Secretagogue

Imagine your body needs a certain hormone. There are two ways to achieve that: you can supply the hormone directly, or you can give a substance that makes the body release the hormone on its own. That is exactly what a secretagogue does: it prompts a gland to release (secrete) one of the body's own hormones. It does not replace the hormone; it merely triggers its own release.

Example

Growth-hormone secretagogues, such as GHRH analogues (substances that mimic the body's growth-hormone-releasing hormone) and GHRP peptides (short protein chains that also stimulate growth-hormone release), make the pituitary (the small hormone gland at the base of the brain) release more of the body's own growth hormone. This differs from giving growth hormone directly.

Why the distinction matters

Because the hormone is released through the body's own control system, similar to a thermostat regulating a heater, the usual safety mechanisms often still kick in: for instance, the body itself slows down production once enough hormone is in the blood. With direct hormone administration, that self-regulation is bypassed.