Category
Growth Hormone Axis
Peptides that act on the growth hormone axis — either mimicking GHRH at the pituitary or stimulating ghrelin receptors to drive pulsatile GH secretion. Includes both GHRPs and GHRH analogs studied for IGF-1 modulation and metabolic effects.
16 peptides in this category
What are growth hormone peptides?
Growth hormone peptides are synthetic compounds that stimulate the pituitary gland to produce and release growth hormone. They fall into two main classes: GHRH analogs (like sermorelin and CJC-1295) that mimic the hypothalamic signal, and GHRPs (like ipamorelin and GHRP-2) that activate ghrelin receptors through a separate pathway. Both classes are studied for their effects on IGF-1 levels, body composition, and metabolic function.
The growth hormone axis is regulated by two opposing hypothalamic signals: growth hormone-releasing hormone (GHRH), which stimulates GH secretion, and somatostatin, which suppresses it. Peptides in this category work at one or both points in that system. GHRH analogs like sermorelin and CJC-1295 bind the GHRH receptor on somatotroph cells, while growth hormone-releasing peptides (GHRPs) such as ipamorelin and GHRP-2 act on the ghrelin receptor (GHSR-1a) through a distinct pathway. Many protocols combine both classes to amplify the GH pulse.
The downstream effects of GH secretion are largely mediated through IGF-1, produced primarily in the liver. Tesamorelin, a stabilized GHRH analog, is the only FDA-approved peptide in this category — indicated for HIV-associated lipodystrophy — which provides a useful window into the established pharmacology. Research into this axis spans body composition, recovery, and metabolic regulation, though most peptides here remain investigational outside that single approved indication.
Related terms
Compounds
Peptides in this category
CJC-1295
PreclinicalCJC-1295 with DAC · DAC:GRF
CJC-1295 is a modified GHRH analog with a Drug Affinity Complex (DAC) that binds to serum albumin, dramatically extending its half-life compared to native GHRH. It produces sustained elevation of GH and IGF-1 levels over days rather than hours. Research focuses on body composition improvements, muscle growth, and fat loss through prolonged GH axis stimulation.
C₁₅₂H₂₅₂N₄₂O₄₂S · 3647.28 Da
Ghrelin
PreclinicalMotilin-related peptide · Growth hormone secretagogue
Ghrelin is a 28-amino-acid acylated peptide hormone primarily produced by gastric X/A-like cells and is the endogenous ligand for the growth hormone secretagogue receptor (GHS-R1a). It stimulates GH release, increases appetite and food intake, promotes energy storage, and modulates sleep and mood. Research explores ghrelin axis manipulation for obesity, cachexia, heart failure, and neurodegenerative diseases.
GHRH
PreclinicalGrowth Hormone-Releasing Hormone · Somatoliberin
GHRH is the endogenous 44-amino-acid hypothalamic peptide that drives the pulsatile secretion of growth hormone from the anterior pituitary. Native GHRH acts through GHRHR, stimulating GH gene transcription and secretion. It has a very short half-life in vivo, making it impractical as a therapeutic — which drove the development of modified analogs like sermorelin, CJC-1295, and tesamorelin. Research into GHRH receptor signaling underpins the entire GH secretagogue drug class.
GHRP-2
Phase IIPralmorelin · Growth Hormone-Releasing Peptide 2
GHRP-2 is a synthetic hexapeptide and potent ghrelin receptor agonist that stimulates growth hormone release from the pituitary. It produces a strong GH pulse with some elevation of cortisol and prolactin at higher doses. Research includes GH deficiency diagnosis, body composition, sleep quality, and appetite stimulation via its ghrelin-mimetic mechanism.
C₄₅H₅₅N₉O₆ · 817.99 Da
GHRP-6
PreclinicalGrowth Hormone-Releasing Peptide 6 · His-DTrp-Ala-Trp-DPhe-Lys-NH₂
GHRP-6 is one of the original synthetic GHRPs, acting as a strong ghrelin receptor agonist. It produces robust GH release accompanied by significant appetite stimulation — a property that makes it both valuable for cachexia research and distinct from cleaner GHRPs like Ipamorelin. Research also shows cytoprotective and cardioprotective properties independent of GH secretion.
C₄₆H₅₆N₁₂O₆ · 873.02 Da
Hexarelin
Phase IIExamorelin · EP 23905
Hexarelin is one of the most potent synthetic GHRP compounds, producing the largest GH pulse among GHRPs. Beyond its GH-stimulating properties, research highlights direct cardioprotective effects through CD36 receptor binding, independent of GH or IGF-1. Studies show benefits in heart failure models, myocardial infarction recovery, and protection against ventricular dysfunction.
IGF-1 LR3
PreclinicalLong R3 IGF-1 · Insulin-like Growth Factor 1 Long R3
IGF-1 LR3 is a modified version of Insulin-like Growth Factor-1 with an arginine substitution and 13-amino-acid N-terminal extension, which reduces binding to IGF-binding proteins and extends its half-life. It promotes muscle cell hyperplasia and hypertrophy by activating the PI3K/AKT/mTOR pathway. Research explores its role in muscle wasting, recovery from injury, and anabolic signaling.
