GPCR Second Messengers — FRCA Primary MCQ

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HardPharmacology - General PrinciplesGPCR Second MessengersFRCA Primary

Regarding signal transduction G-protein coupled receptors (GPCRs) use which intracellular messenger system?

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Correct answer: E — Second messenger systems including cAMP / IP3 / DAG / and calcium via Gs Gi and Gq subtypes

GPCRs activate heterotrimeric G-proteins (alpha / beta / gamma subunits). Gs stimulates adenylyl cyclase → increased cAMP (e.g. beta-adrenoceptors). Gi inhibits adenylyl cyclase → decreased cAMP (e.g. opioid / alpha-2 receptors). Gq activates phospholipase C → IP3 + DAG → intracellular Ca2+ release (e.g. alpha-1 / muscarinic M1/M3). Response timescale: seconds to minutes.

Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care