ABSTRACT
Aim: The aim of the present study was to evaluate the reproductive efficacy of male and female zebrafish following cypermethrin exposure. Methodology: The adult zebrafish (Danio rerio) of both sexes were exposed to cypermethrin at three selected concentrations 0.1, 1.0 and 10 µgl-1 over a period of 21days. After completion of experimental period, the reproductive endpoints such as fecundity, hatchability, testis and ovarian histology and plasma vitellogenin levels were selected and determined in this study. Results: Cypermethrin exposure did not affect the cumulative fecundity rates in experimental fishes over controls. However, cypermethrin at 10 µgl-1 showed a significant reduction in the sperm number in male fishes over control. On the other hand, the same concentration of cypermethrin did not show significant changes in the plasma vitellogenin levels of both male and female fishes over their respective controls. Analysis of testicular and ovarian architectures of male and female zebrafish exposed to cypermethrin at 10 µgl-1 showed no marked differences over controls. In addition, molecular docking studies revealed that the binding energy between the cypermethrin and zebrafish estrogen receptor (zfER) β1 was almost similar to the binding energies exhibited by reference molecules, estradiol and ethinyl estradiol with zfERβ1. Further, binding energies between the ligands (cypermethrin and its metabolites phenoxybenzaldehyde and 3-phenoxybenzoic acid) with zfERα were low as compared to the binding energies between the reference molecules and zfERα. Interpretation: In-vivo studies indicated that cypermethrin at 10µg l-1 leads to spermatotoxicity in zebrafish and in silico analysis showed that the cypermethrin at least in part interfere with the signalling of zfERα.