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

High-frequency rTMS alleviates cognitive impairment and regulates synaptic plasticity in the hippocampus of rats with cerebral ischemia

Poststroke cognitive impairment (PSCI) is a common complication of stroke, but effective treatments are currently lacking. Repetitive transcranial magnetic stimulation (rTMS) is gradually being applied to treat PSCI, but there is limited evidence of its efficacy. To determine rTMS effects on PSCI, we constructed a transient middle cerebral artery occlusion (tMCAO) rat model. Rats were then grouped by random digital table method: the sham group (n = 10), tMCAO group (n = 10) and rTMS group (n = 10). The shuttle box and Morris water maze (MWM) tests were conducted to detect the cognitive functions of the rats. In addition, synaptic density and synaptic ultrastructural parameters, including the active zone length, synaptic cleft width, and postsynaptic density (PSD) thickness, were quantified and analyzed using an electron microscope. What's more, synaptic associated proteins, including PSD95, SYN, and BDNF were detected by western blot. According to the shuttle box and MWM tests, rTMS improved tMCAO rats' cognitive functions, including spatial learning and memory and decision-making abilities. Electron microscopy revealed that rTMS significantly increased the synaptic density, synaptic active zone length and PSD thickness and decreased the synaptic cleft width. The western blot results showed that the expression of PSD95, SYN, and BDNF was markedly increased after rTMS stimulation. Based on these results, we propose that 20 Hz rTMS can significantly alleviate cognitive impairment after stroke. The underlying mechanism might be modulating the synaptic plasticity and up-regulating the expression PSD95, SYN, and BDNF in the hippocampus.

Novel emerging therapy for erectile dysfunction: efficacy and safety of flat magnetic stimulation

BACKGROUND

The erectile dysfunction (ED), which is the inability to achieve and/or sustain a penile erection sufficient to result in a satisfying sexual performance, represents a very common complaint. for men over forty years old. The aim of the study was to evaluate if Flat Magnetic Stimulation (FMS) technology could help individuals with symptomatic erectile dysfunction.

METHODS

Twenty patients with erectile dysfunction, underwent eight sessions of about 30 minutes each in a twice a week frequency with the study device. During treatments, every potential side effect was assessed. The International Index of Erectile Function (IIEF) was compiled by all patients at the beginning, after the eighth treatment and at 1 month from the end of the last treatment. The questionnaire scores were presented as median values along with the interquartile range (IQR) and we set the significance threshold at 0.01.

RESULTS

After the treatment and at 1-month follow-up, the increase in questionnaire scores was statistically significant compared to the baseline, thus supporting the clinical usefulness of this treatment. In particular, the result of the study indicates a statistically significant difference between IIEF score before treatment (Median = 34) and IIEF score after the end of treatment (Median = 45) and between IIEF score before treatment and IIEF score at 1-month follow-up (Median = 54).

CONCLUSIONS

The study findings showed that FMS represents a promising treatment option to individuals affected by symptomatic erectile dysfunction.

Effects of different modalities of transcranial magnetic stimulation on post-stroke cognitive impairment: a network meta-analysis

OBJECTIVE

The study aimed to evaluate, using a network meta-analysis, the effects of different transcranial magnetic stimulation (TMS) modalities on improving cognitive function after stroke.

METHODS

Computer searches of the Cochrane Library, PubMed, Web of Science, Embass, Google Scholar, CNKI, and Wanfang databases were conducted to collect randomized controlled clinical studies on the use of TMS to improve cognitive function in stroke patients, published from the time of database construction to November 2023.

RESULTS

A total of 29 studies and 2123 patients were included, comprising five interventions: high-frequency rTMS (HF-rTMS), low-frequency rTMS (LF-rTMS), intermittent theta rhythm stimulation (iTBS), sham stimulation (SS), and conventional rehabilitation therapy (CRT). A reticulated meta-analysis showed that the rankings of different TMS intervention modalities in terms of the Montreal Cognitive Assessment (MoCA) scores, Mini-Mental State Examination scores (MMSE), and Modified Barthel Index (MBI) scores were: HF-rTMS > LF-rTMS > iTBS > SS > CRT; the rankings of different TMS intervention modalities in terms of the event-related potential P300. amplitude scores were HF-rTMS > LF-rTMS > iTBS > CRT > SS; the rankings of different TMS intervention modalities in terms of the P300 latency scores were: iTBS > HF-rTMS > LF-rTMS > SS > CRT. Subgroup analyses of secondary outcome indicators showed that HF-rTMS significantly improved Rivermead Behavior Memory Test scores and Functional Independence Measurement-Cognitive scores.

CONCLUSIONS

High-frequency TMS stimulation has a better overall effect on improving cognitive functions and activities of daily living, such as attention and memory in stroke patients.

Intermittent theta burst stimulation combined with cognitive training improves cognitive dysfunction and physical dysfunction in patients with post-stroke cognitive impairment

OBJECTIVE

Post-stroke cognitive impairment (PSCI) is a common complication of stroke. Intermittent theta burst stimulation (iTBS) can inducing motor learning. We observed the effects of combination of iTBS with cognitive training on physical/cognitive dysfunctions in PSCI patients.

METHODS

PSCI patients treated with basic treatment & cognitive training (Control group)/iTBS & cognitive training (iTBS group) were enrolled, with Mini-mental State Examination (MMSE)/Montreal Cognitive Assessment (MoCA)/Frontal Assessment Battery (FAB)/barthel index (BI)/Upper Limb Fugl-Meyer Assessment (U-FMA)/Action Research Arm Test (ARAT) scores compared. Gait spatiotemporal parameters/dynamic parameters were analyzed by 3D gait analysis. Correlations between MMSE/MoCA scores and gait parameters in PSCI patients after iTBS & cognitive training were analyzed by Spearman analysis.

RESULTS

Increased MMSE/MoCA/FAB/BI/U-FMA/ARAT scores, step speed, step frequency, stride length, step width, step length on the affected side, percentage of swing phase on the affected side, hip joint flexion angle on the affected side, knee joint flexion angle on the affected side, and ankle plantar flexion angle on the affected side and reduced gait period on the affected side and percentage of stance phase on the affected side were found in patients of both groups after treatment, with the effects in the iTBS group more profound.

CONCLUSION

iTBS & cognitive training obviously improved the cognitive function scores/upper limb function scores/gait parameters in PSCI patients versus cognitive training treatment. After combination therapy, the MMSE/MoCA scores of PSCI patients were significantly correlated with gait parameters. This provided more data support for iTBS & cognitive training application in the rehabilitation treatment of PSCI patients.

High-frequency repetitive transcranial magnetic stimulation improves depressive-like behaviors in CUMS-induced rats by modulating astrocyte GLT-1 to reduce glutamate toxicity

Impaired glutamate recycling plays an important role in the pathophysiology of depression, and it has been demonstrated that glutamate transporter-1 (GLT-1) on astrocytes is involved in glutamate uptake. Studies have shown that repetitive transcranial magnetic stimulation (rTMS) is effective in treating depression, however, the exact mechanism of rTMS treatment remains unclear. Here, we used a chronic unpredictable mild stress (CUMS) protocol to induce depression-like behaviors in rats followed by rTMS treatment. Behavioral assessment was primarily through SPT, FST, OFT and body weight. Histological analysis focused on GFAP and GLT-1 expression, synaptic plasticity, apoptosis and PI3K/Akt/CREB pathway-related proteins. The results showed that rTMS treatment increased sucrose preference, improved locomotor activity, shortened immobility time as well as increased body weight. And rTMS intervention reversed the elevated glutamate concentration in the hippocampus of CUMS rats using an ELISA kit. Moreover, rTMS ameliorated the reduction in GFAP and GLT-1 expression, alleviated the decrease in BDNF, PSD95 and synapsin-1 expression, also reversed the expression levels of BAX and Bcl2 in the hippocampus of CUMS-induced rats. Moreover, rTMS also increased the protein phosphorylation level of PI3K/Akt/CREB pathway. These results suggest that rTMS treatment ameliorates depression-like behaviors in the rat model by reversing the reduction of GLT-1 on astrocytes and reducing glutamate accumulation in the synaptic cleft, which in turn ameliorates synaptic plasticity damage and neuronal apoptosis. The regulation of GLT-1 by rTMS may be through the PI3K/Akt/CREB pathway.

