Effect of unpalatable diets, food restriction and saccharin-adulterated diet on tryptic, chymotryptic, and amylolytic activity in pancreas, intestine and feces of rats.

Growing rats were fed either 10 to 17% protein (casein) diets whose taste was changed daily by addition of aversive stimuli. Under these circumstances food intake and body weight gain were reduced compared with controls fed unadulterated diets. More amylolytic activity per gram pancreas was found in rats fed a 10% protein, aversive diet and in their pair-fed controls fed restricted amounts of an unadulterated diet compared with ad libitum controls. More amylolytic activity per gram chyme of small intestine was also found in rats fed less than ad libitum amounts of a 10% protein diet. The chymotrypsin activity in the pancreas of rats fed a 17% protein, aversive diet was greater than in that of control animals or that of the pair-fed animals. The 2- to 10-fold higher proteolytic activity found in the small intestine and especially in the large intestine and feces of rats fed the aversive diet was specifically related to the adulteration of the diet with sodium saccharin. Feeding a diet containing sodium saccharin led to lower cecal pH. Under conditions of the present experiments, changes in digestive enzyme activity are not directly related to the aversive taste of the diet.