Oral Insulin Stimulates Intestinal Department and Enzyme Maturation in Newborn Pigs

The effects of oral insulin on intestinal tissue growth and brush border enzyme activities in newborn pigs were examined in this study. Newborn unsuckled pigs were bottle-fed for 3 days with artificial milk (M), milk supplemented with 60 mIUmL^-1 of insulin (IM) or hydrolyzed milk (HM). Compared with newborn unsuckled pigs, piglets bottle-fed for 3 days all gained in intestinal weight and length significantly despite a mild loss in body weight during the experimental period. The activities of lactase and alkaline phosphatase (AKP) in the small intestinal mucosa declined markedly in pigs fed with M, but the activity of maltase increased significantly during the experimental period. Dietary protein pre-hydrolysis had no significant effect on intestinal tissue mass or length,but it moderated the decline of intestinal lactase and AKP activities. Dietary supplementation of insulin significantly increased mucosal protein content and brush border activities of lactase, maltase, AKP and aminopeptidase (AP) in the small intestine.The effect of insulin treatment was particularly obvious at the distal region of the small intestine. These results demonstrate that oral insulin can stimulate intestinal digestive enzyme activities in newborn pigs. The finding supports the hypothesis that milk-borne insulin plays a role in regulating postnatal gut development in the suckling young.