前脂肪细胞增殖分化在高脂膳食诱导大鼠肥胖及运动预防肥胖中的作用

The Role of Proliferation and Differentiation of Preadipocyte on High Fat Diet-induced Obesity and Prevention of Obesity through Exercises in Rats

目的:探讨前脂肪细胞增殖分化在高脂膳食诱导大鼠肥胖及运动预防肥胖过程中的作用。方法:40只雄性SD大鼠分为普通膳食安静组(C组,n=8)、普通膳食运动组(E组,n=8)、高脂膳食安静组(H组,n=14)和高脂膳食运动组(HE组,n=10)。C组和H组不运动,E组和HE组大鼠进行跑台运动,运动强度约为75%VO2max水平。12周干预后,记录各组大鼠体重,取附睾、肾周和腹后壁的脂肪垫分别称重,并计算总脂肪量;体视学方法检测脂肪细胞数目及平均直径;Western Blot检测脂肪组织过氧化物酶增殖物受体γ(PPARγ)和CCAAT增强子结合蛋白α(C/EBPα)的蛋白表达水平。结果:(1)H组大鼠体重及腹腔内总脂重均显著高于C组(P<0.01),E组和HE组大鼠肾周、腹后壁脂肪垫重及腹腔内总脂肪量均分别显著低于C组和和H组的相应部位(P<0.01)。(2)H组大鼠腹腔内脂肪总数目显著高于C组(P<0.01)。E组大鼠肾周及腹后壁脂肪细胞平均直径均分别显著低于C组的相应部位(P<0.05,P<0.01),HE组大鼠附睾、肾周及腹壁脂肪细胞平均直径均分别显著低于H组的相应部位(P<0.01)。(3)与C组相比,E组及H组大鼠附睾、肾周及腹壁脂肪组织PPARγ蛋白表达显著升高(P<0.01);H组大鼠附睾及肾周脂肪组织C/EBPα蛋白表达显著高于C组的相应部位(P<0.01),E组大鼠肾周及腹后壁脂肪组织C/EBPα蛋白表达显著高于C组的相应部位(P<0.01),但HE组大鼠肾周脂肪组织C/EBPα蛋白表达显著低于H组(P<0.01)。结论:前脂肪细胞增殖分化能力在高脂膳食诱导肥胖及运动预防肥胖过程中均增强,但其作用及机制皆不同。高脂膳食诱导肥胖过程中前脂肪细胞增殖分化能力的增强可使脂肪细胞数目增多,是机体为适应体脂增多的代偿机制;运动预防肥胖过程中前脂肪细胞增殖分化能力的增强可促进脂肪细胞更新,并使脂肪细胞平均体积缩小,是脂肪细胞贮脂能力改善的适应机制。

Objective To explore the influences of proliferation and differentiation of preadipocytes on high fat diet-induced obesity and obesity prevention through exercises in rats. Methods Forty male Sprague-Dawley rats were divided into a normal diet control group （C,n=8）,a normal diet with exercis- es group （E,n=8）,a high fat diet control group （H,n=14） and a high fat diet with exercises group （HE,n=10）. Group C and group H kept sedentary,while group E and group HE underwent treadmill exercises at about 75%VO2max level. After 12 weeks of intervention,the body weight,epididymal,perire- nal and retroperitoneal fat mass were recorded, and the total fat mass was determinated. Stereology method was used to calculate the number and average diameter of fat ceils. Western Blotting was conducted to measure the expression of PPARγ and C/EBPα protein in adipose tissues. Results （1） The body weight and total fat mass of group H were significantly higher than those of group C （P〈0.01）. Perirenal, retroperitoneal fat and total fat mass of group E and HE were significantly lower than those of group C and H respectively （P〈0.01）. （2） The total fat cell number of group H was significantly higher than that of group C. The average diameter of fat cells in perirenal and retroperitoneal fat pads of group E were significantly lower than that of group C （P〈0.05,P〈0.01）,while that of group HE in epididymal, perirenal and retroperitoneal fat pads was significantly lower than that of group H （P〈 0.01）. （3） Compared with group C,the expression of PPARγ protein of group E and H increased sig- nificantly in epididymal,perirenal and retroperitoneal fat pads （P〈0.01）. The expression of C/EBPα pro- tein of group H was significantly higher than that of group C in epididymal and perirenal fat pads （P〈 0.01）, the expression of C/EBPα protein of group E was significantly higher than that of group C in perirenal and retroperitoneal fat pads （P〈0.01）, while the expression of C/EBPα protein of group HE was significantly lower than that of group H in perirenal fat pads （P〈0.01）. Conclusion The prolifera- tion and differentiation of preadipocyte was enhanced in the development of high fat diet induced obesi- ty and exercises to prevent obesity, but its role and mechanisms were different. The high fat diet in- creases the number of fat ceils which is a compensatory mechanism for the body to adapt to fat accu- mulation, while exercises might promote cell renewal and decrease the average size of fat cells which is an adaptive mechanism to improve fat storage.