The present work is to evaluate the neurotoxicity induced by pyrethroid insecticide "Deltamethrin" at 0.32 mg/kg/day in two main regions of the Wistar rat brain (hippocampus and striatum) and the protective effects of Quercetin at 10 mg/kg/day on this toxicity after 90 days of exposure. The assay of brain parameters showed that Deltamethrin caused a significant increase of mitochondrial metabolite level (proteins, lipids, and carbohydrates) and enzyme activity (glutathione S-transferase and superoxide dismutase); a decreased amount of mitochondrial glutathione level and catalase and glutathione peroxidase activities; and an increase of malondialdehyde (MDA) acid levels of the two regions. Furthermore, mitochondrial functional testing in the brains of treated rats exhibited a significant increase in permeability followed by a mitochondrial swelling. Instead, a statistically significant decrease in mitochondrial respiration (O2 consumption) was recorded in the striatum and hippocampus. Our study showed that the pesticide caused a significant increase of the cytochrome c amount correlated with activation of neuronal apoptosis mechanisms by the significant increase of caspase-3 of hippocampus and striatum. In particular, the results of behavioral tests (open field, classic maze tests of sucrose, and Morris water maze) have significant changes, namely bad behavior of the treated rats, affecting the level of anxiety, learning, and memory, and general motor activity has mainly been shown in treated rats. In addition, the histological cuts clearly confirm cerebral necrosis in the hippocampus and the striatum caused by the pesticide. They allow us to consider the necrotic areas, black spots, reduction, and denaturation of these brain regions in the treated rats. On the other hand, we have studied the protective effects against the neurotoxicity of Deltamethrin (DLM). In this context, after the gavage of Quercetin at the dose of 10 mg/kg/day, we have noticed an improvement in the entire parameters: mitochondrial enzyme, metabolic, histological, and behavioral parameters. This confirmed the improvement of preventive and curative effect of Quercetin against free radicals induced by the DLM.
Keywords: Apoptosis; Caspase-3; Cytochrome-c; Deltamethrin; Mitochondria; Neurotoxicity; Quercetin.