Effects of electric stimulation on motor function and the expression of Rho kinase following cerebral infarction

Objective To investigate the effects of electric stimulation on motor function and expression of Rho kinase following cerebral infarction in rats. Methods Acute cerebral infarction was modeled in adult male Sprague-Dawley ( SD) rats using the permanent middle cerebral artery occlusion ( PMCAO) technique. The rats were randomly divided into sham operation, control, unilateral electric stimulation and bilateral electric stimulation groups ( each group had 36 rats). Electric stimulation was applied to the paralyzed ( unilateral or bilateral) limbs in the last two groups. Motor function recovery and the expression of Rho kinase were examined using a beam walking test ( BWT) and immunohistochemistry respectively at the 3rd, 7th, 14th and 21st day after stimulation. In addition, the cerebral infarction volume was also determined by 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining at different time points. Results Motor function improved significantly in the electric stimulation groups compared with the control group, and the effect in the bilateral electric stimulation group was better than that in the unilateral electric stimulation group. The expression of Rho kinase decreased remarkably in the electric stimulation groups, and it was significantly lower in the bilateral group than in the unilateral electric stimulation group. No difference in cerebral infarction volume was found at the 3rd day. At the 21st day, the cerebral infarction volume had decreased significantly in both stimulation groups compared with the control group, but no difference was seen between the unilateral and bilateral electric stimulation groups. Conclusions Early electric stimulation, especially bilateral electric stimulation, can improve motor function after cerebral infarction and reduce cerebral infarction volume, which may be associated with down-regulation of the expression of Rho kinase in the border zone of the infarction. Key words: Electric stimulation; Cerebral infarction; Motor function; Rho kinase