<prompt> Selective 5-HT1B1D receptor agonist useful in acute migraine is:BuspironeOndansetronFrovatriptanKetanserin  <response>: Triptans like sumatriptan, frovatriptan etc are 5HT1B1D agonists. These are drug of choice for acute severe migraine. Ergot alkaloids like ergotamine can also be used for acute attack of migraine. These also stimulate 5HT1B1D receptors. Two primary hypotheses has been proposed for their action- 1. Activation of 5HT1D1B receptors on pre-synaptic trigeminal nerve endings to inhibit the release of vasodilating peptides and anti- seizure agents may suppress excessive firing of these nerve endings. 2.Vaso-constricting action of direct 5HT agonists triptans and ergot may prevent vaso-dilation and stretching of pain nerve endings. DOC for prophylaxis of migraine is propranolol. 