TISSUE-DEPENDENT UP-REGULATION OF RAT UNCOUPLING PROTEIN-2 EXPRESSIONIN RESPONSE TO FASTING OR COLD

The control of uncoupling protein-2 (UCP2) mRNA expression in rat brow n adipose tissue (BAT), heart and skeletal muscles was examined, Cold exposure (48 h) increased UCP2 mRNA in BAT, heart and soleus muscle by 2.4-, 4.3- and 2.6-fold, respectively, Fasting (48 h) had no effect o n UCP2 mRNA expression neither in BAT nor in heart, but markedly incre ased it in skeletal muscles, While the upregulation of UCP2 mRNA in re sponse to cold exposure is in line with a putative uncoupling role for this protein in thermoregulatory thermogenesis, the unexpected upregu lation of UCP2 in skeletal muscles in response to fasting seems incons istent with its role as an uncoupling protein involved in dietary regu lation of thermogenesis. (C) 1997 Federation of European Biochemical S ocieties.