Chronic methylphenidate treatment enhances water maze performance following traumatic brain injury in rats

Methylphenidate (MPH), a central nervous system stimulant with dopaminergic activity, facilitates neurobehavioral outcome following cortical suction ablation injury, but its potential efficacy following experimental traumatic brain injury (TBI) is unknown. Thus, beginning 24 h after controlled cortical impact injury or sham surgery, male Sprague-Dawley rats were injected (i.p.) once daily for 18 days with either MPH (5 mg/kg) or saline vehicle (VEH) and motor function assessed on post-operative days 1-4, followed by Morris water maze training to find a hidden platform on days 14-18. The MPH treatment regimen was ineffective in accelerating beam-balance or beam-walk recovery, but did significantly decrease swim latencies when compared to VEH-treated controls. The results are consistent with published studies showing improved outcome with MPH therapy. Furthermore, this positive finding with delayed treatment suggests that strategies that enhance catecholamine neurotransmission during the chronic post injury phase may be a useful adjunct in ameliorating some of the neurobehavioral sequelae following TBI in humans.