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

Abstract

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 COX4I1, TET1 and DNMT3A protein levels, mRNA expression levels of Cox4i1, Dnmt3a and Tet1, and determine the DNA methylation frequency of Cox4i1.Results showed that both low and high doses of Ligustri Lucidi Fructus could significantly increase COX activity and concentration of COX4I1(P<0.05), with a decreasing tendency of both TET1 protein and DNMT3a protein expression； however, mRNA expression levels of Cox4i1, Dnmt3a and Tet1 were not significantly changed by Ligustri Lucidi Fructus. In addition, DNA methylation frequency of Cox4i1 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 COX4I1. Moreover, a decreased tendency of DNMT3A protein could be one of the reasons for the lower trend of Cox4i1 methylation rate. In addition, Ligustri Lucidi Fructus may regulate the expression levels of DNMT3A and TET1 in the same direction and its mechanism is not clear.