At therapeutic doses which are the only receptors on which Sumatriptan acts?

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.