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
(Ta) is an important factor affecting the rates of both energy intake and expenditure. To examine the effect of
Ta on energy strategy and the capacity to sustain food shortage, striped hamsters were exposed to a warm condition
(30 °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 °C than at 21 °C. Food restriction induced a significant
decrease in body mass, but the decreased body mass was attenuated at 30 °C relative to 21 °C. This suggests
that striped hamsters could not compensate for the limited food supply by decreasing daily energy
expenditure at 21 °C, whereas they could at 30 °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 Ta-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