Extremely low frequency electromagnetic fields promote cognitive function and hippocampal neurogenesis of rats with cerebral ischemia.

Extremely low frequency electromagnetic fields (ELF-EMF) can improve the learning and memory impairment of rats with Alzheimer's disease, however, its effect on cerebral ischemia remains poorly understood. In this study, we established rat models of middle cerebral artery occlusion/reperfusion. One day after modeling, a group of rats were treated with ELF-EMF (50 Hz, 1 mT) for 2 hours daily on 28 successive days. Our results showed that rats treated with ELF-EMF required shorter swimming distances and latencies in the Morris water maze test than those of untreated rats. The number of times the platform was crossed and the time spent in the target quadrant were greater than those of untreated rats. The number of BrdU+/NeuN+ cells, representing newly born neurons, in the hippocampal subgranular zone increased more in the treated than in untreated rats. Up-regulation in the expressions of Notch1, Hes1, and Hes5 proteins, which are the key factors of the Notch signaling pathway, was greatest in the treated rats. These findings suggest that ELF-EMF can enhance hippocampal neurogenesis of rats with cerebral ischemia, possibly by affecting the Notch signaling pathway. The study was approved by the Institutional Ethics Committee of Sichuan University, China (approval No. 2019255A) on March 5, 2019.