限制进食对下丘脑腹内侧核损伤性肥胖大鼠体重反弹的影响

EFFECT OF FOOD RESTRICTION ON REGAIN OF BODY WEIGHTIN VMHLESIONED OBESE RATS

目的：探讨限制进食后体重快速回升的机理。方法：下丘脑腹内侧核损伤性（ＶＭＨ）肥胖大鼠给予其正常进食量的５０％饲养６天后，收集血样，分析胆固醇、甘油三酯、游离脂肪酸、血浆消瘦素、胰岛素和脂蛋白脂酶的水平和活性。结果：在限制进食后，ＶＭＨ肥胖大鼠体重和血浆消瘦素、胆固醇、甘油三酯以及游离脂肪酸明显下降；肝脏分泌甘油三酯减少，同时血浆中甘油三酯清除加快。但是，血浆胰岛素水平和肝素后脂蛋白脂酶活性并没有下降，仍然维持在很高的水平上。结论：虽然限制进食能够减轻体重、体内脂肪量，降低血浆胆固醇、甘油三酯浓度，但并不能降低血浆胰岛素水平和脂蛋白酯酶活性，即不能消除或减轻脂肪合成亢进的危机。这是停止限制进食、转入正常进食后，体重快速回升的生化基础。

Abstract Objective: To identify the mechanism by which recidivism or regain of body weight often occurs after diet control program is terminated. Methods: Changes in body weight， concentrations of plasma cholesterol， triglyceride， free fatty acids， leptin， insulin and lipoprotein lipase activity as well as hepatic triglyceride secretion rate and fractional clearance rate of triglyceride were observed after food restriction program in which 50％ of normal food intake was provided to ventromedial hypothalamuslesioned obese rats. Results: Body weight and concentrations of plasma cholesterol， triglyceride， free fatty acids， leptin were decreased significantly. Hepatic triglyceride secretion rate was declined， whereas fractional catabolic rate of triglyceride was increased. However， both plasma insulin and postheparin lipoprotein lipase activities were still maintained at a higher level. Conclusion: Food restriction can induce decrease in body weight，plasma cholesterol， triglyceride concentrations， but not ameliorate plasma insulin levels and lipoprotein lipase activity， i.e. it can not eliminate or alleviate the crisis of increased fat formation. This is the mechanism by which recidivism of body weight occurs after diet control is stopped. Key words: body weight cholesterol triglyceride free fatty acids leptin ventromedial hypothalamuslesioned obesity