EARLY DECREASE IN GLUT4 PROTEIN-LEVELS IN BROWN ADIPOSE-TISSUE OF NEW-ZEALAND OBESE MICE

The aim of this study was to determine if the previously described ins ulin resistance in the New Zealand Obese (NZO) mouse is associated wit h a decrease in GLUT4 protein and if such changes occur early in the e volution of the syndrome. GLUT4 levels were measured in whole membrane s isolated from a variety of tissues in 4 and 20-week-old NZO and cont rol NZC mice by Western blotting using a specific antibody to the C te rminal end of the protein. At 20 weeks of age, GLUT4 levels were lower in the NZO mice in brown and white adipose tissue, heart, diaphragm, red and white quadriceps, and red and white gastrocnemius, but not in soleus muscle. At 4 weeks of age, GLUT4 levels were 52% lower in BAT ( 3309 +/- 1006 vs 6951 +/- 1870 cpm P = 0.039) but were not lower in WA T, heart or red quadriceps. It is concluded that adult NZO mice have a decrease in GLUT4 levels in most insulin-sensitive tissues and that i n BAT, this occurs at an early age.