Pulsatile GnRH stimulates gonadotrophs of the anterior pituitary to secrete LH and FSH. The signal transduction pathway used by the GnRH receptor is:

• A Gs, adenylate cyclase, cAMP, PKA
• B Ligand-gated calcium channel opening at the plasma membrane
• C JAK2 activation and STAT phosphorylation
• D Gq, phospholipase C, IP3 and DAG, calcium and PKC ✓

Explanation

The GnRH receptor couples to Gq. Activated Gq stimulates phospholipase C-beta, which cleaves PIP2 into IP3 and DAG. IP3 releases calcium from the endoplasmic reticulum and DAG activates protein kinase C; both signals drive LH and FSH secretion. This contrasts with TSH, LH, FSH and ACTH receptors, which are Gs-coupled and use cAMP. Continuous rather than pulsatile GnRH exposure causes receptor downregulation and suppresses gonadotropin output, the basis of GnRH agonist therapy.

Reference: Ganong's Review of Medical Physiology, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.