Abstract: Body weight , basal metabolic rate (BMR) , and energy metabolism were measured under long photoperiod (16L∶8D , LD) and short photoperiod (8L∶16D , SD) for acclimating Brandt's voles (Microtus brandti) and Mongolian gerbils (Meriones unguiculatus) . Animals were transferred from LD to SD conditions for 6 weeks for voles and 7 weeks for gerbils. Body weights were measured at 32 day intervals at first two weeks and at last 3 days of each week thereafter. Energy intake , digested energy , and metabolizable energy were determined by food trials (metabolic cage) with 32 day intervals. BMRs were measured by using closed circuit respirometer within thermoneutrality at the beginning and the end of acclimation. Under LD and SD conditions, both voles and gerbils tended to increase their body weights , increasing faster within the first 2 weeks and then slowing down , and became stable after 3 weeks. However , the magnitude of changes is different between LD and SD conditions, and also between voles and gerbils. Under SD conditions , body weights were increased by 37 % for voles and 11 % for gerbils , and those were lower than under LD conditions (47 % for voles and 25 %for gerbils). This suggests that there is a sensitive time to photoperiod and SD could constrain the increase in body weight for both species. There were no effect of photoperiod on energy intake, digested energy , and metabolizable energy for both voles and gerbils. Photoperiod also had no significant effect on BMRs for both species. These results suggest that short photoperiod can cue both Brandt's voles and Mongolian gerbils to decrease their body weights and thus decrease the absolute energy requirement per animal for winter survival in their natural environments.

Key words: Photoperiod, Brandt's vole (Microtus brandti), Mongolian gerbil ( Meriones unguiculatus), Body weight, Energy metabolism, Basal metabolic rate

摘要： 本文测定了光周期对雄性布氏田鼠和长爪沙鼠的体重、基础代谢率和能量代谢的影响。动物从长光照(16L∶8D , LD) 转入短光照(8L∶16D , SD) 条件下驯化6 周(田鼠) 和7 周(沙鼠) 。结果显示: (1) 无论在LD还是SD 条件下, 两种动物的体重都趋于增加, 但反应程度不同也具有种间差异性。两种动物的体重对光周期的反应有时段性, 约14 d 前两种动物的体重增加迅速, 而后增加缓慢, 3 周左右趋于稳定。短光照条件下布氏田鼠和长爪沙鼠的体重分别增长了37 %和11 % , 均低于长光照组(分别为47 %和25 %) , 说明短光照条件下布氏田鼠和长爪沙鼠的体重增长较长光照缓慢; (2) 光照对两种动物的摄入能、消化能和可代谢能均没有显著影响,摄入能与体重的增长无关; (3) 光照对两种动物的基础代谢率无显著影响。这些结果表明: 布氏田鼠和长爪沙鼠在自然环境中, 可能以光周期作为一种信号, 当环境温度降低、食物质量变劣时, 采取降低体重以减少绝对能量需求的策略而适应环境。

关键词: 光周期, 布氏田鼠, 长爪沙鼠, 体重, 能量代谢, 基础代谢率