Integrated Use of Oxidative Stress and Histological Biomarkers of <i>T. tinca</i> as Indicators of 17‐Alpha‐Ethynylestradiol Exposure

The potential adverse effects of 17-alpha-ethynylestradiol (50, 100, and 500 μg EE₂/kg b.w., for 30 days) on tench ( Tinca tinca ) were evaluated by integrating biomarkers including physiological (hepato-somatic index, spleen-somatic index, and hematocrit), oxidative stress (catalase, glutathione peroxidase, and glutathione reductase activities; total glutathione level, and lipid peroxidation), metabolic (glutathione S-transferase activity), as well as histopathological (descriptive and analytical studies) responses. The general health status of the EE₂-exposed tench was disturbed based on the increase of somatic indices at high tested doses, and the development of anemia in all exposed individuals. Effective control of reactive oxygen species by the antioxidant defense system of the tench exposed to EE₂ should have occurred because the lipid peroxidation process was irrelevant. Histopathological study revealed the presence of regressive changes in the liver (vacuolar degeneration, and deposits of eosinophilic material), regressive (deposits of eosinophilic material), and progressive (hyperplasia of reticuloendothelial cells) changes in the spleens of exposed fish. The severity of some lesions was dose dependent. The identified injuries did not compromise the functions of these organs. Finally, a common pattern of correlation between parameters of oxidative stress and morphological changes was not detected in the current study.