目的:我们量化了环境温度对小鼠能量稳态和体温的影响。
方法:环境温度(4-33°C)对体温的影响,能量消耗,身体活动,和各种小鼠的食物摄入量(食物饮食,高脂肪饮食,Brs3(-/y),脂肪营养不良)使用连续监测进行测量。
结果:体温主要取决于昼夜节律和身体活动,但也对环境温度。由于基础代谢率而产生的能量消耗量(通过一种新颖的方法计算),食物的热效应,身体活动,和冷诱导的产热被确定为环境温度的函数。测量的静息防御体温与使用傅立叶热传导定律根据能量消耗计算得出的体温相匹配。小鼠在体育活动中捍卫较高的体温。在活动阶段,体温升高的成本占每日总能量消耗的4-16%。在饮食诱导的肥胖和Brs3(-/y)小鼠中测量的参数与对照相似。死后的高热导率表明,小鼠中的大多数绝缘是通过生理机制实现的。
结论:在22°C时,冷诱导的产热是基础代谢率的120%。身体活动期间体温较高是由于较高的设定点,不仅仅是增加运动过程中的发热。老鼠体内的大多数绝缘是通过生理机制,很少有毛皮或脂肪。我们的分析表明,应重新考虑热中性区上限的定义。测量体温可解释能量消耗数据,并提高小鼠对人体能量稳态建模的预测性和实用性。
OBJECTIVE: We quantified the effect of environmental temperature on mouse energy homeostasis and body temperature.
METHODS: The effect of environmental temperature (4-33 °C) on body temperature, energy expenditure, physical activity, and food intake in various mice (chow diet, high-fat diet, Brs3 (-/y) , lipodystrophic) was measured using continuous monitoring.
RESULTS: Body temperature depended most on circadian phase and physical activity, but also on environmental temperature. The amounts of energy expenditure due to basal metabolic rate (calculated via a novel method), thermic effect of food, physical activity, and cold-induced thermogenesis were determined as a function of environmental temperature. The measured resting defended body temperature matched that calculated from the energy expenditure using Fourier\'s law of heat conduction. Mice defended a higher body temperature during physical activity. The cost of the warmer body temperature during the active phase is 4-16% of total daily energy expenditure. Parameters measured in diet-induced obese and Brs3 (-/y) mice were similar to controls. The high post-mortem heat conductance demonstrates that most insulation in mice is via physiological mechanisms.
CONCLUSIONS: At 22 °C, cold-induced thermogenesis is ∼120% of basal metabolic rate. The higher body temperature during physical activity is due to a higher set point, not simply increased heat generation during exercise. Most insulation in mice is via physiological mechanisms, with little from fur or fat. Our analysis suggests that the definition of the upper limit of the thermoneutral zone should be re-considered. Measuring body temperature informs interpretation of energy expenditure data and improves the predictiveness and utility of the mouse to model human energy homeostasis.