Amylin and insulin interact to reduce food intake in rats

We investigated the hypothesis that amylin and insulin, hormones co-secrete d by pancreatic B-cells in response to a nutrient stimulus, interact to red uce food intake. A paradigm was employed that assessed food intake in adult male rats after bolus intravenous (i.v.) infusion at dark onset. In one ex periment, rats received saline or amylin (0.1, 0.5 or 1.0 nmol). All amylin doses significantly suppressed Ih intake, and although significant decreas es in cumulative intake persisted for 2 h after 0.5 and 1.0 nmol, a signifi cant increase of food intake actually occurred relative to saline during th e interval from 1 to 2 h postinfusion. In another experiment, rats received saline, 0.25 nmol amylin, 10 mU insulin, or the combination of amylin plus insulin. Neither amylin nor insulin alone significantly changed cumulative food intake at any time point as compared to saline. However, the combinat ion significantly reduced intake relative not only to saline but also to am ylin and insulin alone after 1, 2, and 4 hours. These data are consistent w ith the hypothesis that endogenous amylin and insulin interact to reduce fo od intake and, ultimately, body weight.