Gonadorelin Acetate 2mg

Gonadorelin is native GnRH -- the same sequence as the endogenous hormone. It has a short half-life (minutes) and stimulates LH and FSH in a pulsatile manner. GnRH agonists like triptorelin, leuprolide, and goserelin are modified analogues with much longer half-lives. Paradoxically, continuous exposure to long-acting GnRH agonists desensitizes GnRH receptors, initially causing a hormone surge followed by suppression of LH and FSH -- the mechanism used therapeutically to treat hormone-sensitive cancers and endometriosis. Gonadorelin's short half-life means it stimulates rather than suppresses when dosed intermittently.

The GnRH stimulation test (also called the GnRH or LHRH challenge test) assesses pituitary function by measuring LH and FSH response to an IV or SC injection of gonadorelin. Blood samples are taken before and at 30 and 60 minutes after injection. A robust LH and FSH rise indicates intact pituitary responsiveness. Blunted or absent response suggests pituitary dysfunction. The test distinguishes hypothalamic from pituitary causes of hypogonadism -- helping determine whether the problem is inadequate GnRH signal or inadequate pituitary response to that signal.

GnRH receptor signaling is frequency-encoded. The pituitary responds differently to different GnRH pulse frequencies: optimal pulsatility (roughly 1 pulse per 90-120 minutes in humans) maintains LH and FSH secretion. Faster pulses shift the ratio toward LH; slower pulses favor FSH. Continuous stimulation desensitizes the receptor entirely and suppresses gonadotropin secretion. This frequency sensitivity is why pulsatile GnRH delivery from a pump can restore fertility in hypothalamic hypogonadism, while continuous GnRH agonist therapy suppresses it -- opposite physiological outcomes from the same receptor.