GHRP-2

GHRP-2 Overview

GHRP-2, also known as Pralmorelin, is a synthetic hexapeptide growth hormone secretagogue that acts as a potent agonist of the ghrelin/growth hormone secretagogue receptor. Historically significant as the first of its kind to be introduced into clinical study, it is currently utilized primarily as a diagnostic test peptide for growth hormone deficiency. Unlike earlier iterations of growth hormone stimulators, GHRP-2 has demonstrated a remarkable ability to stimulate the pituitary gland while maintaining a high degree of specificity.

Clinical interest in GHRP-2 extends beyond simple hormone stimulation. It has been investigated in Stage II clinical trials for the assessment of short stature and is a focal point of ongoing research regarding appetite regulation, muscle preservation, immune modulation, and sleep architecture. One of the most notable features of GHRP-2 is its versatile delivery potential; it remains active through oral and sublingual administration, providing researchers with alternatives to traditional subcutaneous injection methods.

GHRP-2 Structure

The molecular architecture of GHRP-2 is a precisely engineered sequence of six amino acids. This specific arrangement allows it to bypass certain metabolic degradation pathways, contributing to its efficacy across various delivery methods.

Structure Solution Formula: D-Alanyl-3-(2-naphthyl)-D-alanyl-L-alanyl-L-tryptophyl-D-phenylalanyl-L-lysinamide

The sequence is officially represented as: D-Ala-D-2-Nal-Ala-Trp-D-Phe-Lys-NH2

This hexapeptide structure is designed to mimic the natural action of ghrelin, the "hunger hormone," but with a more potent and targeted effect on the release of endogenous growth hormone.

GHRP-2 Effects

1. Protects and Enhances Muscle Structure

Research conducted on animal models, specifically in Yaks (Bos grunniens), indicates that GHRP-2 facilitates muscle growth through a dual-action mechanism: increasing protein deposition while simultaneously decreasing protein degradation. In environmental studies on the Tibetan plateau, GHRP-2 helped subjects overcome growth plateaus caused by food scarcity and harsh conditions.

The peptide functions by inactivating specific proteins known as atrogin-1 and MuRF1. These proteins are key regulators of muscle atrophy. By inhibiting these pathways, GHRP-2 may offer a therapeutic avenue for preventing catabolism (muscle wasting) associated with chronic illnesses, cancer, and autoimmune disorders. Furthermore, by elevating Growth Hormone and Insulin-like Growth Factor-1 (IGF-1) levels, it promotes the accumulation of lean body mass.

2. Stimulates Appetite

GHRP-2 is a documented orexigenic agent, meaning it effectively increases food intake. While appetite stimulation is often viewed through the lens of weight management, it is a critical factor in clinical recovery for patients suffering from chronic disease or "wasting syndrome." The ability to reliably improve nutritional intake can significantly alter long-term health outcomes and recovery speed in compromised research subjects.

3. Cardiovascular Protection

Cell culture studies involving fetal heart cells suggest that GHRP-2 and its analogues (such as GHRP-1 and GHRP-6) provide a protective barrier against apoptosis, or programmed cell death. This protection is likely rooted in the peptide's ability to preserve mitochondrial function, even when nutrient and oxygen supplies are diminished. Studies in canine models have identified specific receptors in heart tissue that respond to GHRP-2, suggesting that the peptide may play a direct role in maintaining cardiac integrity and preventing cellular dysfunction.

4. Immune System Modulation

The thymus is the primary organ responsible for the maturation of T-cells, which are essential for adaptive immunity. As organisms age, the thymus naturally undergoes involution (shrinking), leading to a weakened immune response. GHRP-2 has been shown to rejuvenate thymic function, increasing the diversity and volume of T-cell production. This enhancement supports the body's ability to fight complex infections, monitor for cancerous cells, and maintain general tissue homeostasis.

5. Improvements in Sleep Quality

Sleep architecture is significantly influenced by GHRP-2. Research shows that it can increase the duration of deep sleep (stages 3 and 4) by approximately 50% and REM sleep by about 20%. Deep sleep is the phase most associated with physical repair, cognitive clearing, and energy restoration. By optimizing these cycles, GHRP-2 may assist in improving blood pressure, healing rates, and mental clarity. These findings are especially relevant to aging populations where sleep fragmentation is a common precursor to health decline.

6. Pain Perception and Opioid Receptor Interaction

Interestingly, GHRP-2 appears to influence pain perception through a mechanism independent of growth hormone secretion. Animal models of osteoarthritis showed reduced pain levels almost immediately upon administration, before hormone levels had time to rise. Further investigation revealed that GHRP-2 acts as a selective agonist for specific opioid receptors. Unlike traditional narcotics that cause respiratory depression and high addiction risks, GHRP-2's selectivity suggests it may provide analgesic (pain-relieving) benefits without the dangerous side effects associated with non-selective opioid medications.

