PRESENCE OF LEPTIN RECEPTORS IN RAT SMALL-INTESTINE AND LEPTIN EFFECTON SUGAR ABSORPTION

Leptin is involved in food intake and thermogenesis regulation. Since leptin receptor expression has been found in several tissues including small intestine, a possible role of leptin in sugar absorption by the intestine was investigated. Leptin inhibited D-galactose uptake by ra t small intestinal rings 33% after 5 min of incubation. The inhibition increased to 56% after 30 min. However, neither at 5 min nor at 30 mi n did leptin prevent intracellular galactose accumulation. This leptin effect was accompanied by a decrease of the active sugar transport ap parent V-max (20 vs. 4.8 mu mol/g wet weight 5 min) and apparent K-m ( 15.8 vs. 5.3 mM) without any change in the phlorizin-resistant compone nt. On the other hand, immunohistochemical experiments using anti-lept in monoclonal antibodies recognized leptin receptors in the plasma mem brane of immune cells located in the lamina propria. These results ind icate for the first time that leptin has a rapid inhibitory effect on sugar absorption and demonstrate the presence of leptin receptors in t he intestinal mucosa. (C) 1998 Federation of European Biochemical Soci eties.