Gray E S, Woodin B R, Stegeman J J
Department of Biology, Woods Hole Oceanographic Institution, Massachusetts 02543.
J Exp Zool. 1991 Sep;259(3):330-42. doi: 10.1002/jez.1402590308.
Details concerning the endogenous regulation of hepatic cytochrome P450 monooxygenases in teleosts, and the features of this regulation common among fish species, are poorly known. Gonadally mature female winter flounder (Pseudopleuronectes americanus) have been reported to have severalfold lower levels of microsomal cytochromes P450 and b5 and NADPH-cytochrome c reductase than do males (Stegeman and Woodin ('84) Mar. Environ. Res., 14:422-425). These strong sex differences prompted more detailed study of P450 regulation in winter flounder liver, and a comparison with sex differences in another marine teleost, scup (Stenotomus chrysops). Ethoxyresorufin O-deethylase (EROD) activity/nmol P450 was less in gonadally mature females than in males of both species. Immunoblot analysis with MAb 1-12-3 to P450E (the EROD catalyst) showed that the content of P450E counterpart was also much less in females of both species. Aminopyrine N-demethylase (APND) and testosterone 6 beta-hydroxylase (6 beta-OHase) activities per nmol P450 were higher in gonadally mature female than in mature male flounder, differences not seen in scup. Polyclonal antibodies to scup P450A were shown to detect proteins in a number of teleosts. The levels of anti-P450A cross-reacting protein were greater in mature female than in male flounder, but as with 6 beta-OHase activity, the content of this protein was not sexually differentiated in scup. Estradiol treatment of winter flounder depressed the rates of EROD, APND, 6 beta-OHase, and estradiol 2-OHase activities per mg protein, but APND and 6 beta-OHase activities per nmol P450 were unchanged. Thus, E2 promotes general decreases in some hepatic P450-catalyzed activities, but in achieving sex differences there is also specific regulation of the P450E counterpart, and possibly of the 6 beta-OHase (P450A?). Other factors, temporal or hormonal, can modify the effect of E2 treatment, and may contribute to the specific regulation of P450 forms in naturally maturing fish, and to species differences in this regulation.
关于硬骨鱼肝脏细胞色素P450单加氧酶的内源性调节以及鱼类物种间这种调节的共同特征，目前所知甚少。据报道，性腺成熟的雌性冬比目鱼（美洲拟庸鲽）微粒体细胞色素P450、b5和NADPH - 细胞色素c还原酶的水平比雄性低几倍（斯特格曼和伍丁（1984年）《海洋环境研究》，14:422 - 425）。这些显著的性别差异促使对冬比目鱼肝脏中P450调节进行更详细的研究，并与另一种海洋硬骨鱼鲷（金头鲷）的性别差异进行比较。两种鱼性腺成熟的雌性中，乙氧基异吩恶唑酮O - 脱乙基酶（EROD）活性/每nmol P450低于雄性。用针对P450E（EROD催化剂）的单克隆抗体1 - 12 - 3进行免疫印迹分析表明，两种鱼的雌性中P450E对应物的含量也少得多。每nmol P450的氨基比林N - 脱甲基酶（APND）和睾酮6β - 羟化酶（6β - OHase）活性在性腺成熟的雌性冬比目鱼中高于成熟雄性，而在鲷中未观察到这种差异。针对鲷P450A的多克隆抗体被证明能检测许多硬骨鱼中的蛋白质。抗P450A交叉反应蛋白的水平在成熟雌性冬比目鱼中高于雄性，但与6β - OHase活性一样，这种蛋白的含量在鲷中没有性别差异。用雌二醇处理冬比目鱼会降低每毫克蛋白质的EROD、APND、6β - OHase和雌二醇2 - OHase活性，但每nmol P450的APND和6β - OHase活性不变。因此，E2促进了一些肝脏中P450催化活性的普遍降低，但在形成性别差异时，对P450E对应物以及可能对6β - OHase（P450A？）也有特异性调节。其他因素，无论是时间上的还是激素方面的，都可以改变E2处理的效果，并可能有助于自然成熟鱼类中P450形式的特异性调节以及这种调节中的物种差异。
