Fructose-rich diet and walnuts supplementation differentially regulates hypothalamic and hippocampal glucose transporters expression

Abstract

Introduction: Metabolic syndrome (MS) is a major health risk challenge. Previous studies have shown that fructose-rich diet can induce MS whereas a nut-rich diet may reduce the risk of developing MS. The aim of this study was to examine the effects of fructose-rich diet and walnuts supplementation on the glucose transporters (GLUT) expression in rat hypothalamus and hippocampus. Methods: Male Wistar rats were divided into four groups: (C) - standard chow diet and drinking water; (F) - standard chow and drinking water supplemented with fructose (10%) during 15 weeks; (CW) - standard diet supplemented with 2,4 g of walnuts during the last 6 weeks of the experiment; (FW) - standard chow and drinking water supplemented with fructose (10%) during 15 weeks whereas in the last 6 weeks standard diet was supplemented with walnuts. Hypothalamic and hippocampal membrane protein fraction was isolated using the subcellular protein fractionation kit. The amount of GLUT1, 2 and 3 was measured by Western blot method. Results: In the rat hypothalamus, all treatments increased GLUT1 and GLUT2 protein levels, whereas GLUT3 was increased only in CW and F groups. In the rat hippocampus, GLUT1 content was increased only in FW group, whereas GLUT3 level was decreased in the same group. Decreased amount of membrane GLUT2 was detected in hippocampal tissue of all experimental groups. Conclusion: Fructose-rich diet and walnuts supplementation increased membrane GLUT1 content in rat hypothalamus and hippocampus. In contrast, GLUT2 and GLUT3 membrane content in examined brain regions was differently regulated under applied dietary regimes.