REDUCED CONTENT AND PRESERVED TRANSLOCATION OF GLUCOSE-TRANSPORTER (GLUT-4) IN WHITE ADIPOSE-TISSUE OF OBESE MICE

We investigated glucose transporters (GLUT 1 and GLUT 4) in subcellular membrane fractions of white adipose tissue (WAT) of insulin-resistant obese aurothioglucose (AuTG)- or monosodium glutamate (MSG)-treated mice. In vivo insulin stimulation (0.75 U/kg, EV) promoted, 10 min later, no significant change on glycemia of both AuTG and MSG obese mice, but control mice showed a decrease of 30% (p<0.001). Basal GLUT 4 content in WAT of obese mice was reduced by 40% (p<0.001) when compared to that of nonobese mice. Insulin-stimulated GLUT 4 content was significantly (p<0.01) higher in plasma membrane fraction and lower in microsomal fraction when compared to respective basal values, in all groups. Although the absolute values of GLUT 4 were lower in membrane fractions of obese mice, the relative changes stimulated by insulin were similar among the groups. No effect of obesity or insulin stimulation was observed upon GLUT 1 content. We conclude that WAT of insulin-resistant obese AuTG- and MSG-treated mice has a decreased GLUT 4, but not GLUT 1, content, and the in vivo insulin-stimulated GLUT 4 translocation is preserved.