Treatment with magnesium improves reference memory but not working memory while reducing GFAP expression following traumatic brain injury

Purpose: Previous studies have shown that administration of MgCl ₂ in animal models of brain injury significantly improves functional recovery: however, few studies have examined cognitive recovery. The present study evaluated the effect of MgCl₂ pharmacotherapy on recovery of function following medial frontal cortex contusion injury. Methods: Groups of rats were assigned to either MgCl₂ (1.0 mmol/kg) or saline treatment conditions and prepared with contusion injuries or shams. Drug treatment was administered 15 min and 24 hr following injury. Rats were examined on tests of sensorimotor performance (bilateral tactile adhesive removal) and cognitive ability (reference and working memory). Results: Administration of MgCl ₂ following injury significantly reduced the behavioral impairments observed on the bilateral tactile removal test. The acquisition of reference memory was also significantly improved compared to saline-treated rats; however, treatment did not improve working memory performance. Lesion analysis revealed that administration of MgCl₂ did not significantly reduce lesion size compared to saline-treatment. Examination of glial fibrillary acidic protein (GFAP) expression showed that MgCl₂ did significantly reduce the number of GFAP⁺ cells. Conclusion: These results indicate that MgCl₂ administration significantly improved behavioral outcome following injury in a task dependent manner and reduced GFAP expression.