Alteration in certain enzymological parameters of an Indian major carp, Cirrhinus mrigala exposed to short- and long-term exposure of clofibric acid and diclofenac

The extensive use of pharmaceuticals in human and veterinary medicine may enter the aquatic environment and pose a serious threat to non-target aquatic organisms like fish. In this study, Indian major carp Cirrhinus mrigala was exposed to different concentrations (1, 10 and 100 μg L^?l) of most commonly used pharmaceutical drugs clofibric acid (CA) and diclofenac (DCF) to evaluate its impacts on certain enzymological parameters during short- and long-term exposures. During short-term (96 h) exposure period, plasma glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and gill Na⁺/K⁺-ATPase activity were significantly altered at all concentrations of both the CA- and DCF-treated fish. In long-term exposure (35 days), gill Na⁺/K⁺-ATPase activity was found to be significantly increased at all concentration of CA and DCF exposures throughout the study period (except at the end of 7th day in 10 and 100 µg L-1) . However, a biphasic trend was observed in plasma GOT and GPT activity when compared to the control groups. In both short- and long-term exposure, a significant (P < 0.01 and P < 0.05) changes were observed in all enzymological parameters of fish C. mrigala exposed to different concentrations of CA and DCF. The alterations of these enzymological parameters can be effectively used as potential biomarkers in monitoring of pharmaceutical toxicity in aquatic environment and organisms.     

In vitro metabolism of progesterone, androgens and estrogens by rainbow trout embryos

The purpose of the study was to determine the steroid metabolic pathways used by rainbow trout (Oncorhynchus mykiss) embryos. Whole embryo preparations at 42, 53 and 65 days post fertilization (dpf) were incubated, in vitro, with the tritium-labelled steroids, progesterone (P₄), testosterone (T), androstenedione (A4), 17β-estradiol (E₂), and estrone (E₁), and the metabolites formed were separated and identified by reverse phase high performance liquid chromatography (HPLC). The degree of metabolism for each of the substrates was dependent on the age of the embryos, and was always higher in older embryos. P₄ yielded three metabolites, one of them identified by gas chromatography-mass spectroscopy as 3β,7α-dihydroxy-5α-pregnan-20-one. Several unknown metabolites of a similar profile on HPLC were produced for T and A₄, in addition to A₄ and T as metabolites of T and A ₄ metabolism, respectively. Likewise, E₂ and E₁ yielded each other and an unknown polar metabolite. These observations argue for the presence of 5α-reductase, 7α-hydroxylase and 17β-hydroxysteroid dehydrogenase activity in embryo tissues which, by their conversion of biologically active yolk steroids of maternal origin, may provide a protective environment for the embryo during early development.