EFFECTS OF DUODENAL AND DISTAL ILEAL INFUSIONS OF GLUCOSE AND OLEIC-ACID ON MEAL PATTERNS IN RATS

The mechanisms mediating the anorexic effects of nutrients in the prox imal and distal small intestine are not clearly understood. We determi ned the dose-dependent effects of duodenal and distal ileal infusions of glucose and oleic acid on meal patterns in ad libitum feeding rats. Rats with cannulas in both the duodenum and ileum received a 2-h infu sion of glucose (0, 800, 1,600, 3,200, 6,400, or 12,800 mu mol/h) or o leic acid (0, 48, 240, 640, or 1,280 mu mol/h) into the duodenum or il eum at the start of the dark period, and meal patterns were monitored for 4 h. Cumulative food intake was inhibited dose dependently by ilea l as well as duodenal infusion of both glucose and oleic acid. Ileal g lucose was more inhibitory than duodenal glucose, whereas duodenal ole ic acid was more inhibitory than ileal oleic acid. Duodenal glucose an d oleic acid inhibited feeding by decreasing meal frequency; ileal ole ic acid decreased only meal size, whereas ileal glucose reduced both m eal size and frequency. We interpret these results to suggest that ile al oleic acid and glucose suppress feeding by different mechanisms and that these mechanisms differ from those mediating the anorexic respon ses to oleic acid and glucose in the duodenum.