小哺乳动物在高寒环境中的生存对策 Ⅰ.高原鼠兔和根田鼠褐色脂肪组织(BAT)重量和显微结构的季节性变化

STRATEGIES FOR SURVIVAL IN A COLD ALPINE ENVIRONMENT OF SMALL MAMMALS Ⅰ. SEASONAI VARIATIONS IN THE WEIGHT AND STRUCTURE OF BROWN ADIPOSE TISSUE IN OCHOTONA CUrZONIAE AND MlCROTUS OECONOMUS

本文研究了高寒草甸生态系统中两种非冬眠草食性哺乳动物——高原鼠兔和根田鼠的褐色脂肪组织(BAT)的重量和显微结构的季节性变化,结果表明严寒季节BAT增多、BAT细胞中的脂肪滴小而多、线粒体增大及嵴数目增多,温暖季节较低,这些变化与产热需要有关。

The variations ot scapular (including interscapular and subseapular) brown adipose tissue (BAT) in weight and histology with season and body weight were studied in plateau pika (Ochotona curzontae) and root vole(Microtus oeconomus), at Haibei Alpine Meadow Ecosystem Research Station at an altitude of about 3200 meters at Menyuan, Qinghai Province, from May of 1987 to July, 1988. Plateau pikas and root voles were caught each month and their relative weight of BAT (mass of BAT as a percentage of total BW0.73) were caculated and some month samples were used to make sections for light and electron microscopic investigations. The main results are as follows: 1. The relative weight of BAT decreased with increasing body weight in growing and developing period in both O.curzoniae and M. ceconomus. It has a inversely rela-tionship between BAT weight and body weight. 2. Seasonal changes in the relative weight of BAT were inversely related to season-al changes in ambient temperature. The relative weight of BAT was lowest in June (0.9458%W0.73) and increased rapidly to 3.6624%W0.73 in January in O.curzoniae. Similarly, M.oeconomus had their lowest value of relative weight of BAT in June (0.6829%W0.73) and increased to 2.3976%W0.73 in December. The average relative weight of BAT in O.curzoniae is higher than that of in M. oeconomus(2.1163%W0.73 and 1.4263%W0.73. respectively). Both species showed an increasing in the amount of this tissue when weather became cold in late autumn. 3. Both the histological and ultrastructural changes in BAT have a significant seasonal variations. In the summer the BAT cells have large fat droplets and have many small fat droplets during cold winter. The seasonal changes of mitochondria sizes in BAT cell is Sep. >Dec.>Mar.>Jun.in O.curzcniae and Dec.>Sept.≥Jun.> Mar. in M.oeconomus; and the cristae numbers of BAT mitochondria is Dec.≥Mar.> Jun.>Sept. in O.curzoniae and Dec.?Mar.>Sep1.>Jun. in M. oeaonomus. The results indicated that BAT is related to the requirement of the rmogenesis for cold. In these two native species of small mammals the thermogentsis requirement for cold are present throughout the year and have significant seasonal variations. BAT and NST may be important in thermoregulation and survival for nonhibernating small mam-mals living in told Alpine Meadow Ecosystem.