DEXAMETHASONE PRECOCIOUSLY INDUCES INTESTINAL SUGAR TRANSPORT IN SUCKLING RATS † 474

Abstract

During normal development, intestinal fructose transport is enhanced only in postweaning (>28d) rats. Early introduction of a high fructose diet enhances fructose absorption in weaning (14-28d) but not in suckling (<14d) rats. In contrast, glucose absorption is independent of diet in both weaning and suckling stages. In this study, we determined whether Dexamethasone (DEX) would allow dietary induction of sugar transport in suckling rats. DEX, 0.4ug/g body weight (BW), was administered i.p. once daily to rat pups from d 5-9. Pups were gavage-fed on d 8-9 with sugar solutions containing high fructose (HF) and high glucose (HG) at a volume of 2% BW 2X per d. Pups stayed with dams at all other times. Control litter mates were fed similar solutions but received phosphate buffer i.p. instead of DEX. On d 10, pups were sacrificed and intestinal uptake studies using the everted sleeve technique were performed. Two-way analysis of variance (ANOVA) showed that fructose uptake increased 3X in DEX-treated pups fed HF (P<0.0001) but only 2X in DEX-treated pups fed HG (P<0.0001) over control. There was also a 2X significant increase in glucose uptake in DEX-treated pups fed HG(P<0.0001) and HF (P<0.0001). Uptakes were 2-3X greater in the proximal and middle than in the distal small intestine. DEX-treated pups failed to gain weight compared to control (P<0.0001). There was no statistically significant difference in intestinal lengths and weights across treatment groups. DEX therefore non-specifically enhances transport of nutrients and also allows specific induction of fructose transporters by its substrate. The proximate mechanism of this DEX effect remains unclear and is a subject of future research.