内蒙古小毛足鼠的蛰眠和季节性适应

Hibernation and daily torpor have never been confirmed in desert hamsters before. We first detected fast induced torpor in them. In this proposal, we mainly focused on the patterns, regualtion as well as contributions to seasonal adaptation of torpor from a viewpoint of energetics in desert hamsters. Specific questions were addressed as following: ①The properties of torpor in fasted desert hamsters was investigated by examining changes of metabolic rate and body temperature as a response to different ambient temperatures and then compared to that in other endothermic torpidators ②After desert hamsters being live trapped in different seasons, body mass, thermogenic capacity, food intake, body temperture, activity level and other parameters of thermal physiology were measured to characterize the strategies adaped by hamsters to cope with the seasonal fluctuations in ambient temperature and food supply in the wild. ③Effecs of food avilability, temperature and especially photoperiod as a seasonal signal on torpor expression, energy budget parameters like energy intake, thermogenic capacity and body mass regualtion were examined by manipulaion expertiment in laboratary. ④ Through field survey of food abundance and food stored by desert hamsters in different seasons, we hope to figure out the possiblities, how serious and when if food shortage happened. Ecological significace and contribution of torpor mainly as a means of energy saving were then evaluated. ⑤ Metabolic inhibitor experiment were conducted to examine the physiology of torpor behavior in desert hamsters. Samll body size and torpor make them a promising model to the study of body mass regulation and torpor physiology.

小毛足鼠为非冬眠动物，学术界也一直未发现其日眠行为，我们首次发现禁食可诱导小毛足鼠蛰眠，本项目重点研究其蛰眠特征及调节机制，并从能量学的角度，研究蛰眠在动物季节性适应中的作用：①通过不同环境温度处理，研究小毛足鼠禁食后代谢和体温对环境变化的反应，确定其低体温的性质，并与其它恒温动物的蛰眠比较，理解它们之间的区别和联系；②在野外不同季节对小毛足鼠取样测定，理解其能量代谢特征的季节性适应变化；③通过控制实验室食物供应、光照和温度条件，确定环境条件尤其是光周期信号对小毛足鼠蛰眠、能量摄入、产热水平和体重等能量代谢参数的影响；④在4个季节对小毛足鼠的食物资源及食物储存情况进行调查，结合其蛰眠的诱导条件与环境温度的关系等，揭示蛰眠的生态适应意义；⑤通过代谢抑制剂处理实验，研究小毛足鼠蛰眠的发生机制。研究将增进对小毛足鼠生存对策的理解。小体型和蛰眠的特点，使其成为体重调节和蛰眠研究的理想模型动物。

蛰眠（异温性）是许多哺乳动物环境适应的重要策略，期间动物的体温和代谢常发生剧烈变化，蛰眠的诱导和调控机制及其环境适应意义是本领域的重点研究内容。本项目主要对①小毛足鼠蛰眠过程中体温和代谢调节特点及环境适应意义、②小毛足鼠恒温能力和异温性的发育、③冬季驯化条件下小毛足鼠、黑线仓鼠和三趾跳鼠蛰眠表达、④小毛足鼠、黑线仓鼠和三趾跳鼠等7个物种体温和活动性似昼夜节律特点，以及⑤葡萄糖和脂肪在小毛足鼠蛰眠启动中的作用进行了研究，取得了如下原创性的结果和关键数据：1）只有冬季条件驯化（短光照和低温）的小毛足鼠才可以自发蛰眠；冬季和夏季驯化条件下的小毛足鼠禁食后都可表现蛰眠，且冬季条件驯化下蛰眠（体温下降）程度更深。2）同域分布的三趾跳鼠在冬季条件驯化且禁食后才能表现蛰眠行为，同域分布的黑线仓鼠在冬季驯化条件下具有自发蜇眠的能力。3）小毛足鼠幼体为晚成性，幼体在恒温能力初步建立后（16日龄）（禁食后）即可表现蜇眠，蛰眠代谢率远低于基础代谢率。小毛足鼠幼体（较其他物种）能更早获得异温性，可以帮助其度过能量短缺时期，提高存活几率。随着幼体发育成熟，禁食诱导的蜇眠程度变浅，代谢率高于或接近基础代谢率。4）使用VitalView无线测定系统对小毛足鼠、黑线仓鼠、三趾跳鼠等7个物种的体温和活动性，在有光周期信号和持续黑暗两种条件下（各2周）进行连续监测，发现夜行性物种表现出最显著的自由运行的似昼夜节律，暗示夜行性动物的活动主要由似昼夜节律生物钟驱动，而昼行性更多受环境条件（光照等）影响。5）糖代谢抑制剂2-DG注射可诱导小毛足鼠进入蛰眠，表明葡萄糖代谢通路在蜇眠启动中起重要作用。MA不能诱导小毛足鼠蛰眠，表明脂肪的缺乏在其蜇眠启动中不起作用。本项目在国内开创了小毛足鼠蛰眠生理生态学的初步研究，取得了许多准确可靠的基础数据和丰富的野外工作知识，为该物种以及浑善达克沙地小哺乳动物蛰眠生理学的深入研究和实验动物化打下较好的基础。

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