Role of sympathetic nervous system in immobilization- and cold-induced brown adipose tissue thermogenesis in rats.

The role of the sympathetic nervous system in 10-min cold (5 degrees C)- or 2-min immobilization-induced thermogenesis in brown adipose tissue (BAT) was studied in warm (25 degrees C)-acclimated rats. Both cold- and immobilization-stresses increased heat production (M), interscapular brown adipose tissue temperature ( Tbat ), and colonic temperature ( Tcol ). Resulting from both stresses, the increase in Tbat was greater than that in Tcol , the differences (delta Tbat ) becoming approximately 0.48 and 0.46 degrees C by the cold exposure and the immobilization, respectively. After sympathectomy, Tbat and delta Tbat did not change on immobilization but increased significantly on the cold exposure. Delta Tbat was 0.31 degrees C in the sympathectomized rats at the end of the cold exposure period. Immobilization-induced BAT thermogenesis may be mainly controlled by the sympathetic nervous system. On the other hand cold-induced BAT thermogenesis seems to be controlled by certain hormonal factors as well as the sympathetic nervous system.