Theta burst stimulation: what role does it play in stroke rehabilitation? A systematic review of the existing evidence

Various post-stroke dysfunctions often result in poor long-term outcomes for stroke survivors, but the effect of conventional treatments is limited. In recent years, lots of studies have confirmed the effect of repetitive transcranial magnetic stimulation (rTMS) in stroke rehabilitation. As a new pattern of rTMS, theta burst stimulation (TBS) was proved recently to yield more pronounced and long-lasting after-effects than the conventional pattern at a shorter stimulation duration. To explore the role of TBS in stroke rehabilitation, this review summarizes the existing evidence from all the randomized controlled trials (RCTs) so far on the efficacy of TBS applied to different post-stroke dysfunctions, including cognitive impairment, visuospatial neglect, aphasia, dysphagia, spasticity, and motor dysfunction. Overall, TBS promotes the progress of stroke rehabilitation and may serve as a preferable alternative to traditional rTMS. However, it's hard to recommend a specific paradigm of TBS due to the limited number of current studies and their heterogeneity. Further high-quality clinical RCTs are needed to determine the optimal technical settings and intervention time in stroke survivors.

Non-invasive brain stimulation for functional recovery in animal models of stroke: A systematic review

Motor and cognitive dysfunction occur frequently after stroke, severely affecting a patient´s quality of life. Recently, non-invasive brain stimulation (NIBS) has emerged as a promising treatment option for improving stroke recovery. In this context, animal models are needed to improve the therapeutic use of NIBS after stroke. A systematic review was conducted based on the PRISMA statement. Data from 26 studies comprising rodent models of ischemic stroke treated with different NIBS techniques were included. The SYRCLE tool was used to assess study bias. The results suggest that both repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) improved overall neurological, motor, and cognitive functions and reduced infarct size both in the short- and long-term. For tDCS, it was observed that either ipsilesional inhibition or contralesional stimulation consistently led to functional recovery. Additionally, the application of early tDCS appeared to be more effective than late stimulation, and tDCS may be slightly superior to rTMS. The optimal stimulation protocol and the ideal time window for intervention remain unresolved. Future directions are discussed for improving study quality and increasing their translational potential.

Intermittent theta burst stimulation for poststroke non-spatial attention deficit: a protocol of prospective, double-blinded, single-centre, randomised controlled trial in China

INTRODUCTION

Attention deficit is the most common cognitive impairment after stroke, which can significantly hinder the recovery of both other cognitive domains and motor functions. Increasing evidence suggests that the left dorsolateral prefrontal cortex (DLPFC) is related to non-spatial attention functions, which indicates that it may be a promising target of repetitive transcranial magnetic stimulation (rTMS) for treating poststroke non-spatial attention deficit. Theta burst stimulation (TBS) is a modified pattern of rTMS that delivers shorter stimulation times and exhibits superior therapeutic efficacy. This study aims to provide evidence regarding the efficacy of intermittent TBS (iTBS) over the left DLPFC to improve poststroke non-spatial attention deficits and elucidate the potential neurophysiological mechanisms.

METHODS AND ANALYSIS

In this single-centre, prospective, randomised, sham-controlled clinical trial, patients with non-spatial attention deficits (n=38) received 10 sessions of real iTBS (n=19) or sham iTBS (n=19) over the left DLPFC and a 30-min conventional attention training. Neuropsychological evaluations, electrophysiological examination and neuroimaging scan will be conducted at baseline, postintervention (second week) and 2-week follow-up (fourth week). The primary outcomes are the change in the Montreal Cognitive Assessment scores and the Digital Span Test scores from baseline to the end of the intervention (second week). The secondary outcomes comprise changes in magnetic resonance spectroscopy neuroimaging from baseline to the end of the intervention (second week) as well as attention test batteries (including tests of selective attention, sustained attention, divided attention and shifting attention) and ERP P300 from baseline to endpoint (fourth week).

ETHICS AND DISSEMINATION

This study has been approved by the Institutional Ethical Committee of Tongji Hospital (ID: TJ-IRB20230879). All participants will sign the informed consent. Findings will be published in peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

ChiCTR2300068669.

Long-term iTBS Improves Neural Functional Recovery by Reducing the Inflammatory Response and Inhibiting Neuronal Apoptosis Via miR-34c-5p/p53/Bax Signaling Pathway in Cerebral Ischemic Rats

To investigate intermittent theta-burst stimulation (iTBS) effect on ischemic stroke and the underlying mechanism of neurorehabilitation, we developed an ischemia/reperfusion (I/R) injury model in Sprague-Dawley (SD) rats using the middle cerebral artery occlusion/reperfusion (MCAO/r) method. Next, using different behavioral studies, we compared the improvement of the whole organism with and without iTBS administration for 28 days. We further explored the morphological and molecular biological alterations associated with neuronal apoptosis and neuroinflammation by TTC staining, HE staining, Nissl staining, immunofluorescence staining, ELISA, small RNA sequencing, RT-PCR, and western blot assays. The results showed that iTBS significantly protected against neurological deficits and neurological damage induced by cerebral I/R injury. iTBS also significantly decreased brain infarct volume and increased the number of surviving neurons after 28 days. Additionally, it was observed that iTBS decreased synaptic loss, suppressed activation of astrocytes and M1-polarized microglia, and simultaneously promoted M2-polarized microglial activation. Furthermore, iTBS intervention inhibited neuronal apoptosis and exerted a positive impact on the neuronal microenvironment by reducing neuroinflammation in cerebral I/R injured rats. To further investigate the iTBS mechanism, this study was conducted using small RNA transcriptome sequencing of various groups of peri-infarcted tissues. Bioinformatics analysis and RT-PCR discovered the possible involvement of miR-34c-5p in the mechanism of action. The target genes prediction and detection of dual-luciferase reporter genes confirmed that miR-34c-5p could inhibit neuronal apoptosis in cerebral I/R injured rats by regulating the p53/Bax signaling pathway. We also confirmed by RT-PCR and western blotting that miR-34c-5p inhibited Bax expression. In conclusion, our study supports that iTBS is vital in inhibiting neuronal apoptosis in cerebral I/R injured rats by mediating the miR-34c-5p involvement in regulating the p53/Bax signaling pathway.

Repetitive Transcranial Magnetic Stimulation in Stroke: A Literature Review of the Current Role and Controversies of Neurorehabilitation Through Electromagnetic Pulses

Repetitive transcranial magnetic stimulation (rTMS) is an effective method used for the treatment of various neurological diseases, including stroke, epilepsy, and movement disorders. The pathophysiological mechanism for the effect of TMS is not clear. In this literature review, we conducted a detailed search regarding the effect of rTMS on neurotransmission and neuronal plasticity through the modulation of neuronal excitability. Evidence suggests that intramolecular subatomic mechanisms, including genetic changes related to neuronal prevention and death, play an important role. We also discuss the use of rTMS in the rehabilitation of patients with stroke and its main complications, as well as alternative mechanisms related to recovery, emphasizing the findings of available evidence and touching on possible controversies and limitations of the method.

Different synaptic mechanisms of intermittent and continuous theta-burst stimulations in a severe foot-shock induced and treatment-resistant depression in a rat model

Treatment-resistant depression (TRD) is a condition wherein patients with depression fail to respond to antidepressant trials. A new form of repetitive transcranial magnetic stimulation (rTMS), called theta-burst stimulation (TBS), which includes intermittent theta-burst stimulation (iTBS) and continuous theta-burst stimulation (cTBS), is non-inferior to rTMS in TRD treatment. However, the mechanism of iTBS and cTBS underlying the treatment of TRD in the prefrontal cortex (PFC) remains unclear. Hence, we applied foot-shock stress as a traumatic event to develop a TRD rat model and investigated the different mechanisms of iTBS and cTBS. The iTBS and cTBS treatment were effective in depressive-like behavior and active coping behavior. The iTBS treatments improved impaired long-term potentiation and long-term depression (LTD), whereas the cTBS treatment only improved aberrant LTD. Moreover, the decrease in mature brain-derived neurotrophic factor (BDNF)-related protein levels were reversed by iTBS treatment. The decrease in proBDNF-related protein expression was improved by iTBS and cTBS treatment. Both iTBS and cTBS improved the decreased α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors and downregulation of mammalian target of the rapamycin (mTOR) signaling pathway. The iTBS produces both excitatory and inhibitory synaptic effects, and the cTBS only produces inhibitory synaptic effects in the PFC.

