Abstract

Different environmental contaminants disturb the thyroid system at many levels. AlkylPhenols (APs), by-products of microbial degradation of AlkylPhenol Polyethoxylates (APEOs), constitute an important class of Endocrine Disrupting Chemicals (EDCs), the two most often used environmental APs being 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-t-OP). The purpose of the present study was to investigate the effects on the thyroid gland of the bioindicator Podarcis siculus of OP alone and in combination with NP. We used radioimmunoassay to determine their effects on plasma 3,3′,5-triiodo-L-thyronine (T₃), 3,3′,5,5′-L-thyroxine (T₄), thyroid-stimulating hormone (TSH), and thyrotropin-releasing hormone (TRH) levels in adult male lizards. We also investigated the impacts of AP treatments on hepatic 5′ORD (type II) deiodinase and hepatic content of T₃ and T₄. After OP and OP + NP administration, TRH levels increased, whereas TSH, T₃, and T₄ levels decreased. Lizards treated with OP and OP + NP had a higher concentration of T₃ in the liver and 5′ORD (type II) activity, whereas T₄ concentrations were lower than that observed in the control group. Moreover, histological examination showed that the volume of the thyroid follicles became smaller in treated lizards suggesting that that thyroid follicular epithelial cells were not functionally active following treatment. This data collectively suggest a severe interference with hypothalamus–pituitary–thyroid axis and a systemic imbalance of thyroid hormones.

Graphic Abstract

中文翻译：

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单独的辛基苯酚（OP）及其与壬基苯酚（NP）的组合会改变蜥蜴Po的甲状腺的结构和功能

摘要

不同的环境污染物会在许多层面上影响甲状腺系统。烷基苯酚聚乙氧基化物（APEO）微生物降解的副产物烷基苯酚（APs）构成了一类重要的内分泌干扰化学物质（EDC），最常用的两种环境AP是4-壬基苯酚（4-NP）和4-tert -辛基苯酚（4-t-OP）。本研究的目的是研究单独或联合NP的生物指示剂Podarcis siculus对甲状腺的影响。我们使用放射免疫分析法测定它们对血浆3,3'，5-三碘-L-甲状腺素（T ₃），3,3'，5,5'-L-甲状腺素（T _{4）的影响}），成年雄性蜥蜴的促甲状腺激素（TSH）和促甲状腺激素释放激素（TRH）水平。我们还调查了AP治疗对肝5'ORD（II型）脱碘酶和T ₃和T ₄肝含量的影响。在OP和OP + NP给药后，TRH水平升高，而TSH，T ₃和T ₄水平降低。用OP和OP + NP处理的蜥蜴在肝脏中的T ₃浓度较高，并且具有5'ORD（II型）活性，而T ₄浓度低于对照组。此外，组织学检查显示，在处理过的蜥蜴中，甲状腺滤泡的体积变小，这表明治疗后甲状腺滤泡上皮细胞不具有功能活性。这些数据共同表明严重干扰了下丘脑-垂体-甲状腺轴和甲状腺激素的全身失衡。

图形摘要