I. Ohara et al., THE EFFECT OF PALATABILITY AND FEEDING CONDITIONS ON DIGESTIVE FUNCTIONS IN RATS, Journal of the American College of Nutrition, 15(2), 1996, pp. 186-191
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.