GHRP‑2 (Pralmorelin) – Research Peptide Datasheet

1. Identity

• Name: Growth Hormone‑Releasing Peptide‑2 (GHRP‑2)
• Synonym: Pralmorelin
• Class: Synthetic growth hormone secretagogue; ghrelin receptor (GHS‑R1a) agonist
• Type: Hexapeptide

2. Structural Information

• Sequence: H–D‑Ala–D‑2‑Nal–Ala–Trp–D‑Phe–Lys–NH₂
• Molecular formula: C₄₅H₅₅N₉O₆
• Approximate molecular weight: 817.0 g/mol
• Primary receptor target: Ghrelin / Growth Hormone Secretagogue Receptor (GHS‑R1a)

This optimized hexapeptide contains D‑amino acids and non‑natural residues for enhanced stability and receptor potency relative to endogenous ghrelin fragments.

3. Functional Overview

GHRP‑2 was the first growth hormone secretagogue to advance into clinical testing and is widely used as a test peptide for growth hormone deficiency and as a tool compound for investigating:

• GH/IGF‑1 axis dynamics
• Ghrelin receptor pharmacology
• Appetite and energy homeostasis
• Muscle catabolism and anabolism
• Cardiovascular, immune, sleep, and nociceptive pathways

GHRP‑2 has been reported to be active via oral, sublingual, and parenteral routes in research settings.

4. Documented Research Effects

4.1 Muscle Protein Deposition and Atrophy

• In vivo (yaks):
• Improved average daily gain and growth performance in growth‑retarded yaks under cold, nutrient‑limited conditions
• Increased somatotropic axis hormones (GH, IGF‑1)
• Enhanced muscle protein deposition and reduced growth retardation undefined +1
• In vitro (myocytes):
• Attenuated dexamethasone‑induced upregulation of atrogin‑1 and MuRF1, key ubiquitin ligases mediating muscle protein degradation

Interpretation: GHRP‑2 exerts both systemic (GH/IGF‑1) and direct myocellular effects that favor lean mass preservation and muscle growth, making it suitable for models of sarcopenia, cachexia, and steroid‑induced muscle loss.

4.2 Appetite Regulation

• Healthy subjects: GHRP‑2 administration increases caloric intake and subjective hunger .
• Obese subjects: A similar increase in food intake is observed, indicating preserved sensitivity to ghrelin receptor stimulation .

Use case: Research on orexigenic signaling, appetite control, energy balance, and hyperphagia in metabolic disease.

4.3 Cardiovascular and Mitochondrial Effects

• GHRP‑2 and related peptides reduce apoptosis in cardiomyocytes, likely via mitochondrial protective mechanisms .
• A specific cardiac receptor for growth hormone‑releasing peptides distinct from the classical pituitary GHS‑R has been identified .

Use case: Experimental models of myocardial ischemia, heart failure, and cardioprotective signal transduction.

4.4 Immune System and Thymus

• Ghrelin receptor agonists (including GHRP‑2) are associated with:
• Thymic stimulation and partial reversal of age‑related thymic involution
• Increased T‑cell production and diversity

Use case: Investigating endocrine–immune interactions, immune aging, infection resistance, and tumor immunosurveillance.

4.5 Sleep and Neuroendocrine Integration

• Within the GH secretagogue class, MK‑677 has been shown to:
• Increase deep (slow‑wave) sleep
• Improve overall sleep quality in human subjects

While these studies focus on MK‑677 rather than GHRP‑2, they provide a framework for examining how GHS‑R agonism modulates sleep architecture, cognitive performance, blood pressure, and tissue recovery. GHRP‑2 is a complementary tool for dissecting these neuroendocrine relationships.

4.6 Nociception and Opioid Receptor Interaction

• In mice, supraspinal administration of GHRP‑2 produces antinociceptive effects in multiple pain models .
• These effects are reversed by opioid receptor antagonists, indicating opioid receptor involvement in GHRP‑2‑mediated analgesia .

Use case: Characterizing opioid receptor subtype selectivity, exploring non‑classical analgesic pathways, and evaluating pain modulation with reduced classical opioid liability in preclinical settings.

5. Safety and Use Restrictions

• Animal data report minimal to moderate side effects and good subcutaneous bioavailability; oral bioavailability is species dependent undefined +1 .
• Reported doses and regimens in animals must not be extrapolated to humans.

GHRP‑2 from Peptide Sciences is intended exclusively for controlled laboratory research and educational use by qualified professionals. It is not a pharmaceutical, supplement, cosmetic, or food product and is not approved for human or veterinary administration, diagnosis, or treatment.

6. Authorship and Scientific Acknowledgment

6.1 Article Author

This datasheet content was researched, edited, and structured by Dr. Logan, M.D., Case Western Reserve University School of Medicine, with a B.S. in Molecular Biology.

6.2 Scientific Acknowledgment

Jean‑Alain Fehrentz, Ph.D. is a peptide chemist recognized for extensive work on:

• Peptide synthesis and peptidomimetics
• Enzyme inhibitors
• Ghrelin receptor ligands and growth hormone secretagogues

He is mentioned solely to credit key scientific contributions underlying GHRP‑2 research. This citation does not imply endorsement, promotion, or any form of association with Peptide Sciences or this product.

7. References (v6)

1. Hu R, et al. Effects of GHRP‑2 and Cysteamine Administration on Growth Performance, Somatotropic Axis Hormone and Muscle Protein Deposition in Yaks (Bos grunniens) with Growth Retardation. PLOS ONE. 2016;11(2):e0149461.
2. Yamamoto D, et al. GHRP‑2, a GHS‑R agonist, directly acts on myocytes to attenuate the dexamethasone‑induced expressions of muscle‑specific ubiquitin ligases, Atrogin‑1 and MuRF1. Life Sci. 2008;82(9–10):460–466.
3. Phung LT, et al. The effects of growth hormone‑releasing peptide‑2 (GHRP‑2) on the release of growth hormone and growth performance in swine. Domest. Anim. Endocrinol. 2000;18(3):279–291.
4. Laferrère B, Abraham C, Russell CD, Bowers CY. Growth hormone releasing peptide‑2 (GHRP‑2), like ghrelin, increases food intake in healthy men. J. Clin. Endocrinol. Metab. 2005;90(2):611–614.
5. Laferrère B, Hart AB, Bowers CY. Obese subjects respond to the stimulatory effect of the ghrelin agonist growth hormone‑releasing peptide‑2 on food intake. Obesity (Silver Spring). 2006;14(6):1056–1063.
6. Muccioli G, et al. Growth hormone‑releasing peptides and the cardiovascular system. Ann. Endocrinol. (Paris). 2000;61(1):27–31.
7. Bodart V, et al. Identification and characterization of a new growth hormone‑releasing peptide receptor in the heart. Circ. Res. 1999;85(9):796–802.
8. Taub DD, Murphy WJ, Longo DL. Rejuvenation of the aging thymus: growth hormone‑mediated and ghrelin‑mediated signaling pathways. Curr. Opin. Pharmacol. 2010;10(4):408–424.
9. Gopinath G, et al. Prolonged oral treatment with MK‑677, a novel growth hormone secretagogue, improves sleep quality in man. Neuroendocrinology. 1997;66(4):278–286.
10. Zeng P, et al. Ghrelin receptor agonist, GHRP‑2, produces antinociceptive effects at the supraspinal level via the opioid receptor in mice. Peptides. 2014;55:103–109.
11. Moulin A, Ryan J, Martinez J, Fehrentz J. Recent developments in ghrelin receptor ligands. ChemMedChem. 2007;2:1242–1259.