长爪沙鼠免疫功能、体脂含量和器官重量的季节变化

小型哺乳动物的体脂含量与免疫功能有关,并受环境条件的影响。为了进一步理解野生长爪沙鼠对环境的生存适应策略,我们于2004 年夏季(7～8月)和2005年冬季(1～3月)测定了野生长爪沙鼠的体重、体脂含量和脏器重量,以及由匙孔血蓝蛋白(KLH)对雄鼠所介导的体液免疫反应。结果发现:雄鼠的胴体干重和体脂含量都显著高于雌鼠,其他各项指标无性别差异。冬季雌雄沙鼠的体重、胴体干重、体脂含量和褐色脂肪组织的湿重,以及雄鼠的睾丸湿重都显著高于夏季。脾脏的重量冬季趋于降低。处理组(注射KLH )动物血清中抗KLH 抗体的含量在冬季和夏季都显著高于对照组(注射生理盐水),且冬季处理组显著高于夏季处理组。本研究结果为动物种群调节的“冬季免疫增强假说”提供了一个新的野外例证。没有检测到免疫器官和产热器官、免疫器官和繁殖器官之间的权衡关系。

Seasonal changes in immune function, body fat mass and organ mass in Mongolian gerbils (Meriones unguiculatus)

Body fat mass is related to immune function in some small mammal species and can be affected by temperature, photoperiod, and population density. In order to understand their survival strategies, we measured seasonal changes in body mass, body fat mass, and organ masses in male and female wild Mongolian gerbils (Meriones unguiculatus) in summer (July and August)in 2004 and winter (January to March) in 2005,as well as the serum antibody contents of anti-keyhole limpet haemocyanin (KLH)after injections with KLH antigen in wild male gerbils. No sexual differences were found in organ mass but the carcass dry mass and body fat mass in male gerbils were higher than in females. Body mass, carcass dry mass, body fat mass, and brown adipose tissue mass for both sexes, as well as testes wet mass in males were significantly higher in winter than that in summer. Spleen mass showed a tendency to decrease in winter. Serum antibody levels of anti-KLH were significantly higher in KLH-challenged gerbils than controls in both summer and winter and also higher in winter compared with summer. Our results provide new evidence from wild Mongolian gerbils to support the hypothesis of “winter immunoenhancement hypothesis”. No trade-offs were detected between thermogenic and immunological organs and between reproductive and immunological organs.