Effects of exposure to three environmental chemicals on the selected biochemical parameters of the blood plasma of rainbow trout, Oncorhynchus mykiss (Walbaum)

Rainbow trout Oncorhynchus mykiss at a weight of 115 ± 24 g (mean ± SD) were experimentally injected with di(2-ethylhexyl)phthalate (DEHP), 2,3,7,8-tetrachlorodibenzo-p-dioxine (TCDD) and gamma isomer of hexachlorocyclohexane (γ-HCH ) to evaluate nitrogen metabolism (total protein [TP], blood urea nitrogen, uric acid [UA], creatinine), carbohydrate metabolism (glucose), mineral metabolism (inorganic phosphate[P], total calcium [Ca_t]), and catalytic activity of enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], alkaline phosphatase [ALP], lactate dehydrogenase [LD]). After 21 days, the tested xenobiotics, administered by the intraperitoneally route, caused the following effect: in comparison with negative controls, fish injected with DEHP at concentrations of 200 or 50 mg kg^-1 of body weight were found to have a higher level of P and lower level of Ca_t and decreased catalytic concentrations of ALT, AST, ALP and LD in the plasma of the peripheral blood. A higher level of TP and P and a decreased catalytic concentration of ALT were found when TCDD was administered at a dose of 2 μg kg^-1. A decrease in the catalytic concentrations of ALT and ALP occurred in fish injected with γ-HCH in a dose of 50 mg kg^-1. UA and P levels were decreased in fish injected with γ-HCH in a dose of 5 mg kg^-1. DEHP and TCDD caused neutrophilic leucocytosis with a marked left shift. Both concentrations of γ-HCH led to an increase in polychromatophilic erythrocytes. The frequency of micronuclei varied in all experimental groups, including the controls, ranging between 0.8 and 2.1 ‰. Histological examination in fish injected with DEHP at a concentration of 200 mg kg^-1 revealed eosinophilic droplets in the epithelium of renal tubules and histological examination in fish injected with γ-HCH at a higher concentration revealed an increased activation of sinusoidal cells in the liver, a fibrous thickening of bile duct walls, bile duct hyperplasia and a periductal inflammatory.