Neurocognitive and Affective Disorders Induced by Inorganic Mercury Exposure in Male Wistar Rats: Unraveling the Role of Oxidative Stress
Neurocognitive and Affective Disorders Induced by Inorganic Mercury Exposure in Male Wistar Rats: Unraveling the Role of Oxidative Stress
Sofia Azirar*, Abdelghafour El Hamzaoui*, Mouloud Lamtai, Mohamed Yassine El Brouzi, Aboubaker El Hessni, Abdelhalem Mesfioui
ABSTRACT
In this study, we assessed the impact of prolonged exposure to low doses of mercury (Hg) on affective and cognitive impairments in male Wistar rats, highlighting the significance of understanding chronic exposure to environmental levels of Hg that may not immediately show overt toxicity. 24 rats received either NaCl 0.9% (control group) or mercurial chloride (HgCl2) via intraperitoneal injections at 0.25, 0.5, or 1 mg/kg for eight weeks. Behavioral evaluations included the open field (OFT), elevated plus maze (EPM), and forced swimming tests (FST) for anxiety and depression assessments, alongside the Y maze and Morris water maze (MWM) tests for memory and learning. In addition, markers of oxidative stress (OS) in the hippocampus— catalase (CAT), nitric oxide (NO), and lipid peroxidation (LPO)—were measured post-treatment. Results revealed dose-dependent increases in anxiety and depression-like behaviors, such as significant reductions in time spent in the center area (TCA) in OFT at 0.5 and 1 mg/kg compared to controls (p < 0.001) and increased immobility time in FST across all doses compared to controls (p < 0.001). Memory impairments were most pronounced at 1 mg/kg in the Y maze test (p < 0.01) and in MWM (p < 0.001). OS markers correlated with behavioral changes, with elevated LPO (p < 0.001 at 0.5 and 1 mg/kg compared to controls) and decreased CAT activity across doses (p < 0.001), implicating OS in Hg-induced neurotoxicity. Although these findings suggest a link between low-dose Hg exposure and neurobehavioral impairment, further studies are needed to clarify causative mechanisms.
Keywords | Mercury neurotoxicity, Oxidative stress, Cognitive impairment, Hippocampus, Behavioral disorders
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