Effects of amylin-related peptides on food intake, meal patterns, and gastric emptying in rats

2001.—We previously demonstrated that amylin inhibits food intake and gastric emptying in rats with half-maximal effective doses (ED50s) of 8 and 3 pmol kg1 min1 and maximal inhibitions of 78 and 60%, respectively. In this study of identical design, rats received intravenous infusions of salmon calcitonin (sCT), rat calcitonin (rCT), rat calcitonin gene-related peptide (rCGRP), and rat adrenomedullin (rADM) for 3 h at dark onset, and food intake was measured for 17 h or for 15 min and gastric emptying of saline was measured during the final 5 min. sCT, rCGRP, and rADM inhibited food intake with estimated ED50s of 0.5, 26, and 35 pmol kg1 min1 and maximal inhibitions of 88, 90, and 49%, respectively. rCT was not effective at doses up to 100 pmol kg1 min1. sCT, rCGRP, rADM, and rCT inhibited gastric emptying with ED50s of 1, 130, 160, and 73

Role of Capsaicin-Sensitive Peripheral Sensory Neurons in Anorexic Responses to Intravenous Infusions of Cholecystokinin, Peptide YY-(3–36), and Glucagon-Like Peptide-1 in Rats

Cholecystokinin (CCK)-induced suppression of feeding is mediated by vagal sensory neurons that are destroyed by the neurotoxin capsaicin (CAP). Here we determined whether CAP-sensitive neurons mediate anorexic responses to intravenous infusions of gut hormones peptide YY-(3–36) [PYY-(3–36)] and glucagon-like peptide-1 (GLP-1). Rats received three intraperitoneal injections of CAP or vehicle (VEH) in 24 h. After recovery, non-food-deprived rats received at dark onset a 3-h intravenous infusion of CCK-8 (5, 17 pmol·kg−1·min−1), PYY-(3–36) (5, 17, 50 pmol·kg−1·min−1), or GLP-1 (17, 50 pmol·kg−1·min−1). CCK-8 was much less effective in reducing food intake in CAP vs. VEH rats. CCK-8 at 5 and 17 pmol·kg−1·min−1 reduced food intake during the 3-h infusion period by 39 and 71% in VEH rats and 7 and 18% in CAP rats. In contrast, PYY-(3–36) and GLP-1 were similarly effective in reducing food intake in VEH and CAP rats. PYY-(3–36) at 5, 17, and 50 pmol·kg−1·min−1 reduced food intake during the 3-h infusion period by 15, 33, and 70% in VEH rats and 13, 30, and 33% in CAP rats. GLP-1 at 17 and 50 pmol·kg−1·min−1 reduced food intake during the 3-h infusion period by 48 and 60% in VEH rats and 30 and 52% in CAP rats. These results suggest that anorexic responses to PYY-(3–36) and GLP-1 are not primarily mediated by the CAP-sensitive peripheral sensory neurons (presumably vagal) that mediate CCK-8-induced anorexia