Regulation of gene expression after combined scalp acupuncture and transcranial magnetic stimulation in middle cerebral artery occlusion mice

Regulation of Genes Related to Cognition after tDCS in an Intermittent Hypoxic Brain Injury Rat Model

Background: Hypoxic brain injury is a condition caused by restricted oxygen supply to the brain. Several studies have reported cognitive decline, particularly in spatial memory, after exposure to intermittent hypoxia (IH). However, the effect and mechanism of action of IH exposure on cognition have not been evaluated by analyzing gene expression after transcranial direct current stimulation (tDCS). Hence, the purpose of this study was to investigate the effects of tDCS on gene regulation and cognition in a rat model of IH-induced brain injury. Methods: Twenty-four 10-week-old male Sprague−Dawley rats were divided into two groups: IH exposed rats with no stimulation and IH-exposed rats that received tDCS. All rats were exposed to a hypoxic chamber containing 10% oxygen for twelve hours a day for five days. The stimulation group received tDCS at an intensity of 200 µA over the frontal bregma areas for 30 min each day for a week. As a behavior test, the escape latency on the Morris water maze (MWM) test was measured to assess spatial memory before and after stimulation. After seven days of stimulation, gene microarray analysis was conducted with a KEGG mapper tool. Results: Although there were no significant differences between the groups before and after stimulation, there was a significant effect of time and a significant time × group interaction on escape latency. In the microarray analysis, significant fold changes in 12 genes related to neurogenesis were found in the stimulation group after tDCS (p < 0.05, fold change > 2 times, the average of the normalized read count (RC) > 6 times). The highly upregulated genes in the stimulation group after tDCS were SOS, Raf, PI3K, Rac1, IRAK, and Bax. The highly downregulated genes in the stimulation group after tDCS were CHK, Crk, Rap1, p38, Ras, and NF-kB. Conclusion: In this study, we confirmed that SOS, Raf, PI3K, Rac1, IRAK, and Bax were upregulated and that CHK, Crk, Rap1, p38, Ras, and NF-kB were downregulated in a rat model of IH-induced brain injury after application of tDCS.

Repetitive Transcranial Magnetic Stimulation Improves Neuropathy and Oxidative Stress Levels in Rats with Experimental Cerebral Infarction through the Nrf2 Signaling Pathway

Ischemic stroke poses a serious threat to human health. Its high morbidity, disability, and lethality rates have led to it being a research hotspot. Cerebral ischemia reperfusion injury is a difficult point in the treatment of ischemic stroke. In recent years, studies have shown that repeated transcranial magnetic stimulation (rTMS) can enhance cerebral ischemic tolerance and have a significant protective effect on reperfusion injury after ischemia, but its specific mechanism is unknown. The Nrf2/pathway plays a vital role in ischemia-reperfusion injury in the body environment. Therefore, in this experiment, the middle cerebral artery occlusion (MCAO) reperfusion model of SD rats was made to simulate the occurrence of experimental cerebral infarction by the suture method. After treatment with rTMS, it was studied whether it can regulate the expression of Nrf2 and HO-1, affect the content of MDA and SOD activity, and then activate the Nrf2 pathway to exert its brain protection. The results showed that after MCAO reperfusion, the neurological deficit score of rats increased, and the time to remove the bilateral stickers and the time to cross the balance beam increased, suggesting the successful establishment of the experimental cerebral infarction model. Detecting the brain tissue of experimental cerebral infarction rats found that the expression of Nrf2 and HO-1 decreased, the content of MDA increased, and the activity of SOD decreased. After rTMS treatment, the neuromotor function of experimental cerebral infarction rats improved, the expression of Nrf2 and HO-1 in the brain tissue gradually increased, the content of MDA decreased, and the activity of SOD increased. It indicates that the expression of Nrf2 and HO-1 in experimental cerebral infarction rats is reduced. After treatment with rTMS, it can improve the neuromotor function damage of the rats and reduce the level of oxidative stress. The mechanism may be through promoting the activation of the Nrf2 signaling pathway, acting on the expression of antioxidant proteins, such as HO-1 and SOD1, reducing oxidative stress damage, and playing a protective effect on brain tissue.