additionally, data have suggested that GHK-Cu may reactivate apoptotic mechanisms via caspases 3 and 7, key enzymes that are considered to govern programmed cell death.

Interestingly, in non-cancerous cell models, GHK-Cu exhibited a contrasting effect, promoting the proliferation of NIH-3T3 fibroblasts, which represents a widely used model for evaluating cellular growth and extracellular matrix remodeling. This dual functionality highlights the peptide’s potential to modulate cellular responses in various biological contexts selectively.

 

GHK-Cu: Wound Evaluation Relative to Zinc Oxide

A controlled study^[7] was conducted to assess the efficacy of GHK-Cu in promoting wound recovery compared to zinc oxide. Eighteen New Zealand White rabbits were divided into three categories of research models: one receiving GHK-Cu, another receiving zinc oxide, and a control group receiving a placebo. Standardized wounds were induced on each rabbit, followed by exposure for 21 consecutive days.

Upon further evaluation, the researchers observed that “the mean percentage of wound contraction was significantly higher [in]” the group exposed to GHK-Cu, and exhibited significantly better-supported wound recovery outcomes relative to the zinc oxide and placebo groups.

 

Cooper Peptides and Helium-Neon Lasers

A subsequent investigation^[8] explored the wound-recovery potential of GHK-Cu compared to helium-neon lasers at energy levels of 1 J/cm² and 3 J/cm². This study divided 24 New Zealand White rabbits into groups receiving either GHK-Cu or laser exposure at varying intensities. Standardized wounds were introduced, and the subjects were monitored over 28 days. Post-experimental analysis indicated that the combination of GHK-Cu and higher-intensity laser implication correlated with better-supported wound recovery. Notably, the rabbits exposed to GHK-Cu exhibited reduced neutrophil infiltration, indicative of lower inflammatory response, and increased neovascularization, suggesting an accelerated regenerative process.

 

Cooper Peptides: Ulcers

A clinical trial^[9] was conducted to evaluate the potential of a GHK-Cu peptide complex gel in diabetic research models with neuropathic ulcers. Research models were enrolled in a standardized wound care protocol, with only those requiring sharp wound debridement included in this randomized, placebo-controlled study. Research models were assigned to different groups in laboratory settings, where one group received the GHK-Cu gel. In contrast, the control group was exposed to standard wound care with a placebo implication.

Post-trial analysis suggested that subjects in the GHK-Cu gel group exhibited an apparent increase in wound closure, with recovery rates exceeding 98%. Specifically, the peptide complex appeared to facilitate the closure of 98.5% of plantar ulcers, whereas the control group exhibited an apparently significantly lower recovery rate of 60.8%. These findings suggest that GHK-Cu may support wound recovery through mechanisms of tissue remodeling and cellular regeneration.

 

GHK-Cu: Antioxidative and Anti-inflammatory Potential

Research suggests that GHK-Cu may exert anti-inflammatory and antioxidative effects, particularly in cigarette smoke (CS)-induced lung inflammation.^[10]

In murine models exposed to CS, the introduction of copper peptide was associated with a potential reduction in pro-inflammatory cytokines, such as interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), in bronchoalveolar lavage fluid. Additionally, the peptide complex appeared to modulate neutrophil-driven inflammation, as indicated by a decrease in myeloperoxidase (MPO) activity in lung tissues.

At the molecular level, copper peptides like GHK-Cu are hypothesized to interact with regulatory pathways associated with inflammation and oxidative stress. The peptide may attenuate nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling by inhibiting IκBα phosphorylation, potentially reducing the expression of pro-inflammatory genes. Furthermore, it has been proposed that GHK-Cu supports the activation of nuclear factor erythroid 2-related factor 2 (Nrf2), a pathway considered critical for cellular antioxidant defenses, thereby possibly promoting gene expression that may mitigate oxidative damage.

The study also examined the impact of GHK-Cu on oxidative stress markers, including malondialdehyde (MDA) and glutathione (GSH). A decrease in MDA levels and a possible restoration of GSH suggest that the -Cu component may contribute to cellular protection against oxidative injury. These findings suggest a potential for GHK-Cu in inflammation and oxidative stress; however, further research is needed to elucidate its precise mechanisms of action.

 

Cooper Peptides and Neurological Impacts

Experimental studies suggest that copper peptides, such as GHK-Cu, may have potential neuromodulatory impacts under certain laboratory settings.

One study^[1] examined its role in pain modulation by introducing the peptide to mice subjected to a thermal stimulus. Murine models were placed on a moderately heated plate, and their response time to pain, as assessed by paw licking, was measured. Following GHK-Cu exposure, a significant reduction in response latency was observed compared to control conditions, suggesting a potential analgesic effect associated with the peptide.

