INHIBITORY EFFECT OF THE ALPHA(1)-ADRENERGIC ANTAGONIST PRAZOSIN ON FOOD-INTAKE IN PYGMY GOATS

The effect of the intraperitoneally (IP) injected alpha(1)-adrenergic antagonist prazosin (15, 40, 130 and 537 mu g/kg b.wt.) on feed intake and plasma free fatty acid (FFA) levels was studied in 12 adult femal e African pygmy goats. Prazosin produced a dose-dependent long-lasting hypophagia and a dose-dependent increase in plasma FFA levels. The hy pophagic effect of prazosin and the elevation in plasma FFA induced by prazosin were abolished by concomitant injection of the beta-adrenerg ic antagonist propranolol (500 mu g/kg b.wt.). The hypophagic effect o f prazosin (40 mu g/kg) was also abolished by concomitant injection of the hypertonic agent angiotensin II (AII: 1 mu g/kg). The results sug gest that blockade of alpha(1)-adrenergic receptors by prazosin-produc ing hypotension elicits a counterregulatory sympathetic activation, wh ich reduces voluntary food intake by activation of beta-adrenergic rec eptors. The dose dependence of the inhibition of food intake and of th e elevation of plasma FFA after prazosin suggests that the hypophagia due to prazosin may be partly a consequence of elevated plasma FFA.