Ghrelin
Ghrelin (endogenous growth hormone secretagogue)
The body's own hunger hormone and the natural trigger for growth hormone release, and the template for the entire GHRP peptide class.
Overview
Ghrelin is a 28-amino-acid hormone made mainly in the stomach, discovered in 1999. It is the primary natural stimulator of growth hormone secretion and the only known circulating hormone that increases appetite. Every synthetic GH secretagogue, from the GHRPs to ipamorelin, works by mimicking it. It is a well-characterized hormone rather than an approved therapeutic.
Mechanism of action
Activates the GH secretagogue receptor (GHS-R1a) in the pituitary and hypothalamus, driving GH release and appetite.
Key studies & citations
- Animal1999
Ghrelin is a growth-hormone-releasing acylated peptide from stomach
Discovery paper: identified ghrelin as the endogenous ligand of the GH secretagogue receptor, produced mainly in the stomach.
Nature - Animal2000
Ghrelin induces adiposity in rodents
Peripheral ghrelin increased food intake and body fat in rodents, establishing its role in energy balance.
Nature - Animal2001
A role for ghrelin in the central regulation of feeding
Central ghrelin strongly stimulated feeding in rats via hypothalamic NPY and AgRP neurons; anti-ghrelin antibody suppressed feeding.
Nature - Human2001
Ghrelin enhances appetite and increases food intake in humans
Intravenous ghrelin raised buffet energy intake by about 28% in nine healthy volunteers; first circulating hormone shown to stimulate food intake in man.
Journal of Clinical Endocrinology and Metabolism
Frequently asked questions
Why does ghrelin matter for peptides?
It is the natural hormone that peptide GH secretagogues imitate. Understanding ghrelin explains how compounds like ipamorelin and the GHRPs work.