无斑鹞鲼蛋白质对大鼠胆固醇代谢的影响

Effect of Dietary Protein from Aetobatus flagelum on Cholesterol Metabolism in Rats

目的:探讨无斑鹞鲼蛋白(Aetobatus flagelum protein,AFP)对高胆固醇模型大鼠胆固醇代谢的影响,并对其可能的作用机制加以研究。方法:5周龄雄性Sprague-Dawley(SD)大鼠,适应性饲养1周后,按体质量随机分为酪蛋白对照组、5%AFP组、10%AFP组,分别给予高胆固醇饲料及分别添加5%和10%AFP的高胆固醇饲料。28 d后测定大鼠血清总胆固醇(total cholesterol,TC)、高密度脂蛋白胆固醇(high density lipoprotein cholesterol,HDL-C)水平,肝脏TC、游离胆固醇水平,粪便中胆汁酸和中性固醇含量以及肝脏3-羟基-3-甲基戊二酸单酰辅酶A(3-hydroxy-3-methyl glutaryl coenzyme A reductase,HMG-Co A)、胆固醇酰基转移酶2(acyl coenzyme Acholesterol acyltransferase 2,ACAT2)、胆固醇7α-羟化酶1(cholesterol 7α-hydroxylase 1,CYP7A1)的m RNA表达量。结果:与酪蛋白对照组相比,无斑鹞鲼蛋白可显著降低大鼠血清和肝脏中的TC含量(P<0.05),明显增加血清HDL-C含量(P<0.05),极显著降低大鼠动脉粥样硬化指数(P<0.01)。此外,无斑鹞鲼蛋白可明显增加大鼠粪便中胆汁酸和中性固醇的排出量(P<0.05),并可降低大鼠肝脏中ACAT2 m RNA的表达量(P<0.05),增加CYP7A1 m RNA的表达量(P<0.05),而对HMG-Co A m RNA的作用不显著。结论:无斑鹞鲼蛋白可明显降低大鼠血清和肝脏中的TC含量,降低大鼠血清动脉粥样硬化指数,其作用机制主要与增加肝脏内胆固醇的分解代谢以及促进粪便中性固醇和胆汁酸的排出有关。

Objective： To investigate the effect of dietary Aetobatus flagelum protein（AFP） on cholesterol metabolism in high cholesterol diet-fed rats and to explore the possible mechanism involved. Methods： Twenty-one male SD rats were randomly divided into 3 groups, including normal control group（casein）, 5% AFP-treated group（containing 5% AFP）, 10% AFP-treated group（containing 10% AFP）. After 28 days of consecutive administration, serum total cholesterol（TC）, high density lipoprotein cholesterol（HDL-C）, hepatic cholesterol concentrations（TC and free cholesterol）, and fecal bile acid and neutral steroid were determined. The m RNA expression of key enzymes related to cholesterol metabolism, such as HMG-Co A reductase, acyl-Co A-cholesterol acyltrasferase 2（ACAT2）, and cholesterol 7α-hydroxylase 1（CYP7A1）, was also determined. Results： The levels of serum and hepatic TC were significantly decreased in rats fed AFP compared with the control group（P 0.05）, while the concentration of serum HDL-C was increased and consequently the atherogenic index was very significantly decreased in the AFP groups compared with in control group（P 0.01）. Moreover, dietary Aetobatus flagelum protein significantly aggrandized the concentrations of fecal bile acid and neutral steroid（P 0.05）. The activity of ACAT2 in liver was inhibited by dietary AFP, whereas the activity of hepatic HMG-Co A was not affected. On the other hand, the m RNA expression of the CYP7A1 gene was significantly decreased（P 0.05）. Conclusion： Aetobatus flagelum protein could significantly decrease serum and hepatic cholesterol accumulation, and lead to a decrease in serum atherogenic index, mainly through promoting the metabolism of cholesterol and the excretion of fecal bile acid and neutral steroid.