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 Mg ²⁺, 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 Mg²⁺-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 Mg²⁺-normal diet. On the placing and tactile removal tests Mg ²⁺ deficiency significantly worsened recovery compared to the Mg ²⁺-enriched and Mg²⁺-normal diet conditions. There were no statistically significant differences between the Mg²⁺-normal and Mg²⁺-enriched diets on the sensorimotor tests. On the acquisition of reference memory there were no significant difference between diet conditions; however, the Mg²⁺-deficient diet showed a trend toward compared to the other diet conditions. The Mg²⁺-deficient diet resulted in a larger lesion cavity compared to the other diet conditions. These findings suggest that dietary Mg²⁺ modulates recovery of function.