低碳水化合物饮食对正常和肥胖大鼠体质量和糖脂代谢的影响

Effects of low-carbohydrate diet on body weight and glycolipid metabolism in normal rats and obese rats

目的·探讨低碳水化合物饮食(low-carbohydrate diet,LCD)对正常体质量大鼠和肥胖大鼠的体质量及糖脂代谢的影响。方法·将80只正常体质量雄性Sprague-Dawley大鼠随机分为3组,分别喂以正常对照饲料(control diet,CD组,n=10)、LCD饲料(LCD组,n=10)和传统高脂饲料(high-fat diet,HFD组,n=60)8周。第8周末,从HFD组大鼠筛选出30只肥胖大鼠,再随机分为3组,其中2组分别将饲料由HFD变换为LCD(HFD-LCD组)、正常对照饲料(HFD-CD组),余下1组维持HFD(HFD组),继续喂养8周。CD组和LCD组饲料维持不变。检测指标包括大鼠体质量、饲料摄入量、内脏脂肪量和血生化指标(空腹血糖、三酰甘油、总胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇和血清β-羟基丁酸酯浓度)。结果·在正常体质量大鼠中,从第6周开始,LCD组大鼠体质量即显著低于HFD组(均P<0.05),与CD组大鼠体质量间差异无统计学意义(均P>0.05);到第16周末,LCD组总胆固醇显著高于CD组(P=0.001),高密度脂蛋白胆固醇显著低于CD组(P=0.021)。在肥胖大鼠中,第16周末,HFDLCD组大鼠体质量显著低于HFD组和HFD-CD组(均P<0.05),且HFD-LCD组大鼠较HFD-CD组内脏局部脂肪减少,三酰甘油降低,高密度脂蛋白胆固醇升高(均P<0.05)。在多元线性回归分析中,对于正常体质量大鼠,LCD和β-羟基丁酸酯对体质量都无明显作用(均P>0.05)。对于肥胖大鼠,相对于HFD组,HFD-LCD(β=-88.56,P=0.000)和HFD-CD(β=-39.08,P=0.007)干预均导致体质量减少;β-羟基丁酸酯在HFD-CD组1~2倍的范围内对减重有利(β=-34.92,P=0.006)。结论·LCD干预正常体质量大鼠和肥胖大鼠,对体质量和血脂代谢指标可能有不同作用。LCD对正常体质量大鼠无减重作用,反而导致总胆固醇升高;而LCD对肥胖大鼠具有减重和改善部分糖脂代谢的作用。

Objective·To explore the effects of low-carbohydrate diet(LCD)on body weight and glycolipid metabolism in obese rats and normal weight rats.Methods·Eighty male normal weight Sprague-Dawley rats were divided randomly into three groups,i.e.,normal control diet group(CD group,n=10),LCD group(n=10)and traditional high-fat diet group(HFD group,n=60).After eight weeks,30 obese rats were selected from HFD group.Then the obese rats were divided randomly into three groups.The feed of two groups was changed from HFD to LCD(HFD-LCD group)or CD(HFDCD group),and the rest group was fed with HFD continuously.The experiment lasted for another eight weeks.The feed of CD group and LCD group remained unchanged.The measurement indicators included body weight,feed intake,visceral fat,and blood biochemical indexes(fasting blood glucose,triacylglycerol,total cholesterol,high-density lipoprotein cholesterol,low-density lipoprotein cholesterol and serumβ-hydroxybutyrate concentration).Results·In normal rats,from the 6th week,the body weight of LCD group was significantly lower than that of HFD group(P<0.05),and there was no significant difference between LCD group and CD group(P>0.05).But at the end of the 16th week,total cholesterol of LCD group was significantly higher than that of CD group(P=0.001)and high-density lipoprotein cholesterol was lower(P=0.021).In the obese rats,at the end of the 16th week,the body weight of HFD-LCD group was significantly lower than that of HFD group and HFD-CD group(P<0.05).Compared with HFD-CD group,HFDLCD group had less visceral fat,lower triacylglycerol and higher high-density lipoprotein cholesterol(P<0.05).In multiple linear regression analysis,in normal body weight rats,LCD intervention andβ-hydroxybutyrate had no obvious effect on body weight(P>0.05).In the obese rats,compared with HFD group,the intervention of HFD-LCD(β=-88.56,P=0.000)and HFD-CD(β=-39.08,P=0.007)resulted in the decrease of body weight.β-hydroxybutyrate level was helpful to weight loss in the range of 1-2 times of HFD-CD group(β=-34.92,P=0.006).Conclusion·LCD may have different effects on body weight and lipid metabolism between normal weight rats and obese rats,LCD has no weight loss effect on the normal weight rats,but can increase total cholesterol;however,in obese rats LCD can reduce weight and improve the metabolism of glycolipid.