DIFFERENTIAL REGULATION OF UNCOUPLING PROTEINS BY CHRONIC TREATMENTS WITH BETA(3)-ADRENERGIC AGONIST BRL-35135 AND METFORMIN IN OBESE FA FAZUCKER RATS/

The expressions of uncoupling proteins 2 and 3 (UCP2; UCP3) mRNA were studied in obese (fa/fa) Zucker rats treated with two weight gain redu cing agents for three weeks. The specific beta(3)-adrenoceptor agonist BRL 35135 (0.5 mg/kg/day orally) increased the expression of UCP3 mRN A by 3.8-fold (P < 0.0001; two-way ANOVA) and that of UCP1 mRNA by 2.6 -fold (P = 0.014) in brown adipose tissue, but had no effect on expres sion of UCP3 mRNA in white fat or in the soleus muscle, or on UCP2 mRN A expression in brown or white fat. The antihyperglycemic metformin (3 00 mg/kg/day orally) had no effect on expressions of UCP1, UCP2 or UCP 3 in any tissue studied. Concentrations of plasma insulin were signifi cantly correlated with the levels of white fat UCP2 mRNA tin the contr ol group: r = 0.89, P = 0.0015) and UCP3 mRNA tin the control group: r = 0.80, P = 0.009) suggesting that insulin may play a role in the con trol of UCP2 and UCP3 mRNA expressions in white adipose tissue. (C) 19 98 Academic Press.