GHRP-2

GHRP‑2 (Pralmorelin)

Important: GHRP‑2 from Peptide Sciences is supplied strictly for laboratory research and educational use only. It is not for human or animal consumption or any medical application.

What is GHRP‑2?

GHRP‑2 (growth hormone‑releasing peptide‑2), also known as pralmorelin, is a synthetic peptide designed to mimic the action of the natural hormone ghrelin. By binding to the ghrelin/growth hormone secretagogue receptor (GHS‑R1a), it stimulates the release of growth hormone (GH) and influences multiple physiological systems.

Key characteristics:

• First‑in‑class synthetic growth hormone secretagogue
• Used clinically in some regions as a diagnostic agent for GH deficiency
• Extensively studied in humans and animals for its impact on GH/IGF‑1, appetite, muscle, heart, immunity, sleep, and pain pathways

GHRP‑2 Structure

• Type: Synthetic hexapeptide
• Sequence: H–D‑Ala–D‑2‑Nal–Ala–Trp–D‑Phe–Lys–NH₂
• Molecular formula: C₄₅H₅₅N₉O₆
• Approx. molecular weight: 817.0 g/mol
• Mechanism: Potent agonist at the ghrelin (GHS‑R1a) receptor

This compact hexapeptide incorporates D‑amino acids and unnatural residues (e.g., D‑2‑Nal) to enhance stability, receptor affinity, and bioactivity compared with endogenous ghrelin fragments.

Documented Research Areas

1. Muscle Maintenance and Growth

• In growth‑retarded yaks, GHRP‑2 increased growth performance, improved somatotropic axis activity, and enhanced muscle protein deposition despite environmental and nutritional stress .
• Cell culture studies show that GHRP‑2 directly suppresses the expression of atrogin‑1 and MuRF1, two major genes driving muscle protein breakdown, in glucocorticoid‑exposed myocytes .

These findings suggest that GHRP‑2 supports lean body mass through both endocrine (GH/IGF‑1) and direct muscle‑cell mechanisms, making it a useful peptide for research into atrophy, cachexia, and anabolic signaling.

2. Appetite Stimulation and Metabolic Research

In controlled clinical studies:

• GHRP‑2 significantly increases food intake in healthy men .
• Obese subjects retain a robust feeding response to GHRP‑2, indicating preserved sensitivity of ghrelin pathways .

Because appetite loss is a central feature of many chronic conditions, GHRP‑2 offers researchers a reliable tool for investigating:

• Mechanisms of hunger and satiety
• Energy balance and weight regulation
• Interventions targeting ghrelin signaling

3. Cardiovascular Protection

Preclinical and translational work indicates that GHRP‑2 and related peptides:

• Reduce apoptosis (programmed cell death) of heart muscle cells, especially under stress conditions .
• Act via specific cardiac peptide receptors distinct from the pituitary GH secretagogue receptor, broadening the map of ghrelin‑related targets in the heart .

These observations support ongoing investigation of GHRP‑2 as a model compound for cardioprotective signaling, ischemia‑reperfusion injury, and mitochondrial resilience.

4. Immune and Thymus Function

Age‑related shrinkage of the thymus leads to reduced T‑cell output and weakened adaptive immunity. Ghrelin receptor agonists have been shown to:

• Stimulate and partially rejuvenate thymic tissue
• Enhance the number and diversity of T‑cells produced

By interacting with ghrelin/GH pathways, GHRP‑2 is valuable for exploring links between endocrine function, immune aging, infection resistance, and cancer surveillance in experimental systems.

5. Sleep Quality and Neuroendocrine Balance

The ghrelin secretagogue class has been associated with meaningful changes in sleep architecture. In particular, MK‑677—an orally active small‑molecule GH secretagogue—has been reported to:

• Increase deep slow‑wave sleep (stages 3 and 4)
• Improve perceived sleep quality in human subjects

While these data are specific to MK‑677, they highlight a shared axis where ghrelin receptor activation, GH release, and sleep regulation intersect. GHRP‑2 is frequently used as a complementary agent to study:

• GH–sleep interactions
• Recovery, cognition, and cardiovascular parameters related to sleep
• The role of ghrelin signaling in circadian rhythms

6. Pain Perception and Opioid Pathways

GHRP‑2’s effects are not limited to endocrine actions. In mouse models:

• Central (supraspinal) administration of GHRP‑2 produces antinociceptive effects .
• These effects are blocked by opioid receptor antagonists, indicating that GHRP‑2 engages opioid receptors or closely associated pathways .

Notably, GHRP‑2 appears to show a degree of selectivity among opioid receptor subtypes, making it a promising tool compound for:

• Parsing out opioid receptor contributions to pain modulation
• Designing strategies to separate analgesic effects from classic opioid side effects in preclinical research

Research Use and Restrictions

• Form: Supplied as a research‑grade peptide, suitable for controlled in vitro and approved in vivo studies.
• Not for: Human consumption, medical treatment, diagnostic use, or unsupervised self‑experimentation.
• All handling should follow institutional, local, and national regulations for experimental peptide use.

Per‑kilogram dosing data in animals reported in the literature must not be extrapolated to humans. Any such extrapolation would be scientifically unsound and ethically unacceptable.

Article Author

Content compiled and organized by Dr. Logan, M.D., Case Western Reserve University School of Medicine, with a background in molecular biology and translational research.

Scientific Acknowledgment

Jean‑Alain Fehrentz, Ph.D., a peptide chemist trained at the University of Nancy and long‑time researcher in Montpellier, has contributed extensively to:

• Ghrelin receptor ligand design
• Peptide and peptidomimetic chemistry
• Growth hormone secretagogue development

He is referenced here strictly to credit the foundational scientific literature underlying GHRP‑2 research. His mention does not imply any endorsement, sponsorship, or association with Peptide Sciences or this product.

Referenced Citations (v3)

Same reference set:

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5. Laferrère, B. et al. Obesity (Silver Spring). 2006;14(6):1056–1063.
6. Muccioli, G. et al. Ann. Endocrinol. (Paris). 2000;61(1):27–31.
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10. Zeng, P. et al. Peptides. 2014;55:103–109.
11. Moulin, A. et al. ChemMedChem. 2007;2:1242–1259.