The Effects of Different Repetitive Transcranial Magnetic Stimulation (rTMS) Protocols on Cortical Gene Expression in a Rat Model of Cerebral Ischemic-Reperfusion Injury

Abstract

Although repetitive Transcranial Magnetic Stimulation (rTMS) in treatment of stroke in humans has been explored over the past decade the data remain controversial in terms of optimal stimulation parameters and the mechanisms of rTMS long-term effects. This study aimed to explore the potential of different rTMS protocols to induce changes in gene expression in rat cortices after acute ischemic-reperfusion brain injury. The stroke was induced by middle cerebral artery occlusion (MCAO) with subsequent reperfusion. Changes in the expression of 96 genes were examined using low-density expression arrays after MCAO alone and after MCAO combined with 1Hz, 5Hz, continuous (cTBS) and intermittent (iTBS) theta-burst rTMS. rTMS over the lesioned hemisphere was given for two weeks (with a 2-day pause) in a single daily session and a total of 2400 pulses. MCAO alone induced significant upregulation in the expression of 44 genes and downregulation in 10. Two weeks of iTBS induced significant increase in the expression of 52 genes. There were no downregulated genes. 1Hz and 5Hz had no significant effects on gene expression, while cTBS effects were negligible. Upregulated genes included those involved in angiogenesis, inflammation, injury response and cellular repair, structural remodeling, neuroprotection, neurotransmission and neuronal plasticity. The results show that long-term rTMS in acute ischemic-reperfusion brain injury induces complex changes in gene expression that span multiple pathways, which generally promote the recovery. They also demonstrate that induced changes primarily depend on the rTMS frequency (1Hz and 5Hz vs. iTBS) and pattern (cTBS vs. iTBS). The results further underlines the premise that one of the benefits of rTMS application in stroke may be to prime the brain, enhancing its potential to cope with the injury and to rewire. This could further augment its potential to favorably respond to rehabilitation, and to restore some of the loss functions.

Non-Invasive Brain Stimulation to Enhance Post-Stroke Recovery

“…In a model of experimental stroke, induced by transient 90 min of middle cerebral artery occlusion, rats were exposed 4 days later to a 1 Hz, 5 Hz, and continuous or intermittent theta-burst rTMS protocol. At the end of the stimulation period (Ljubisavljevic et al, 2015 ), only intermittent theta-burst rTMS protocol induced differential up-regulation of 52 genes in rat cortices, these genes being involved in angiogenesis, inflammation, neuroprotection and cellular repair, all these mechanisms promoting recovery (Nih et al, 2012 ; Poittevin et al, 2013 ). In the same model, but with a different rTMS protocol using high-frequency stimulation applied 1 h after the onset of ischemia, neuroprotective effect was evidenced via anti-apoptosis of the cells located at the margin of the infarct (Gao et al, 2010 ).…”

Repetitive Transcranial Magnetic Stimulation Activates Glial Cells and Inhibits Neurogenesis after Pneumococcal Meningitis

“…Furthermonre, studies reporting increased neurogenesis with increased neural stem cell progenitor proliferation, were often performed in healthy rodent models in the absence of neuroinflammation [25,26,62]. Additionally, induced neuroregeneration upon rTMS therapy was mostly found in adult rodent models [23,25,62]. These results might therefore differ from our infant model, where the rate of endogenous neurogenesis is already considerably high [11].…”

“…We applied a comparably short stimulation protocol with four stimulation trains per day on 2 consecutive days, which represents a setup that showed beneficial effect in treatment of human neglect patients after stroke [57–59]. This is in contrast to stimulation for up to 60 days in studies with reported positive effect on neurogenesis [23,60,61]. In addition, we isolated brain tissues 24 hours after the last stimulation train to assess short-term effects of TBS, compared to some studies with significant longer poststimulation assessment [53].…”

Restraint devices for repetitive transcranial magnetic stimulation in mice and rats

“…To solve these problems, we designed the restraint devices to improve the delivery of rTMS and replicated some previous conclusions in humans or animals (Maeda et al, 2000;Muller et al, 2014) to confirm the effectiveness. As compared to previous restraint methods, the methods appeared to more practical, especially making the delivery of rTMS more convenient (Hesselberg et al, 2016;Lim et al, 2014;Ljubisavljevic et al, 2015;Sasso et al, 2016). However, their usefulness and effectiveness need to be verified by more researchers in the future.…”

“…Therefore, it is necessary to take some measures to restrain the animals. In previous literature, investigators used the anesthesiology method (Sasso et al, ; Sykes et al, ), or by hand (Hesselberg, Wegener, & Buchholtz, ; Lim, Lee, Yoo, & Kwon, ; Sasso et al, ), or cloth, bag and straps (Ljubisavljevic et al, ); Tang et al, ), or some undefined devices (Guo et al, ). In animals, rTMS is often used 1–2 times each day (for minutes to tens of minutes each time), lasts for a few of days or tens of days (Fleischmann & Hirschmann, ; Guo et al, ; Ji et al, ).…”