Cerebellum of Rats, As Affected by Zinc Oxide Nanoparticles and The Role of Selenium

Abstract

The progressive utility and application of zinc oxide nanoparticles (ZnO NPs) in medical and industrial purposes raises the debates about their safety use.  Modern research recorded brain (CNS) as a target for NPs- toxicity. We sought to investigate the effects of selenium (Se) on ZnO NPs-neurotoxicity in rats. Forty adult male rats (Rattus norvegicus) weighing 180-200 g were randomly divided into four groups; control, Se-administered (0.2 mg/kg/day), ZnO NP-exposed (1 g/kg/day for 5 consecutive days), and ZnO NPs + Se, were used. Nanoparticles of ZnO appeared spherical with nearly uniform size and a mean diameter of 25.3 nm by transmission electron microscope (TEM). Exposure of rats to ZnO NPs recorded histopathological and ultrastructure lesions including; vacuolated molecular layer with apoptotic nerve cells, damaged and shrunken Purkinje cells (PC), swollen Bergman astrocytes and degenerated granular cells overlapped in gliosis. At EM level, PC appeared with ill-defined nuclear criteria and ruptured mitochondria, Bergmann astrocytes exhibited vacuolated cytoplasm with damaged mitochondria, granular cells had heterochromatic nuclei with irregular nuclear envelopes and vacuolated cytoplasm and molecular layer with dysmyelinated nerve fibers. The present results confirmed ZnO NPs-induced DNA injury in rat’s cerebellum at the dose level of 1g/kg /day as recorded from comet data. However, administration of Se prior to ZnO NPs –exposure improved the histological, ultrastructural and molecular criteria of cerebellum. Conclusion: The study confirmed the neurotoxicity of ZnO NPs in rat's cerebellum and suggests a promising neuro-protective role of Se as a food supplement.