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 °C), low temperature (4±1 °C, 45 days) and during reacclimation to 22 °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 °C.3.The intensity of the cold-induced enhancement of the sympathetic innervation and UCP1 expression gradually decreases during reacclimation to 22 °C, but with the seventh day level still higher compared to the animals acclimated to room temperature.4.Electron-microscopy study of IBAT shows that changes of the strongly activated tissue in cold undergo gradual restitution during reacclimation to 22 °C, but are observed already on the first day through a massive accumulation of glycogen, accompanied by a change in the lipid profile.