This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.N.S, Subject name: Pharmacology
[{'content': 'At therapeutic doses which are the only receptors on which Sumatriptan acts? \nSelect and explain. \nA. 5HT1A, B. 5HT1B/1D, C. 5 HT3, D. 5 HT4', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. b (5HT1B/ID) (Ref. KDT 5th/pg. 146, 153)5HT Receptors5-HT1Autoreceptors; inhibit serotonergic neural activity in brain.5-HT1A - present in raphe nuclei and hippocampus, buspirone may act through these receptors.5-HT1B/1DConstricts cranial blood vessels and inhibits release of inflammatory neuropeptides in them;Sumatriptan acts through these receptors.5-HT2APreviously D type receptor; most important postjunctional receptor mediating direct actions of 5-HT like vascular and visceral smooth muscle contraction, platelet aggregation, neuronal activation in brain; Ketanserin blocks these receptors.Ritanserin, another 5-HT2 antagonist, has little or no alpha-blocking action.5-HT3Previously M type receptor; depolarizes neurones by gating cation channels; elicits reflex effects of 5-HT - emesis, gut peristalsis, bradycardia, transient hypotension, apnoea, pain, itch.Ondansetron acts by blocking these receptors.5-HT4Mediate intestinal secretion, augmentation of peristalsis.Renzapride is a selective 5-HT4 agonist.', 'role': 'assistant'}]