Another investigation^[11] explored the anxiolytic properties of GHK-Cu in male rats using an elevated plus maze, a paradigm for anxiety-related behavior. In this model, increased time spent in the maze’s ‘open arms’ indicates reduced anxiety. Rats exposed to GHK-Cu exhibited “significant changes in some measures of increased anxiety” compared to unexposed counterparts, suggesting that the peptide may modulate anxiety-like behaviors.

Further research^[12] studied the impact of GHK-Cu on aggression and stress responses in a rodent model. Pairs of rats subjected to mild electrical stimulation typically exhibited heightened aggression toward one another. However, when GHK-Cu was introduced 12 minutes prior to stimulation, the frequency of aggressive interactions decreased approximately fivefold compared to control conditions. These findings suggest a potential for GHK-Cu in modulating stress-induced behavioral responses, though additional studies are required to elucidate its underlying mechanisms of action.

 

AHK-Cu: Collagen Synthesis in Wrinkle Reduction

Copper and copper peptides, including AHK-Cu, are commonly incorporated in dermatological studies. Preclinical studies suggest that AHK-Cu may have the potential to stimulate collagen synthesis. Collagen is considered to be crucial in maintaining skin structure and elasticity, contributing to a firmer and more resilient dermal matrix. Additionally, collagen appears to support dermal hydration by attracting water molecules to both cellular components and the extracellular matrix, which may reduce the appearance of fine lines and wrinkles.^[4] Experimental findings suggest that AHK-Cu exposure has been associated with a visible decrease in wrinkle formation in research models under laboratory conditions.

 

Cooper Peptides (AHK-Cu): Hair Follicle Growth

Research suggests that AHK-Cu may exert multifaceted effects on hair follicle growth through vascular and molecular mechanisms. One proposed mechanism involves the upregulation of vascular endothelial growth factor (VEGF), a key mediator of angiogenesis. VEGF is considered to facilitate the formation and expansion of capillary networks that supply nutrients to hair follicles, supporting their growth and maintenance. Studies in research models indicate that AHK-Cu may support blood flow to existing hair follicles while promoting neovascularization, potentially contributing to follicular regeneration and increased follicle density.

Additionally, AHK-Cu appears to potentially impact hair loss by modulating the expression of transforming growth factor-beta 1 (TGF-β1). Dihydrotestosterone (DHT), a derivative of testosterone, is a factor implicated in androgenic alopecia and hair follicle reduction and thinning. DHT has been found via scientific studies to exert its effects, in part, through the activation of TGF-β1, which has been associated with hair follicle miniaturization and apoptosis. Preclinical studies suggest that AHK-Cu may mitigate the impact of DHT by downregulating TGF-β1, thereby offering a potential protective effect against hair follicle degeneration.^[13] Further investigation is required to elucidate the precise molecular interactions underlying these observations.

Disclaimer: The products mentioned are not intended for human or animal consumption. Research chemicals are intended solely for laboratory experimentation and/or in-vitro testing. Bodily introduction of any sort is strictly prohibited by law. All purchases are limited to licensed researchers and/or qualified professionals. All information shared in this article is for educational purposes only.

 

References:

