The Miniature Pig as an Animal Model for the Study of Intestinal Enzyme Development

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Abstract
Studies of intestinal enzyme development and regulation relevant to the human infant require an animal model with a rate of maturation similar to that of the human infant. Hanford miniature pigs were weaned at 3 days of age to a standard swine weaning formula. At 1, 2, 3, 4, 5, and 6 wk of age, duodenal jejunal, and ileal segments were analyzed for protein content and lactase, sucrase, maltase, glucoamylase, and acid β-galactosidase activities. Protein content of the small intestine changed significantly with age only in the ileum (p < 0.05). Lactase activity fell significantly with age in all segments of the small intestine (p < 0.001); activity was highest in the jejunum. Sucrase and maltase activities were present in all segments of the small intestine at 1 wk of age. Sucrase increased significantly (2-fold, p < 0.02) with age only in the ileum and maltase increased significantly with age in the jejunum (by 50%, p < 0.05) and the ileum (3-fold, p < 0.001). Activities were highest in the jejunum. Glucoamylase activity was present at 1 wk of age and showed a small but significant increase with age only in the duodenum (p < 0.005). Acid β-galactosidase activity demonstrated small but significant decreases with age in all small intestinal segments. Glucoamylase and acid β-galactosidase activities were similar in all segments. In the 6-wk-old pigs, activities of all the enzymes tested were similar to those found in young human infants. Our data demonstrate that the small intestinal enzyme development of the infant miniature pig is more advanced postnatally than other more commonly used animal species. The degree of small intestinal maturation and the similar intestinal enzyme distribution compared with that of the human infant suggest that the infant miniature pig is an excellent model for studies of intestinal enzyme development and regulation.