Time dependent alterations in dopamine tissue levels and metabolism after experimental traumatic brain injury in rats.

Several studies have demonstrated alterations in the dopamine (DA) system after traumatic brain injury (TBI). The present study investigated the temporal changes in DA tissue levels and metabolism at 1-h or 1, 7, 14, and 28 days after cortical impact or sham injury in rats. DA and DOPAC levels were measured by HPLC in the frontal cortex (FC) and striatum. DA levels were significantly increased at 1h in the contralateral FC and at 1 day in the ipsilateral FC versus respective sham groups. DA and DOPAC levels were significantly increased bilaterally at 1h in the striatum versus sham. These data indicate that TBI induces an early increase in DA and DOPAC, which returns to sham levels over time.