Evaluating the toxicological effects of agrochemicals on glucocorticoid receptor and serum cortisol level in Mozambique tilapia

The agricultural sector is considered to be the backbone of a countries economy. To increase the crop yield, there is an extensive use of agrochemicals in the form of insecticides, herbicides, nutrient mixture, fungicides, etc. This is necessarily involved in controlling the unwanted organisms; however, it leads to toxicity in a nearby ecosystem. Aquatic habitats being a complexed ecosystem are distressed with the increasing concentration of agrochemicals, which leads to an alteration in nontarget species at various trophic levels. Fishes are considered to be the dynamic players of this ecosystem and are the first one to be acquainted with any contaminants present in it. In this context, the present study was aimed to find the sublethal effects (1/10th of the LC50 value) of four different agrochemicals (imidacloprid-insecticide, pyrazosulfuron ethyl-herbicide, curzate-fungicide and micronutrient mixture) on the stress physiology of Oreochromis mossambicus. The hormonal titer of cortisol and gene expression of its receptor was carried out to understand the toxicity of diverse agrochemicals. The results suggested that there was a significant decrease in hormonal titer of cortisol upon the exposure of curzate and imidacloprid, with a significant downregulation of glucocorticoid receptor under the exposure of imidacloprid. Thus, the novel findings suggest that fishes were found to be devoid of stress response which may be due to hypothalamus pituitary interrenal exhaustion.