DRPSHP

Scientific Reference

GHRP-6

Evidence profile: Human Phase 1 evidence

GHRP-6 predates the discovery of its own receptor. Chemists built it in the 1980s while screening small synthetic peptides for the ability to make pituitary cells secrete growth hormone, and only years later did cloning of the receptor reveal that it responds to ghrelin, the hormone produced chiefly in the stomach. The compound is the hexapeptide His-D-Trp-Ala-Trp-D-Phe-Lys-NH2, with two D-amino acids that make it hard for peptidases to cut. It turns up in pituitary cell assays, receptor-binding work, animal studies and human endocrine experiments, and because ghrelin signalling is bound up with hunger it has also been a reference tool in feeding research. Nearly all of this is laboratory and short-term physiological work.

Mechanism of Action

The target is GHS-R1a, a G protein-coupled receptor that couples through Gq to phospholipase C and a rise in intracellular calcium; on pituitary somatotrophs that signal ends in growth hormone release. The same receptor is found in the arcuate nucleus of the hypothalamus on neurons producing neuropeptide Y and agouti-related peptide, and rodent experiments tie those cells to the drive to eat. Beyond growth hormone, modest rises in ACTH, cortisol and prolactin have been recorded after exposure. Whether somatostatin pathways shape the response is suggested but poorly pinned down.

Molecular Information

  • Type: Growth hormone secretagogue (GHRP)
  • Molecular weight: 873.0 g/mol
  • Molecular formula: C46H56N12O6

Published Research

  • Pharmacokinetic study of Growth Hormone-Releasing Peptide 6 (GHRP-6) in nine male healthy volunteers

    Cabrales A et al. · European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences · 2013 · Clinical

    PMID 23099431 — View on PubMed

  • Effects of ghrelin, GH-releasing peptide-6 (GHRP-6) and GHRH on GH, ACTH and cortisol release in hyperthyroidism before and after treatment

    Molica P et al. · Pituitary · 2010 · Clinical

    PMID 20602173 — View on PubMed

  • Growth hormone responses to GH-releasing peptide (GHRP-6) in hypothyroidism

    Pimentel-Filho FR et al. · Clinical endocrinology · 1997 · Clinical

    PMID 9156038 — View on PubMed

  • Different effects of growth hormone releasing peptide (GHRP-6) and GH-releasing hormone on GH release in endogenous and exogenous hypercortisolism

    Borges MH et al. · Clinical endocrinology · 1997 · Clinical

    PMID 9274702 — View on PubMed

  • Growth hormone secretion after the administration of GHRP-6 or GHRH combined with GHRP-6 does not decline in late adulthood

    Micic D et al. · Clinical endocrinology · 1995 · Clinical

    PMID 7734029 — View on PubMed

  • Growth hormone-releasing peptide-6 stimulates sleep, growth hormone, ACTH and cortisol release in normal man

    Frieboes RM et al. · Neuroendocrinology · 1995 · Clinical

    PMID 7617137 — View on PubMed