干旱区生态环境知识资源中心

The capacity of small mammals to sustain periods of food shortage largely depends on the adaptive regulation of energy budget in response to the decrease in food supply. In addition to food availability, ambient temperature (T-a) is an important factor affecting the rates of both energy intake and expenditure. To examine the effect of T-a on energy strategy and the capacity to sustain food shortage, striped hamsters were exposed to a warm condition (30 degrees C) and were then restricted to 70% of ad libitum food intake. Body mass, energy intake and expenditure and physiological markers indicative of thermogenesis were measured. Warm exposure had no effect on body mass and digestibility, but decreased energy intake, basal metabolic rate and maximum nonshivering thermogenesis. The mitochondria protein content, cytochrome c oxidase activity and uncoupling protein 1 level of brown adipose tissue were significantly lower in hamsters at 30 degrees C than at 21 degrees C. Food restriction induced a significant decrease in body mass, but the decreased body mass was attenuated at 30 degrees C relative to 21 degrees C. This suggests that striped hamsters could not compensate for the limited food supply by decreasing daily energy expenditure at 21 degrees C, whereas they could at 30 degrees C The significant reductions in the rates of metabolism and thermogenesis in warm-acclimated hamsters increase the capacity to cope with food shortage. Although, it remains uncertain whether this response represents some generalized evolutionary adaptation, the T-a-dependent adjustment in the capacity to survive food restriction may reflect that warm acclimation plays an important role in adaptive regulation of both physiology and behavior in response to the variations of food availability. (C) 2015 Elsevier Inc. All rights reserved.