Growth hormone secretagogue (GHS)

A secretagogue is a substance that causes another substance to be secreted. Growth hormone secretagogues are peptides and small molecules that act on the pituitary gland to release growth hormone, rather than supplying growth hormone directly. They fall into two families defined by the receptor they use.

The first family are GHRH analogues, which mimic the hypothalamic hormone that normally signals the pituitary: sermorelin, tesamorelin and CJC-1295. The second are ghrelin receptor agonists, originally called growth-hormone-releasing peptides: GHRP-6, GHRP-2 and ipamorelin. The two receptors act on the pituitary through different pathways, which is why the research literature so often studies a GHRH analogue and a ghrelin agonist together.

Because they stimulate the body's own growth hormone rather than replace it, secretagogues preserve the pulsatile pattern of natural release and are subject to the body's feedback control. They are prohibited at all times by the World Anti-Doping Agency under the S2 category. The article on growth hormone secretagogues covers the families in more depth.