The Implications of Microglial Regulation in Neuroplasticity-Dependent Stroke Recovery

Stroke causes varying degrees of neurological deficits, leading to corresponding dysfunctions. There are different therapeutic principles for each stage of pathological development. Neuroprotection is the main treatment in the acute phase, and functional recovery becomes primary in the subacute and chronic phases. Neuroplasticity is considered the basis of functional restoration and neurological rehabilitation after stroke, including the remodeling of dendrites and dendritic spines, axonal sprouting, myelin regeneration, synapse shaping, and neurogenesis. Spatiotemporal development affects the spontaneous rewiring of neural circuits and brain networks. Microglia are resident immune cells in the brain that contribute to homeostasis under physiological conditions. Microglia are activated immediately after stroke, and phenotypic polarization changes and phagocytic function are crucial for regulating focal and global brain inflammation and neurological recovery. We have previously shown that the development of neuroplasticity is spatiotemporally consistent with microglial activation, suggesting that microglia may have a profound impact on neuroplasticity after stroke and may be a key therapeutic target for post-stroke rehabilitation. In this review, we explore the impact of neuroplasticity on post-stroke restoration as well as the functions and mechanisms of microglial activation, polarization, and phagocytosis. This is followed by a summary of microglia-targeted rehabilitative interventions that influence neuroplasticity and promote stroke recovery.

The Putative Role of Neuroinflammation in the Interaction between Traumatic Brain Injuries, Sleep, Pain and Other Neuropsychiatric Outcomes: A State-of-the-Art Review

Sleep disturbances are widely prevalent following a traumatic brain injury (TBI) and have the potential to contribute to numerous post-traumatic physiological, psychological, and cognitive difficulties developing chronically, including chronic pain. An important pathophysiological mechanism involved in the recovery of TBI is neuroinflammation, which leads to many downstream consequences. While neuroinflammation is a process that can be both beneficial and detrimental to individuals' recovery after sustaining a TBI, recent evidence suggests that neuroinflammation may worsen outcomes in traumatically injured patients, as well as exacerbate the deleterious consequences of sleep disturbances. Additionally, a bidirectional relationship between neuroinflammation and sleep has been described, where neuroinflammation plays a role in sleep regulation and, in turn, poor sleep promotes neuroinflammation. Given the complexity of this interplay, this review aims to clarify the role of neuroinflammation in the relationship between sleep and TBI, with an emphasis on long-term outcomes such as pain, mood disorders, cognitive dysfunctions, and elevated risk of Alzheimer's disease and dementia. In addition, some management strategies and novel treatment targeting sleep and neuroinflammation will be discussed in order to establish an effective approach to mitigate long-term outcomes after TBI.

Cerebral Theta-Burst Stimulation Combined with Physiotherapy in Patients with Incomplete Spinal Cord Injury: A Pilot Randomized Controlled Trial

OBJECTIVE

To measure the effects of cerebral intermittent theta-burst stimulation with physiotherapy on lower extremity motor recovery in patients with incomplete spinal cord injury.

DESIGN

Randomized, double-blinded, sham-controlled trial.

SUBJECTS

Adults with incomplete spinal cord injury.

METHODS

A total of 38 patients with incomplete spinal cord injury were randomized into either an intermittent theta-burst stimulation or a sham group. Both groups participated in physiotherapy 5 times per week for 9 weeks, and cerebral intermittent theta-burst stimulation or sham intermittent theta-burst stimulation was performed daily, immediately before physiotherapy. The primary outcomes were lower extremity motor score (LEMS), root-mean square (RMS), RMS of the quadriceps femoris muscle, walking speed (WS), and stride length (SL). Secondary outcomes comprised Holden Walking Ability Scale (HWAS) and modified Barthel Index (MBI). The outcomes were assessed before the intervention and 9 weeks after the start of the intervention.

RESULTS

Nine weeks of cerebral intermittent theta-burst stimulation with physiotherapy intervention resulted in improved recovery of lower extremity motor recovery in patients with incomplete spinal cord injury. Compared with baseline, the changes in LEMS, WS, SL, RMS, HWAS, and MBI were significant in both groups after intervention. The LEMS, WS, SL, RMS, HWAS, and MBI scores were improved more in the intermittent theta-burst stimulation group than in the sham group.

CONCLUSION

Cerebral intermittent theta-burst stimulation with physiotherapy promotes lower extremity motor recovery in patients with incomplete spinal cord injury. However, this study included a small sample size and lacked a comparison of the treatment effects of multiple stimulation modes, the further research will be required in the future.

Transcranial magnetic stimulation set-up for small animals

Transcranial magnetic stimulation (TMS) is widely applied on humans for research and clinical purposes. TMS studies on small animals, e.g., rodents, can provide valuable knowledge of the underlying neurophysiological mechanisms. Administering TMS on small animals is, however, prone to technical difficulties, mainly due to their small head size. In this study, we aimed to develop an energy-efficient coil and a compatible experimental set-up for administering TMS on rodents. We applied a convex optimization process to develop a minimum-energy coil for TMS on rats. As the coil windings of the optimized coil extend to a wide region, we designed and manufactured a holder on which the rat lies upside down, with its head supported by the coil. We used the set-up to record TMS-electromyography, with electromyography recorded from limb muscles with intramuscular electrodes. The upside-down placement of the rat allowed the operator to easily navigate the TMS without the coil blocking their field of view. With this paradigm, we obtained consistent motor evoked potentials from all tested animals.

Low-Frequency Repetitive Transcranial Magnetic Stimulation in the Early Subacute Phase of Stroke Enhances Angiogenic Mechanisms in Rats

Objective To characterize the repetitive transcranial magnetic stimulation (rTMS) induced changes in angiogenic mechanisms across different brain regions.Methods Seventy-nine adult male Sprague-Dawley rats were subjected to a middle cerebral artery occlusion (day 0) and then treated with 1-Hz, 20-Hz, or sham stimulation of their lesioned hemispheres for 2 weeks. The stimulation intensity was set to 100% of the motor threshold. The neurological function was assessed on days 3, 10, and 17. The infarct volume and angiogenesis were measured by histology, immunohistochemistry, Western blot, and real-time polymerase chain reaction (PCR) assays. Brain tissue was harvested from the ischemic core (IC), ischemic border zone (BZ), and contralateral homologous cortex (CH).Results Optical density of angiopoietin1 and synaptophysin in the IC was significantly greater in the low-frequency group than in the sham group (p=0.03 and p=0.03, respectively). The 1-Hz rTMS significantly increased the level of Akt phosphorylation in the BZ (p<0.05 vs. 20 Hz). Endothelial nitric oxide synthase phosphorylation was increased in the IC (p<0.05 vs. 20 Hz), BZ (p<0.05 vs. 20 Hz), and CH (p<0.05 vs. 20 Hz and p<0.05 vs. sham). Real-time PCR demonstrated that low-frequency stimulation significantly increased the transcriptional activity of the TIE2 gene in the IC (p<0.05).Conclusion Low-frequency rTMS of the ipsilesional hemisphere in the early subacute phase of stroke promotes the expression of angiogenic factors and related genes in the brain, particularly in the injured area.

