The effect of pyrethroid pesticide deltamethrin on the gonad histology of freshwater fish 'Oreochromis niloticus' and the effect of vitamin E

The aim of this study is to determine the alterations occuring in ovaries and testes of Oreochromis niloticus exposed to deltamethrin and to examine the possible effect of vitamin E on this subject. Deltamethrin, is a commonly used pyrethroid pesticide. Vitamin E is a antioxidant that plays an important role in protecting cells against toxicity by inactivating free radicals generated following pesticides exposure. Therefore, it was evaluated whether deltamethrin induced histopathological changes in the reproductive system (ovaries and testes) of Oreochromis niloticus, and the possible protective effect of vitamin E against deltamethrin inducing adverse effects in O. niloticus were investigated. The fish were divided into four groups, i.e., control group, vitamin E-treated group, deltamethrin-treated group, vitamin E+ deltamethrin- treated group. In control group and vitamin E-treated group, ovary and testes were normal at the end of 7?th, 14?th and 21?st days. In the ovaries of vitamin E-treated fish, it was observed that oocytes were well developed and there were bigger oocytes than those in control group. In the testes, the most important difference between control group and vitamin E-treated group was that, the number of spermatozoa in seminiferous tubules of the fish fed with vitamin E supported diet was higher. Testes and ovary were found to be effected with the deltamethrin. The deformed oocytes, atretic oocytes, melanomacrophage centers, oocytes without nuclei surrounded by macrophages, focal necrotic areas were noted in ovary of Nile Tİlapia. Deltamethrin caused cell necrosis, nuclear pycnosis, decreasing number of spermatogenic cells, decreasing spermatozoa within the lumen of the seminiferous tubule, decreasing number of spermatocyte cells, hypertrophy of spermatogonia cells, degeneration of spermatogonia cells, increasing number of macrophages in testes. Pesticide and diet quality made an impact on gonad histopathology. In treatments of deltamethrin, group fed with control diet showed much greater damage in comparison with group fed with vitamin E supplemented diet. Vitamin E decreased some histopathological changes induced by deltamethrin, but did not confer complete protection.