L-肉碱对热应激大鼠机体脂质代谢的影响

摘要

This experiment was conducted to investigate the effects of L-carnitine on lipid metabolism of rats under heat stress. Forty-eight healthy adult male SD rats were selected and equally divided into 3 groups ( con-trol group, heat stress group and heat stress+L-carnitine group) . The heat-stressed rats was exposed to 43 ℃for 60 min at the same time each trial day. The heat stress+L-carnitine group was given 300 mg/kg body weight of L-carnitine and the control group and the heat stress group were given the same volume of saline. The experiment period was 14 days. Body weight, average daily feed intake, rectal temperature, plasma lipid con-tent, gastrocnemius lipid metabolism enzyme activity were determined. The results showed as follows: 1 ) compared with the control group, the average daily gain of rats at 8 to 14 days in heat stress group and heat stress+L-carnitine group was significantly decreased (P<0.01), but the feed/gain was significantly increased ( P<0.01) , the rectal temperature at 1, 7 and 14 days was significantly increased ( P<0.01) . 2) The activities of gastrocnemius hormone sensitive lipase at 7 days and the gastrocnemius muscle lipoprotein lipase at 14 days of rats in heat stress+L-carnitine group were significantly higher than those of the control group ( P<0.05) , but no significant difference of these two parameters were found between heat stress group and control group ( P>0.05) . 3) The plasma free fatty acid content of rats at 14 days of heat stress group was significantly higher than that of the control group ( P<0.05) . However, the plasma free fatty acid content of rats at 14 days of heat stress+L-carnitine group was significantly decreased compared with that of heat stress group ( P<0.05) . 4) No significant changes among the three groups in other measured parameters ( body weight, average daily feed in-take, plasma triglycerides and total cholesterol content, gastrocnemius carnitine acyl transferase and fatty acid synthase activity) were found ( P>0.05) . It is concluded that under the heat stress condition, L-carnitine can alleviate the abnormal metabolism of body fat in rats through lipolysis enzyme ( hormone sensitive lipase, lipo-protein lipase) , allow the plasma free fatty acid content to physiological level, thus reduce the effects of heat stress on the metabolism of the body.%本文旨在探讨L-肉碱对热应激大鼠机体脂质代谢的影响. 选用48只成年健康雄性SD大鼠,以大鼠在43 ℃烘箱内每次热处理60 min建立热应激模型. 将试验大鼠均分为对照组、热应激组、热应激+L-肉碱组,每天热应激处理前1h 灌胃1 次,热应激+L-肉碱组灌胃300 mg/kg体重的L-肉毒碱,对照组和热应激组灌胃等量生理盐水,共14 d. 检测大鼠的体重、平均日采食量、肛温、血浆脂质含量、腓肠肌脂肪代谢酶活性的变化. 结果显示:1)与对照组相比,热应激组和热应激+L-肉碱组大鼠8~14 d平均日增重极显著下降( P<0.01) ,料重比极显著升高( P<0.01) ,1、7、14 d肛温极显著升高( P<0.01). 2)热应激+L-肉碱组大鼠7 d腓肠肌激素敏感脂酶、14 d腓肠肌脂蛋白脂酶活性显著高于对照组(P<0.05),而热应激组相应时间点这2个指标与对照组没有显著差异( P>0.05). 3)热应激组大鼠14 d血浆游离脂肪酸含量极显著高于对照组( P<0.01) ,而热应激+L-肉碱组大鼠14 d血浆游离脂肪酸含量与热应激组相比极显著下降( P<0.01). 4)其他所测指标(体重、平均日采食量、血浆甘油三酯和总胆固醇含量、腓肠肌肉碱脂酰转移酶和脂肪酸合成酶活性)3组间没有显著差异(P>0.05). 由此可见,在热应激条件下,L-肉碱能通过脂类分解酶(激素敏感脂酶、脂蛋白脂酶)途径缓解大鼠机体脂肪代谢的异常,使血浆游离脂肪酸含量趋于正常,从而减少热应激对机体代谢的影响.