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 micrograms/kg b.wt.) on feed intake and plasma free fatty acid (FFA) levels was studied in 12 adult female African pygmy goats. Prazosin produced a dose-dependent long-lasting hypophagia and a dose-dependent increase in plasma FFA levels. The hypophagic effect of prazosin and the elevation in plasma FFA induced by prazosin were abolished by concomitant injection of the beta-adrenergic antagonist propranolol (500 micrograms/kg b.wt.). The hypophagic effect of prazosin (40 micrograms/kg) was also abolished by concomitant injection of the hypertonic agent angiotensin II (AII: 1 microgram/kg). The results suggest that blockade of alpha 1-adrenergic receptors by prazosin-producing hypotension elicits a counterregulatory sympathetic activation, which reduces voluntary food intake by activation of beta-adrenergic receptors. The dose dependence of the inhibition of food intake and of the elevation of plasma FFA after prazosin suggests that the hypophagia due to prazosin may be partly a consequence of elevated plasma FFA.
Institut für Veterinär-Physiologie, Universität Zürich, Switzerland.
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D020155:3-Hydroxybutyric Acid; D058668:Adrenergic alpha-1 Receptor Antagonists; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D006041:Goats; D006885:Hydroxybutyrates / Q000097:blood; D011224:Prazosin / Q000008:administration & dosage / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology
D058668:Adrenergic alpha-1 Receptor Antagonists; D005230:Fatty Acids, Nonesterified; D006885:Hydroxybutyrates; D018340:Receptors, Adrenergic, alpha-1; D011943:Receptors, Adrenergic, beta; D011433:Propranolol; D020155:3-Hydroxybutyric Acid; D011224:Prazosin