IGF-2
PreclinicalInsulin-like Growth Factor 2 · Somatomedin A
IGF-2 is a 67-amino-acid peptide growth factor closely related to IGF-1, primarily active during fetal and neonatal development. In adults, research highlights its potent cognitive effects — IGF-2 administration after training enhances long-term memory consolidation in rodents by a remarkable degree, acting through IGF2R and mannose-6-phosphate receptors in the hippocampus. It has also emerged as a candidate for treating cognitive deficits in aging and neurodegenerative disease.
Ipamorelin
PreclinicalNNC 26-0161
Ipamorelin is a selective growth hormone secretagogue and ghrelin receptor agonist. Unlike other GHRPs, it stimulates GH release with high selectivity — producing minimal cortisol, ACTH, or prolactin elevation. It is among the most studied GHRPs for its clean GH pulse profile, making it a preferred research peptide for GH axis studies with reduced side effect concern.
C₃₈H₄₉N₉O₅ · 711.86 Da
Mechano Growth Factor
PreclinicalMGF · IGF-1Ec
Mechano Growth Factor (MGF) is a splice variant of the IGF-1 gene expressed in response to mechanical loading and muscle damage. Unlike systemic IGF-1, MGF activates satellite cells (muscle stem cells) to proliferate before differentiating — a critical step in muscle repair and growth. Research indicates it plays a distinct, non-overlapping role with systemic IGF-1 in tissue regeneration.
Mod GRF 1-29
PreclinicalCJC-1295 without DAC · Modified GRF 1-29
Mod GRF 1-29 is a modified version of GHRH(1-29) with four amino acid substitutions that increase stability and half-life without the DAC albumin-binding component. It produces a natural, pulsatile GH release and is commonly paired with GHRPs (like Ipamorelin) for a synergistic GH pulse. Its shorter duration preserves natural pituitary feedback mechanisms.
Octreotide
ApprovedSandostatin · SMS 201-995
Octreotide is a synthetic 8-amino-acid somatostatin analog with a much longer half-life than native somatostatin. FDA-approved for acromegaly, carcinoid syndrome, VIPomas, and variceal bleeding, it is also used off-label for Cushing's disease, thyroid cancer, and refractory diarrhea. Long-acting release (LAR) formulations allow monthly dosing. It is among the most clinically important peptide drugs in endocrinology.
PEG-MGF
PreclinicalPEGylated Mechano Growth Factor
PEG-MGF is a PEGylated (polyethylene glycol-modified) form of Mechano Growth Factor, designed to dramatically extend its biological half-life from minutes to days while preserving activity. PEGylation allows systemic delivery and sustained satellite cell activation without the need for local injection. Research shows enhanced muscle hypertrophy signaling compared to unmodified MGF.
Sermorelin
ApprovedGHRH(1-29) · GRF 1-29 NH2
Sermorelin is a synthetic analog of the first 29 amino acids of endogenous growth hormone-releasing hormone (GHRH). It stimulates the pituitary to produce and secrete growth hormone in a pulsatile, physiologic manner. FDA-approved for GH deficiency in children, it is extensively researched in adults for body composition, sleep quality, and age-related GH decline.
C₁₄₉H₂₄₆N₄₄O₄₂S · 3357.88 Da
Somatostatin
ApprovedSRIF · Somatotropin Release-Inhibiting Factor
Somatostatin is a 14-amino-acid cyclic peptide and the primary endogenous inhibitor of growth hormone secretion. It also inhibits insulin, glucagon, gastrin, cholecystokinin, and secretin release, slows GI motility, and reduces splanchnic blood flow. Its short half-life drove the development of longer-acting analogs (octreotide, lanreotide) used clinically for acromegaly, neuroendocrine tumors, and GI bleeding.
Tesamorelin
ApprovedEgrifta · TH9507
Tesamorelin is a stabilized synthetic GHRH analog FDA-approved for reduction of excess abdominal fat in HIV-infected adults with lipodystrophy. It stimulates pulsatile GH secretion while preserving natural feedback regulation. Research demonstrates significant visceral adipose tissue reduction, improved lipid profiles, and cognitive benefits, making it a key study compound for metabolic dysfunction.
Research applications
What researchers are studying
Pulsatile GH stimulation
CJC-1295 with DAC extends the half-life of GHRH signaling by binding albumin, producing sustained elevation of GH and IGF-1 compared to native GHRH. Ipamorelin is studied alongside it for its selectivity — unlike GHRP-6, it does not significantly raise cortisol or prolactin at research doses.
Body composition research
Tesamorelin has been studied in randomized controlled trials showing statistically significant reductions in visceral adipose tissue in HIV-positive adults. Research on sermorelin in age-related GH decline suggests modest improvements in lean mass and sleep architecture, though effect sizes vary considerably.
IGF-1 axis modulation
Because GH stimulates hepatic IGF-1 production, secretagogue peptides are frequently studied as indirect tools for examining the GH/IGF-1 axis without exogenous GH. This makes them useful in models investigating growth, tissue repair, and metabolic regulation where direct IGF-1 administration would be confounding.
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