- Physiology: GnRH is a decapeptide hormone produced and secreted by the hypothalamus in a pulsatile manner.
- Function: It stimulates the anterior pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
- Role in Reproductive Axis:
- LH and FSH regulate gonadal function — ovarian estrogen and progesterone production in females, and testosterone production in males.
- Pulsatile secretion of GnRH is essential for normal reproductive hormone balance and fertility.
- Clinical relevance: Alterations in GnRH secretion (e.g., continuous vs pulsatile) affect downstream hormone levels and can be therapeutically targeted in hormone-sensitive cancers.
This contrasts with GnRH agonists, which mimic GnRH but when given continuously, cause downregulation of receptors leading to hormone suppression.