黑线仓鼠应对温度变化的能量学策略及内温性体温调节机理

The level of energy metabolism plays an important role in influencing many aspects of an animal species, including distribution and abundance. Endothermy is one of main ecological adaptations to changes in ambient temperature in small mammals. There are strong relationships between energy intake and endothermic thermogenesis, the rate of basal and maximal metabolism, which would be help and significant to further understand endothermy. In the present study, energy metabolism, body temperature, thermal conductance, morphology and rate of oxygen consumption of mitochondria in visceral organs are measured in striped hamsters. Activity of digestive enzymes, levels of serum leptin, concentrations and mRNA expression of uncoupling protein 1 (UCP1) of brown adipose tissue (BAT) are also measured. The characteristics and physiological mechanisms of thermoregulation and metabolic thermogenesis are studied in striped hamsters under different stage of lifespan and different ambient temperatures. Energy strategy and mechanisms of endothermic thermoregulation will be explored in animals that are acclimated to changes in ambient temperature, by which the "Assimilation Capacity Model (hypothesis) of endothermic evolution" will be examined within intra-species levels. A trade-off strategy between endothermic thermogenesis and "heat dissipation limitation" will be elucidated in striped hamsters. Finally, data from this study will be help to further understand and explore evolutionary significance and survival mechanisms of adaptation to ambient environment changes in small mammals.

动物的能量代谢水平，在决定物种的分布和丰富度等方面占有十分重要的地位。内温性是小型哺乳动物应对温度变化最主要的生态学适应之一。动物在能量摄入与内温性产热、基础代谢率和最大代谢率之间存在密切联系，这对于深入理解内温性进化具有重要的意义。本项目通过测定能量代谢、体温、热传导率、内脏代谢活性器官的形态和线粒体耗氧速率、消化酶活性、血清瘦素水平、褐色脂肪组织解偶联蛋白1（UCP1）含量和mRNA表达等参数，整合研究不同环境温度下、不同生活史阶段黑线仓鼠的体温调节、代谢产热特征和生理机制，探讨动物适应温度变化的能量学策略及其内温性体温调节机制，在种内水平上检验内温性进化的"同化能力模型"（假说）；阐明动物在"内温性产热"和"热耗散限制"之间的权衡策略，检验"热耗散限制"假说，深入理解和揭示小型哺乳动物应对环境变化的生存适应机理和进化意义。

内温性是小型哺乳动物应对温度变化最主要的生态学适应之一。为阐明内温性产热与能量代谢之间的联系，本项目通过测定能量代谢率、体温、热传导率、代谢活性器官的形态和线粒体耗氧速率、消化酶活性、血清瘦素水平、褐色脂肪组织解偶联蛋白1（UCP1）表达等参数，整合研究了不同环境温度下、不同生活史阶段黑线仓鼠的体温调节、代谢产热特征和生理机制。主要研究结果为：1）代谢产热适应性调节是黑线仓鼠维持体温稳定的重要策略，环境温度和被毛是影响其能量摄入和支出的重要因子，被毛的作用与动物所处的环境温度有关，低温下被毛对动物降低能量摄入，减少食物利用、降低能量消耗具有更重要意义。2）黑线仓鼠体重的季节性变化不显著，与“调定点假说”的预测不同；但脂肪含量和血清瘦素季节性变化显著，符合该假说。研究结果初步阐明了黑线仓鼠体重和能量代谢的季节性变化模式。3）瘦素对能量代谢和体重的调节作用与气候的季节性变化有关：夏季血清瘦素升高具有抑制能量摄入的作用，冬季血清瘦素可能是促进代谢产热的重要因子。4）BAT COX活性和UCP1表达的适应性变化是其代谢产热的分子机制之一。5）黑线仓鼠通过增加能量摄入，补偿低温和哺乳幼体的双重能量需求，消化酶活性显著增加、消化能力增强，是应对摄食量增加的重要消化策略。结果表明，黑线仓鼠的体温调节属于内温性进化的“同化能力模型”；不同的生活史阶段，小型哺乳动物在“内温性产热”和“热耗散限制”之间的采取权衡策略，以应对环境温度的变化，进而提高自身的生存适应能力。