Muldoon Breda M, Hogan Natacha S
Toxicology Graduate Program, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada; Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
Toxicology Centre, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada; Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, SK S7N 5A8, Canada.
Comp Biochem Physiol C Toxicol Pharmacol. 2016 Feb;180:1-10. doi: 10.1016/j.cbpc.2015.10.013. Epub 2015 Nov 6.
Small-bodied freshwater fish are commonly used in regulatory testing for endocrine disrupting compounds (EDCs) but most lack a sensitive and quantifiable androgen-specific biomarker. Brook stickleback (Culaea inconstans) are a North American freshwater fish whose males produce an androgen-regulated glycoprotein in the kidney called spiggin. Although spiggin induction in females has been used as an androgen-specific biomarker of exposure in other stickleback species it has not been characterized in brook stickleback. Therefore, our objective was to develop a bioassay using brook stickleback to measure estrogenic and androgenic responses and establish the sensitivity of traditional and novel biomarkers of exposure. We first developed and optimized a qPCR assay to measure spiggin and vitellogenin transcript levels in kidney and liver tissue, respectively. Basal levels were differentially expressed in mature wild-caught male and female brook stickleback. To determine their sensitivity to EDCs, fish were exposed to nominal concentrations of 1, 10 and 100ng/L of 17α-methyltestosterone (MT) or 17α-ethinylestradiol (EE2) for 21days (sampled at 7 and 21days) under semi-static renewal conditions. MT and EE2 exposure induced spiggin and vitellogenin transcripts in female kidneys and male livers, respectively. Exposure to EE2 also increased hepatosomatic index in both sexes and decreased gonadosomatic index in females. Histopathological alterations were observed in the kidney of EE2-exposed fish and an increase in kidney epithelium cell height occurred in MT-exposed females. Given the sensitivity of these endpoints, the brook stickleback is a promising new freshwater fish model for EDC evaluation and a potential bioindicator for EDCs in North American freshwater environments.
小型淡水鱼常用于内分泌干扰化合物（EDCs）的监管测试，但大多数缺乏敏感且可量化的雄激素特异性生物标志物。溪刺鱼（Culaea inconstans）是一种北美淡水鱼，其雄性在肾脏中产生一种受雄激素调节的糖蛋白，称为spiggin。尽管在其他刺鱼物种中，雌性spiggin的诱导已被用作暴露的雄激素特异性生物标志物，但在溪刺鱼中尚未对其进行表征。因此，我们的目标是开发一种使用溪刺鱼的生物测定法，以测量雌激素和雄激素反应，并确定传统和新型暴露生物标志物的敏感性。我们首先开发并优化了一种qPCR测定法，分别测量肾脏和肝脏组织中spiggin和卵黄蛋白原的转录水平。在成熟的野生捕获雄性和雌性溪刺鱼中，基础水平存在差异表达。为了确定它们对EDCs的敏感性，在半静态更新条件下，将鱼暴露于标称浓度为1、10和100ng/L的17α-甲基睾酮（MT）或17α-乙炔雌二醇（EE2）中21天（在第7天和第21天取样）。MT和EE2暴露分别在雌性肾脏和雄性肝脏中诱导了spiggin和卵黄蛋白原转录本。暴露于EE2还增加了两性的肝体指数，并降低了雌性的性腺体指数。在暴露于EE2的鱼的肾脏中观察到组织病理学改变，在暴露于MT的雌性中，肾上皮细胞高度增加。鉴于这些终点的敏感性，溪刺鱼是用于EDC评估的一种有前景的新淡水鱼模型，也是北美淡水环境中EDCs的潜在生物指示剂。