Research Data Summary

Biological System

Primary Mechanism

Observed Research Outcome

Muscle Structure

Inhibition of Atrogin-1 and MuRF1

Reduction in muscle atrophy and catabolism

Endocrine System

GHS-R Agonism

Elevated endogenous Growth Hormone and IGF-1

Metabolism

Ghrelin Mimicry

Increased caloric intake and nutritional uptake

Immunity

Thymic Rejuvenation

Increased T-cell population and diversity

Neurology

Sleep Cycle Modulation

50% increase in Deep Sleep (Stages 3 and 4)

Pain Management

Opioid Receptor Agonism

Direct antinociceptive (pain-blocking) effects

Article Author

The literature provided was researched, edited, and organized by Dr. Logan, M.D. Dr. Logan holds a doctorate degree from Case Western Reserve University School of Medicine and a B.S. in Molecular Biology. His expertise focuses on the clinical application of peptide therapies and hormonal regulation.

Scientific Journal Author

Jean-Alain Fehrentz, born in Nancy, France, in 1955, is a distinguished figure in peptide chemistry. He earned his Ph.D. from the University of Nancy in 1983 and has held prestigious positions at the CNRS and Sanofi Research. With over 100 scientific publications, his work focuses on peptide synthesis, enzyme inhibitors, and growth hormone interactions.

Jean-Alain Fehrentz is referenced here as a leading scientist in the development and research of GHRP-2. This reference is for acknowledgment of his exhaustive contributions to the field of endocrinology and does not constitute an endorsement of this product. There is no formal affiliation between Peptide Sciences and Dr. Fehrentz.

Storage and Handling

GHRP-2 should be stored in a cool, dry place away from direct sunlight. For long-term preservation, the lyophilized powder should be kept at -20 degrees Celsius. Once reconstituted with bacteriostatic water, the solution should be refrigerated at 2 to 8 degrees Celsius and used within the timeframe recommended by laboratory protocols to ensure peptide stability and prevent degradation.

Referenced Citations

[1] R. Hu 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, vol. 11, no. 2, p. e0149461, 2016.

[2] D. Yamamoto 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., vol. 82, no. 9–10, pp. 460–466, Feb. 2008.1

[3] L. T. Phung et al., "The effects of growth hormone-releasing peptide-2 (GHRP-2) on the release of growth hormone and growth p2erformance in swine," Domest. Anim. Endocrinol., vol. 18, no. 3, pp. 279–291, Apr. 2000.3

[4] B. Laferrère, C. Abraham, C. D. Russell, and C. Y. Bowers, "Growth hormone releasing peptide-2 (GHRP-2), like ghrelin, increases fo4od intake in healthy men," J. Clin. Endocrinol. Metab., vol. 90, no. 2, pp. 611–614, Feb. 2005.5

[5] B. Laferrère, A. B. Hart, and C. Y. Bowers, "Obese subjects respond to the stimulatory effect of the ghrelin agonist growth h6ormone-releasing peptide-2 on food intake," Obes. Silver Spring Md, vol. 14, no. 6, pp. 1056–1063, Jun. 2006.78

[6] G. Muccioli et al., "Growth hormone-releasing peptides and the cardiovascular system," Ann. Endocrinol., vol. 61, n9o. 1, pp. 27–31, F10eb. 2000.

[7] V. Bodart et al., "Identification and characterization of a new growth hormone-releasing peptide receptor in the heart," Circ. Res., vol. 85, no. 9, pp. 796–802, Oct. 1999.

[8] D. D. Taub, W. J. Murphy, and D. L. Longo, "Rejuvenation of the aging thymus: growth hormone-mediated and ghrelin-mediated signaling pathways," Curr. Opin. Pharmacol., vol. 10, no. 4, pp. 408–424, Aug. 2010.

[9] G. Gopinadh et al., "Prolonged oral treatment with MK-677, a novel growth hormone secretagogue, improves sleep quality in man," Neuroendocrinology, vol. 66, no. 4, pp. 278–286, Oct. 1997.

[10] P. Zeng et al., "Ghrelin receptor agonist, GHRP-2, produces antinociceptive effects at the supraspinal level via the opioid receptor in mice," Peptides, vol. 55, pp. 103–109, May 2014.

[11] Moulin, A., Ryan, J., Martinez, J. and Fehrentz, J. (2007), Recent Developments in Ghrelin Receptor Ligands. ChemMedChem, 2: 1242-1259.