长爪沙鼠褐色脂肪组织和肝脏产热特征的季节性变化

长爪沙鼠（Meriones unguiculatus）是一种栖息于典型草原和荒漠草原非冬眠群居性的小型哺乳动物。为研究其产热功能的季节变化，我们分别在2003年秋季（9月下旬）、冬季（11月下旬）、2004年春季（3月底-4月下旬）和夏季（7月下旬），分别测定了其体重、褐色脂肪组织和肝脏的重量、线粒体总蛋白含量和细胞色素c氧化酶活力，以及褐色脂肪组织中解偶联蛋白1（Uncoupling protein1，UCPl）的含量等。结果显示：除雄鼠的体重显著高于雌鼠外，其它各项指标均无性别差异。体重和褐色脂肪组织的重量都在冬季较高，显著高于夏季，而肝脏的重量在夏季显著高于其它季节。褐色脂肪组织和肝脏的线粒体蛋白含量和细胞色素c氧化酶活力以及UCP1含量，都在冬季较高，夏季较低。这些结果表明：在野外条件下，褐色脂肪组织和肝脏在细胞水平上产热能力的提高和UCP1含量的增加，是长爪沙鼠抵御寒冷的重要方式。

Seasonal changes in thermogenic properties of brown adipose tissue and liver in Mongolian gerbils Meriones unguiculatus

Mongolian gerbils are non-hibernating small mammals that inhabit the deserts and typical steppe areas of the Inner Mongolian grasslands in China. In order to understand seasonal changes in cellular and molecular thermogenic properties in male and female gerbils, we measured body mass, brown adipose tissue(BAT)and liver mass, mitochondrial protein(MP)contents and cytochrome c oxidase(COX)activity in BAT and liver, as well as uncoupling protein 1(UCP1)contents in BAT in the fall(late September)and winter(late November), and spring(late March and April)and summer(late July). No significant sexual differences were found for the above mentioned parameters except that the body mass of male gerbils was higher than that of females. Both body mass and BAT mass were higher in winter than in summer, while liver mass was higher in summer than during other seasons. MP contents, COX activity in whole BAT and liver, and BAT UCP1 contents all showed the highest levels in winter and lowest in summer. These data indicate that increases in thermogenic capacity at both cellular and molecular levels in BAT and liver are important physiological adjustments to cope with the cold stress in wild Mongolian gerbils.