温度和高脂食物对黑线仓鼠代谢产热和体脂累积的影响

能量代谢的适应性调节是小型哺乳动物应对环境季节性变化的主要策略之一。为探讨不同温度下动物在代谢产热能量支出与脂肪累积之间的权衡策略,以成年雄性黑线仓鼠为研究对象开展了3 个实验:实验1 将动物驯化于高脂和低脂食物;实验2 将动物暴露于低温(5℃)和暖温(30℃);实验3 将饲喂高脂食物的动物暴露于低温。以食物平衡法测定摄食量、摄入能和消化率,以开放式氧气分析仪测定代谢产热,以索氏抽提法测定脂肪含量。结果发现,取食高脂食物的黑线仓鼠摄食量显著减少,但脂肪累积显著增加;暖温下摄食量显著减少,但体脂含量显著增加,低温下摄食量显著升高,但体脂含量显著减少;饲喂高脂食物的黑线仓鼠在低温下摄入能显著增加,非颤抖性产热增强,但体脂含量显著降低。结果表明高脂食物对黑线仓鼠体脂累积的影响与环境温度有关,低温诱导脂肪动员,暖温促进脂肪贮存;低温下黑线仓鼠增加能量摄入不能完全补偿用于产热的能量支出,导致脂肪动员增加;暖温下代谢产热降低是脂肪累积的主要因素;与能量摄入相比代谢产热的能量支出在体脂累积的适应性变化中发挥更重要的作用。

Effects of temperature and high-fat diet on metabolic thermogenesis and body fat content in striped hamsters

Adaptive regulation of energy metabolism is employed by small mammals to cope with seasonal environmental changes. In order to explore the strategy of trade-off between the energy expenditure of metabolic thermogenesis and body fat content, three experiments were designed using adult male hamsters. In experiment 1, animals were subjected to high or low-fat diet (HF or LF); in experiment 2, animals were exposed to either cold (5℃) or warm temperature (30℃); in experiment 3, animals were fed with high fat diet and transferred into a cold temperature (5℃). Food intake, energy intake and digestibility were measured using a food balance method; metabolic thermogenesis was measured using an open-flow respirometry system; body fat content was measured by ether extraction in a Soxhlet apparatus. The results showed that, in experiment 1, food intake was significantly reduced, but body fat content increased in HF group compared to that in LF group. In experiment 2, animals consumed significantly less food at the warm, but showed higher fat content than cold group. However, they increased energy intake and nonshivering thermogenesis, but decreased fat content in the cold compared to that in warm. In experiment 3, the HF hamsters showed significantly higher energy intake and nonshivering thermogenesis, but lower body fat content at the cold compared to the hamsters maintained at room temperature. These findings indicated that the effect of high fat diet on body fat accumulation was dependent on ambient temperature. The exposure to the cold induced body fat mobilization and the warm exposure increased fat storage. The striped hamsters increased thermogenesis at cold, but it was not completely compensated by energy intake, resulting in a significant elevation of fat mobilization. The reduction of thermogenesis when warm was the main factor inducing fat accumulation. The energy expenditure associated with metabolic thermogenesis played more important roles in body fat regulation than energy intake.