Magnesium dietary manipulation and recovery of function following controlled cortical damage in the rat.

Previous research has shown that dietary magnesium (Mg2+) deficiency prior to injury worsens recovery of function and that systemic administration of Mg2+ pre or post-injury significantly improves functional recovery. The purpose of the present study was to determine if manipulations in dietary Mg2+ would alter functional recovery following unilateral cortical injuries. Two weeks prior to injury, rats were placed on a customized diet enriched with Mg2+, deficient in Mg2+, or on a standard Mg2+ diet. Rats were then prepared with unilateral cortical contusion injuries (CCI) of the sensorimotor cortex. Two days following CCI, rats were tested on a battery of sensorimotor (vibrissae-forelimb placing and bilateral tactile adhesive removal tests), as well as the acquisition of reference memory in the Morris water maze. Serum analysis for Mg2+ prior to injury showed a diet-dependent modulation in levels. The Mg(2+)-enriched diet showed significantly higher levels of serum Mg2+ compared to the normal diet and the Mg(2+)-deficient diet showed significantly lower levels compared to the Mg(2+)-normal diet. On the placing and tactile removal tests Mg2+ deficiency significantly worsened recovery compared to the Mg(2+)-enriched and Mg(2+-)normal diet conditions. There were no statistically significant differences between the Mg(2+)-normal and Mg(2+)-enriched diets on the sensorimotor tests. On the acquisition of reference memory there were no significant difference between diet conditions; however, the Mg(2+)-deficient diet showed a trend toward impaired performance compared to the other diet conditions. The Mg(2+)-deficient diet resulted in a larger lesion cavity compared to the other diet conditions. These findings suggest that dietary Mg2+ modulates recovery of function.

Magnesium and riboflavin combination therapy following cortical contusion injury in the rat.

Previous research has shown that magnesium chloride (MgCl(2)) and riboflavin (B(2)) both significantly improve functional recovery when administered shortly after frontal cortical contusion injury (CCI). The purpose of the present study was to examine the ability of combination treatments of MgCl(2) and B(2) to improve functional outcome following unilateral CCI. One hour post-injury, rats were administered MgCl(2) (1.0 mmol/kg), B(2) (7.5mg/kg), MgCl(2)+B(2) (1 mmol/kg+7.5mg/kg), 1/2 MgCl(2)+1/2 B(2) (0.5 mmol/kg and 3.75 mg/kg), or saline. Two days following CCI rats were tested on a battery of sensorimotor (vibrissae-->forelimb placing and tactile removal test) and motor (staircase test). A regimen of MgCl(2)+B(2) significantly reduced the initial impairment and facilitated the rate of recovery on the tactile removal test and facilitated the rate of recovery on the forelimb placing test. The half-dose combination did not significantly improve functional recovery on the tactile removal test compared to the individual treatments; however, it did improve performance on the forelimb placing test compared to saline treatment. Administration of MgCl(2) improved performance on the placing and tactile removal tests on 2 post-operative days, as did treatment with B(2) on the tactile removal test. The results indicate that the full combination of MgCl(2)+B(2) significantly improved functional recovery to a greater extent than the individual treatments or the low dose combination group on forelimb placing but not on tactile removal. These findings suggest that administration of MgCl(2)+B(2) may provide better therapeutic action than individual treatments.