1. Pickart L, Margolina A. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. Int J Mol Sci. 2018 Jul 7;19(7):1987. doi: 10.3390/ijms19071987. PMID: 29986520; PMCID: PMC6073405. https://pmc.ncbi.nlm.nih.gov/articles/PMC6073405/
2. Amelia Milner, Nadiyah Alshammari, James A. Platts, Computational study of copper binding to DAHK peptide, Inorganica Chimica Acta, Volume 528, 2021, 120589, ISSN 0020-1693, https://doi.org/10.1016/j.ica.2021.120589
3.  Pickart L, Vasquez-Soltero JM, Margolina A. GHK and DNA: resetting the human genome to health. Biomed Res Int. 2014;2014:151479. doi: 10.1155/2014/151479. Epub 2014 Sep 11. PMID: 25302294; PMCID: PMC4180391. https://pubmed.ncbi.nlm.nih.gov/25302294/
4. Leonard M. Patt, Ph.D., Procyte, Neova  DNA Repair Factor Nourishing Lotion Stimulates Collagen and Speeds Natural Repair Process. https://www.dermacaredirect.co.uk/skin/frontend/default/dermacare/pdf/neova-dna-nourishing-study.pdf
5. Maquart FX, Pickart L, Laurent M, Gillery P, Monboisse JC, Borel JP. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett. 1988 Oct 10;238(2):343-6. doi: 10.1016/0014-5793(88)80509-x. PMID: 3169264. https://pubmed.ncbi.nlm.nih.gov/3169264/
6. Siméon A, Emonard H, Hornebeck W, Maquart FX. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures. Life Sci. 2000 Sep 22;67(18):2257-65. doi: 10.1016/s0024-3205(00)00803-1. PMID: 11045606. https://pubmed.ncbi.nlm.nih.gov/11045606/
7. Cangul IT, Gul NY, Topal A, Yilmaz R. Evaluation of the effects of tripeptide-copper complex and zinc oxide on open-wound healing in rabbits. Vet Dermatol. 2006 Dec;17(6):417-23. doi: 10.1111/j.1365-3164.2006.00551.x. PMID: 17083573. https://pubmed.ncbi.nlm.nih.gov/17083573/
8. Gul NY, Topal A, Cangul IT, Yanik K. The effects of tripeptide copper complex and helium-neon laser on wound healing in rabbits. Vet Dermatol. 2008 Feb;19(1):7-14. doi: 10.1111/j.1365-3164.2007.00647.x. PMID: 18177285. https://pubmed.ncbi.nlm.nih.gov/18177285/
9. Mulder GD, Patt LM, Sanders L, Rosenstock J, Altman MI, Hanley ME, Duncan GW. Enhanced healing of ulcers in patients with diabetes by treatment with glycyl-l-histidyl-l-lysine copper. Wound Repair Regen. 1994 Oct;2(4):259-69. doi: 10.1046/j.1524-475X.1994.20406.x. PMID: 17147644. https://pubmed.ncbi.nlm.nih.gov/17147644/
10. Zhang, Q., Yan, L., Lu, J., & Zhou, X. (2022). Glycyl-L-histidyl-L-lysine-Cu2+ attenuates cigarette smoke-induced pulmonary emphysema and inflammation by reducing oxidative stress pathway. Frontiers in molecular biosciences, 9, 925700. https://doi.org/10.3389/fmolb.2022.925700
11. Bobyntsev II, Chernysheva OI, Dolgintsev ME, Smakhtin MY, Belykh AE. Anxiolytic effects of Gly-His-Lys peptide and its analogs. Bull Exp Biol Med. 2015 Apr;158(6):726-8. doi: 10.1007/s10517-015-2847-3. Epub 2015 Apr 23. PMID: 25900608. https://pubmed.ncbi.nlm.nih.gov/25900608/
12. Sever’yanova LА, Dolgintsev ME. Effects of Tripeptide Gly-His-Lys in Pain-Induced Aggressive-Defensive Behavior in Rats. Bull Exp Biol Med. 2017 Dec;164(2):140-143. doi: 10.1007/s10517-017-3943-3. Epub 2017 Nov 27. PMID: 29181666. https://pubmed.ncbi.nlm.nih.gov/29181666/
13. Pyo HK, Yoo HG, Won CH, Lee SH, Kang YJ, Eun HC, Cho KH, Kim KH. The effect of tripeptide-copper complex on human hair growth in vitro. Arch Pharm Res. 2007 Jul;30(7):834-9. doi: 10.1007/BF02978833. PMID: 17703734. https://pubmed.ncbi.nlm.nih.gov/17703734/

FOXO4-D-Retro-Inverso (FOXO4-DRI), also called Proxofim peptide, is a synthetic variant of the endogenous FOXO4 protein. This synthetic variant is developed with D-amino acids in place of the endogenously occurring L-amino acids.^[1] This modification was made in the hope of supporting stability by reducing susceptibility to proteolytic degradation, thereby increasing the potential to extend a cellular lifespan.

Despite these structural alterations, FOXO4-DRI appears to retain an ability to modulate transcription and cellular signaling pathways. As a retro-inverso peptide, researchers report that it mirrors the structural topology of the native peptide while exhibiting potentially more robust resistance to enzymatic breakdown.

Retro-inverso peptides, such as FOXO4-DRI, are synthesized by reversing the amino acid sequence and altering the chirality of the peptide backbone. This design appears to confer several advantages, including possible prolonged stability and preserved bioactivity. Due to their structural resilience, these peptides have been explored in various biological contexts, particularly in understanding protein-protein interactions.

 

Mechanism of Action

FOXO4-DRI is believed to function by modulating the interaction between the FOXO4 protein and the tumor suppressor protein p53.

Under normal conditions, FOXO4 is suggested to bind to p53, thereby inhibiting its role in promoting apoptosis. However, FOXO4-DRI is thought to disrupt this interaction by potentially competitively binding to p53. It is believed that this reduces instances of FOXO4 successfully exerting its regulatory effects. This disruption facilitates p53-mediated apoptosis and is thought to selectively target senescent cells— particularly those that have lost their functional capacity due to cellular aging.^[2]

The selective elimination through immune and waste removal biological systems that impact senescent cells through FOXO4-DRI-mediated apoptosis is thought to contribute to improved cellular turnover and tissue homeostasis. Research suggests that this process may support overall cellular function by removing old or dysfunctional cells, allowing for the proliferation of more functional cells. This mechanism has been a focal point for researchers studying the potential role of FOXO4-DRI in modulating cellular senescence.

