The effect of low frequency electrical stimulation on basic fibroblast growth factor and epidermal growth factor expression and on endogenous neural stem cell proliferation in the brains of rats with acute cerebral infarction

Abstract

Objective To observe the effects of low frequency electrical stimulation （LFES） on the proliferation of endogenous brain neural stem cells （NSCs） and on the expression of basic fibroblast growth factor （bFGF）and epidermal growth factor （EGF） in rats with acute cerebral infarction; to explore the therapeutic mechanism of LFES in improving neural function. Methods Fifty-four rats were randomly divided into a LFES group, a placebo stimulation group and a sham-operated group. Each group was further divided into 3rd day, 7th day and 14th day subgroups, with 6 rats in each subgroup. An acute cerebral infarction model was induced in the rats of the LFES and placebo stimulation groups by middle cerebral artery occlusion （MCAO）. Three days after the operation, rats in the LFES group began LFES treatment （frequency 30 Hz, pulse width 250 μs, current intensity 3 mA, 10 min/d） ,while the placebo stimulation group was treated identically but without electricity. The rats in the sham-operated group had no special treatment. The expression of nestin positive cells in the subgranular zone of the hippocampus and the subventricular zone was detected by immunohistochemical staining. The expression of bFGF, EGF proteins and mRNA in the ischemic hemisphere was detected by Western blotting and RT-PCR analysis. A screen test was applied to evaluate motor function. Results Nestin-positive cells in the subgranular and subventricular zones of rats in the LFES group increased significantly more than in the placebo stimulation group at the 7th and 14th day. The expression of bFGF, EGF proteins and mRNA in the ischemic hemisphere was up-regulated compared to the placebo stimulation group at the 7th and 14th day. At the 14th day a difference in motor function was observed in rats in the LFES group compared with the placebo stimulation group. Conclusion LFES can promote the proliferation of endogenous brain NSCs and the expression of bFGF and EGF in rats with acute cerebral infarction. It can also improve motor function and enhance neural plasticity in the brain. Key words: Low frequency electrical stimulation; Neural stem cells; Basic fibroblast growth factor; Epidermal growth factor; Cerebral infarction