Amelioration of Paraquat-Induced Hippocampal Damage and Cognitive Impairment by Selenium and Magnesium in Mice

Paraquat (Pq) is an extremely toxic herbicide that causes oxidative stress by generating superoxide anions, leading to cellular damage and cognitive impairments. This study investigated the effects of selenium and magnesium on hippocampal tissue in a mouse model of Pq-induced cognitive deficits. Thirty-five adult male mice weighing 15-28 g were divided into seven groups: Group A received normal saline at (0.5 mL/kg b.w), Group B (Pq-induced at 10 mg/kg b.w.), Groups C and D treated with selenium (0.3 mg/kg b.w) and magnesium (100 mg/kg b.w.) intraperitonially, and Groups E, F, and G (post-treated with selenium, magnesium, and both respectively after Pq exposure). Paraquat was administered daily for 3 weeks, while selenium and magnesium were administered intraperitoneally for 2 weeks. Hippocampal and hypothalamic tissues were analyzed histologically (Hematoxylin and Eosin), and orexin neurons were stained using immunohistochemistry. Markers of oxidative stress (glutathione GSH, superoxide dismutase SOD, catalase CAT, malondialdehyde MDA) were measured in brain tissue and blood serum. Cognitive function was assessed using the Morris water maze. Histological analysis revealed cellular changes in the Pq-treated and post-treatment groups (Pq+Mg, Pq+Se+Mg), whereas the other groups maintained intact morphology. Selenium treatment enhanced orexin neuron immunopositivity. The Pq-induced group exhibited elevated MDA levels and reduced SOD, CAT, and GSH levels in contrast with the control and post-treated groups. Selenium and magnesium treatments improved performance in the Morris water maze, with selenium significantly ameliorating oxidative damage. ​These findings suggest selenium and magnesium provide better protection against Pq-induced cognitive impairment than their combination.