 

Scientific Research and Studies

 

Proxofim Peptide and Cellular Senescence

The FOXO4 protein is considered to play a crucial role in maintaining the viability of senescent cells by preventing the tumor suppressor protein p53 from binding to DNA and initiating apoptosis. Proxofim is hypothesized to disrupt this interaction and is thought to allow the engagement of p53 with DNA and promote the selective elimination of senescent cells. This process, often described as the rejuvenation of biological systems, is believed to support cellular homeostasis by facilitating the clearance of dysfunctional cells.^[3]

Elimination of senescent cells may lead to a redistribution of metabolic resources toward functional cells, potentially supporting cellular growth, maintenance, and function. While Proxofim does not appear to halt the senescence process entirely, research suggests it may mitigate FOXO4-mediated cellular aging and may thereby decelerate the accumulation of non-functional cells. The biological process of senescence is impacted by various intrinsic and extrinsic factors, which may have contributed to cellular apoptosis or the secretion of inflammatory mediators implicated in cellular aging and cellular age-related pathologies.

 

Proxofim Peptide and Cellular Healthspan

Cellular aging is characterized by the progressive accumulation of irreparable cellular damage, which ultimately diminishes the healthspan of the cell—the period during which cells maintain optimal function. Distinct from lifespan, which denotes the total duration of life, healthspan is a critical determinant of physiological function. Proxofim is proposed to modulate cellular senescence by mitigating the adverse impacts of FOXO4 signaling, thereby preserving cellular integrity and function. While the peptide’s impact on overall lifespan remains inconclusive, its potential role in supporting cellular function and delaying cellular age-associated deterioration warrants further investigation.

A 2017 study conducted on aging cells of murine research models explored the impacts of Proxofim on physiological parameters. Murine models receiving the peptide appeared to exhibit improvements in physical endurance, renal function, and hair density compared to the control group. Although no significant extension in cellular lifespan was observed, the findings suggest that Proxofim may contribute to better-supported tissue function and a reduction in cellular age-associated dysfunction.

Furthermore, research by Baar et al. (2017) highlights the broader implications of FOXO4-DRI analogs. The research states the following about cells observed in laboratory settings;

“independent of aging and age-related diseases, FOXO4-DRI may be useful against the progression, stemness, and migration of cancer. Given that SASP factors influence these, it will be particularly interesting to determine whether FOXO4-DRI affects those p53-wt cancer cells that have adopted a more migratory and stem-like state due to reprogramming by chronic SASP exposure. In any case, the here reported beneficial effects of FOXO4-DRI provide a wide range of possibilities for studying the potential of … removal of senescence against diseases for which few options are available.”^[4]

 

Proxofim Peptide and Cardiovascular Function

Cellular age-related decline in proteasome activity has been associated with an increased risk of cardiovascular disorders. The proteasome enzyme reportedly plays a critical role in maintaining cellular homeostasis by facilitating the degradation of damaged or dysfunctional proteins. Research suggests that reduced proteasome activity may contribute to the accumulation of senescent cells, which may negatively impact cardiovascular function as cells age.^[5]

The FOXO4 protein is considered to be a key regulator of proteasome activity; however, its endogenous function may be insufficient in mitigating cellular damage associated with cellular aging. Preliminary findings suggest that the Proxofim peptide may support the selective clearance of senescent cells, thereby potentially impacting cellular age-related cardiovascular processes.^[6] While these insights provide a foundation for further investigation, additional studies are required to elucidate the precise mechanisms and potential implications of Proxofim in cardiovascular function.

 

Proxofim Peptide and Insulin Signaling Regulation

Research^[7] suggests that FOXO proteins may be critical regulators of the insulin signaling pathway. These proteins may play a role in the regulation of cellular metabolism, cell cycle progression, oxidative stress responses, and cellular senescence. Dysregulation of FOXO protein expression has been correlated in studies with pathological conditions, including metabolic disorders, oncogenesis, and premature death of cells. Altered FOXO activity is particularly relevant in insulin resistance and diabetes, where disruptions in insulin signaling are said to contribute to hyperlipidemia and hyperglycemia. This may, in some way, increase the risk of vascular complications, nephropathy, and other metabolic dysfunctions.

