女贞子对正常大鼠肝脏COX活性的影响及其DNA甲基化调节机制的初步研究

Effect of Ligustri Lucidi Fructus on hepatic COX activity in normal rats and preliminary investigation of its DNA methylation mechanism

探讨女贞子对大鼠肝脏细胞色素c氧化酶(cytochrome c oxidase,COX)活性的影响及可能的DNA甲基化机制。实验采用女贞子的水提物按2.0 g·kg^(-1)和6.0 g·kg^(-1)灌胃大鼠30 d,处死大鼠后,取肝脏测定COX活性、COX的亚基之一COX4I1蛋白浓度、测定Cox4i1,Dnmt3a,Tet1基因mRNA表达水平、TET1和DNMT3A的蛋白水平以及检测Cox4i1DNA甲基化频率。结果显示女贞子低剂量和高剂量能显著性升高COX的活性和COX4I1的浓度(P<0.05);有降低TET1蛋白和DNMT3A的蛋白表达量的趋势;但未显著改变Cox4i1,Dnmt3a,Tet1基因mRNA表达。与空白对照组相比,女贞子高剂量组甲基化频率有降低的趋势但未达到显著水平。该研究表明:女贞子对大鼠肝脏的COX酶活性有促进作用,其可能通过促进COX4I1的蛋白量增加实现;女贞子对DNMT3A的蛋白表达有降低趋势,其可能是Cox4i1DNA甲基化频率有降低趋势的原因。女贞子对于DNMT3A和TET1的蛋白表达可能有同向调节作用,具体机制仍不明确。

The study aims to investigate the effect of Ligustri Lucidi Fructus on cytochrome c oxidase （COX） activity in rat hepatic tissues and explore its possible mechanism of DNA methylation. Male SD rats received aqueous extract of Ligustri Lucidi Fructus （2. 0, 6.0 g kg-1 ） by intragastric administration for 30 d. After the rats were sacrificed, hepatic tissues of rats were taken to detect COX activity, protein concentration of COX411, TET1 and DNMT3A protein levels, mRNA expression levels of Cox4il, Dnmt3a and Tetl, and determine the DNA methylation frequency of Cox4il. Results showed that both low and high doses of Ligustri Lucidi Fructus could significantly increase COX activity and concentration of COX411 （ P 〈 0. 05 ）, with a decreasing tendency of both TET1 protein and DN- MT3a protein expression; however, mRNA expression levels of Cox4il, Dnmt3a and Tetl were not significantly changed by Ligustri Lucidi Fructus. In addition, DNA methylation frequency of Cox4il in high dose group showed a declining tendency as compared with the blank control group, but without significant difference. These results indicated that Ligustri Lucidi Fructus had promotive effect on hepatic COX activity in rats, which may be achieved by increasing protein content of COX411. Moreover, a decreased tendency of DN- MT3A protein could be one of the reasons for the lower trend of Cox4il methylation rate. In addition, Ligustri Lucidi Fructus may regu- late the expression levels of DNMT3A and TET1 in the same direction and its mechanism is not clear.