Histological and immunohistochemical changes in cerebellum of chick embryos after exposure to neonicotinoid insecticide imidacloprid

Abstract

IntroductionImidacloprid was the first insecticide of the wide group of neonicotinoids introduced to the market. Neonicotinoids were developed in the late 1980s and in early 1990s as a response to the widespread insect's resistance to older insecticides, such as organophosphates, pyrethroids, and carbamates, and their health and environmental issues. Imidacloprid is a widely applied pesticide due to its higher affinity for insect nicotinic acetylcholine receptors, and it acts on nervous system. MethodsThe present study was carried out on 300 fertile eggs of white leghorn chicken obtained from government poultry farm after taking permission from animal ethical committee. Chicken eggs exposed to imidacloprid with doses of 5μg, 10μg, and 20μg in a volume of 5μl, 10μl, and 20μl respectively and control same as test group. The embryos were terminated on 21st day, eggshells broken with a scalpel, and embryos removed. Dissection of chick head was done for collection of brain. Histological and immunohistochemical processing was done for cerebellum of chick embryos using neurofilament polypeptide (NFP) and glial fibrillary acidic protein (GFAP) markers and observed under microscope and using photographs. ResultsThe results show that experimental group had comparatively more cases of histological changes, GFAP immunoreactive in glial cells, and NFP immunoreactive in neuropil and neurons. Patchy clustering and degenerative changes in neurons with focal pyknosis and karyolysis in comparison to controls were seen. DiscussionImidacloprid exposure increases the risks of histological changes. Comparatively higher doses proved more toxic and also caused many histological and immunohistochemical changes in cerebellum of chick embryos.