While further investigation is required to elucidate the precise mechanisms, preliminary studies suggest that Proxofim peptide may modulate insulin signaling by impacting downstream metabolic pathways. Research suggests that this interaction could contribute to improved glucose homeostasis by mitigating excessive blood glucose accumulation. By modulating FOXO-associated pathways, Proxofim may hold the potential to address metabolic imbalances linked to insulin resistance.

 

Proxofim and Cellular Age-Related Male Hypogonadism

Cellular age-related male hypogonadism, also referred to by researchers as late-onset hypogonadism (LOH), is characterized by a progressive decline in serum testosterone levels. The condition is often accompanied by reduced libido, dysfunction with the physical ability to mate, increased adiposity, and disturbances in behavioral patterns. This decline is said to be primarily associated with the dysfunction of senescent Leydig cells, which reside in the interstitial compartment of the testes. Leydog cells are considered to play a crucial role in testosterone biosynthesis.

A recent in vitro study^[8] studied the potential impacts of Proxofim peptide on senescent Leydig cells. The study exposed peptides to a cellular model in which Leydig cells, previously isolated from male murine models, were induced into a senescent state through hydrogen peroxide exposure. Findings suggested that FOXO4 protein plays a role in maintaining the viability of these senescent cells by mitigating apoptosis. Exposure to Proxofim peptide appeared to disrupt FOXO4 activity and may facilitate p53-mediated apoptosis, thereby selectively eliminating dysfunctional Leydig cells.

Subsequent studies in endogenously aged murine cell cultures further supported these observations. Proxofim peptide exposure was associated with improved Leydig cell function, better-supported testicular function, and increased testosterone secretion. These findings suggest that Proxofim peptide may hold potential as a targeted approach for addressing cellular senescence in Leydig cells and mitigating the physiological effects of cellular age-related hypogonadism. Further research is necessary to elucidate its precise mechanisms and broader implications.

 

Proxofim and Neurodegenerative Pathophysiology

Cellular age-related cognitive decline is a multifactorial process, and the precise mechanisms underlying neurodegenerative disorders, such as Alzheimer’s disease, remain incompletely understood. Research^[9] suggests that alterations in proteasome enzyme activity may contribute to neurodegeneration, as proteasomal function declines with cellular age. This enzymatic downregulation has been observed in conditions such as Parkinson’s disease, Alzheimer’s disease, and prion-related disorders. However, it remains unclear whether this reduction in proteasome activity is a causative factor or a secondary consequence of disease progression.

Emerging studies^[10] suggest that FOXO transcription factors exhibit altered expression patterns in the central nervous system of individuals affected by neurodegenerative disorders. Given the regulatory role of FOXO proteins in cellular homeostasis, it has been hypothesized that exogenous FOXO-modulating peptides, including Proxofim, may help restore FOXO equilibrium and mitigate neurodegenerative processes. However, further research is necessary to elucidate the extent of this potential intervention.

Scientific reports suggest that:

“Forkhead box O (FoxO) transcription factors have been implicated in the mechanisms regulating aging and longevity. The functions of FoxOs are regulated by diverse post-translational modifications (e.g., phosphorylation, acetylation, ubiquitination, methylation, and glycosylation). FoxOs exert both detrimental and protective effects on NDDs (Neurodegenerative diseases). Therefore, an understanding of the precise function of FoxOs in NDDs will be helpful for developing appropriate treatment strategies.”

Disclaimer: The products mentioned are not intended for human or animal consumption. Research chemicals are intended solely for laboratory experimentation and/or in-vitro testing. Bodily introduction of any sort is strictly prohibited by law. All purchases are limited to licensed researchers and/or qualified professionals. All information shared in this article is for educational purposes only.

 

References:

