Which pair of hypothalamic releasing hormones signals its target pituitary cell primarily through Gq coupling and the phosphoinositide cascade?
- A GnRH and TRH ✓
- B GHRH and CRH
- C TRH and somatostatin
- D GnRH and dopamine
Correct answer: A. GnRH and TRH
Explanation
GnRH acting on gonadotrophs and TRH acting on thyrotrophs both couple through Gq, activating phospholipase C-beta, raising IP3, DAG and cytosolic calcium. GHRH and CRH are stimulatory hormones acting via Gs and cAMP, while somatostatin and dopamine inhibit secretion via Gi, so every other pairing contains at least one Gs- or Gi-coupled hormone.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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