The growth-hormone axis: secretagogues versus exogenous hormone

The growth-hormone axis is pulsatile: hypothalamic GHRH stimulates release, ghrelin-receptor signalling amplifies it, and somatostatin restrains it. Two research peptides map onto this architecture. CJC-1295 is a GHRH analogue with a modified sequence that extends its half-life, studied for its ability to raise circulating GH and IGF-1 while preserving the pulsatile pattern of release. Ipamorelin is a selective growth-hormone secretagogue receptor agonist, notable in the literature for stimulating GH release with comparatively little effect on cortisol or prolactin. The important conceptual point is that secretagogues work through an intact regulatory loop, whereas exogenous growth hormone bypasses it. The published human pharmacology on GH and IGF-1 response is reasonably clear; long-term outcome data in healthy adults is not.