Gene Expression Profile Changes in the Stimulated Rat Brain Cortex After Repetitive Transcranial Magnetic Stimulation

Repetitive transcranial magnetic stimulation (rTMS) is gaining popularity as a research tool in neuroscience; however, little is known about its molecular mechanisms of action. The present study aimed to investigate the rTMS-induced transcriptomic changes; we performed microarray messenger RNA, micro RNA, and integrated analyses to explore these molecular events. Eight adult male Sprague-Dawley rats were subjected to a single session of unilateral rTMS at 1 Hz (n = 4) or sham (n = 4). The left hemisphere was stimulated for 20 minutes. To evaluate the cumulative effect of rTMS, eight additional rats were assigned to the 1-Hz (n = 4) or sham (n = 4) rTMS groups. The left hemisphere was stimulated for 5 consecutive days using the same protocol. Microarray analysis revealed differentially expressed genes in the rat cortex after rTMS treatment. The overrepresented gene ontology categories included the positive regulation of axon extension, axonogenesis, intracellular transport, and synaptic plasticity after repeated sessions of rTMS. A single session of rTMS primarily induced changes in the early genes, and several miRNAs were significantly related to the mRNAs. Future studies are required to validate the functional significance of selected genes and refine the therapeutic use of rTMS.

Anti-apoptosis effects of codonolactone on cerebral ischemia-reperfusion injury

Codonolactone is the main biologically active ingredient in Atractylodes lancea. Studies have shown various functions of codonolactone, while its protective effect against neurotoxicity caused by ischemic stroke is unclear. This study investigated the roles of codonolactone in inflammation, oxidative stress and apoptosis after cerebral ischemia-reperfusion (I/R) injury. Rats with codonolactone treatment, I/R treatment and the sham operation group were used in this study. After reperfusion for 24 hours, nerve damage was detected by nerve staining, and the neurological deficits of the rats were analyzed. The contents of superoxide dismutase (SOD), malondialdehyde (MDA), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in rat brain tissues were also determined. Western blot analysis was performed to determine the expression levels of Akt/Nrf2 pathway-associated proteins. Compared with the I/R group, the cerebral blood flow, infarct volume, brain water content, coronary blood flow and neurological deficits in the codonolactone treatment group, especially with the 80 mg/kg dosage, were significantly reduced. Codonolactone could significantly reduce the expression levels of caspase-3 and Bax, and significantly increase the expression levels of Bcl-2 after I/R. In addition, codonolactone could significantly reduce MDA content and the expression levels of TNF-α and IL-1β in ischemic brain tissues. It also significantly increased SOD activity, the expression levels of heme oxygenase-1 (HO-1) and the phosphorylation of Akt and Nrf2. Codonolactone ameliorated the cerebral I/R injury by improving anti-oxidant, anti-inflammatory activities and reducing apoptosis. Besides, the Akt/Nrf2 pathway was involved in the pharmacological action of the codonolactone.

Long-Term Motor Cortical Electrical Stimulation Ameliorates 6-Hydroxydopamine-Induced Motor Dysfunctions and Exerts Neuroprotective Effects in a Rat Model of Parkinson's Disease

OBJECTIVE

Cortical electrical stimulation (CES) can modulate cortical excitability through a plasticity-like mechanism and is considered to have therapeutic potentials in Parkinson's disease (PD). However, the precise therapeutic value of such approach for PD remains unclear. Accordingly, we adopted a PD rat model to determine the therapeutic effects of CES. The current study was thus designed to identify the therapeutic potential of CES in PD rats.

METHODS

A hemiparkinsonian rat model, in which lesions were induced using unilateral injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle, was applied to identify the therapeutic effects of long-term (4-week) CES with intermittent theta-burst stimulation (iTBS) protocol (starting 24 h after PD lesion observation, 1 session/day, 5 days/week) on motor function and neuroprotection. After the CES intervention, detailed functional behavioral tests including gait analysis, akinesia, open-field locomotor activity, apomorphine-induced rotation as well as degeneration level of dopaminergic neurons were performed weekly up to postlesion week 4.

RESULTS

After the CES treatment, we found that the 4-week CES intervention ameliorated the motor deficits in gait pattern, akinesia, locomotor activity, and apomorphine-induced rotation. Immunohistochemistry and tyrosine hydroxylase staining analysis demonstrated that the number of dopamine neurons was significantly greater in the CES intervention group than in the sham treatment group.

CONCLUSION

This study suggests that early and long-term CES intervention could reduce the aggravation of motor dysfunction and exert neuroprotective effects in a rat model of PD. Further, this preclinical model of CES may increase the scope for the potential use of CES and serve as a link between animal and PD human studies to further identify the therapeutic mechanism of CES for PD or other neurological disorders.

Different combinations of high-frequency rTMS and cognitive training improve the cognitive function of cerebral ischemic rats

Poststroke cognitive impairment (PSCI) occurs frequently after stroke, but lacks effective treatments. Previous studies have revealed that high-frequency repetitive transcranial magnetic stimulation (rTMS) has a beneficial effect on PSCI and is often used with other cognitive training methods to improve its effect. This study aimed to evaluate the effect of different combinations of rTMS and cognitive training (rTMS-COG) on PSCI and identify the optimal combination protocol. A cerebral infarction rat model was established by transient middle cerebral artery occlusion (tMCAO). The Morris water maze test was conducted to assess the cognitive function of rats. RNA sequencing and bioinformatics analysis were employed to study the underlying mechanisms. rTMS, COG and rTMS-COG all had beneficial effects on PSCI, while cognitive training immediately after rTMS (rTMS-COG_0h) achieved a better effect than cognitive training 1 h and 4 h after rTMS, rTMS and COG. We identified 179 differentially expressed genes (DEGs), including 24 upregulated and 155 downregulated genes, between the rTMS-COG_0h and rTMS groups. GO analysis revealed that the major categories associated with the DEGs were antigen procession and presentation, regulation of protein phosphorylation and axoneme assembly. KEGG analysis showed that the DEGs were enriched in processes related to phagosome, circadian entrainment, dopaminergic synapse, apelin signaling pathway, long-term depression, neuroactive ligand-receptor interaction, axon guidance and glucagon signaling pathway. PPI analysis identified Calb2, Rsph1, Ccdc114, Acta2, Ttll9, Dnah1, Dlx2, Dlx1, Ccdc40 and Ccdc113 as related genes. These findings prompt exploration of the potential mechanisms and key genes involved in the effect of rTMS-COG_0h on PSCI.

Astrocytes contribute to the neuronal recovery promoted by high-frequency repetitive magnetic stimulation in in vitro models of ischemia

After decades of effort, there are no effective clinical treatments to induce the recovery of ischemia-injured tissues, and among the several strategies that have been explored, repetitive transcranial magnetic stimulation has proven to be one of the most promising, with beneficial effects in limb motor function, aphasia, hemispatial neglect, or dysphagia. Despite the clinical evidences, little is known about the mechanisms underlying those effects. The present study aimed to explore the cellular and molecular effects of high-frequency repetitive magnetic stimulation (HF-rMS) on an in vitro model of ischemia. Using primary cortical cultures exposed to oxygen and glucose deprivation followed by reperfusion, we observed that HF-rMS treatment prevents the ischemia-induced neuronal death by 21.2%, and the neurite degeneration triggered by ischemia. Our results also demonstrate that with this treatment there is an increase of 89.2% on the number cells expressing ERK1/2, of 20.1% on the number of cells expressing c-Fos, and a synaptogenic effect, through an increase of 62.9% in the number of synaptic puncta as well as of 49.4% in their intensity. Interestingly, our results indicate that astrocytes are crucial to the beneficial effects triggered by HF-rMS after ischemia, thus suggesting a direct effect of HF-rMS on these cells. The modulation of astrocytes with this non-invasive brain stimulation technique is a promising approach to promote the recovery of ischemia-induced injured tissues; however, it is essential to understand how these effects can be modulated in order to optimize the protocols and enhance the beneficial outcomes.

