Department of Pharmaceutical and Pharmacological Sciences, University of Padova, Padova 35131, Italy.
Department of Medicine, General Pathology and Cytopathology Unit, University of Padova, Padova 35131, Italy.
World J Gastroenterol. 2017 Nov 14;23(42):7519-7530. doi: 10.3748/wjg.v23.i42.7519.
To ascertain whether cholestasis affects the expression of two CYP3A isoforms (CYP3A1 and CYP3A2) and of pregnane X receptor (PXR) and constitutive androstane receptor (CAR).
Cholestasis was induced by bile duct ligation in 16 male Wistar rats; whereas 8 sham-operated rats were used as controls. Severity of cholestasis was assessed on histological examination of liver sections, and serum concentrations of albumin, AST, ALT, GGT, ALPK and bilirubin. Gene and protein expressions of PXR, CAR, CYP3A1 and CYP3A2 were assessed by means of qRT-PCR and Western blot, respectively. Alterations in CYP3A activity were measured by calculating the kinetic parameters of 4-OH and 1'-OH-midazolam hydroxylation, marker reactions for CYP3A enzymes.
The mRNA and protein expression of CYP3A1 increased significantly in mild cholestasis ( < 0.01). At variance, mRNA and protein expression of CYP3A2 didn't change in mild cholestasis, whereas the expression and activity of both CYP3A1 and CYP3A2 decreased dramatically when cholestasis became severe. Consistently with these observations, the nuclear expression of both PXR and CAR, which was measured because they both translocate into the cell nucleus after their activation, virtually disappeared in the late stage of cholestatic injury, after an initial increase. These results indicate that early- and late-stage cholestasis affects CYP3A-mediated drug metabolism differently, probably as consequence of the different activation of PXR and CAR.
Early- and late-stage cholestasis affects CYP3A-mediated drug metabolism differently. PXR and CAR might be targeted therapeutically to promote CYP3A-mediated liver detoxification.
确定胆汁淤积是否会影响两种 CYP3A 同工酶（CYP3A1 和 CYP3A2）以及孕烷 X 受体（PXR）和组成型雄烷受体（CAR）的表达。
通过胆管结扎在 16 只雄性 Wistar 大鼠中诱导胆汁淤积；而 8 只假手术大鼠作为对照。通过肝组织学检查评估胆汁淤积的严重程度，并检测血清白蛋白、AST、ALT、GGT、ALPK 和胆红素浓度。通过 qRT-PCR 和 Western blot 分别评估 PXR、CAR、CYP3A1 和 CYP3A2 的基因和蛋白表达。通过计算 4-OH 和 1'-OH-咪达唑仑羟化的动力学参数来测量 CYP3A 活性的变化，这是 CYP3A 酶的标记反应。
轻度胆汁淤积（<0.01）时 CYP3A1 的 mRNA 和蛋白表达显著增加。相反，轻度胆汁淤积时 CYP3A2 的 mRNA 和蛋白表达没有变化，而当胆汁淤积变得严重时，CYP3A1 和 CYP3A2 的表达和活性都显著下降。与这些观察结果一致，PXR 和 CAR 的核表达都发生了变化，因为它们在激活后都会转移到细胞核中，在胆汁淤积性损伤的晚期，也就是在最初的增加之后，几乎消失了。这些结果表明，早期和晚期胆汁淤积对 CYP3A 介导的药物代谢的影响不同，可能是由于 PXR 和 CAR 的不同激活所致。
早期和晚期胆汁淤积对 CYP3A 介导的药物代谢的影响不同。PXR 和 CAR 可能是治疗靶点，以促进 CYP3A 介导的肝脏解毒。
