MODIFICATIONS OF GLUCOSE AND LIPID-METABOLISM IN COLD-ACCLIMATED LEANAND GENETICALLY-OBESE RATS

Modifications of glucose and lipid metabolism in cold-acclimated lean and genetically obese rats. J. Appl. Physiol. 76(3): 1106-1112, 1994. - Glucose turnover rate, 2-deoxy-D-[H-3]glucose (2-DG) uptake, lipid s ynthesis in liver, white adipose tissue, and brown adipose tissue (BAT ) were measured in lean FA/FA and genetically obese fa/fa rats either kept at 21 degrees C or acclimated to a cold environment (4 degrees C) . After 10 days at 4 degrees C, lean rats increased their glucose turn over rate; 2-DG uptake as well as lipid synthesis in BAT were markedly stimulated. After cold acclimation, obese rats also increased glucose turnover; however, BAT glucose utilization was only slightly stimulat ed. Basal hyperinsulinemia and muscle insulin resistance of the obese group (as assessed by reduced 2-DG uptake in the soleus muscle) were p resent at room temperature and persisted at 4 degrees C. Total BAT lip id synthesis was increased to the same extent as in lean rats. Obese r at liver lipid synthesis, already much higher than normal at 21 degree s C, was further increased by cold exposure. We conclude that obese co ld-acclimated fa/fa rats do not improve their muscle insulin resistanc e and barely improve BAT glucose utilization. We further suggest that an additional activation of hepatic lipid synthesis and oxidation ther eof could participate in the heat production needed by the cold-acclim ated obese rats.