THE EFFECT OF PALATABILITY AND FEEDING CONDITIONS ON DIGESTIVE FUNCTIONS IN RATS

Objective: Information concerning various post prandial gastrointestin al functions modulated by taste stimulation is rather limited. Thus, e ffects of different types of palatability and feeding condition on dig estive functions were studied. Methods: Male Sprague-Dawley rats were divided into two different feeding groups, meal feeding and ad libitum . In meal feeding, the daily feeding period was shortened gradually an d was restricted eventually only 3 hours. In ad libitum feeding, food was freely available for 24 hours until experiment. After each rat in both feeding groups was fed 8.29mM saccharin or 1.28mM quinine flavore d diet as a taste stimulant for 15 minutes, changes of gastric and int estinal nitrogen and pH and pancreatic amylase activities were compare d with meal feeding vs ad libitum feeding. Results: In meal feeding, n o difference was observed between before and after taste stimulation o r between saccharin and quinine flavored diets on gastric and intestin al nitrogen contents, pH in the stomach and in the small intestine, an d amylase activity. On the other hand, in ad libitum feeding, intestin al nitrogen contents tended to stagnate until 60 minutes after tasting quinine, although there was little difference between saccharin and q uinine diets on gastric nitrogen Contents. Gastric juice was hardly se creted before tasting (pH 6.2) and then pH in the stomach changed to b ecome more acid following taste stimulation. Although amylase secreted in small intestine was hardly secreted before tasting,activities afte r tasting saccharin were increased immediately and lasted until 120 mi nutes. Amylase activity in rats fed the quinine diet, however, showed slower increase and faster recovery than that in rats fed the sacchari n diet. Conclusions: The results confirmed that various postingestive functions after taste stimulation depend on feeding conditions and it suggests that the ad libitum feeding condition is more appropriate tha n meal feeding on the experiment related to gustatory response.