ABSTRACT
Objective: To investigate the regulation of CYP3A4 and P-gp by berberine hydrochloride ( BBR) via pregnane X re-ceptor (PXR) pathway. Methods: pLKO. 1-PXR vector, a lentivirus plasmid expressing PXR shRNA, was packaged into 293T cells. Human hepatoma (HepG2) cells were infected with the lentivirus and the cell clones stably expressing PXR shRNA were selected by puromycin according to pLKO. 1 vector characteristics. Real-time RT-PCR and Western blot were used to evaluate CYP3A4 and P-gp mRNA and protein in berberine treated HepG2 cells and PXR-silenced HepG2 cells. Results: The PXR expression in PXR silenced cells significantly decreased (P<0.01) when compared with that in HepG2 cells, while there was no significant difference (P >0. 05) in the expression of CYP3A4 and P-gp between the groups. Compared with that in HepG2 cells, the inhibition of berberine on the mRNA and protein expression of CYP3A4 and P-gp in PXR-silenced HepG2 cells was weakened (P<0. 05 or P<0. 01). Conclu-sion: Berberine can regulate the expression of CYP3A4 and P-gp via PXR signaling pathway, while it is not the only one.
ABSTRACT
Objective To examine the effect of berberine hydrochloride ( BER ) on the pharmacokinetic profiles of midazolam,a substrate of CYP3A,in rats. Methods The rats were intragastrically given different doses of BER (50,100, 200 mg?kg-1) or ketoconazole (75 mg?kg-1) for 10 days.Single-pass duodenum perfusion of 20 mg?kg-1 MDZ was performed and the inguinal artery was cannulated for blood sampling.Plasma concentrations of MDZ and 1'-OH-MDZ were analyzed by high performance liquid chromatography ( HPLC) with the CYP3A inhibitor ketoconazole serving as positive control. Results BER (50,100,200 mg?kg-1) and ketoconazole (75 mg?kg-1) could significantly increase the AUC(0-t),AUMC(0-t)and Cmax of MDZ in a dose-dependent manner ( P<0.05) ,and reduce the clearance rate ( CLz ) of MDA and its apparent volume of distribution in the body ( Vz ) ( P<0. 05). But they failed to dramatically affect the half-life ( t1/2z ) and the peak time ( tmax ) of MDZ. Additionally,BER ( 100,200 mg?kg-1 ) and ketoconazole ( 75 mg?kg-1 ) could significantly dose-dependently decrease the AUC(0-t),AUMC(0-t)and Cmaxof 1'-OH-MDZ,and profoundly increase the CLz,tmax and Vz of 1'-OH-MDZ (P<0.05),but they had no remarkable influences on the t1/2z.The ratio of AUC(1'-OH-MDZ)/AUC(MDZ) was decreased with the increase of BER concentration. Conclusion BER can inhibit the in vivo metabolism of MDZ in a dose-dependant manner, which is associated with the suppression of the activity of CYP3A.
ABSTRACT
Pregnane X receptor ( PXR) , a member of the nuclear receptor subfamily, plays an important role in the regulation of drug metabolic enzymes and transporters. PXR can regulate the expression of downstream target genes through transforming a large number of exogenous and endogenous chemical substances, and can be activated by a variety of Chinese herbal medicines. The same as PXR, constitutive androstane receptor ( CAR) can participate in the regulation of drug metabolic enzyme CYP450 and become the targets of drug action through combining with exogenous ligands to regulate the expression of CYP2B6, CYP3A4, CYP2C19 and UGT1A1.