Treatment with Vitamin B₃ Improves Functional Recovery and Reduces GFAP Expression following Traumatic Brain Injury in Rats

Previous studies have shown that administration of vitamin B₃ (B₃) in animal models of ischemia significantly reduced the size of infarction and improved functional recovery. The present study evaluated the effect of administration of B₃ on recovery of function following traumatic brain injury (TBI), incorporating the bilateral medial frontal cortex contusion injury model. Groups of rats were assigned to B₃ (500 mg/kg) or saline (1.0 ml/kg) treatment conditions and received contusion injuries or sham surgeries. Drug treatment was administered 15 min and 24 h following injury. Rats were examined on a variety of tests to measure sensorimotor performance (bilateral tactile adhesive removal), skilled forelimb use (staircase test), and cognitive ability (reference and working memory) in the Morris Water Maze. Administration of B₃ following injury significantly reduced the behavioral impairments observed on the bilateral tactile removal test, but not on skilled forelimb use. The acquisition of reference and working memory tests were also significantly improved compared to saline-treated rats. Examination of the brains revealed that administration of B₃ significantly reduced the size of the lesion compared to treatment with saline. In addition, examination of glial fibrillary acidic protein (GFAP) expression around the lesion revealed that B₃ significantly reduced the number of GFAP⁺ astrocytes. These results indicate that B₃ administration significantly improved behavioral outcome following injury, reduced the size of the lesion, and reduced the expression of GFAP. The current findings suggest that B₃ may have therapeutic potential for the treatment of TBI.