GHRP-6

Overview

GHRP-6 (growth hormone-releasing peptide-6) is a synthetic six-amino-acid peptide and one of the first compounds with which researchers could deliberately evoke growth hormone release. It belongs to the growth hormone secretagogues: compounds that prompt the pituitary to release growth hormone.

Unlike the GHRH analogues in this domain (such as CJC-1295 and Sermorelin), GHRP-6 does not act on the GHRH receptor but on the ghrelin receptor. That makes it a complementary, second point of engagement on the same axis — and the two routes reinforce each other.

At Peptalis, GHRP-6 is available strictly for research use only — in-vitro laboratory research, not for human or animal use.

Mechanism of action

GHRP-6 activates the ghrelin receptor (GHS-R1a) on the pituitary and hypothalamus, evoking growth hormone release.

Ghrelin-receptor activation

• GHRP-6 binds the ghrelin receptor (GHS-R1a), the same receptor as the stomach hormone ghrelin; activation on pituitary somatotrophs evokes a growth hormone pulse.
• On the GHRH route it acts synergistically with GHRH analogues: together they give a stronger GH response than either alone (Bowers 1990).

Additional effects

• Via the ghrelin receptor in the hypothalamus, GHRP-6 has also been associated with appetite stimulation.
• The human evidence consists of GH/IGF-I release and pharmacokinetics in healthy volunteers (Hayashi 1991; Cabrales 2012), not functional clinical endpoints.

Research findings

• Discovery + human: GHRP stimulates GH release in healthy men and acts synergistically with GHRH (Bowers 1990)
• Human: intranasal administration raised plasma GH and IGF-I in healthy men (Hayashi 1991)
• Human (phase I): pharmacokinetics of GHRP-6 in nine healthy volunteers (Cabrales 2012)
• Mechanism/history: GHRPs led to the discovery of ghrelin and the ghrelin receptor (Bowers 1993/2012)

Mechanism & preclinical

• GHRP-6 was identified as a synthetic GH secretagogue acting via the ghrelin receptor; the research around it ultimately led to the discovery of the endogenous hormone ghrelin (Bowers 1990; 1993).
• The receptor route and the synergy with GHRH are well mapped.

Human studies

• In healthy men, GHRP evoked dose-dependent GH release and enhanced the effect of GHRH (Bowers 1990).
• Intranasal administration raised plasma GH and IGF-I in healthy men (Hayashi 1991).
• A phase I study characterized the pharmacokinetics in nine healthy volunteers (Cabrales 2012). The human data concern hormonal/pharmacokinetic outcomes, not functional clinical endpoints.

Research context

This profile describes what has been done and found in research. Regulatory and clinical facts are facts about the respective trials and authorities, not claims about a Peptalis product; the compound is for in-vitro laboratory research only (RUO).

Open questions

• The human data are hormonal/pharmacokinetic in healthy volunteers; functional clinical endpoints are lacking.
• GHRP-6 has no approved indication; the long-term profile with repeated use has not been systematically studied in humans.
• The relative contribution of the ghrelin route versus the GHRH route in combined protocols is an open research question.

Research outlook

GHRP-6 is a well-characterized model system for the ghrelin receptor and the regulation of the GH/IGF-I axis.

Its synergy with GHRH analogues makes it a useful tool to study the two complementary routes to GH release side by side.

Scientific interest

Classic ghrelin-mimetic secretagogue — the second point of engagement alongside the GHRH analogues.

Historical importance: GHRP research led to the discovery of ghrelin.

Synergy with GHRH — a clear example of two routes reinforcing each other.

Specifications

References

1. Growth hormone (GH)-releasing peptide stimulates GH release in normal men and acts synergistically with GH-releasing hormone · Bowers CY, et al. · J Clin Endocrinol Metab · 1990
2. Intranasal administration of His-D-Trp-Ala-Trp-D-Phe-LysNH2 (growth hormone releasing peptide) increased plasma growth hormone and insulin-like growth factor-I levels in normal men · Hayashi S, et al. · Endocrinol Jpn · 1991
3. GH releasing peptides--structure and kinetics · Bowers CY · J Pediatr Endocrinol · 1993
4. Pharmacokinetic study of Growth Hormone-Releasing Peptide 6 (GHRP-6) in nine male healthy volunteers · Cabrales A, et al. · Eur J Pharm Sci · 2012

Availability

Not in catalogue · Profile complete · verification and sourcing not yet finished