Traumatic brain injury reduces dopamine transporter protein expression in the rat frontal cortex.

Disturbances in dopamine neurotransmission contribute to frontal lobe dysfunction after traumatic brain injury. The changes in dopamine neurotransmission may be mediated by alterations in the dopamine transporter, which plays a key role in maintaining dopamine homeostasis. To determine whether the dopamine transporter system is altered after traumatic brain injury, dopamine transporter protein was examined bilaterally in the rat frontal cortex by Western blot at 1, 7, and 28 days after controlled cortical impact or sham injury ( = 6/group). Dopamine transporter protein expression was decreased in the injured (ipsilateral) cortex at 7 days and bilaterally at 28 days in injured sham control rats. The decrease in dopamine transporter protein levels may reflect a traumatic brain-injury-induced down-regulation of dopamine transporter and/or a loss of dopaminergic fibers.