Muscle Growth Research Peptides

25 research peptides demonstrate muscle growth properties. This collection covers their mechanisms, evidence base, and research applications.

Preclinical | Growth Hormone Secretagogue

Ipamorelin is the most selective growth hormone secretagogue (GHS) available, a synthetic pentapeptide (MW ~711.86 g/mol, formula C38H49N9O5) that stimulates pulsatile GH release from the pituitary gland without significantly affecting cortisol,...

Mechanism: Ipamorelin (sequence: Aib-His-D-2Nal-D-Phe-Lys-NH2) selectively binds to the Growth Hormone Secretagogue Receptor (GHS-R1a) on anterior pituitary somatotroph cells, increasing cAMP and activating...

Preclinical | Growth Hormone Secretagogue

CJC-1295 is a synthetic analogue of growth hormone-releasing hormone (GHRH) originally developed by ConjuChem Technologies for HIV-associated lipodystrophy. It exists in two forms: with DAC (Drug Affinity Complex) for extended half-life of 5.8-8.

Mechanism: CJC-1295 binds to GHRH receptors (GHRHR) on pituitary somatotroph cells, activating intracellular cAMP signaling to stimulate both the transcription of the GH gene and pulsatile release of endogenous...

Phase I–II Clinical Trials | Growth Hormone Secretagogue

Sermorelin is a synthetic 29-amino-acid peptide (MW ~3357.9 g/mol) corresponding to the first 29 amino acids of naturally occurring growth hormone-releasing hormone (GHRH).

Mechanism: Sermorelin binds to GHRH receptors (GHRHR) on somatotroph cells in the anterior pituitary gland, stimulating both transcription of the HGH gene and pulsatile release of endogenous growth hormone.

Preclinical | Growth Hormone Secretagogue

GHRP-6 (Growth Hormone-Releasing Peptide 6) is a synthetic hexapeptide that functions as a potent growth hormone secretagogue by binding to the ghrelin receptor (GHS-R1a).

Mechanism: GHRP-6 functions as a synthetic ghrelin mimetic by binding to GHS-R1a in the pituitary and hypothalamus, triggering pulsatile GH release and raising IGF-1 levels.

Phase I–II Clinical Trials | Growth Hormone Secretagogue

GHRP-2 (pralmorelin) is a synthetic hexapeptide growth hormone secretagogue (D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2, MW ~817.97 g/mol) that stimulates potent, dose-dependent GH release via the ghrelin receptor (GHS-R).

Mechanism: GHRP-2 (C45H55N9O6) binds to and activates ghrelin (GH secretagogue) receptors on pituitary somatotrophs, triggering robust pulsatile GH release.

Phase I–II Clinical Trials | Growth Hormone Secretagogue

MK-677 (Ibutamoren) is a potent, long-acting, orally-active, non-peptide ghrelin receptor (GHS-R1a) agonist that stimulates growth hormone release without injections.

Mechanism: MK-677 binds to the ghrelin receptor (GHS-R1a) in the pituitary gland and hypothalamus, mimicking the hunger hormone ghrelin.

Phase I–II Clinical Trials | Growth Hormone Secretagogue

Hexarelin is a synthetic hexapeptide growth hormone secretagogue that binds to the ghrelin receptor (GHS-R1a). It is considered one of the most potent GHRPs available, stimulating greater GH release than GHRH alone.

Mechanism: Hexarelin binds to and activates the ghrelin/growth hormone secretagogue receptor (GHS-R1a) in the pituitary and hypothalamus through a triple mechanism: direct stimulation of pituitary somatotroph...

Preclinical | Growth Factor

IGF-1 LR3 is a modified version of insulin-like growth factor 1 (IGF-1) with an extended N-terminal sequence (13 additional amino acids) and an arginine-to-glutamic acid substitution at position 3.

Mechanism: IGF-1 LR3 binds to IGF-1 receptors on target cells with high affinity, initiating tyrosine kinase signaling that activates the PI3K/Akt/mTOR pathway, increasing protein synthesis, glucose uptake, and...

Preclinical | Muscle & Performance

PEG-MGF (Pegylated Mechano Growth Factor) is a synthetic, PEGylated form of the C-terminal peptide of mechano growth factor (MGF), a splice variant of the IGF-1 gene (IGF-1Ec in humans, IGF-1Eb in rodents).

Mechanism: MGF is produced from the IGF-1 gene by alternative splicing of exons 4, 5, and 6. The unique C-terminal E domain of MGF (24 amino acids in the Ec splice variant) is responsible for its distinct...

Animal/Preclinical Only | Growth Factor

Follistatin 344 is a naturally occurring glycoprotein (344 amino acids) that binds and neutralizes activin and myostatin, two TGF-β superfamily members that inhibit muscle growth. By blocking myostatin, follistatin allows greater muscle hypertrophy.

Mechanism: Binds activin A, activin B, and myostatin with high affinity, preventing them from signaling through ActRII/ActRIIB receptors and downstream SMAD2/3 phosphorylation.

Preclinical | Growth Hormone Secretagogue

Alexamorelin is a synthetic growth hormone-releasing peptide (GHRP) structurally related to GHRP-6. It was investigated as a GH secretagogue in limited preclinical studies but never advanced to meaningful clinical development.

Mechanism: Alexamorelin is believed to act as a ghrelin receptor (GHS-R1a) agonist, stimulating growth hormone release from the anterior pituitary.

Phase I–II Clinical Trials | Growth Hormone Secretagogue

Tabimorelin (NN703) is a synthetic, orally active growth hormone secretagogue developed by Novo Nordisk. It completed Phase II clinical trials demonstrating significant GH release in both healthy subjects and GH-deficient adults.

Mechanism: Tabimorelin acts as a ghrelin receptor (GHS-R1a) agonist, stimulating growth hormone release from the anterior pituitary gland. It has oral bioavailability, distinguishing it from injectable GHRPs.

Preclinical | Growth Factor

MGF (Mechano Growth Factor) is a splice variant of IGF-1, specifically the E-domain peptide of the IGF-1Ec isoform. It is produced naturally in mechanically stressed muscle tissue and plays a role in muscle repair and satellite cell activation.

Mechanism: MGF is expressed as part of the IGF-1 gene through alternative splicing in response to mechanical overload or tissue damage.

Preclinical | Growth Factor

IGF-1 DES (Des(1-3)IGF-1) is a truncated form of insulin-like growth factor 1, missing the first three N-terminal amino acids (Gly-Pro-Glu).

Mechanism: Des(1-3)IGF-1 binds the IGF-1 receptor (IGF-1R) with similar affinity to native IGF-1, but has markedly reduced binding to the six IGF binding proteins (IGFBP-1 through IGFBP-6).

FDA Approved | Hormone

Human growth hormone (hGH, somatotropin) is a 191-amino acid protein produced by the anterior pituitary gland. Recombinant human growth hormone (rhGH, somatropin) is FDA-approved for numerous indications including pediatric and adult growth hormone...

Mechanism: Growth hormone binds to the GH receptor (GHR), a type I cytokine receptor, activating the JAK2-STAT5 signaling pathway.