Ingestion of potato starch decreases chymotrypsin but does not affect trypsin, amylase, or lipase activity in the pancreas in rats

Adaptation of digestive enzymes in the pancreas was evaluated in rats fed diets composed of potato starch as a carbohydrate source. Male Sprague-Dawley rats at 7 weeks were fed 4 different diets containing 60% sucrose, cornstarch, or 2 kinds of starch derived from different potato varieties. Enzyme activity in the pancreas of rats was determined at 0, 1, 3, and 5 weeks. Although amylase activity slightly increased with increasing pancreatic weights in all diet groups, there were no differences in amylase activity among diet groups throughout the experimental period. Although lipase activity increased abruptly from 1 to 3 weeks of feeding in all diet groups, there were no differences in lipase activity among the 4 diet groups throughout the feeding period. Trypsin activity was not affected by the type of diet or feeding period from 1 to 5 weeks. Chymotrypsin activities in rats fed the 2 potato starch diets were lower than those in rats fed the sucrose or cornstarch diet at 1, 3, and 5 weeks. These results indicate that ingestion of potato starch suppresses only chymotrypsin activity in the pancreas of rats. Although the mechanism is not clear at present, protease inhibitor in potato starch is probably involved in suppressing chymotrypsin activity in the rat pancreas in vivo.