Volume 50: 289-297, 2001

The Activity of Antioxidant Enzymes and the Content of Uncoupling Protein-1 in the Brown Adipose Tissue of Hypothyroid Rats: Comparison with Effects of Iopanoic Acid

N. PETROVIĆ, G. CVIJIĆ, V. DAVIDOVIĆ

Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Yugoslavia

Received April 27, 2000
Accepted October 13, 2000


Summary
The activity of antioxidant enzymes, copper-zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutase (MnSOD) and catalase (CAT), as well as that of the mitochondrial FAD-dependent a-glycerophosphate dehydrogenase (a-GPD) in the rat interscapular brown adipose tissue (IBAT) were studied after the treatment with methimazole (MMI) for three weeks or with iopanoic acid (IOP) for five days. Besides, the mitochondrial concentration of uncoupling protein-1 (UCP-1) and the activity of catecholamine degrading enzyme monoamine oxidase (MAO) in the IBAT as well as the activity of the catecholamine synthesizing enzyme, dopamine b-hydroxylase (DBH) in rat serum were examined. Judging by the significantly enhanced level of serum DBH, which is an index of sympathetic activity, and that of IBAT MAO, the increase in MnSOD and CAT activities in the IBAT of hypothyroid (MMI-treated) rats seems to be due to elevated activity of sympathetic nervous system (SNS). However, CuZnSOD activity is not affected by SNS. On the contrary, IOP, which is a potent inhibitor of T4 deiodination into T3 producing "local" hypothyroidism, did not change either SNS activity or activities of IBAT antioxidant enzyme. However, both treatments significantly decreased IBAT UCP-1 content and a-GPD activity suggesting that the optimal T3 concentration in the IBAT is necessary for maintaining basal levels of these key mitochondrial parameters.


Key words
Brown adipose tissue · Hypothyroidism · Rat · Antioxidant enzymes · Uncoupling protein

Reprint requests
Vukosava Davidović, Institute of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Studentski trg 16, 11000 Belgrade, Yugoslavia. Fax: 381 11 639 064, e-mail:
vukana@bf.bio.bg.ac.yu

PHYSIOLOGICAL RESEARCH
© 2001 by the Institute of Physiology, Czech Academy of Sciences

ISSN 0862 - 8408

Issue 3