Parasympathetic Preganglionic NT — FRCA Primary MCQ
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Correct answer: A — Acetylcholine at neuronal nicotinic receptors
Explanation lettering: E = shown as A · A = shown as D · D = shown as E
The correct answer is E. Parasympathetic preganglionic neurones release acetylcholine within autonomic ganglia. It binds neuronal nicotinic (Nn) receptors on postganglionic neurones, opening ligand-gated cation channels and producing rapid depolarisation. This arrangement also applies to sympathetic preganglionic transmission. Acetylcholine acting at muscarinic receptors (B) principally describes transmission from parasympathetic postganglionic neurones to effector organs, not fast ganglionic transmission. Noradrenaline at alpha-adrenoceptors (D) is characteristic of many sympathetic postganglionic neuroeffector junctions. Adrenaline at beta-adrenoceptors (A) mainly represents circulating adrenal catecholamine action, while dopamine at D1 receptors (C) is not the standard transmitter–receptor pairing in parasympathetic ganglia.
Reference: Becker DE. Basic and clinical pharmacology of autonomic drugs. Anesthesia Progress. 2012;59(4):159–168. https://pubmed.ncbi.nlm.nih.gov/23241039/