Hanioka N, Jinno H, Nishimura T, Ando M
Division of Environmental Chemistry, National Institute of Health Sciences, Kamiyoga, Tokyo, Japan.
Arch Toxicol. 1997;72(1):9-16. doi: 10.1007/s002040050462.
We examined the effect of 1,1-dichloroethylene (1,1-DCE) on microsomal cytochrome P450 (P450) enzymes in rat liver and kidney. Rats were treated intraperitoneally with 1,1-DCE daily for 4 days, at doses of 200, 400, and 800 mg/kg. Among the P450-dependent monooxygenase activities in liver microsomes, testosterone 2alpha-hydroxylase (T2AH), which is associated with CYP2C11 activity, was remarkably decreased by 800 mg/kg 1,1-DCE. The level relative to control activity was < 10%. Furthermore, immunoblotting showed that 1,1-DCE (> or = 400 mg/kg) significantly decreased CYP2C11/6 protein levels in liver microsomes. In addition, 7-methoxyresorufin O-demethylase (MROD), 7-ethoxycoumarin O-deethylase (ECOD), benzphetamine N-demethylase (BZND), chlorzoxazone 6-hydroxylase (CZ6H), and testosterone 6beta-hydroxylase (T6BH) activities were significantly decreased by the highest dose of 1,1-DCE (by 40-70%). However, the activities of other P450-dependent monooxygenases, namely 7-ethoxyresorufin O-deethylase (EROD), 7-benzyloxyresorufin O-debenzylase (BROD), aminopyrine N-demethylase (APND), erythromycin N-demethylase (EMND), lauric acid omega-hydroxylase (LAOH), and testosterone 7alpha-hydroxylase (T7AH) were not affected by 1,1-DCE at any dose. Immunoblotting showed CYP1A1/2, CYP2B1/2, CYP2E1, and CYP3A2/1 protein levels were significantly decreased by 60-66% by 1,1-DCE (800 mg/kg), whereas that of CYP4A1/2 was not affected by any dose of 1,1-DCE. By contrast, among the P450-dependent monooxygenase activities in kidney microsomes, only CZ6H activity was increased by 1,1-DCE (1.6-fold at 800 mg/kg). Also, it was observed that 1,1-DCE (800 mg/kg) significantly increased CYP2E1 protein levels by immunoblotting (approximately 1.5-fold). These results suggest that 1,1-DCE changes the constitutive P450 isoforms in the rat liver and kidney, and that these changes closely relate to the toxicity of 1,1-DCE.
我们研究了1,1 - 二氯乙烯（1,1 - DCE）对大鼠肝脏和肾脏微粒体细胞色素P450（P450）酶的影响。大鼠连续4天每天腹腔注射1,1 - DCE，剂量分别为200、400和800 mg/kg。在肝脏微粒体中依赖P450的单加氧酶活性中，与CYP2C11活性相关的睾酮2α - 羟化酶（T2AH）在给予800 mg/kg 1,1 - DCE后显著降低。相对于对照活性的水平<10%。此外，免疫印迹显示1,1 - DCE（≥400 mg/kg）显著降低了肝脏微粒体中CYP2C11/6蛋白水平。另外，最高剂量的1,1 - DCE（800 mg/kg）使7 - 甲氧基试卤灵O - 脱甲基酶（MROD）、7 - 乙氧基香豆素O - 脱乙基酶（ECOD）、苄非他明N - 脱甲基酶（BZND）、氯唑沙宗6 - 羟化酶（CZ6H）和睾酮6β - 羟化酶（T6BH）的活性显著降低（降低40 - 70%）。然而，其他依赖P450的单加氧酶，即7 - 乙氧基试卤灵O - 脱乙基酶（EROD）、7 - 苄氧基试卤灵O - 脱苄基酶（BROD）、氨基比林N - 脱甲基酶（APND）、红霉素N - 脱甲基酶（EMND）、月桂酸ω - 羟化酶（LAOH）和睾酮7α - 羟化酶（T7AH）的活性在任何剂量的1,1 - DCE作用下均未受到影响。免疫印迹显示，1,1 - DCE（800 mg/kg）使CYP1A1/2、CYP2B1/2、CYP2E1和CYP3A2/1蛋白水平显著降低60 - 66%，而CYP4A1/2的蛋白水平在任何剂量的1,1 - DCE作用下均未受到影响。相比之下，在肾脏微粒体中依赖P450的单加氧酶活性中，只有CZ6H活性被1,1 - DCE增加（800 mg/kg时增加1.6倍）。同样，通过免疫印迹观察到1,1 - DCE（800 mg/kg）使CYP2E1蛋白水平显著增加（约1.5倍）。这些结果表明，1,1 - DCE改变了大鼠肝脏和肾脏中的组成型P450同工型，并且这些改变与1,1 - DCE的毒性密切相关。
