Abstract
ABSTRACT: Intestinal lactase activity is maintained at high levels in suckling rats during the first 2 wk after birth. When 12-day-old rat pups were either mother fed (MF) or artificially reared (AR) with natural rat milk or several artificial formulas, the small intestines had gained similar weight in all animal groups by 16 days except in AR rats fed a chemically defined formula. In the ileum, villus length was similar in MF and AR rats, but crypt depth was significantly higher in all groups of AR rats. Heal absorptive cells in both MF and AR rats showed immature characteristics, including supranuclear vacuoles, apical tubular systems, and pinocytotic vesicles. Jejunal lactase specific activity and total intestinal lactase activity were significantly higher in AR rats fed rat milk than MF rats at 16 days. Heal lactase specific activity was similar in these two animal groups. In contrast, AR rats fed artificial formulas supplemented with either glucose or lactose as the sole carbohydrate source exhibited significantly lower ileal lactase specific activity and total intestinal lactase activity than MF rats. Intestinal sucrase activity was prematurely elevated in all AR rats, even when fed natural rat milk. Addition of prolactin (3.3 μg/ml) to an artificial formula did not prevent the premature decrease in intestinal lactase specific and total activities in AR rats. We conclude that (1) natural rat milk plays a cardinal role in maintaining lactase activity during the suckling period; (2) the lactose and prolactin content of rat milk are not essential components in maintaining lactase activity in AR rat pups; and (3) the artificial feeding procedure, rather than dietary composition, induces premature elevation of sucrase activity.
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Yeh, KY., Holt, P. Rat Milk Maintains Intestinal Lactase Activity in Rat Pups whereas Artificial Formulas Do Not. Pediatr Res 19, 963–967 (1985). https://doi.org/10.1203/00006450-198509000-00019
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DOI: https://doi.org/10.1203/00006450-198509000-00019