The Characteristics of Nonshivering Thermogenesis and Cellular Respiration in The Tree Shrews

The nonshivering thermogenesis (NST) of the tree shrew (Tupaia belangeri chinensis) was measured with Kalabukov-Skvortsov respirometer within thermal neutral zone (30℃) by a subcutanueous injection of noradrenaline at different seasons,and some biochemical characteristics of cellular respiration were measured at the same time.The maximum nonshivering thermogenesis (NSTmax) was 2.57±0.21 in winter and 2.21±0.12mlO2/g·h in summer,which were 75.9% and 61.2% of the value expected from NSTmax=30W-0.45 (Heldmaier,1971),respectively,The NSTmax was.lower than that of small mammals in the temperate zone,higher than that of which in the tropics,and its seasonal variation was significant (P<0.001).The weight of brown adipose tissue (BAT) was not only different significantly between winter (0.623±0.015 g) and summer (0.532±0.08 g),but also its thermogenic activities were differntial obviously.The total and mitochondrial protein,the activity of cytochrome C oxidase and α-glycero-phosphate oxidse of BAT were obviously hiher in winter than in summer,But these biochemical indexes in the liver maintained a constant in both seasons.It was obvious that the NSTmax and the activity of BAT showed acclimatization to the seasons,which was responsible for the geographical distributions of the tree shrew,Its thermoregulatory patterns,therefore,appeared to be a transitive type from the tropic to the temperate zone.