Research Applications
Growth Hormone Secretion Research
GHRP-6 is one of the most extensively used tools in GH research. It has been instrumental in characterizing the ghrelin/GHS-R1a signaling system, understanding somatotroph physiology, and developing GH stimulation test protocols for diagnosing GH deficiency.
Body Composition and Anabolism
Research demonstrates GHRP-6 produces dose-dependent GH increases that promote lean body mass, enhance nitrogen retention, and reduce adiposity. Studies show GH peak levels of 20-50 ng/mL following standard doses, comparable to insulin tolerance test responses.
Post-Operative Gastroparesis
GHRP-6's prokinetic effects have been studied for recovery of gastrointestinal motility after surgery. Preclinical and early clinical data show accelerated gastric emptying and reduced ileus duration.
Appetite Stimulation in Wasting Conditions
The potent orexigenic effect of GHRP-6 has been researched for treating anorexia and cachexia in cancer, HIV/AIDS, and chronic illness, where the appetite stimulation (typically a disadvantage) becomes therapeutically valuable.
Cardioprotection
Like other GH secretagogues, GHRP-6 demonstrates cardioprotective effects through cardiac GHS-R1a activation. Studies show reduced cardiomyocyte apoptosis, improved post-ischemic recovery, and anti-fibrotic effects in cardiac tissue.
Sleep Enhancement
GHRP-6 before bedtime amplifies nocturnal GH pulses and enhances slow-wave sleep duration and quality, contributing to improved recovery and regeneration during sleep.
Mechanism of Action
GHS-R1a Receptor Agonism
GHRP-6 binds to the growth hormone secretagogue receptor 1a (GHS-R1a) on pituitary somatotroph cells. As one of the original ligands used to characterize this receptor, GHRP-6 activates Gq/11-coupled PLC signaling, triggering IP3-mediated calcium release and PKC activation, driving GH granule exocytosis.
Hypothalamic Dual Action
GHRP-6 acts at multiple hypothalamic sites: it stimulates GHRH-producing neurons in the arcuate nucleus to increase GHRH release, and simultaneously suppresses somatostatin-producing neurons. This dual hypothalamic action, combined with direct pituitary stimulation, produces a particularly robust GH response.
Strong Orexigenic Effect
Among GH secretagogues, GHRP-6 produces the most pronounced appetite stimulation. This occurs through GHS-R1a activation on hypothalamic NPY/AgRP neurons, triggering vigorous feeding behavior within 20-30 minutes of administration. This orexigenic effect directly mirrors that of endogenous ghrelin.
Cortisol and Prolactin Stimulation
GHRP-6 activates ACTH release from corticotroph cells and prolactin from lactotroph cells, producing dose-dependent elevations of both hormones. These off-target effects are more pronounced than with GHRP-2 or ipamorelin but typically remain within physiological ranges.
Gastric Motility Enhancement
Through GHS-R1a receptors in the enteric nervous system, GHRP-6 enhances gastric motility and acid secretion, mimicking ghrelin's prokinetic effects. This property has been investigated for post-operative gastroparesis.
Biological Pathways
PLC/IP3/Calcium Exocytosis
GHS-R1a activation on somatotrophs engages Gq/11, activating PLC-β. IP3 triggers ER calcium release. Combined with PKC-mediated calcium channel opening, this produces the calcium transient required for GH granule exocytosis.
NPY/AgRP Appetite Circuit
In the hypothalamus, GHRP-6-activated GHS-R1a signaling increases NPY and AgRP expression through AMPK activation and FOXO1 nuclear translocation. These potent orexigenic neuropeptides then act on MC4R (antagonism by AgRP) and Y1/Y5 receptors (NPY) to drive feeding behavior.
GH/JAK2/STAT5/IGF-1 Axis
Released GH activates the JAK2/STAT5 cascade in hepatocytes and other target cells. STAT5 drives IGF-1 gene transcription. IGF-1 then mediates the majority of GH's anabolic effects through its receptor tyrosine kinase and downstream PI3K/Akt/mTOR signaling.
