Dietary lipid modulation of Na +/glucose co-transporter (SGLT1), [formula omitted] ATPase, and ornithine decarboxylase gene expression in the rat small intestine in diabetes mellitus

Abstract

Nutrient transport is increased in streptozotocin-induced diabetes mellitus (DM) in rats. Variations in dietary lipid composition have been shown to modulate nutrient transport during intestinal adaptation in DM. Here, we examined Na +/glucose cotransporter (SGLT1), Na +,K +-ATPase and ornithine decarboxylase (ODC) gene expression in the small intestine in DM. One week after the animals had been given streptozotocin or injected with vehicle, they were randomly allocated to receive either standard chow or semisynthetic isocaloric diets with triglycerides enriched with polyunsaturated fatty acid (PUFA) or saturated fatty acid (SFA). Two weeks later they were killed and brush border membrane (BBM) and basolateral membrane (BLM) fractions and RNA were isolated from the mucosa of the proximal and distal small intestine. Western and Northern blotting were performed with antibodies and cDNA probes specific to SGLT1, the Na +,K +-ATPase α 1 and β 1 subunit isoforms, and ODC. Increased levels of immunodetectable SGLT1, Na +,K +-ATPase α 1 and β 1 subunit, and ODC expression and their corresponding mRNAs were observed in DM versus control rats fed chow. All of these parameters were increased in diabetic and in nondiabetic rats fed SFA as compared with PUFA. These findings suggest that the increased glucose uptake in diabetes, and in response to feeding a saturated as compared with a polyunsaturated diet, is achieved by transcriptional events that modulate transport function and cell proliferation.