Early Repetitive Transcranial Magnetic Stimulation Exerts Neuroprotective Effects and Improves Motor Functions in Hemiparkinsonian Rats

Repetitive transcranial magnetic stimulation (rTMS) is a popular noninvasive technique for modulating motor cortical plasticity and has therapeutic potential for the treatment of Parkinson's disease (PD). However, the therapeutic benefits and related mechanisms of rTMS in PD are still uncertain. Accordingly, preclinical animal research is helpful for enabling translational research to explore an effective therapeutic strategy and for better understanding the underlying mechanisms. Therefore, the current study was designed to identify the therapeutic effects of rTMS on hemiparkinsonian rats. A hemiparkinsonian rat model, induced by unilateral injection of 6-hydroxydopamine (6-OHDA), was applied to evaluate the therapeutic potential of rTMS in motor functions and neuroprotective effect of dopaminergic neurons. Following early and long-term rTMS intervention with an intermittent theta burst stimulation (iTBS) paradigm (starting 24 h post-6-OHDA lesion, 1 session/day, 7 days/week, for a total of 4 weeks) in awake hemiparkinsonian rats, the effects of rTMS on the performance in detailed functional behavioral tests, including video-based gait analysis, the bar test for akinesia, apomorphine-induced rotational analysis, and tests of the degeneration level of dopaminergic neurons, were identified. We found that four weeks of rTMS intervention significantly reduced the aggravation of PD-related symptoms post-6-OHDA lesion. Immunohistochemically, the results showed that tyrosine hydroxylase- (TH-) positive neurons in the substantia nigra pars compacta (SNpc) and fibers in the striatum were significantly preserved in the rTMS treatment group. These findings suggest that early and long-term rTMS with the iTBS paradigm exerts neuroprotective effects and mitigates motor impairments in a hemiparkinsonian rat model. These results further highlight the potential therapeutic effects of rTMS and confirm that long-term rTMS treatment might have clinical relevance and usefulness as an additional treatment approach in individuals with PD.

Mechanism of Intermittent Theta-Burst Stimulation in Synaptic Pathology in the Prefrontal Cortex in an Antidepressant-Resistant Depression Rat Model

Intermittent theta-burst stimulation (iTBS), a form of repetitive transcranial magnetic stimulation, is considered a potential therapy for treatment-resistant depression. The synaptic mechanism of iTBS has long been known to be an effective method to induce long-term potentiation (LTP)-like plasticity in humans. However, there is limited evidence as to whether the antidepressant effect of iTBS is associated with change in synaptic function in the prefrontal cortex (PFC) in preclinical study. Hence, we applied an antidepressant (i.e., fluoxetine)-resistant depression rat model induced by severe foot-shocks to investigate the antidepressant efficacy of iTBS in the synaptic pathology. The results showed that iTBS treatment improved not only the impaired LTP, but also the aberrant long-term depression in the PFC of antidepressant-resistant depression model rats. Moreover, the mechanism of LTP improvement by iTBS involved downstream molecules of brain-derived neurotrophic factor, while the mechanism of long-term depression improvement by iTBS involved downstream molecules of proBDNF. The aberrant spine morphology was also improved by iTBS treatment. This study demonstrated that the mechanism of the iTBS paradigm is complex and may regulate not only excitatory but also inhibitory synaptic effects in the PFC.

Low intensity repetitive magnetic stimulation reduces expression of genes related to inflammation and calcium signalling in cultured mouse cortical astrocytes

Repetitive transcranial magnetic stimulation (rTMS) is a form of non-invasive brain stimulation frequently used to induce neuroplasticity in the brain. Even at low intensities, rTMS has been shown to modulate aspects of neuronal plasticity such as motor learning and structural reorganisation of neural tissue. However, the impact of low intensity rTMS on glial cells such as astrocytes remains largely unknown. This study investigated changes in RNA (qPCR array: 125 selected genes) and protein levels (immunofluorescence) in cultured mouse astrocytes following a single session of low intensity repetitive magnetic stimulation (LI-rMS - 18 mT). Purified neonatal cortical astrocyte cultures were stimulated with either 1Hz (600 pulses), 10Hz (600 or 6000 pulses) or sham (0 pulses) LI-rMS, followed by RNA extraction at 5 h post-stimulation, or fixation at either 5 or 24-h post-stimulation. LI-rMS resulted in a two-to-four-fold downregulation of mRNA transcripts related to calcium signalling (Stim1 and Orai3), inflammatory molecules (Icam1) and neural plasticity (Ncam1). 10Hz reduced expression of Stim1, Orai3, Kcnmb4, and Ncam1 mRNA, whereas 1Hz reduced expression of Icam1 mRNA and signalling-related genes. Protein levels followed a similar pattern for 10Hz rMS, with a significant reduction of STIM1, ORAI3, KCNMB4, and NCAM1 protein compared to sham, but 1Hz increased STIM1 and ORAI3 protein levels relative to sham. These findings demonstrate the ability of 1Hz and 10Hz LI-rMS to modulate specific aspects of astrocytic phenotype, potentially contributing to the known effects of low intensity rTMS on excitability and neuroplasticity.

Theta-burst transcranial magnetic stimulation promotes stroke recovery by vascular protection and neovascularization

Rationale: The integrity and function of the blood-brain barrier (BBB) is compromised after stroke. The current study was performed to examine potential beneficial effects and underlying mechanisms of repetitive transcranial magnetic stimulation (rTMS) on angiogenesis and vascular protection, function, and repair following stroke, which are largely unknown.

Methods: Using a rat photothrombotic (PT) stroke model, continuous theta-burst rTMS was administered once daily to the infarcted hemisphere for 5 min, beginning 3 h after PT stroke. This treatment was applied for 6 days. BBB integrity, blood flow, vascular associated proteins, angiogenesis, integrity of neuronal morphology and structure, and behavioral outcome were measured and analyzed at 6 and/or 22 days after PT stroke.

Results: We report that rTMS significantly mitigated BBB permeabilization and preserved important BBB components ZO-1, claudin-5, occludin, and caveolin-1 from PT-induced degradation. Damage to vascular structure, morphology, and perfusion was ameliorated by rTMS, resulting in improved local tissue oxygenation. This was accompanied with robust protection of critical vascular components and upregulation of regulatory factors. A complex cytokine response was induced by PT, particularly at the late phase. Application of rTMS modulated this response, ameliorating levels of cytokines related to peripheral immune cell infiltration. Further investigation revealed that rTMS promoted and sustained post-ischemic angiogenesis long-term and reduced apoptosis of newborn and existing vascular endothelial cells. Application of rTMS also inhibited PT-induced excessive astrocyte-vasculature interactions and stimulated an A1 to A2 shift in vessel-associated astrocytes. Mechanistic studies revealed that rTMS dramatically increased levels of PDGFRβ associated with A2 astrocytes and their adjacent vasculature. As well, A2 astrocytes displayed marked amplification of the angiogenesis-related factors VEGF and TGFβ. PT induced a rise in vessel-associated expression of HIF-1α that was starkly intensified by rTMS treatment. Finally, rTMS preserved neuronal morphology, synaptic structure integrity and behavioral outcome.

Conclusions: These results indicate that rTMS can exert powerful protective and restorative effects on the peri-infarct microvasculature after PT stroke by, in part, promoting HIF-1α signaling and shifting vessel-associated astrocytic polarization to the A2 phenotype. This study provides further support for the potent protective effects of rTMS in the context of ischemic stroke, and these findings implicate vascular repair and protection as an important underlying phenomenon.

Individual head models for estimating the TMS-induced electric field in rat brain

In transcranial magnetic stimulation (TMS), the initial cortical activation due to stimulation is determined by the state of the brain and the magnitude, waveform, and direction of the induced electric field (E-field) in the cortex. The E-field distribution depends on the conductivity geometry of the head. The effects of deviations from a spherically symmetric conductivity profile have been studied in detail in humans. In small mammals, such as rats, these effects are more pronounced due to their less spherical head, proportionally much thicker neck region, and overall much smaller size compared to the TMS coils. In this study, we describe a simple method for building individual realistically shaped head models for rats from high-resolution X-ray tomography images. We computed the TMS-induced E-field with the boundary element method and assessed the effect of head-model simplifications on the estimated E-field. The deviations from spherical symmetry have large, non-trivial effects on the E-field distribution: for some coil orientations, the strongest stimulation is in the brainstem even when the coil is over the motor cortex. With modelling prior to an experiment, such problematic coil orientations can be avoided for more accurate targeting.

