中缅树鼩的非颤抖性产热及细胞呼吸特征

THE CHARACTERISTICS OF NONSHIVERINGTHERMOGENESIS AND CELLULAR RESPIRATIONIN THE TREE SHREWS

中缅树鼩(Tupaia belangeri chinensis)是东南亚树鼩中分布最北的一个种。在热中性区内的非颤抖性产热(nonshivering thermogenesis NST)分别为2.57±0.21(冬)和2.21±0.12(夏)mlO_2/(g·h);分别为体重预期值的75.9％和61.2％,两者不仅冬季显著高于夏季,而且亦高于典型的热带种类,但低于温带类群。褐色脂肪组织(brown adipose tissue,BAT)的重量冬季为0.622±0.015 S,夏季0.532±0.80 g,冬季也显著高于夏季;同时,BAT总蛋白含量、线粒体蛋白含量以及细胞α-磷酸甘油氧化酶和细胞色素C氧化酶活性,冬季也显著高于夏季,但增加的比例较温带种类低;而肝脏细胞的上述指标及线粒体状态Ⅲ、状态Ⅳ呼吸等,冬夏两季均无显著差异。因此,中缅树鼩的NST和细胞产热能力介于热带与温带类群之间,显示出向温带类型过渡的趋势。

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 diffe-rent 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), res-pectively, 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±0.08g), but also its thermogenic activities were differntial obviously. The total and mitochondrial protein, the activity of cytochrome C oxidase and α-glycero-phosphate oxidase 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 ofthe tree shrew, Its thermoregulatory patterns, therefore, appeared to be a transitive type from the tropic to the temperate zone.