Abstract
Long-term cold exposure resulted in good effects on lipid metabolism and energy balance of obese rats. However, different effects were observed between obese rats: OLETF and obese Zucker rats, in food intake, weight-reducing effect through growth, morphology of brown adipose tissue (BAT) and amount of adipocytokines in blood and adipose tissues. In this time we analyzed changes in blood lipids and hormones, and expressions of UCP1, GLUT4, insulin receptor, leptin receptor and PGC1 of BAT by Western blot analysis in OLETF and LETO (lean) rats. Methods: Male OLETF and LETO rats aged 7 weeks were allocated into 3 groups; 25°C for 11 weeks (W group), 10°C for 11 weeks (C group) after acclimation to 10°C for 9 weeks and 25°C for 2 weeks (D group). BAT was isolated after 11 weeks acclimation and analyzed mass value and morphological change. Results: Serum lipid levels of OLETF were higher than those of LETO, similar tendency as in Zucker fatty rats but their degree was not so remarkable. They were decreased during cold acclimation. Changes in amount of UCP1 in BAT during cold acclimation and deacclimation were similar to those of Zucker rats, but amount of UCP1 in W group was relatively high in OLETF and increase during cold acclimation was not so strikingly. Expressions of GLUT4, insulin receptor and PGC1 of BAT were differentially expressed among OLETF/LETO rats and obese/lean Zucker rats during cold acclimation and deacclimation. [J Physiol Sci. 2007;57 Suppl:S194]
