暖温经历对雌性黑线仓鼠能量代谢、产热和体脂含量的影响

The effects of warm temperature on energy metabolism,thermogenesis and body fat content in female striped hamsters

能量代谢的生理调节是小型哺乳动物应对不同环境温度的重要策略之一,为探讨暖温下代谢产热在体重和体脂适应性调节中的作用和机理,本研究将雌性黑线仓鼠(Cricetulus barabensis)分别暴露于暖温(30℃)1个月、3个月和4个月,测定体重、摄入能、代谢产热、体脂含量、褐色脂肪组织(BAT)细胞色素c氧化酶(COX)活性和解偶联蛋1(UCP_1)mRNA表达等。结果显示,暖温对黑线仓鼠体重无显著影响,但使脂肪含量显著增加。与室温组(21℃)相比,暖温组消化率显著升高,但摄入能和消化能显著降低;暖温下非颤抖性产热(NST)显著降低,脑、肝脏和心脏COX活性,BAT COX活性和UCP_1mRNA的表达显著下调。结果表明,暖温下降低代谢产热补偿了能量摄入的减少,机体处于正能量平衡状态,是脂肪含量显著增加的主要原因之一。脑、肝脏、心脏和BAT代谢活性降低是代谢产热降低的主要机制,与脂肪累积有关。

Proper adjustment of energy metabolism is one of the most important strategies in small mammals in response to variations in ambient temperature. The present study was designed to test the roles and mechanisms of metabolic thermogen- esis in the adaptive regulation of body mass and body fat under warm temperatures. Body mass, energy intake, metabolic thermogenesis were determined in striped hamsters that were acclimated to warm temperature （ 30℃ ） for 1, 3 and 4 months. Cytochrome c oxydase （COX） activity and mRNA expression of uncoupling protein 1 （UCP1 ） in brown adipose tis- sue （BAT） were also measured. The results showed that warm temperature had no effect on body mass, but significantly increased body fat. Digestibility increased significantly in warm-acclimated hamsters compared to those maintained at 21 ℃ , but the gross and digestive energy intake were significantly reduced. Nonshivering thermogenesis （NST） was reduced sig- nificantly under warm temperature. COX activity in brain, liver and heart was significantly reduced, and BAT COX activity and UCP1 mRNA expression significantly were decreased in warm-exposed hamsters compared to those maintained at 21℃. These findings suggest that the decrease in the energy expended for metabolism and thermogenesis compensates for the de- creased energy intake, resulting in a positive energy balance, and consequently contributes to the increase in fat deposition. Down-regulation of metabolic rate of brain, liver, heart and BAT is the physiological mechanism underpinning the reduction of metabolic thermogenesis, which may be involved in the fat deposition in response to warm temperature.