Potential Benefits of IGF-1 LR3 Peptides in Tissue Growth

by | Dec 21, 2022 | Research


Scientists have created IGF-1 LR3 peptides by modifying the amino acid sequence of IGF-1. The new peptide has similar effects but higher potency and improved stability. The LR3 in the name describes the two modifications to the IGF-1 molecule.

Long R3 IGF-1, or IGF-1 LR3, is an analog of insulin-like growth factor 1 (IGF-1). IGF-1 is an anabolic peptide hormone naturally found in the human body. Primarily, it is a mediator of the anabolic effects of the human growth hormone (HGH).

HGH stimulates the production of IGF-1 in the liver and almost all other tissues in your body. The IGF-1 produced in the liver is released in the bloodstream and exerts anabolic effects on the whole body, while the IGF-1 produced in all other tissues acts locally to stimulate growth.

The first is R3 which describes the replacement of the 3rd amino acid in IGF-1 with arginine. Scientists ascribed an additional 13 amino acids to the N-terminus of the R3 IGF-1 molecule, turning it into Long R3 IGF-1.
IGF-1 LR3 is an experimental peptide with potent anabolic and mitogenic effects, and its potential uses are still under active investigation.



Scientists developed IGF-1 analogs such as IGF-1 LR3 primarily for in vitro experiments to stimulate cell growth. IGF-1 and its analogs are highly anabolic towards actively proliferating cells. They can speed up cell replication in most tissues, ultimately shortening the time required to create a cell culture and use it to conduct laboratory studies.

IGF-1 LR3 works by activating IGF-1 receptors in most human and animal cells. Activating these anabolic receptors increases protein synthesis and tissue growth. It is much more stable and effective than IGF-1 alone, which makes it particularly effective for speeding up cell growth and proliferation.

One of the main advantages of IGF-1 LR3 over other IGF-1 analogs is its bioavailability. IGF-1 LR3 binds to a much lesser degree to IGF-1 proteins than other available analogs. Therefore, its affinity to the anabolic IGF-1 receptors is much higher, and animal studies show that continuous infusion with IGF-1 LR3 leads to a 2-fold higher anabolic effect than IGF-1. Researchers also noted that “LR3 IGF-I remained more potent than IGF-I in several of these effects even when the peptides were given by once-daily injection.[1]

The reduced affinity to IGF-1 binding proteins also results in a shorter half-life of IGF-1 LR3. Animal studies show that IGF-1 LR3 is eliminated within 4 hours of an intramuscular injection.[2] At the same time, it caused significantly higher weight gain and organ mass increase in the tested animals compared to IGF-1.

The metabolites of IGF-1 LR3 have a longer half-life and can remain detectable in test animals for up to 16 hours after injection. In comparison, a high percentage of the natural IGF-1 binds to IGF-1 binding proteins, which reduces its effectiveness and prolongs its half-life by up to 15 hours.[3]

According to one study in a mice model of muscular dystrophy, IGF-1 LR3 administration was highly effective in reducing contraction-mediated injury.[4] Contraction damage is a major contributing factor to the pathophysiology of muscular dystrophy, so minimizing it may prove to be a promising intervention.

Another animal trial by Hill et al. also revealed that an IGF-1 LR3 infusion for 8 hours has a protective effect against loss of muscle mass loss and muscle catabolism during periods of restricted energy intake and caloric deficit. The researchers reported that “Long(R3)-IGF-1 infusion tended to preserve whole-body and muscle protein in beef heifers on a low-quality diet.” The continuous infusion also led to significant suppression of the natural IGF-1 synthesis.[5]

One trial in guinea pigs also reported a significant increase in the organ weight of the animals after a 7-day infusion of IGF-1 LR3. The researchers note that the infusion most significantly enlarged the adrenals, gut, kidneys, and spleen.[6]

It is important to note that IGF-1 LR3 and all other IGF-1 analogs mediate only the anabolic effects of HGH.

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.



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