Effect of long-term exercise under restricted-feeding on intestinal content of cholecystokinin and on the pancreas in aging rats.

The effects of exercise (5000 m/day running from 100 to 600 days of age) on the cholecystokinin (CCK) content in the proximal intestine, and the enzyme and insulin contents of the pancreas were examined in food-restricted rats. Food restriction decreased the body weight and the wet weights of the pancreas and proximal intestine but not the wet weight of the stomach. Food restriction also decreased the chymotrypsin content of the pancreas but not its amylase content. The contents of enzymes in the pancreas were not affected by exercise. The insulin content of the pancreas was lower in lean rats produced by food restriction and/or exercise than in controls. Exercise increased the wet weight of the proximal intestine and the CCK content of the intestine. The increase in the CCK content may be due to compensational change in the efficiency of digestion of luminal nutrients induced by exercise.