Abstract
Metallothionein (MT) is thought to have an antioxidant function and is strongly expressed during activation of thermogenesis and increased oxidative stress in brown adipose tissue (BAT). Localization and regulation of MT expression in BAT was therefore investigated in rats and mice. Immunohistochemical analysis of BAT from rats exposed to 4 degrees C for 24 h showed that MT and uncoupling protein 1 (UCP1) were coexpressed in differentiated adipocytes, and both cytoplasmic and nuclear localization of MT was observed. Cold induction of MT-1 expression in BAT was also observed in mice. Administration of norepinephrine to rats and isoproterenol to mice stimulated MT and UCP1 expression in BAT, implying a sympathetically mediated pathway for MT induction. In mice, zinc, and particularly dexamethasone, induced MT-2 expression in BAT and liver. Surprisingly, zinc also induced UCP1 in BAT, suggesting that elevated zinc may induce thermogenesis. We conclude that expression of MT in mature brown adipocytes upon beta-adrenoceptor activation is consistent with a role in protecting against physiological oxidative stress or in facilitating the mobilization or utilization of energy reserves.
Original language | English |
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Pages (from-to) | R1082-R1089 |
Number of pages | 8 |
Journal | American Journal of Physiology-Regulatory Integrative and Comparative Physiology |
Volume | 278 |
Issue number | 4 |
Publication status | Published - Apr 2000 |
Keywords
- uncoupling protein 1
- dexamethasone
- cold exposure
- thermogenesis
- oxidative stress
- ADIPOSE-TISSUE
- OXIDATIVE STRESS
- GENE-EXPRESSION
- UNCOUPLING PROTEIN
- RAT HEPATOCYTES
- NULL MICE
- LOCALIZATION
- CELLS
- THERMOGENESIS
- PARAQUAT