1. Huang, Yuzhao, et al. “Senolytic Peptide FOXO4-DRI (Proxofim) Selectively Removes Senescent Cells From in vitro Expanded Human Chondrocytes.” Frontiers in bioengineering and biotechnology vol. 9 677576. 29 Apr. 2021, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8116695/
2. Sun, Yan et al. “FOXO4 Inhibits the Migration and Metastasis of Colorectal Cancer by Regulating the APC2/β-Catenin Axis.” Frontiers in cell and developmental biology vol. 9 659731. 23 Sep. 2021. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8495124/
3. Krimpenfort P, Berns A. Rejuvenation by Therapeutic Elimination of Senescent Cells. Cell. 2017 Mar 23;169(1):3-5. https://pubmed.ncbi.nlm.nih.gov/28340347/
4. Marjolein P. Baar et al, Targeted Apoptosis of Senescent Cells Restores Tissue Homeostasis in Response to Chemotoxicity and Aging. Vol 169 Issue 1, https://doi.org/10.1016/j.cell.2017.02.031
5. Anne-Laure Bulteau, Luke I. Szweda, Bertrand Friguet, Age-Dependent Declines in Proteasome Activity in the Heart, Archives of Biochemistry and Biophysics, Volume 397, Issue 2, 2002, Pages 298-304, ISSN 0003-9861, https://doi.org/10.1006/abbi.2001.2663
6. Murtaza G, Khan AK, Rashid R, Muneer S, Hasan SMF, Chen J. FOXO Transcriptional Factors and Long-Term Living. Oxid Med Cell Longev. 2017;2017:3494289. doi: 10.1155/2017/3494289. Epub 2017 Aug 15. https://pubmed.ncbi.nlm.nih.gov/28894507
7. Lee, S., & Dong, H. H. (2017). FoxO integration of insulin signaling with glucose and lipid metabolism. The Journal of Endocrinology, 233(2), R67–R79.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5480241/
8. Zhang, C., Xie, Y., Chen, H., Lv, L., Yao, J., Zhang, M., Xia, K., Feng, X., Li, Y., Liang, X., Sun, X., Deng, C., & Liu, G. (2020). FOXO4-DRI alleviates age-related testosterone secretion insufficiency by targeting senescent Leydig cells in aged mice. Aging, 12(2), 1272–1284. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7053614/
9. Ciechanover A, Brundin P. The ubiquitin-proteasome system in neurodegenerative diseases: sometimes the chicken, sometimes the egg. Neuron. 2003 Oct 9;40(2):427-46. https://pubmed.ncbi.nlm.nih.gov/14556719
10. Wei Hu, Zhi Yang, Wenwen Yang, Mengzhen Han, Baoping Xu, Zihao Yu, Mingzhi Shen, Yang Yang, Roles of forkhead box O (FoxO) transcription factors in neurodegenerative diseases: A panoramic view, Progress in Neurobiology, Volume 181, 2019, 101645, ISSN 0301-0082, https://doi.org/10.1016/j.pneurobio.2019.101645

Bremelanotide, also known as PT-141, is a synthetic cyclic heptapeptide derived from Melanotan II (MT-II), a synthetic analog of the melanocortin hormone α-melanocyte-stimulating hormone (α-MSH).^[1][2] It was initially investigated for its potential role in addressing hypoactive sexual desire disorder (HSDD) in female research models, as evaluated in Phase IIb clinical trials by qualified researchers. Research has also explored its potential applications in managing acute hemorrhage, suggesting broader physiological interactions beyond its primary area of study.

 

Mechanism of Action

The biological activity of Bremelanotide is hypothesized to be mediated through its selective agonism of melanocortin receptors, particularly MC3R and MC4R.^[3] MC3R is predominantly expressed in the hypothalamus and has been linked to energy homeostasis, metabolic regulation, and neuroendocrine modulation. Research suggests that MC3R activity may impact feeding behavior, glucose metabolism, and lipid balance, though the precise regulatory mechanisms remain under investigation.

Conversely, MC4R is believed to play a critical role in suppressing hunger hormone signaling and regulating energy expenditure. Preclinical data suggest that its activation within the CNS may contribute to neurogenic control of metabolic functions, potentially impacting the regulation of adipose stores. In addition, MC4R has been proposed to have a role in reproductive signaling. Receptor activation is often hypothesized to impact neuroendocrine pathways linked to reproductive physiology.

Preliminary studies suggest that Bremelanotide’s binding to MC3R and MC4R may lead to neuronal activation in the hypothalamus. This may potentially trigger downstream signaling cascades associated with autonomic and neuroendocrine responses. Laboratory studies of murine research models suggest that this interaction may contribute to behavioral responses related to copulatory arousal. However, further research is necessary to elucidate the exact mechanisms underlying these findings.

 

Scientific Research and Studies

 

Early Investigations of Bremelanotide Peptide

An early 2000s study^[4] investigated the potential neuropharmacological impacts of Bremelanotide in murine models, focusing on its possible role in modulating mating behavior. The study involved observing female murine models to study behavioral responses following peptide exposure.

Observations suggested that while research models exhibited increased solicitation related to mating behavior, there were no notable alterations in motor activity, lumbar lordosis, or other mating-related behaviors. Based on these findings, researchers hypothesized that Bremelanotide does not act as a general motor stimulant but may potentially exert selective pharmacological impacts on the central nervous system (CNS), particularly through melanocortin receptor activation. The study further suggested that central melanocortin pathways might be integral to neurochemical mechanisms underlying copulation-related arousal.

