EFFECT OF NALOXONE AND ANTIDEPRESSANTS ON HYPERPHAGIA PRODUCED BY PEPTIDE-YY

Central injection of peptide YY (PYY) elicits a powerful feeding response with a short latency in satiated rats. Because of this effect, PYY has been implicated as a neurochemical signal in bulimia nervosa. Serotonin agonists and opioid antagonists induce anorectic effects upon feeding behavior in humans and animals. Therefore, to investigate a possible interaction between PYY-induced eating and these anorexigenic agents rats were given injections of either naloxone (100 mug/3 mul, ICV, and 10 mg/kg, SC), fluoxetine (3-30 mug/3 mul and 5-10 mg/kg, IP), or clomipramine (3-30 mug/3 mul and 5-10 mg/kg, IP) prior to fourth ventricular injections of PYY (15 mug/18 mul). Central and peripheral naloxone and IP but not central injections of fluoxetine blocked PYY-induced intake. Clomipramine had no effect. This suggests that PYY-stimulated feeding may require the action of endogenous opioids and may be inhibited by serotonergic function.