Impact of pesticide and herbicide on pituitary and gonadal hormone secretion in Heteropneustes fossilis (Bloch)

Abstract

The reproductive toxicity, mainly changes in hormonal status and gonadosomatic index (GSI), of the insecticide chlorpyrifos and herbicide 2, 4- Dichlorophenoxyacetic acid (2, 4-D) was studied in both male and female fish namely Heteropneustes fossilis. Pituitary and gonadal hormone quantification was performed using enzyme- immunoassay (ELISA). Sample of blood and gonads were collected for hormones (testosterone, estradiol, gonadotropin I (GtH I) and gonadotropin II (GtH II)) analysis and determination of GSI respectively. Chlorpyrifos at dose levels of 1.42 ppm and 0.28 ppm and 2, 4-D of 3.00 ppm and 0.60 ppm were exposed to fish population for 30 days. Chlorpyrifos brought about marked reduction in all the studied plasma hormonal level except in GtH I of female fish. Of the two pesticides used in the present experimental setup, 2, 4-D at higher concentration is found to be more potent in declining all the hormonal parameters at the terminal part of the experiment, except estradiol at higher dose of treatment. GSI was significantly reduced in female fish (p<0.01) compared to male during pre-spawning and spawning phases.