Researchers further noted the stability and selectivity of this response across varied experimental conditions, citing, “The ability of PT-141 to enhance solicitation in two distinctive testing environments indicates that the effect [appears] selective and stable, and suggests that central melanocortin systems are part of the neurochemical network that evokes appetitive sexual behavior in female rats.” These findings provided preliminary data that suggests the role of melanocortin receptors in modulating copulatory motivation may warrant further investigation into the underlying neuroendocrine mechanisms.

 

Neurophysiological Interactions of Bremelanotide in the Central Nervous System

Studies on the Bremelanotide peptide have focused on its potential interactions within the central nervous system (CNS), particularly in brain regions implicated in neuroendocrine and behavioral responses. Preclinical studies utilizing murine models with elevated levels of reproductive hormones have reportedly displayed behavioral modifications following peptide introduction. According to reports, these studies have primarily assessed appetitive behaviors, such as increased locomotion and solicitation, alongside consummatory responses, including lordosis.

Experimental findings suggest that Bremelanotide exposure may be associated with heightened hunger-related behaviors without significantly altering consummatory responses. These studies report that the peptide’s impacts were observed following both peripheral and direct introduction into the lateral ventricles or the medial preoptic area (mPOA) but not the ventromedial hypothalamus. The mPOA has been implicated in modulating the drive toward mating behaviors across various species, though its precise role remains under investigation. Bremelanotide’s interaction with this region, as well as other hypothalamic and limbic structures, suggests potential involvement in neural pathways associated with behavioral modulation. It has been hypothesized that Bremelanotide may exert its impacts through the activation of dopamine terminals within the mPOA, though further research is required to validate this hypothesis.^[5]

To further elucidate these mechanisms, a randomized, double-blinded, placebo-controlled crossover study^[6] incorporated psychometric assessments, functional neuroimaging, and hormonal analyses to examine the impact of MC4R agonism on neural processing. Results suggested that MC4R agonists, including Bremelanotide, might support an increase in copulatory motivation for up to 24 hours relative to placebo controls. Functional neuroimaging analyses suggested increased activation in the cerebellar and supplementary motor regions, alongside possible deactivation of the secondary somatosensory cortex when exposed to erotic stimuli. Additionally, MC4R agonism was associated with heightened functional connectivity between the amygdala and insular cortex under similar conditions. These findings suggest a potential role of melanocortin receptor modulation in neural circuits governing behavioral and neuroendocrine responses. Further studies are warranted to delineate the precise neurophysiological mechanisms underlying these observations.

 

Melanocortin Receptor Activation and Cavernosal Response

Bremelanotide has been hypothesized to activate melanocortin 4 receptors (MC4R) and modulate vasodilatory pathways, potentially influencing erectile function in male animal models.

Research^[7] suggests that this activation may upregulate the production of nitric oxide (NO) within penile tissues, which may ultimately contribute to increased cavernosal pressure. Bremelanotide, a synthetic derivative of Melanotan-II (MT-II), shares a similar receptor affinity profile, with both peptides exhibiting agonistic properties toward melanocortin receptors.

Experimental findings suggest that melanocortin agonists might induce dose-dependent elevations in cavernosal pressure. The non-selective MC3R and MC4R antagonist SHU 9119 did not appear to directly impact systemic or cavernosal blood pressure; however, it seemingly inhibited the cavernosal pressure increases induced by melanocortin agonists. Additionally, SHU 9119 was reported to suppress the depressor response potentially associated with melanocortin activation.

Further studies investigated the role of the NO-cyclic GMP-dependent pathway in melanocortin-mediated cavernosal responses. When a pharmacological combination of phentolamine mesylate, papaverine, and prostaglandin E1 (PGE1) was locally introduced to cavernosal tissue, cavernosal pressure reportedly increased fourfold. The involvement of neuronal NO release was examined through bilateral pudendal nerve transection and inhibition of NO synthase via L-NAME. These interventions appeared to negate the cavernosal pressure increases observed with melanocortin agonists, suggesting that central melanocortin receptor activation might influence penile tissue responses through NO-mediated neural pathways.

These findings provide preliminary insights into the potential physiological interactions between melanocortin receptor activation and neurovascular regulation, though further research is necessary to elucidate the precise mechanisms involved.

 

Bremelanotide Peptide and Hemorrhagic Shock

In 2009, a modified form of Bremelanotide was explored for its potential role in mitigating hemorrhagic shock. As an agonist of both melanocortin 1 receptor (MC1R) and melanocortin 4 receptor (MC4R), the peptide has been hypothesized to exert protective impacts against ischemic injury by supporting tissue resilience under conditions of reduced blood perfusion.

Preclinical investigations suggest that its receptor interactions may contribute to vascular stability and modulate systemic responses to hypovolemia. To further assess its viability in this context, a structurally altered analog, PL-6983, was developed and advanced to Phase IIb clinical trials.

