Jh. Beattie et al., COLD-INDUCED EXPRESSION OF THE METALLOTHIONEIN-1 GENE IN BROWN ADIPOSE-TISSUE OF RATS, American journal of physiology. Regulatory, integrative and comparative physiology, 39(5), 1996, pp. 971-977
Heat production by brown adipose tissue (BAT) is important for thermor
egulation in a cold environment. During thermogenesis, oxygen utilizat
ion increases, with an associated rise in free radical generation. Our
objective was to investigate the expression of metallothionein (MT),
which is thought to have an antioxidant Sole in BAT of rats transferre
d from 25 to 6 degrees C for 6 or 24 h or maintained at 25 degrees C t
hroughout the study (control group). For comparison, MT expression was
also measured in white adipose tissue (WAT), liver, and kidney. MT-1
mRNA and 18S rRNA were measured by Northern blotting using specific di
goxigenin-labeled antisense oligonucleotide probes with chemiluminesce
nce detection, and MT-1 protein was determined by radioimmunoassay. MT
-1 mRNA in BAT increased after 6 h, and the mRNA level after 24 h was
equivalent to that in liver 6 h after injection of rats with 10 mg Zn/
kg. By 24 h, liver and kidney MT-1 protein had increased relative to t
he controls by 3- and 1.4-fold, respectively, but in BAT the relative
induction was 16-fold. Zn injection did not affect BAT MT-1. As with M
T-1-protein protein, Zn in BAT increased only after 24-h cold exposure
. WAT MT-1 was not affected by any treatment. It is concluded that col
d exposure induces MT-1 in BAT, but in contrast to other tissues induc
tion may be independent of Zn.