Adaptive changes in interscapular brown adipose tissue during reacclimation after cold: The role of redox regulation

1. The level of antioxidative defence, intensity of sympathetic innervation, expression of uncoupling protein 1 (UCP1), and ultrastructure of interscapular brown adipose tissue (IBAT) were studied in rats acclimated to room (22 +/- 1 degrees C), low temperature (4 +/- 1 degrees C, 45 days) and during reacclimation to 22 degrees C (days 1, 3, and 7). 2. The cold-induced increase in catalase, glutathione peroxidase, glutathione reductase, thioredoxin reductase, as well as a decrease in the activities of CuZn- and Mn-superoxide dismutases, shows specific dynamics of restitution during reacclimation to 22 degrees C. 3. The intensity of the cold-induced enhancement of the sympathetic innervation and UCPI expression gradually decreases during reacclimation to 22 degrees C, but with the seventh day level still higher compared to the animals acclimated to room temperature. 4. Electron-microscopy study of MAT shows that changes of the strongly activated tissue in cold undergo gradual restitution during reacclimation to 22 degrees C, but are observed already on the first day through a massive accumulation of glycogen, accompanied by a change in the lipid profile. (c) 2007 Elsevier Ltd. All rights reserved.