Traditional Chinese medicine Rhizoma curcumae activates PXR and affects cytochrome P450 3A in the rat liver

Aim To investigate whether Rhizoma curcumaecould induce pregnane X receptor(PXR)-mediated transcriptional expression of CYP3A4 and study the modulatory effects on the enzyme activity and mRNA expression of CYP3A in the rat liver.Methods Transient cotransfection reporter gene assays were performed in HepG2 cells;the rat liver microsomal cytochrome P450 and CYP3A isoenzyme-erythromycin N-demethylase(ERD)activities were determined by UV chromatography;the mRNA expression level of CYP3A was detected by reverse transcriptase-polymerase chain reaction(RT-PCR).Results In vitroinvestigation showed Rhizoma curcumaeand its four selected constituents could induce the CYP3A4 transcriptional expression by activating PXR.In vivoinvestigation showed the CYP450 content of liver microsomes and enzyme activity of CYP3A were markedly increased and induced by Rhizoma curcumaeextract;at the mRNA level, the expression of CYP3A1 and CYP3A2 gene were markedly induced by Rhizoma curcumaeextract.Conclusions Rhizoma curcumaeand its four selected constituents could induce the expression of the CYP3A4 gene transcriptional expression through activating PXR;Rhizoma curcumaeextract could increase and induce the enzyme activity and mRNA expression of CYP3A.