Repetitive transcranial magnetic stimulation activates glial cells and inhibits neurogenesis after pneumococcal meningitis

Pneumococcal meningitis (PM) causes damage to the hippocampus, a brain structure critically involved in learning and memory. Hippocampal injury-which compromises neurofunctional outcome-occurs as apoptosis of progenitor cells and immature neurons of the hippocampal dentate granule cell layer thereby impairing the regenerative capacity of the hippocampal stem cell niche. Repetitive transcranial magnetic stimulation (rTMS) harbours the potential to modulate the proliferative activity of this neuronal stem cell niche. In this study, specific rTMS protocols-namely continuous and intermittent theta burst stimulation (cTBS and iTBS)-were applied on infant rats microbiologically cured from PM by five days of antibiotic treatment. Following two days of exposure to TBS, differential gene expression was analysed by whole transcriptome analysis using RNAseq. cTBS provoked a prominent effect in inducing differential gene expression in the cortex and the hippocampus, whereas iTBS only affect gene expression in the cortex. TBS induced polarisation of microglia and astrocytes towards an inflammatory phenotype, while reducing neurogenesis, neuroplasticity and regeneration. cTBS was further found to induce the release of pro-inflammatory cytokines in vitro. We conclude that cTBS intensified neuroinflammation after PM, which translated into increased release of pro-inflammatory mediators thereby inhibiting neuroregeneration.

Multimodal treatment for spinal cord injury: a sword of neuroregeneration upon neuromodulation

Spinal cord injury is linked to the interruption of neural pathways, which results in irreversible neural dysfunction. Neural repair and neuroregeneration are critical goals and issues for rehabilitation in spinal cord injury, which require neural stem cell repair and multimodal neuromodulation techniques involving personalized rehabilitation strategies. Besides the involvement of endogenous stem cells in neurogenesis and neural repair, exogenous neural stem cell transplantation is an emerging effective method for repairing and replacing damaged tissues in central nervous system diseases. However, to ensure that endogenous or exogenous neural stem cells truly participate in neural repair following spinal cord injury, appropriate interventional measures (e.g., neuromodulation) should be adopted. Neuromodulation techniques, such as noninvasive magnetic stimulation and electrical stimulation, have been safely applied in many neuropsychiatric diseases. There is increasing evidence to suggest that neuromagnetic/electrical modulation promotes neuroregeneration and neural repair by affecting signaling in the nervous system; namely, by exciting, inhibiting, or regulating neuronal and neural network activities to improve motor function and motor learning following spinal cord injury. Several studies have indicated that fine motor skill rehabilitation training makes use of residual nerve fibers for collateral growth, encourages the formation of new synaptic connections to promote neural plasticity, and improves motor function recovery in patients with spinal cord injury. With the development of biomaterial technology and biomechanical engineering, several emerging treatments have been developed, such as robots, brain-computer interfaces, and nanomaterials. These treatments have the potential to help millions of patients suffering from motor dysfunction caused by spinal cord injury. However, large-scale clinical trials need to be conducted to validate their efficacy. This review evaluated the efficacy of neural stem cells and magnetic or electrical stimulation combined with rehabilitation training and intelligent therapies for spinal cord injury according to existing evidence, to build up a multimodal treatment strategy of spinal cord injury to enhance nerve repair and regeneration.

Repetitive Transcranial Magnetic Stimulation Alleviates Neurological Deficits After Cerebral Ischemia Through Interaction Between RACK1 and BDNF exon IV by the Phosphorylation-Dependent Factor MeCP2

Repetitive transcranial magnetic stimulation (rTMS) is acknowledged as a form of neurostimulation, especially for functional recovery. The foundational knowledge of molecular mechanism is limited regarding its role in cerebral ischemia, for which the present study was designed. Primary neurons were treated with oxygen-glucose deprivation (OGD) and repetitive magnetic stimulation (rMS), in which brain-derived neurotrophic factor (BDNF) and transcription of BDNF exons were examined. Then, adenovirus vectors carrying siRACK1 sequence were delivered to primary neurons, followed by detection of the transcription of BDNF exons and the extent of methyl CpG binding protein 2 (MeCP2) phosphorylation. Results showed that BDNF and the transcription of BDNF exons were upregulated by rMS and OGD treatment, but decreased by extra treatment of RACK1 siRNA. Then, the mechanism investigations demonstrated that rMS increased the extent of MeCP2 phosphorylation to promote the interaction between RACK1 and BDNF exon IV. The aforementioned findings were further confirmed in vivo in middle cerebral artery occlusion (MCAO)-induced rat models, as indicated by improved neurological functions and reduced area of cerebral infarction. The study offers potential evidence for improvement of neurological deficits, highlighting the important role of rTMS for treatment of cerebral ischemia.

Repetitive transcranial magnetic stimulation in stroke rehabilitation: review of the current evidence and pitfalls

Acute brain ischemia causes changes in several neural networks and related cortico-subcortical excitability, both in the affected area and in the apparently spared contralateral hemisphere. The modulation of these processes through modern techniques of noninvasive brain stimulation, namely repetitive transcranial magnetic stimulation (rTMS), has been proposed as a viable intervention that could promote post-stroke clinical recovery and functional independence. This review provides a comprehensive summary of the current evidence from the literature on the efficacy of rTMS applied to different clinical and rehabilitative aspects of stroke patients. A total of 32 meta-analyses published until July 2019 were selected, focusing on the effects on motor function, manual dexterity, walking and balance, spasticity, dysphagia, aphasia, unilateral neglect, depression, and cognitive function after a stroke. Only conventional rTMS protocols were considered in this review, and meta-analyses focusing on theta burst stimulation only were excluded. Overall, both HF-rTMS and LF-rTMS have been shown to be safe and well-tolerated. In addition, the current literature converges on the positive effect of rTMS in the rehabilitation of all clinical manifestations of stroke, except for spasticity and cognitive impairment, where definitive evidence of efficacy cannot be drawn. However, routine use of a specific paradigm of stimulation cannot be recommended yet due to a significant level of heterogeneity of the studies in terms of protocols to be set and outcome measures that have to be used. Future studies need to preliminarily evaluate the most promising protocols before going on to multicenter studies with large cohorts of patients in order to achieve a definitive translation into daily clinical practice.

Beneficial Effects of Theta-Burst Transcranial Magnetic Stimulation on Stroke Injury via Improving Neuronal Microenvironment and Mitochondrial Integrity

Recent work suggests that repetitive transcranial magnetic stimulation (rTMS) may beneficially alter the pathological status of several neurological disorders, although the mechanism remains unclear. The current study was designed to investigate the effects of rTMS on behavioral deficits and potential underlying mechanisms in a rat photothrombotic (PT) stroke model. From day 0 (3 h) to day 5 after the establishment of PT stroke, 5-min daily continuous theta-burst rTMS (3 pulses of 50 Hz repeated every 200 ms, intensity at 200 G) was applied on the infarct hemisphere. We report that rTMS significantly attenuated behavioral deficits and infarct volume after PT stroke. Further investigation demonstrated that rTMS remarkably reduced synaptic loss and neuronal degeneration in the peri-infarct cortical region. Mechanistic studies displayed that beneficial effects of rTMS were associated with robust suppression of reactive micro/astrogliosis and the overproduction of pro-inflammatory cytokines, as well as oxidative stress and oxidative neuronal damage especially at the late stage following PT stroke. Intriguingly, rTMS could effectively induce a shift in microglial M1/M2 phenotype activation and an A1 to A2 switch in astrocytic phenotypes. In addition, the release of anti-inflammatory cytokines and mitochondrial MnSOD in peri-infarct regions were elevated following rTMS treatment. Finally, rTMS treatment efficaciously preserved mitochondrial membrane integrity and suppressed the intrinsic mitochondrial caspase-9/3 apoptotic pathway within the peri-infarct cortex. Our novel findings indicate that rTMS treatment exerted robust neuroprotection when applied at least 3 h after ischemic stroke. The underlying mechanisms are partially associated with improvement of the local neuronal microenvironment by altering inflammatory and oxidative status and preserving mitochondrial integrity in the peri-infarct zone. These findings provide strong support for the promising therapeutic effect of rTMS against ischemic neuronal injury and functional deficits following stroke.

