GHK-Cu and AHK-Cu: Copper Peptides and Cell Interaction Research Studies

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.

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References:

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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/