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目的:研究甘草酸18位差向异构体18α-甘草酸、18β-甘草酸对Caco-2细胞上P-糖蛋白功能和表达的影响。方法:建立Caco-2细胞模型,采用罗丹明-123摄取法评价P-糖蛋白的功能;利用流式细胞术和荧光定量PCR分析Caco-2细胞膜上P-糖蛋白的表达。结果:中、高浓度(10,60μmol.L-1)α-GL使细胞内Rho-123摄取增加,对P-gp表现出抑制作用,但没有呈现出剂量依赖性;β-GL各浓度组使细胞内Rho-123摄取减少,对P-gp表现出诱导作用,但也没有表现出剂量依赖性。二者对Caco-2细胞上P-gp功能的影响呈相反的趋势;Caco-2细胞与药物孵育72 h后,中、高浓度(10,60μmol.L-1)α-GL下调MDR1 mRNA表达,β-GL只在高浓度(60μmol.L-1)上调了MDR1 mRNA表达;高浓度(60μmol.L-1)β-GL在蛋白水平对P-gp有诱导作用,α-GL各浓度没有表现出对P-gp表达的影响。结论:转录水平上α-GL,β-GL对P-gp的影响与α-GL,β-GL对CYP3A的影响呈现一定的同向性,甘草酸18位差向异构体对CYP3A与P-gp的影响有相似的立体选择性,其机制是否与孕烷X受体(PXR)有关,有待进一步研究。
Objective: To study the effect of 18α-glycyrrhizic acid and 18β-glycyrrhizic acid on the function and expression of P-glycoprotein on Caco-2 cells. Methods: Caco-2 cell model was established. The function of P-glycoprotein was evaluated by rhodamine-123 uptake method. The expression of P-glycoprotein on Caco-2 cell membrane was analyzed by flow cytometry and real-time PCR. Results: The medium and high concentrations of α-GL (10,60μmol.L-1) increased the intracellular Rho-123 uptake and inhibited the expression of P-gp but did not show dose-dependent effect. Reduced intracellular Rho-123 uptake and induction of P-gp did not appear to be dose-dependent. The effect of P-gp on Caco-2 cells showed the opposite trend. After Caco-2 cells were incubated with drugs for 72 h, the expression of MDR1 mRNA was down-regulated by medium and high concentrations of α-GL (10,60 μmol·L -1) , β-GL up-regulates MDR1 mRNA expression only at high concentration (60μmol.L-1); high concentration (60μmol.L-1) β-GL induces P-gp at protein level, Demonstrating the effect on P-gp expression. CONCLUSION: The effect of α-GL and β-GL on P-gp at the transcriptional level is in the same direction as that of α-GL and β-GL. CYP3A and P The effect of -gp has similar stereoselectivity, and its mechanism is related to pregnane X receptor (PXR), pending further study.