Intrahippocampal Effects of Nickel Injection on the Affective and Cognitive Response in Wistar Rat: Potential Role of Oxidative Stress

The present study focused on affective and cognitive behaviors in male Wistar rats, following direct and unique exposure to nickel chloride (NiCl 2 ), as well as the possible involvement of oxidative stress. The rats were exposed to NiCl 2 (300 μM), by intracerebral administration of 2 μL of this metal at the right hippocampus, using the stereotaxic approach. Five days after the surgery, a battery of behavioral tests was performed, including the open-field test (OFT) and elevated plus maze test (EPM) to assess the state of anxiety-like behavior and forced swimming test (FST) for depressive-like behavior. Y-maze and Morris Water Maze (MWM) were used to evaluate working memory and spatial learning. Thereafter, oxidative stress markers of the hippocampus were evaluated. The results confirm that NiCl 2 exerts anxiogenic effects in both anxiety tests and depressogenic effects in the FST. In addition, MWM and Y-maze data show that NiCl 2 causes memory and spatial learning disorders. The biochemical assay results showed that intrahippocampal injection of NiCl 2 increased the levels of nitric oxide and lipid peroxidation ( p < 0.001), while the activities of catalase and superoxide dismutase were significantly decreased in the hippocampus ( p < 0.01). Overall, these results suggest that NiCl 2 causes affective and cognitive disorders and oxidative stress in rats.