title: Evaluation of toxicity limit and sex hormone production in response to cythion and BHC in the vitellogenic catfish Clarias batrachus.
abstract: The impact of cythion (organophosphorous) and BHC (organochlorine) on survival and the effects of their sublethal concentrations on plasma levels of testosterone, estradiol-17 beta, and estrone were assessed in the female catfish Clarias batrachus. Initial median lethal concentrations [LC(I)50] for 96 hr of exposure to cythion and BHC were recorded as 12 and 16 ppm, respectively. Their sublethal concentrations (SL) for the same period of exposure were 7 and 12 ppm. The 96-hr safe concentration (SC) was 1 ppm for cythion and 2 ppm for BHC. Longer exposure to 4 weeks brought down the SL concentration to 4 and 8 ppm for cythion and BHC, respectively, but no change was observed in SC. Sublethal concentrations of either pesticide apparently affected sex hormone production after 4 weeks of exposure, as was evident by decreased levels of sex hormones in blood plasma. Both pesticides caused greater reduction in plasma sex hormone levels at SL concentrations than at SC. The magnitude of inhibition of testosterone and estradiol-17 beta levels at either concentration was similar for both pesticides, but estrone levels were highly affected by BHC compared to cythion. Thus, it might be inferred that cythion and BHC toxicity affected sex hormone production due to the impairment in the synthesis and/or release of these steroids.
mesh_terms: D000818:Animals; D002397:Catfishes / Q000378:metabolism*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000096:biosynthesis*; D001556:Hexachlorocyclohexane / Q000633:toxicity*; D008294:Malathion / Q000633:toxicity*; D013045:Species Specificity
chemical_list: D012739:Gonadal Steroid Hormones; D001556:Hexachlorocyclohexane; D008294:Malathion