侧脑室注射共轭亚油酸(CLA)对大鼠糖脂代谢的影响

Effects of Intracerebroventricular Administration of Conjugated Linoleic Acid(CLA) on Glucose and Lipid Metabolism in Rats

观察侧脑室注射共轭亚油酸(Conjugated linoleic acid,CLA)对SD大鼠糖脂代谢的影响及其可能的机制。方法:向正常SD大鼠侧脑室内注射共轭亚油酸(CLA),分别于注射后2、4、8、12、24小时采血,试剂盒法测血糖、胰岛素、瘦素、血甘油三脂、血胆固醇、血高密度脂蛋白。48小时后处死,分离动物的脂肪(皮下、内脏、肾周、睾周)进行称重,计算体脂比。结果:与对照组相比,侧脑室注射CLA48小时后,大鼠脂体比、皮下脂肪、睾周脂肪均下降。术后2-12h血糖降低,血清胰岛素浓度也降低,而且持续的时间较长(48h)。侧脑室注射CLA对脂代谢有影响,2h时血清甘油三酯升高、胆固醇降低、4h时高密度脂蛋白升高。结论:共轭亚油酸能够通过中枢神经系统调节外周糖脂代谢,这可能与其能减轻体重的机制有关。

Objective：Dietary conjugated linoleic acid （CLA） is being investigated for beneficial effects for disease prevention and treatment, including obesity, in a variety of experimental models, but the mechanism is not clear. By Intracerebroventricular administration of CLA, our experiment was conducted to extend these observations to hypothalamus and other regions within the central nervous system so that the mechanism of the actions of CLA might be more easily elucidated. Methods：For the experiment, normal Sprague-Dawley rats were divided into three groups and received ICV injections of either 150 nmol CLA, or LA as non-conjugated control, or normal saline. We collected the blood sample at 2, 4, 8, 12, 24 hours and triglycerides, total cholesterol, HDL cholesterol, and glucose concentrations in the plasma were measured using kits. The rats were dissected after 48 hours and adipose tissues （subcutaneous, mesenteric, retroperitoneal, epididymal） were removed, blotted dry, and immediately weighed. Results：The fat/body weight, subcutaneous and retro-peritoneal adipose tissue decreased after 48 hours. The plasma glucose decreased at 2-12 hours and insulin concentration also reduced. The plasma triglycerides increased and total cholesterol decreased at 2 hour and HDL concentration increased at 4 hour. Conclusions：The present study indicates that intracerebroventricular administration of conjugated linoleic acid can affect glucose metabolism and induce lipolysis. CLA can affect glucose and lipid metabolism through central nervous system （CNS）, which may be related with the beneficial effect on weight-loss. Our experiment indicated that the relationship between CLA taken as supplements or as part of naturally occurring foods and weight loss could be more complex than initially thought. There are several indications that various isoforms could have different biological actions, although we used 50/50 combinations of isomers. Furthermore, we should turn attention to CLA isomer investigation.