Role of dopamine on functional recovery in the contralateral hemisphere after focal stroke in the somatosensory cortex.

Functional recovery after a stroke is important for patients' quality of life. Not only medical care during the acute phase, but also rehabilitation during the chronic phase after a stroke is important. However, the mechanisms underlying functional recovery, particularly the chronic phase after stroke, are still not fully understood. Thus, further basic study on brain after focal stroke is necessary. In this study, we found that the concentration of dopamine (DA) increased during first week after a stroke in the hemisphere contralateral in the site of stroke by in vivo microdialysis. When we applied haloperidol (HPD), a potent DA receptor blocker, functional recovery was inhibited. Interestingly, administration of aripiprazole (ARP), a novel partial agonist of the DA receptor, during the chronic phase improved the remodeling of neuronal circuits in somatosensory cortex (SSC). These findings indicate that the DAergic system play a critical role in functional compensation by the non-infarcted hemisphere after a focal stroke in SSC. It is also revealed that administration of HPD/ARP to stroke patients affects functional recovery after a stroke, and stimulation of the DAergic system during the chronic phase of stroke potentially benefits stroke patients.