Arukwe Augustine, Ibor Oju R, Adeogun Aina O
Department of Biology, Norwegian University of Science and Technology (NTNU), Høgskoleringen 5, N-7491 Trondheim, Norway.
Department of Zoology, University of Ibadan, Ibadan, Nigeria; Department of Zoology and Environmental Biology, University of Calabar, Calabar, Nigeria.
Gen Comp Endocrinol. 2017 Dec 1;254:22-37. doi: 10.1016/j.ygcen.2017.09.007. Epub 2017 Sep 14.
Receptor (i.e. genomic) and non-receptor (or non-genomic) effects of endocrine toxicology have received limited or almost non-existent attention for tropical species and regions. In the present study, we have evaluated the effects of di-(2-ethylhexyl) phthalate (DEHP) on neuro- and interrenal steroidogenesis of the African catfish (Clarias gariepinus) using molecular, immunochemical and physiological approaches. Juvenile fish (mean weight and length: 5.6±0.6g and 8.2±1.2cm, respectively), were randomly distributed into ten 120L rectangular glass tanks containing 60L of dechlorinated tap water, at 50 fish per exposure group. The fish were exposed to environmentally relevant concentrations of DEHP, consisting of 0 (ethanol solvent control), 10, 100, 200, and 400μg DEHP/L water and performed in two replicates. Brain, liver and head kidney samples were collected at day 3, 7 and 14 after exposure, and analysed for star, p450scc, cyp19a1, cyp17, cyp11β-, 3β-, 17β- and 20β-hsd, and 17β-ohase mRNA expression using real-time PCR. The StAR, P450scc and CYP19 proteins were measured using immunoblotting method, while estradiol-17β (E2) and testosterone (T) were measured in liver homogenate using enzyme immunoassay (EIA). Our data showed a consistent and unique pattern of biphasic effect on star and steroidogenic enzyme genes with increases at low concentration (10μg/L) and thereafter, a concentration-dependent decrease in both the brain and head kidney, that paralleled the expression of StAR, P450scc and CYP19 proteins. Cellular E2 and T levels showed an apparent DEHP concentration-dependent increase at day 14 of exposure. The observed consistency in the current findings and in view of previous reports on contaminants-induced alterations in neuro- and interrenal steroidogenesis, the broader toxicological and endocrine disruptor implication of our data indicate potentials for overt reproductive, metabolic, physiological and general health consequences for the exposed organisms.
内分泌毒理学的受体（即基因组）和非受体（或非基因组）效应在热带物种和地区受到的关注有限或几乎不存在。在本研究中，我们使用分子、免疫化学和生理学方法评估了邻苯二甲酸二（2-乙基己基）酯（DEHP）对非洲鲶鱼（Clarias gariepinus）神经和肾上腺类固醇生成的影响。幼鱼（平均体重和体长分别为5.6±0.6克和8.2±1.2厘米）被随机分配到十个120升的矩形玻璃水箱中，每个暴露组50条鱼，水箱中装有60升脱氯自来水。鱼暴露于与环境相关浓度的DEHP中，浓度分别为0（乙醇溶剂对照）、10、100、200和400μg DEHP/升水，实验重复两次。在暴露后第3、7和14天收集脑、肝和头肾样本，使用实时PCR分析star、p450scc、cyp19a1、cyp17、cyp11β-、3β-、17β-和20β-hsd以及17β-ohase mRNA的表达。使用免疫印迹法测量StAR、P450scc和CYP19蛋白，同时使用酶免疫测定法（EIA）在肝匀浆中测量雌二醇-17β（E2）和睾酮（T）。我们的数据显示，对star和类固醇生成酶基因存在一致且独特的双相效应模式，在低浓度（10μg/L）时增加，此后在脑和头肾中均出现浓度依赖性下降，这与StAR、P450scc和CYP19蛋白的表达平行。细胞E2和T水平在暴露第14天呈现出明显的DEHP浓度依赖性增加。鉴于当前研究结果的一致性以及先前关于污染物诱导神经和肾上腺类固醇生成改变的报道，我们数据更广泛的毒理学和内分泌干扰含义表明，暴露生物可能会出现明显的生殖、代谢、生理和整体健康后果。
