关键词: 基础代谢率, 消化酶, 能量代谢, 高脂食物, 黑线仓鼠, 解偶联蛋白

Abstract: The present study was aimed at examining the effect of a high-fat diet on energy metabolism in small mammals with different levels of basal metabolic rate (BMR). Adult female striped hamsters (Cricetulus barabensis) were assigned into high and low BMR groups according to BMR levels recorded during baseline measurements, and then each group was randomly sub-divided into either low or high-fat diet groups, which were fed low or high-fat diets for 6 weeks. Body mass, energy intake, metabolic rate, and digestive enzyme activities, as well as cytochrome c oxidase (COX) activity and mRNA expression of uncoupling protein (UCP) of brown adipose tissue (BAT), major visceral organs and muscle were measured. The results showed that body masses of either high or low BMR groups were not affected by a high-fat diet. The high-fat diet group significantly decreased food intake, gross energy intake and digestive energy intake, but increased lipase activity of small intestine and digestibility compared with the low-fat diet group, while the differences were not significant between high and low BMR groups. The metabolic rate during the night was significantly higher than that during the day. The metabolic rate of high-BMR animals during the night was higher in the high-fat diet group than that in low-fat diet group. The COX activity of BAT, muscle and visceral organs was not affected by a high-fat diet, and they were not different between high and low BMR groups. The high-fat diet induced a significant up-regulation of UCP2 expression in liver only. These findings suggest that plastic regulation of energy intake and the morphological and functional adjustments of the digestive system are employed by striped hamsters to cope with a high fat diet. A notable circadian rhythm of metabolic rate is observed in striped hamsters, which is associated the high-fat diet acclimation and is also related to their own BMR level. There is a tissue specific gene expression of UCP, and it may not be the factor resulting in individual differences in BMR.

Key words: Basal metabolic rate, Digestive enzymes, Energy metabolic rate, High-fat diet, Striped hamster, Uncoupling proteins