Repetitive Transcranial Magnetic Stimulation Improves Mild Cognitive Impairment Associated with Alzheimer’s Disease in Mice by Modulating the miR-567/NEUROD2/PSD95 Axis

BACKGROUND: Mild cognitive impairment (MCI) is a typical symptom of early Alzheimer’s disease (AD) and is driven by the dysfunction of microRNAs (miRs). Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique for handling neuropsychiatric disorders and has universally effects on the functions of miRs. In the current study, the improvement effects of rTMS on MCI associated with AD were explored by focusing on miR-567/NEUROD2/PSD95 axis. METHODS: MCI was induced in mice using scopolamine and was treated with rTMS of two frequencies (1 Hz and 10 Hz). The changes in cognitive function, brain structure, neurotrophic factor levels, and activity of miR-567/NEUROD2/PSD95 axis were assessed. The interaction between rTMS and miR-567 was further verified by inducing the level of miR-567 in AD mice. RESULTS: The administrations of rTMS improved the cognitive function of AD mice and attenuated brain tissue destruction, which were associated with the restored production of BDNF and NGF. Additionally, rTMS administrations suppressed the expression of miR-567 and up-regulated the expressions of NEUROD2 and PSD95, which contributed to the improved condition in central nerve system. With the induced level of miR-567, the effects of rTMS were counteracted: the learning and memorizing abilities of mice were impaired, the brain neuron viability was suppressed, and the production of neurotrophic factors was suppressed even under the administration of rTMS. The changes in brain function and tissues were associated with the inhibited expressions of NEUROD2 and PSD95. CONCLUSION: The findings outlined in the current study demonstrated that rTMS treatment could protect brain against AD-induced MCI without significant side effects, and the function depended on the inhibition of miR-567.