Cortical electrical stimulation with varied low frequencies promotes functional recovery and brain remodeling in a rat model of ischemia.

In this study, we investigated whether fully implantable CES with low current density and varying low-frequency burst impulse train enhances functional recovery and promotes brain remodeling in both the ipsilesional and contralesional cortex. Adult rats received occlusion of the right middle cerebral artery for 120min. One week after ischemia, electrodes were implanted to rats with CES lasting 2 weeks followed by 4-week observation period. After 2-week stimulation and 4-week observation period, body weight (BW) of the rats in CES group was higher than that in no stimulation (NS) group. Limb placement test, foot-fault test and beam walking test demonstrate that CES significantly enhanced functional recovery. Immunohistochemical study has shown that CES enhanced angiogenesis and dendritic sprouting, and suppressed inflammatory response in the ischemic cortex. CES also promoted dendritic sprouting and suppressed inflammatory response in the contralesional cortex. These results suggest the stimulation protocol is safe, and greatly improves functional recovery and brain remodeling in the 4 weeks following 2 weeks stimulation.