THE EFFECTS OF STREPTOZOTOCIN DIABETES ON SODIUM-GLUCOSE TRANSPORTER (SGLT1) EXPRESSION AND FUNCTION IN RAT JEJUNAL AND ILEAL VILLUS-ATTACHED ENTEROCYTES

Rats treated with streptozotocin for 17 days were used to determine th e cellular origin of enhanced brush border glucose transport in the di abetic small intestine. In the jejunum of both normal and diabetic rat s, phlorizin-sensitive (SGLT1-mediated) glucose transport was shown, b y section autoradiography, to take place in upper villus enterocytes. The distribution of brush border SGLT1 transporters along villi, deter mined using immunogold cytochemistry, was similar to that found for gl ucose uptake. Longer villi, supporting a larger number of absorbing en terocytes in the diabetic jejunum, appeared to be responsible for incr eased glucose uptake in this condition. SGLT1 protein and SGLT1-mediat ed glucose transport were undetectable in normal distal ileal villi. H owever, following treatment with streptozotocin, both SGLT1 protein an d SGLT1-mediated glucose transport were found to be present in basal i leal villus enterocytes. SGLT1 protein and SGLT1-mediated glucose tran sport both increased during enterocyte migration to the villus tip. Ce llular induction of the SGLT1 transporter, as well as longer villi con tribute to enhanced glucose transport in diabetic rat distal ileum. Cl ose correlation between the positional expression of SGLT-1 protein an d absorptive function suggests that transporter density is an importan t determinant for up-regulation of sodium-dependent glucose transport in diabetes.