Protective Effects of Repetitive Transcranial Magnetic Stimulation Against Streptozotocin-Induced Alzheimer's Disease.

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation under investigation for treatment of a wide range of neurological disorders. In particular, the therapeutic application of rTMS for neurodegenerative diseases such as Alzheimer's disease (AD) is attracting attention. However, the mechanisms underlying the therapeutic efficacy of rTMS have not yet been elucidated, and few studies have systematically analyzed the stimulation parameters. In this study, we found that treatment with rTMS contributed to restoration of memory deficits by activating genes involved in synaptic plasticity and long-term memory. We evaluated changes in several intracellular signaling pathways in response to rTMS stimulation; rTMS treatment activated STAT, MAPK, Akt/p70S6K, and CREB signaling. We also systematically investigated the influence of rTMS parameters. We found an effective range of applications for rTMS and determined the optimal combination to achieve the highest efficiency. Moreover, application of rTMS inhibited the increase in cell death induced by hydrogen peroxide. These results suggest that rTMS treatment exerts a neuroprotective effect on cellular damage induced by oxidative stress, which plays an important role in the pathogenesis of neurological disorders. rTMS treatment attenuated streptozotocin (STZ)-mediated cell death and AD-like pathology in neuronal cells. In an animal model of sporadic AD caused by intracerebroventricular STZ injection, rTMS application improved cognitive decline and showed neuroprotective effects on hippocampal histology. Overall, this study will help in the design of stimulation protocols for rTMS application and presents a novel mechanism that may explain the therapeutic effects of rTMS in neurodegenerative diseases, including AD.