Blockade of reserpine emesis in pigeons by metoclopramide

Reserpine (0.5 mg/kg i.m.) produced emesis in pigeons with 60% of the animals responding. Metoclopramide HCl at 10, 20 and 40 mg/kg p.o. administered 30 min before or after reserpine injection was effective in blocking reserpine emesis. Metoclopramide was unable to antagonize reserpine-induced sedation and hypotension in rats, thus inviting discussion of its possible mechanism in blocking reserpine emesis.