n-3、n-6PUFA高脂饮食对SD大鼠肝脏胆固醇合成相关基因表达影响

Effects of high-fat diet rich in n-3 or n-6PUFA on the expression of related genes regulating hepatic cholesterol synthesis in SD rats

目的探讨n-3、n-6多不饱和脂肪酸(PUFA)高脂饮食对SD大鼠肝脏Srebp2及Hmgcr表达的影响。方法 SD大鼠随机分为3组,分别为对照组(NC)、n-3 PUFA组(TUF)及n-6 PUFA组(SUF),8周后测量血清总胆固醇(TCH)水平,实时定量PCR检测Srebp2及Hmgcr基因表达,Western blotting检测SREBP2及HMGCR蛋白表达。结果 TUF组、SUF组血清TCH含量均显著降低(P<0.001),TUF组最低。TUF组、SUF组Srebp2及Hmgcr基因表达水平均显著增高(P=0.007,P=0.012),SUF组Srebp2最高,TUF组Hmgcr最高。TUF组HMGCR蛋白表达显著高于NC组及SUF组,SUF组与NC组差异无显著性;三组SREBP2蛋白表达。结论 n-3、n-6PUFA降低血清胆固醇不是通过抑制Srebp2及Hmgcr表达实现的。

Objective To investigate the effects of high-fat diet rich in n-3 or n-6PUFA on the expressions of Srebp2 and Hmgcr in SD rats. Methods Eighteen normal male SD rats were randomly divided into 3 groups, including normal control group （NC） , high-n-3PUFA formula diet group （TUF） and high-n-6PUFA formula diet group （SUF） （n = 6）. After 8 weeks, the total serum cholesterol （TCH） was measured. Srebp2 and Hmgcr gene expressions were detected by quantitative real-time PCR and the proteins were observed by Western blotting. Results Serum TCH in both the TUF and SUF groups were significantly lower than that of the NC group （ P 〈 0. 001 ）, and that in the TUF group was the lowest. Meanwhile, gene expressions of Srebp2 and Hmgcr in both the TUF and SUF groups were significantly higher than that of the NC group （P =0. 007, P =0. 012）. Western blotting showed that HMGCR in the TUF group was higher than that in the NC and SUF groups, while it was not significantly different between SUF and NC groups. There was no significant difference among the SREBP2 expressions in the three groups. Conclusions Overfeeding of n-3 or n-6PUFA reduces the serum TCH in rats, but it is not resulted from the inhibition of Srebp2 and Hmgcr expressions.