GnRH
Gonadotropin-releasing hormone (GnRH) is a hypothalamic decapeptide, encoded by the GNRH1 gene, that commands the reproductive axis. Released in episodic pulses from the median eminence, it binds GnRH receptors on pituitary gonadotrophs and drives the synthesis and secretion of LH and FSH; pulse frequency itself encodes information, favoring LH at low frequency and FSH at high frequency. Continuous exposure paradoxically desensitizes the receptor, a property exploited clinically: GnRH agonists and antagonists suppress gonadotropin output in prostate cancer, endometriosis, precocious puberty and assisted reproduction. Pulsatile GnRH administration, by contrast, restores pituitary function in hypothalamic hypogonadism, making the peptide uniquely both a stimulatory and an inhibitory therapeutic.
