Chronic infusion of the amylin antagonist AC 187 increases feeding in Zucker fa/fa rats but not in lean controls.

Numerous studies have established the pancreatic B-cell hormone amylin as an important anorectic peptide affecting meal-ending satiety. In the present study, we investigated the effect of a chronic infusion of the amylin antagonist AC 187 on food intake. The studies were performed using obese Zucker fa/fa rats, which are hyperamylinemic but have a defective leptin and insulin signaling system. A chronic intraperitoneal infusion of the amylin antagonist AC 187 (10 microg/kg/h) significantly increased dark phase and total food intake in Zucker but not in lean control rats. During the 8-day infusion experiment, AC 187 had no clear effect on body weight gain in either group. After acute administration, amylin and its agonist salmon calcitonin (sCT) equally reduced food intake in Zucker and lean control rats while cholecystokinin's (CCK) anorectic effect was weaker in the Zucker rats. We provide evidence for amylin being a potential long-term regulator of food intake because AC 187 increased food intake in obese fa/fa rats but not in lean control animals, which have low baseline amylin levels. Amylin may play some role as lipostatic feedback signal similar to leptin and insulin at least when the leptin and insulin feedback signaling systems are deficient. Despite basal hyperamylinemia in the Zucker rats, they do not seem to be less sensitive to the anorectic effects of amylin or its agonist sCT than respective controls. This contrasts with CCK whose anorectic action is reduced in Zucker rats when compared with lean controls.