 

Bremelanotide Peptide and Infectious Disease

Research on melanocortin receptors (MC1R) suggests that they may modulate immune responses, particularly in fungal infections. In experimental murine models, MC1R activation has been associated with antifungal and anti-inflammatory properties^[9], suggesting a possible role in host defense mechanisms. Given the limitations of conventional antifungal research tools, many of which exhibit restrictive mechanisms of action and significant adverse impacts, MC1R-targeting compounds may offer an alternative strategy for infection management. This might prove particularly relevant for immunocompromised individuals, where fungal infections pose substantial morbidity and mortality risks.

 

Bremelanotide Peptide and Oncological Research

MC1R has been implicated in DNA repair mechanisms, suggesting its potential relevance in oncological studies. Genetic variants of MC1R have been linked to increased susceptibility to basal cell carcinoma and squamous cell carcinoma, suggesting a role in cutaneous oncogenesis. Investigations into melanocortin receptor modulation propose that alterations in Bremelanotide or its derivatives may influence cellular repair pathways, potentially contributing to strategies aimed at mitigating cancer risk or progression^[10]. However, further research is required to determine the mechanistic implications of MC1R modulation in cancer mitigation.

Disclaimer: The products mentioned are not intended for human or animal consumption. Research chemicals are intended solely for laboratory experimentation and/or in-vitro testing. Bodily introduction of any sort is strictly prohibited by law. All purchases are limited to licensed researchers and/or qualified professionals. All information shared in this article is for educational purposes only.

 

References:

1. Pfaus, J., Giuliano, F., & Gelez, H. (2007). Bremelanotide: an overview of preclinical CNS effects on female sexual function. The journal of sexual medicine, 4 Suppl 4, 269–279. https://doi.org/10.1111/j.1743-6109.2007.00610.x
2. National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 9941379, Bremelanotide. Retrieved August 10, 2023 from Pubchem.
3. Renquist, B. J., Lippert, R. N., Sebag, J. A., Ellacott, K. L., & Cone, R. D. (2011). Physiological roles of the melanocortin MC₃ receptor. European journal of pharmacology, 660(1), 13–20. https://doi.org/10.1016/j.ejphar.2010.12.025
4. Renquist, B. J., Lippert, R. N., Sebag, J. A., Ellacott, K. L., & Cone, R. D. (2011). Physiological roles of the melanocortin MC₃ receptor. European journal of pharmacology, 660(1), 13–20. https://doi.org/10.1016/j.ejphar.2010.12.025
5. Vemulapalli, R., Kurowski, S., Salisbury, B., Parker, E., & Davis, H. (2001). Activation of central melanocortin receptors by MT-II increases cavernosal pressure in rabbits by the neuronal release of NO. British journal of pharmacology, 134(8), 1705–1710. https://doi.org/10.1038/sj.bjp.0704437
6. Thurston, L., Hunjan, T., Mills, E. G., Wall, M. B., Ertl, N., Phylactou, M., Muzi, B., Patel, B., Alexander, E. C., Suladze, S., Modi, M., Eng, P. C., Bassett, P. A., Abbara, A., Goldmeier, D., Comninos, A. N., & Dhillo, W. S. (2022). Melanocortin 4 receptor agonism enhances sexual brain processing in women with hypoactive sexual desire disorder. The Journal of Clinical Investigation, 132(19), e152341. https://doi.org/10.1172/JCI152341
7. Adan, R. A., Tiesjema, B., Hillebrand, J. J., la Fleur, S. E., Kas, M. J., & de Krom, M. (2006). The MC4 receptor and control of appetite. British journal of pharmacology, 149(7), 815–827. https://doi.org/10.1038/sj.bjp.0706929
8. Pfaus, J. G., Shadiack, A., Van Soest, T., Tse, M., & Molinoff, P. (2004). Selective facilitation of sexual solicitation in the female rat by a melanocortin receptor agonist. Proceedings of the National Academy of Sciences of the United States of America, 101(27), 10201–10204. https://doi.org/10.1073/pnas.0400491101
9. H. Ji et al., “The Synthetic Melanocortin (CKPV)2 Exerts Anti-Fungal and Anti-Inflammatory Effects against Candida albicans Vaginitis via Inducing Macrophage M2 Polarization,” PLoS ONE, vol. 8, no. 2, Feb. 2013 https://doi.org/10.1371/journal.pone.0056004
10. Maresca V, Flori E, Picardo M. Skin phototype: a new perspective. Pigment Cell Melanoma Res. 2015 Jul;28(4):378-89. doi: 10.1111/pcmr.12365. Epub 2015 Apr 11. PMID: 25786343. https://pubmed.ncbi.nlm.nih.gov/25786343/