Frequency-specific effects of low-intensity rTMS can persist for up to 2 weeks post-stimulation: A longitudinal rs-fMRI/MRS study in rats

BACKGROUND

Evidence suggests that repetitive transcranial magnetic stimulation (rTMS), a non-invasive neuromodulation technique, alters resting brain activity. Despite anecdotal evidence that rTMS effects wear off, there are no reports of longitudinal studies, even in humans, mapping the therapeutic duration of rTMS effects.

OBJECTIVE

Here, we investigated the longitudinal effects of repeated low-intensity rTMS (LI-rTMS) on healthy rodent resting-state networks (RSNs) using resting-state functional MRI (rs-fMRI) and on sensorimotor cortical neurometabolite levels using proton magnetic resonance spectroscopy (MRS).

METHODS

Sprague-Dawley rats received 10 min LI-rTMS daily for 15 days (10 Hz or 1 Hz stimulation, n = 9 per group). MRI data were acquired at baseline, after seven days and after 14 days of daily stimulation and at two more timepoints up to three weeks post-cessation of daily stimulation.

RESULTS

10 Hz stimulation increased RSN connectivity and GABA, glutamine, and glutamate levels. 1 Hz stimulation had opposite but subtler effects, resulting in decreased RSN connectivity and glutamine levels. The induced changes decreased to baseline levels within seven days following stimulation cessation in the 10 Hz group but were sustained for at least 14 days in the 1 Hz group.

CONCLUSION

Overall, our study provides evidence of long-term frequency-specific effects of LI-rTMS. Additionally, the transient connectivity changes following 10 Hz stimulation suggest that current treatment protocols involving this frequency may require ongoing "top-up" stimulation sessions to maintain therapeutic effects.

Restraint devices for repetitive transcranial magnetic stimulation in mice and rats

INTRODUCTION

Repetitive transcranial magnetic stimulation has been widely used for the treatment of neurological and psychiatric diseases. Rodent animals including mice and rats are often used to investigate the potential cellular and molecular mechanisms for the therapeutic effects of repetitive transcranial magnetic stimulation. So far there is no report about an easy-to-use device to restrain rodent animals for repetitive transcranial magnetic stimulation.

METHODS AND RESULTS

We introduced the design and use of the restraint device for mice or rats. In the mouse device, western blot and real-time PCR analysis showed that，in stimulated mouse frontal cortex, 10 Hz high frequency stimulation for 10 sessions resulted in enhanced expression of NR2B-containing N-methyl-D-aspartic acid receptors and reduced α1 subunit of inhibitory GABA_A receptors, whereas 0.5 Hz low frequency stimulation for 10 sessions caused decreased expression of NR2B subunit and increased α1 subunit of GABA_A receptors. In the rat device, measures of motor evoke potentials indicated that 10 Hz stimulation for 10 sessions increased the excitability of stimulated cortex, whereas 0.5 Hz for 10 sessions reduced it.

CONCLUSIONS

These results suggested the effectiveness of the devices. Thus, the two devices are practical and easy-to-use to investigate the mechanisms of repetitive transcranial magnetic stimulation.

Repetitive transcranial magnetic stimulation in stroke rehabilitation: review of the current evidence and pitfalls

Acute brain ischemia causes changes in several neural networks and related cortico-subcortical excitability, both in the affected area and in the apparently spared contralateral hemisphere. The modulation of these processes through modern techniques of noninvasive brain stimulation, namely repetitive transcranial magnetic stimulation (rTMS), has been proposed as a viable intervention that could promote post-stroke clinical recovery and functional independence. This review provides a comprehensive summary of the current evidence from the literature on the efficacy of rTMS applied to different clinical and rehabilitative aspects of stroke patients. A total of 32 meta-analyses published until July 2019 were selected, focusing on the effects on motor function, manual dexterity, walking and balance, spasticity, dysphagia, aphasia, unilateral neglect, depression, and cognitive function after a stroke. Only conventional rTMS protocols were considered in this review, and meta-analyses focusing on theta burst stimulation only were excluded. Overall, both HF-rTMS and LF-rTMS have been shown to be safe and well-tolerated. In addition, the current literature converges on the positive effect of rTMS in the rehabilitation of all clinical manifestations of stroke, except for spasticity and cognitive impairment, where definitive evidence of efficacy cannot be drawn. However, routine use of a specific paradigm of stimulation cannot be recommended yet due to a significant level of heterogeneity of the studies in terms of protocols to be set and outcome measures that have to be used. Future studies need to preliminarily evaluate the most promising protocols before going on to multicenter studies with large cohorts of patients in order to achieve a definitive translation into daily clinical practice.

The clinical utility of repetitive transcranial magnetic stimulation in reducing the risks of transitioning from acute to chronic pain in traumatically injured patients

Pain is a multifaceted condition and a major ongoing challenge for healthcare professionals having to treat patients in whom pain put them at risk of developing other conditions. Significant efforts have been invested in both clinical and research settings in an attempt to demystify the mechanisms at stake and develop optimal treatments as well as to reduce individual and societal costs. It is now universally accepted that neuroinflammation and central sensitization are two key underlying factors causing pain chronification as they result from maladaptive central nervous system plasticity. Recent research has shown that the mechanisms of action of repetitive transcranial magnetic stimulation (rTMS) make it a particularly promising avenue in treating various pain conditions. This review will first discuss the contribution of neuroinflammation and central sensitization in the transition from acute to chronic pain in traumatically injured patients. A detailed discussion on how rTMS may allow the restoration from maladaptive plasticity in addition to breaking down the chain of events leading to pain chronification will follow. Lastly, this review will provide a theoretical framework of what might constitute optimal rTMS modalities in dealing with pain symptoms in traumatically injured patients based on an integrated perspective of the physiopathological mechanisms underlying pain.

Noninvasive Brain Stimulation to Enhance Functional Recovery After Stroke: Studies in Animal Models

Background. Stroke is the leading cause of adult disability, but treatment options remain limited, leaving most patients with incomplete recovery. Patient and animal studies have shown potential of noninvasive brain stimulation (NIBS) strategies to improve function after stroke. However, mechanisms underlying therapeutic effects of NIBS are unclear and there is no consensus on which NIBS protocols are most effective. Objective. Provide a review of articles that assessed effects and mechanisms of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) in animal stroke models. Methods. Articles were searched in PubMed, including cross-references. Results. Nineteen eligible studies reporting effects of rTMS or tDCS after stroke in small rodents were identified. Seventeen of those described improved functional recovery or neuroprotection compared with untreated control or sham-stimulated groups. The effects of rTMS could be related to molecular mechanisms associated with ischemic tolerance, neuroprotection, anti-apoptosis, neurogenesis, angiogenesis, or neuroplasticity. Favorable outcome appeared most effectively when using high-frequency (>5 Hz) rTMS or intermittent theta burst stimulation of the ipsilesional hemisphere. tDCS effects were strongly dependent on stimulation polarity and onset time. Although these findings are promising, most studies did not meet Good Laboratory Practice assessment criteria. Conclusions. Despite limited data availability, animal stroke model studies demonstrate potential of NIBS to promote stroke recovery through different working mechanisms. Future studies in animal stroke models should adhere to Good Laboratory Practice guidelines and aim to further develop clinically applicable treatment protocols by identifying most favorable stimulation parameters, treatment onset, adjuvant therapies, and underlying modes of action.

