Secretagogue
A substance that stimulates another cell or gland to secrete a hormone or other compound, acting upstream to trigger endogenous release rather than supplying the hormone directly.
In the peptide research context, “secretagogue” most commonly refers to growth hormone secretagogues — compounds that stimulate the pituitary to release GH endogenously. This is the mechanism of GHRPs (like GHRP-2, GHRP-6, Ipamorelin) and GHRHs (like CJC-1295, Mod-GRF 1-29), and it distinguishes these peptides from exogenous recombinant HGH, which bypasses pituitary regulation.
The secretagogue approach is often preferred in research because it preserves pulsatile GH release, maintains negative feedback sensitivity, and works within the body’s natural regulatory framework. Stacking a GHRH with a GHRP is a common research protocol because the two classes act synergistically — GHRH primes the pituitary while GHRP amplifies the pulse and suppresses somatostatin, resulting in greater GH output than either alone.