Sanderson J Thomas, Boerma Joke, Lansbergen Gideon W A, van den Berg Martin
Institute for Risk Assessment Sciences (IRAS), University of Utrecht, P.O. Box 80176, 3508 TD, Utrecht, The Netherlands.
Toxicol Appl Pharmacol. 2002 Jul 1;182(1):44-54. doi: 10.1006/taap.2002.9420.
Various pesticides known or suspected to interfere with steroid hormone function were screened in H295R cells for effects on catalytic activity and mRNA expression of aromatase. Dibutyl-, tributyl-, and triphenyltin chloride decreased aromatase and ethoxyresorufin O-deethylase activities concentration dependently (1-300 nM; 24-h exposure). However, these decreases occurred only at cytotoxic concentrations, indicated by decreases in mitochondrial MTT reduction and intracellular neutral red uptake. The organotins did not cause direct inhibition during the catalytic assay (1-1000 nM; 1.5-h exposure). The same was true for p,p'-DDT, and o,p-DDT, and o,p-DDE, which decreased aromatase activity only at cytotoxic concentrations (> or =10 microM; 24-h exposure). p,p'-DDE had no effect on aromatase activity or cell viability at 1 and 10 microM. Various imidazole-like fungicides were aromatase inhibitors. Imazalil and prochloraz were potent mixed inhibitors (K(i)/K(i)(') = 0.04/0.3 and 0.02/0.3 microM, respectively), whereas propiconazole, difenoconazole, and penconazole were less potent competitive inhibitors (K(i) = 1.9, 4.5, and 4.7 microM, respectively). Fenarimol, tebuconazole, and hexaconazole decreased aromatase activity close to cytotoxic concentrations. Vinclozolin, as was shown previously for atrazine, induced aromatase activity and CYP19 mRNA levels about 2.5- and 1.5-fold, respectively. To investigate the mechanism of aromatase induction in H295R cells, the ability of the pesticides to increase intracellular cAMP levels was examined. Vinclozolin (100 microM) and atrazine (30 microM) increased cAMP levels about 1.5-fold above control. Forskolin and isobutyl methylxanthine (IBMX) increased cAMP levels 3 and 1.8-fold, respectively. Time-response curves for cAMP induction and concentration-response curves for aromatase induction by vinclozolin, atrazine, and IBMX were similar, suggesting that the mechanism of aromatase induction by these pesticides is mediated through inhibition of phosphodiesterase activity.
在H295R细胞中筛选了各种已知或疑似干扰类固醇激素功能的农药，以研究其对芳香化酶催化活性和mRNA表达的影响。二丁基氯化锡、三丁基氯化锡和三苯基氯化锡浓度依赖性地降低芳香化酶和乙氧基试卤灵O - 脱乙基酶的活性（1 - 300 nM；暴露24小时）。然而，这些降低仅在细胞毒性浓度下出现，表现为线粒体MTT还原和细胞内中性红摄取减少。在催化试验中（1 - 1000 nM；暴露1.5小时），有机锡未引起直接抑制。对硫磷、对硫磷和对硫磷 - 滴滴伊也是如此，它们仅在细胞毒性浓度（≥10 μM；暴露24小时）下降低芳香化酶活性。在1和10 μM时，对硫磷 - 滴滴伊对芳香化酶活性或细胞活力没有影响。各种咪唑类杀菌剂是芳香化酶抑制剂。抑霉唑和咪鲜胺是强效的混合抑制剂（K(i)/K(i)'分别为0.04/0.3和0.02/0.3 μM），而丙环唑、苯醚甲环唑和戊唑醇是较弱的竞争性抑制剂（K(i)分别为1.9、4.5和4.7 μM）。氯苯嘧啶醇、戊唑醇和己唑醇在接近细胞毒性浓度时降低芳香化酶活性。如先前对阿特拉津的研究所示，乙烯菌核利分别诱导芳香化酶活性和CYP19 mRNA水平约2.5倍和1.5倍。为了研究H295R细胞中芳香化酶诱导的机制，检测了农药增加细胞内cAMP水平的能力。乙烯菌核利（100 μM）和阿特拉津（30 μM）使cAMP水平比对照升高约1.5倍。福斯高林和异丁基甲基黄嘌呤（IBMX）分别使cAMP水平升高3倍和1.8倍。乙烯菌核利、阿特拉津和IBMX诱导cAMP的时间 - 反应曲线以及诱导芳香化酶的浓度 - 反应曲线相似，表明这些农药诱导芳香化酶的机制是通过抑制磷酸二酯酶活性介导的。
