Rodrigues Aline Cristina Ferreira, Moneró Tatiana de Oliveira, Frighetto Rosa Toyoko Shiraishi, de Almeida Eduardo Alves
Departamento de Química e Ciências Ambientais, IBILCE, UNESP, Av. Cristóvão Colombo 2265, 15054-000, São José do Rio Preto, SP, Brazil.
Embrapa Suínos e Aves, Br 153, Km 110, Caixa Postal 21, 89700-000, Concórdia, SC, Brazil.
Environ Sci Pollut Res Int. 2015 Nov;22(22):17367-74. doi: 10.1007/s11356-014-3670-5. Epub 2014 Oct 5.
In the aquatic environment, biotransformation enzymes are established biomarkers for assessing PAH exposure in fish, but little is known about the effect of 17β-estradiol (E2) on these enzymes during exposure to benzo(a)pyrene (BaP). In this study, Nile tilapia (Oreochromis niloticus) were exposed for 3, 5, and 10 days to BaP (300 μg L(-1)) and E2 (5 μg L(-1)). These substances were applied isolated or mixed. In the mixture experiment, fish were analyzed pre- and postexposure in order to better understand whether preexposure to the hormone masks the responses activated by PAH or vice versa. Phase I enzymes ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin-O-depenthylase (PROD), and benzyloxyresorufin-O-debenzylase (BROD) activities as well as the phase II enzyme glutathione S-transferase (GST) were analyzed. Isolated E2 treatment decreased EROD activity after 3 days, but this enzyme activity returned to control values after 5 and 10 days of exposure. Isolated BaP treatment significantly induced EROD activity after 3 and 5 days, and the activity returned to control levels after ten exposure days. Combined treatment (E2 + Bap) significantly increased EROD activity, both in the pre- and postexposure. This increase was even higher than in the isolated BaP treatment, suggesting a synergism between these two compounds. When E2 and BaP were used singly, they did not change BROD and PROD activities. However, combined treatment (E2 + Bap) significantly increased PROD activity. Isolated BaP treatment increased GST activity after 10 days. However, this response was not observed in the mixture treatment, suggesting that E2 suppressed the GST induction modulated by BaP. The results put together indicated that E2 altered the biotransformation pathway regarding enzymes activated by BaP in Nile tilapia.
在水生环境中，生物转化酶是评估鱼类多环芳烃暴露的既定生物标志物，但对于17β-雌二醇（E2）在暴露于苯并(a)芘（BaP）期间对这些酶的影响知之甚少。在本研究中，尼罗罗非鱼（Oreochromis niloticus）分别暴露于BaP（300 μg L(-1)）和E2（5 μg L(-1)）3天、5天和10天。这些物质单独或混合使用。在混合实验中，对鱼在暴露前后进行分析，以便更好地了解预先暴露于激素是否会掩盖多环芳烃激活的反应，反之亦然。分析了I相酶乙氧基异吩唑酮-O-脱乙基酶（EROD）、戊氧基异吩唑酮-O-脱戊基酶（PROD）和苄氧基异吩唑酮-O-脱苄基酶（BROD）的活性以及II相酶谷胱甘肽S-转移酶（GST）。单独使用E2处理3天后EROD活性降低，但在暴露5天和10天后该酶活性恢复到对照值。单独使用BaP处理3天和5天后显著诱导EROD活性，暴露10天后活性恢复到对照水平。联合处理（E2 + BaP）在暴露前和暴露后均显著增加EROD活性。这种增加甚至高于单独使用BaP处理，表明这两种化合物之间存在协同作用。当单独使用E2和BaP时，它们不会改变BROD和PROD活性。然而，联合处理（E2 + BaP）显著增加了PROD活性。单独使用BaP处理10天后增加了GST活性。然而，在混合处理中未观察到这种反应，表明E2抑制了BaP调节的GST诱导。综合结果表明，E2改变了尼罗罗非鱼中由BaP激活的酶的生物转化途径。
