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
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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
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