Kocarek T A, Schuetz E G, Guzelian P S
Department of Medicine, Medical College of Virginia, Richmond 23298.
Toxicol Lett. 1994 Apr;71(2):183-96. doi: 10.1016/0378-4274(94)90179-1.
We previously reported that when primary cultures of rat hepatocytes were treated with phenobarbital (PB) or one of several organochlorine pesticides, including Mirex, there was co-induction of cytochrome P450 2B1 and 2B2 mRNAs and immunoreactive proteins, whereas Kepone selectively induced 2B2 (Kocarek et al. (1991) Mol. Pharmacol. 40, 203-210). Indeed, Kepone treatment actively suppressed induction of 2B1 and 2B2 mRNAs in hepatocytes cotreated with phenobarbital. Because Kepone differs chemically from Mirex only in the replacement of 2 chlorine atoms with a ketone group, which exists in aqueous solution as a gem-diol and appears to confer weak estrogenic properties, we treated hepatocyte cultures with one of 3 potent estrogens, beta-estradiol, 17 alpha-ethinylestradiol or diethylstilbestrol. Treatment with each of these estrogens induced 2B1 and 2B2 mRNA only at very high doses (10(-4) M). Beta-Estradiol (10(-4) M) treatment also induced 2B1/2 mRNA in hepatocyte cultures prepared from a prepubescent female rat. The anti-estrogen tamoxifen failed to reverse 2B1/2 mRNA induction following beta-estradiol or Kepone treatment of adult hepatocyte cultures. High doses of beta-estradiol or 17 alpha-ethinylestradiol failed to induce 2B1/2 mRNA in treated rats. We also examined the effects of chloral hydrate, a simple gem-diol, on 2B1/2 mRNA induction in the hepatocyte cultures. Treatment with chloral hydrate (3 x 10(-3) M), like Kepone (10(-5) M), suppressed 2B1/2 mRNA induction following phenobarbital (10(-4) M) treatment, while Kepone alcohol (10(-5) M), which is not a gem-diol, produced less suppression. Our results suggest that selective induction by Kepone of 2B2 is unlikely related to its effects as a weak classical estrogen, while the ability of Kepone to suppress induction of 2B1 and 2B2 by PB may be related to its properties as a gem-diol.
我们之前报道过，当用苯巴比妥（PB）或几种有机氯农药（包括灭蚁灵）之一处理大鼠肝细胞原代培养物时，细胞色素P450 2B1和2B2的mRNA及免疫反应性蛋白会共同被诱导，而开蓬则选择性地诱导2B2（科卡雷克等人（1991年），《分子药理学》40卷，203 - 210页）。实际上，在用苯巴比妥共同处理的肝细胞中，开蓬处理会积极抑制2B1和2B2 mRNA的诱导。由于开蓬与灭蚁灵在化学上的差异仅在于两个氯原子被一个酮基取代，该酮基在水溶液中以偕二醇形式存在且似乎具有弱雌激素特性，我们用三种强效雌激素之一，即β - 雌二醇、17α - 乙炔雌二醇或己烯雌酚处理肝细胞培养物。用这些雌激素中的每一种处理时，只有在非常高的剂量（10⁻⁴ M）下才会诱导2B1和2B2 mRNA。β - 雌二醇（10⁻⁴ M）处理也会在由青春期前雌性大鼠制备的肝细胞培养物中诱导2B1/2 mRNA。抗雌激素他莫昔芬未能逆转β - 雌二醇或开蓬处理成年肝细胞培养物后2B1/2 mRNA的诱导。高剂量的β - 雌二醇或17α - 乙炔雌二醇未能在处理的大鼠中诱导2B1/2 mRNA。我们还研究了水合氯醛（一种简单的偕二醇）对肝细胞培养物中2B1/2 mRNA诱导的影响。用水合氯醛（3×10⁻³ M）处理，与开蓬（10⁻⁵ M）一样，会抑制苯巴比妥（10⁻⁴ M）处理后2B1/2 mRNA的诱导，而开蓬醇（10⁻⁵ M，它不是偕二醇）产生的抑制作用较小。我们的结果表明，开蓬对2B2的选择性诱导不太可能与其作为弱经典雌激素的作用有关，而开蓬抑制PB诱导2B1和2B2的能力可能与其作为偕二醇的特性有关。
