Konno Yoshihiro, Sekimoto Masashi, Nemoto Kiyomitsu, Degawa Masakuni
Department of Molecular Toxicology and COE program in the 21st Century, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
Toxicol Appl Pharmacol. 2004 Apr 1;196(1):20-8. doi: 10.1016/j.taap.2003.12.009.
Male and female of F344 rats were treated per os with nicardipine (Nic) and nifedipine (Nif), and changes in the levels of mRNA and protein of hepatic cytochrome P450 (P450) enzymes, CYP2B1, CYP2B2, CYP3A1, CYP3A2, CYP3A9, and CYP3A18 were examined. Furthermore, hepatic microsomal activities for pentoxyresorufin O-dealkylation (PROD) and nifedipine oxidation, which are mainly mediated by CYP2B and CYP3A subfamily enzymes, respectively, were measured. Analyses of RT-PCR and Western blotting revealed that Nic and Nif induced predominantly CYP3A and CYP2B enzymes, respectively. As for the gene activation of CYP2B enzymes, especially CYP2B1, Nif showed high capacity in both sexes of rats, whereas Nic did a definite capacity in the males but little in the females. Gene activations of CYP3A1, CYP3A2, and CYP3A18 by Nic occurred in both sexes of rats, although that of CYP3A9 did only in the male rats. Although gene activations of CYP3A1 and CYP3A2 by Nif were observed in both sexes of rats, a slight activation of the CYP3A9 gene occurred only in female rats, and the CYP3A18 gene activation, in neither male nor female rats. Thus, changes in levels of the mRNA or protein of CYP2B and CYP3A enzymes, especially CYP2B1 and CYP3A2, were closely correlated with those in hepatic PROD and nifedipine oxidation activities, respectively. The present findings demonstrate for the first time the sex difference in the Nic- and Nif-mediated induction of hepatic P450 enzymes in rats and further indicate that Nic and Nif show different specificities and sex dependencies in the induction of hepatic P450 enzymes.
给F344大鼠的雄性和雌性经口给予尼卡地平（Nic）和硝苯地平（Nif），检测肝细胞色素P450（P450）酶CYP2B1、CYP2B2、CYP3A1、CYP3A2、CYP3A9和CYP3A18的mRNA和蛋白质水平的变化。此外，分别测定主要由CYP2B和CYP3A亚家族酶介导的戊氧基试卤灵O-脱烷基化（PROD）和硝苯地平氧化的肝微粒体活性。RT-PCR和蛋白质印迹分析表明，Nic和Nif分别主要诱导CYP3A和CYP2B酶。至于CYP2B酶的基因激活，尤其是CYP2B1，Nif在大鼠的雌雄两性中均表现出高诱导能力，而Nic在雄性大鼠中有一定诱导能力，在雌性大鼠中诱导能力较弱。Nic对CYP3A1、CYP3A2和CYP3A18的基因激活在大鼠雌雄两性中均有发生，而对CYP3A9的基因激活仅在雄性大鼠中发生。虽然Nif对CYP3A1和CYP3A2的基因激活在大鼠雌雄两性中均有观察到，但CYP3A9基因仅在雌性大鼠中有轻微激活，而CYP3A18基因在雄性和雌性大鼠中均未激活。因此，CYP2B和CYP3A酶，尤其是CYP2B1和CYP3A2的mRNA或蛋白质水平变化分别与肝PROD和硝苯地平氧化活性变化密切相关。本研究结果首次证明了大鼠中Nic和Nif介导的肝P450酶诱导存在性别差异，并进一步表明Nic和Nif在肝P450酶诱导中表现出不同的特异性和性别依赖性。
