Repetitive transcranial magnetic stimulation in a rat model of middle cerebral artery occlusion：variation of nerve regeneration microenvironment in infarcted brain areas and recovery of rat neurological function / 中国组织工程研究

ABSTRACT

BACKGROUND:At home and abroad, a large number of studies have demonstrated that repetitive transcranial magnetic stimulation can evoke changes in cortical excitability that can be sustained beyond the time of stimulation, which provides a new research direction for application of magnetic stimulation in rehabilitation treatment for cerebral infarction. However, its long-term clinical efficacy and safety deserve further investigation. OBJECTIVE: To observe the influence of repetitive transcranial magnetic stimulation on nerve regeneration microenvironment in the infarcted cerebral area and rat neurological functional recovery after cerebral infarction. METHODS:The rats were randomly divided into model group, sham stimulation group and repetitive transcranial magnetic stimulation group (80%, 100% and 120% motor threshold subgroups). Right middle cerebral artery occlusion models were established in rats by the intraluminal suture method. At 24 hours after middle cerebral artery occlusion, 20 Hz repetitive transcranial magnetic stimulation was performed in each repetitive transcranial magnetic stimulation subgroup at the designated motor thresholds. Rats in the sham stimulation group underwent sham stimulation, while the model group rats were not given any treatment. RESULTS AND CONCLUSION: Seven days after middle cerebral artery occlusion, cerebral infarction volume in the repetitive transcranial magnetic stimulation group was significantly less than that in the model and sham stimulation groups (P < 0.05). RT-PCR and Western blot assays showed that at 72 hours after middle cerebral artery occlusion, aquaporin 4/9 mRNA and protein expression in the repetitive transcranial magnetic stimulation group was significantly increased than in the model group (P < 0.05). Compared with 1 day after middle cerebral artery occlusion, neurological deficit scores at 15 days after repetitive transcranial magnetic stimulation was significantly improved (P < 0.05). Immunohistochemical detection results showed that glial fibrilary acidic protein expression in the ischemic penumbra in each repetitive transcranial magnetic stimulation subgroup was significantly lower than that in the model group (P < 0.05). The results reveal that repetitive transcranial magnetic stimulation can aleviate rat neurological deficits and improve nerve regeneration microenvironment by inducing cerebral ischemic tolerance, reducing nerve cel apoptosis and decreasing aquaporin 4/9 mRNA and protein expression.