Vagal-Gut Motility Pathway
GHS-R1a receptors on vagal afferent neurons and enteric neurons mediate GHRP-6's prokinetic effects. Activation enhances cholinergic neurotransmission in the myenteric plexus, increasing gastric contractility and intestinal transit.
Dosage Information
Calculation Results
Syringe Fill Level (100u syringe)
Protocols
No protocols featuring this peptide yet.
Browse All ProtocolsStability & Storage
GHRP-6 is supplied as a lyophilized white powder. Store at -20°C for long-term stability (18-24 months) or 2-8°C for up to 6 months. Protect from light and moisture.
Reconstitute with bacteriostatic water. The solution should be clear and colorless. Store reconstituted GHRP-6 at 2-8°C and use within 21-28 days.
The D-amino acid substitutions at positions 2 (D-Trp) and 5 (D-Phe) provide significant protease resistance. In-vivo half-life following subcutaneous injection is approximately 15-25 minutes, necessitating multiple daily injections for sustained GH elevation. GHRP-6 is compatible with most GHRH analogs for combination use in the same syringe.
Side Effects & Precautions
Intense Hunger
GHRP-6 produces the strongest appetite stimulation among GH secretagogues, with intense hunger occurring 20-30 minutes post-injection and lasting 1-2 hours. This is mediated by hypothalamic NPY/AgRP activation and directly mimics the hunger signal of endogenous ghrelin.
Cortisol and Prolactin Elevation
GHRP-6 increases cortisol by 20-40% and prolactin by 15-30% at GH-stimulating doses. While typically remaining within physiological ranges, these elevations distinguish GHRP-6 from more selective alternatives and may be relevant with chronic use.
Water Retention
Fluid retention in face and extremities is common during initial use, mediated by GH-stimulated renal sodium retention. Typically resolves within 2-4 weeks.
Injection Site Reactions
Mild pain, redness, and occasional small welts at injection sites are common and self-limiting.
Tingling and Numbness
Carpal tunnel-like symptoms (tingling, numbness in hands) may occur with sustained GH elevation. Dose-dependent and reversible with dose reduction.
Dizziness and Headache
Brief lightheadedness or mild headache may occur following injection, typically resolving within 30-60 minutes.
Gastric Effects
Enhanced gastric acid secretion may cause mild stomach discomfort in some users, particularly when administered on an empty stomach.
Research Use Only. This information is for educational and research purposes only. Not intended for medical advice or self-medication.
Regulatory Status
GHRP-6 is not approved by the FDA, EMA, or most regulatory authorities for clinical therapeutic use. It is classified as an investigational research compound and is available from peptide synthesis companies for laboratory research purposes.
GHRP-6 has been used in numerous clinical research studies under institutional review board approval but has not undergone the formal Phase 3 clinical trial process required for drug approval in most jurisdictions.
WADA prohibits GHRP-6 under category S2 (Peptide Hormones, Growth Factors, Related Substances, and Mimetics) of the prohibited list, banned both in-competition and out-of-competition. GHRP-6 was among the first GH secretagogues added to the WADA prohibited list.
Research Studies
On the In Vitro and In Vivo Activity of a New Synthetic Hexapeptide That Acts on the Pituitary to Release Growth Hormone
Bowers CY, Momany F, Reynolds GA, Hong A.
Growth Hormone Releasing Peptides — Structure and Kinetics
Bowers CY.
Ghrelin: Discovery of the Natural Endogenous Ligand for the Growth Hormone Secretagogue Receptor
Kojima M, Hosoda H, Date Y, et al.
GHRP-6 Stimulation of the GH-IGF-1 Axis
Popovic V, Damjanovic S, Micic D, et al.
Gastric Motility Effects of Growth Hormone Secretagogues
Asakawa A, Inui A, Kaga T, et al.
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