High-Frequency Repetitive Magnetic Stimulation Enhances the Expression of Brain-Derived Neurotrophic Factor Through Activation of Ca2+-Calmodulin-Dependent Protein Kinase II-cAMP-Response Element-Binding Protein Pathway

Repetitive transcranial magnetic stimulation (rTMS) can be used in various neurological disorders. However, neurobiological mechanism of rTMS is not well known. Therefore, in this study, we examined the global gene expression patterns depending on different frequencies of repetitive magnetic stimulation (rMS) in both undifferentiated and differentiated Neuro-2a cells to generate a comprehensive view of the biological mechanisms. The Neuro-2a cells were randomly divided into three groups—the sham (no active stimulation) group, the low-frequency (0.5 Hz stimulation) group, and high-frequency (10 Hz stimulation) group—and were stimulated 10 min for 3 days. The low- and high-frequency groups of rMS on Neuro-2a cells were characterized by transcriptome array. Differentially expressed genes were analyzed using the Database of Annotation Visualization and Integrated Discovery program, which yielded a Kyoto Encyclopedia of Genes and Genomes pathway. Amphetamine addiction pathway, circadian entrainment pathway, long-term potentiation (LTP) pathway, neurotrophin signaling pathway, prolactin signaling pathway, and cholinergic synapse pathway were significantly enriched in high-frequency group compared with low-frequency group. Among these pathways, LTP pathway is relevant to rMS, thus the genes that were involved in LTP pathway were validated by quantitative real-time polymerase chain reaction and western blotting. The expression of glutamate ionotropic receptor N-methyl d-aspartate 1, calmodulin-dependent protein kinase II (CaMKII) δ, and CaMKIIα was increased, and the expression of CaMKIIγ was decreased in high-frequency group. These genes can activate the calcium (Ca²⁺)–CaMKII–cAMP-response element-binding protein (CREB) pathway. Furthermore, high-frequency rMS induced phosphorylation of CREB, brain-derived neurotrophic factor (BDNF) transcription via activation of Ca²⁺–CaMKII–CREB pathway. In conclusion, high-frequency rMS enhances the expression of BDNF by activating Ca²⁺–CaMKII–CREB pathway in the Neuro-2a cells. These findings may help clarify further therapeutic mechanisms of rTMS.

Combined rTMS/fMRI Studies: An Overlooked Resource in Animal Models

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulation technique, which has brain network-level effects in healthy individuals and is also used to treat many neurological and psychiatric conditions in which brain connectivity is believed to be abnormal. Despite the fact that rTMS is being used in a clinical setting and animal studies are increasingly identifying potential cellular and molecular mechanisms, little is known about how these mechanisms relate to clinical changes. This knowledge gap is amplified by non-overlapping approaches used in preclinical and clinical rTMS studies: preclinical studies are mostly invasive, using cellular and molecular approaches, while clinical studies are non-invasive, including functional magnetic resonance imaging (fMRI), TMS electroencephalography (EEG), positron emission tomography (PET), and behavioral measures. A non-invasive method is therefore needed in rodents to link our understanding of cellular and molecular changes to functional connectivity changes that are clinically relevant. fMRI is the technique of choice for examining both short and long term functional connectivity changes in large-scale networks and is becoming increasingly popular in animal research because of its high translatability, but, to date, there have been no reports of animal rTMS studies using this technique. This review summarizes the main studies combining different rTMS protocols with fMRI in humans, in both healthy and patient populations, providing a foundation for the design of equivalent studies in animals. We discuss the challenges of combining these two methods in animals and highlight considerations important for acquiring clinically-relevant information from combined rTMS/fMRI studies in animals. We believe that combining rTMS and fMRI in animal models will generate new knowledge in the following ways: functional connectivity changes can be explored in greater detail through complementary invasive procedures, clarifying mechanism and improving the therapeutic application of rTMS, as well as improving interpretation of fMRI data. And, in a more general context, a robust comparative approach will refine the use of animal models of specific neuropsychiatric conditions.

Epigenome Interactions with Patterned Neuronal Activity

The temporal coding of action potential activity is fundamental to nervous system function. Here we consider how gene expression in neurons is regulated by specific patterns of action potential firing, with an emphasis on new information on epigenetic regulation of gene expression. Patterned action potential activity activates intracellular signaling networks selectively in accordance with the kinetics of activation and inactivation of second messengers, phosphorylation and dephosphorylation of protein kinases, and cytoplasmic and nuclear calcium dynamics, which differentially activate specific transcription factors. Increasing evidence also implicates activity-dependent regulation of epigenetic mechanisms to alter chromatin architecture. Changes in three-dimensional chromatin structure, including chromatin compaction, looping, double-stranded DNA breaks, histone and DNA modification, are altered by action potential activity to selectively inhibit or promote transcription of specific genes. These mechanisms of activity-dependent regulation of gene expression are important in neural development, plasticity, and in neurological and psychological disorders.

The Differential Effects of Repetitive Magnetic Stimulation in an In Vitro Neuronal Model of Ischemia/Reperfusion Injury

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive therapy that has been implicated in treatment of serious neurological disorders. However, the neurobiological mechanisms underlying the effects of rTMS remain unclear. Therefore, this study examined the differential effects of repetitive magnetic stimulation (rMS) in an in vitro neuronal model of ischemia/reperfusion (I/R) injury, depending on low and high frequency. Neuro-2a cells were differentiated with retinoic acid and established for in vitro neuronal model of I/R injury under a subsequent 3 h of oxygen and glucose deprivation/reoxygenation (OGD/R) condition. After the I/R injury, the differentiated neuronal cells were stimulated with rMS on day 1 and randomly divided into three groups: OGD/R+sham, OGD/R+low-frequency, and OGD/R+high-frequency groups. High-frequency rMS increases cell proliferation through activation of extracellular signal-regulated kinases and AKT-signaling pathway and inhibits apoptosis in OGD/R-injured cells. Furthermore, high-frequency rMS increases Ca²⁺–calmodulin-dependent protein kinase II (CaMKII)-cAMP-response element binding protein (CREB) signaling pathway, further leading to alternation of brain-derived neurotrophic factor expression and synaptic plasticity in OGD/R injured cells. These results verified the neurobiological mechanisms of frequency-dependent rMS in I/R injury-treated neuronal cells. These mechanisms will help develop more powerful and credible rTMS stimulation treatment protocols.

Dexmedetomidine preconditioning plays a neuroprotective role and suppresses TLR4/NF-κB pathways model of cerebral ischemia reperfusion

BACKGROUND

Dexmedetomidine has been reported to play an efficient role on multi-organ protection. Our study aims to investigate the neuroprotective of dexmedetomidine preconditioning on cerebral ischemic reperfusion (I/R) injury and investigate the underlining signaling mechanisms.

METHODS

Cerebral I/R models were established with SD rats through middle cerebral artery occlusion (MCAO). After 2h of ischemia followed by 7days of reperfusion, the degree of cerebral tissue injury was detected by HE, Nissl and TUNEL staining. Glial fibrillary acidic protein (GFAP) positive and TNF-α positive cells were stained by immunohistochemistry and counted under microscope. TLR4, NF-κB and TIR-domain containing adapter-inducing interferon-β (TRIF) expression were detected by real time PCR and western blot.

RESULTS

Dexmedetomidine preconditioning markedly prevented the ischemia-induced cellular damage observed from HE and Nissl staining in hippocampus and cortex. Dexmedetomidine observably decreased the number of apoptotic cells in TUNEL staining. Besides, yohimbine could specifically suppress the protective effect of dexmedetomidine. GFAP expression was distinctly inhibited by dexmedetomidine preconditioning (10μg/kg, 20μg/kg) in cerebral ischemia area. Dexmedetomidine preconditioning inhibited the expression of TLR4 and NF-κB and increased that of TRIF.

CONCLUSION

The results of this study suggest that dexmedetomidine preconditioning plays a neuroprotective role against I/R injury. Dexmedetomidine might suppress TLR4/NF-??B pathway and drive TLR4/TRIF signaling pathway to reduce the inflammatory injury.

β-Caryophyllene Pretreatment Alleviates Focal Cerebral Ischemia-Reperfusion Injury by Activating PI3K/Akt Signaling Pathway

β-Caryophyllene (BCP) has been reported to be protective against focal cerebral ischemia-reperfusion (I/R) injury by its anti-oxidative and anti-inflammatory features. Recent study demonstrates that the BCP exhibits potential neuroprotection against I/R injury induced apoptosis, however, the mechanism remains unknown. Therefore, we investigate the underlying anti-apoptotic mechanism of BCP pretreatment in I/R injury. Sprague-Dawley rats (pretreated with BCP suspensions or solvent orally for 7 days) were subjected to transient Middle Cerebral Artery Occlusion (MCAO) for 90 min, followed by 24 h reperfusion. Results showed that BCP pretreatment improved the neurologic deficit score, lowered the infarct volume and decreased number of apoptotic cells in the hippocampus. Moreover, in western blot and RT-qPCR detections, BCP pretreatment down-regulated the expressions of Bax and p53, up-regulated the expression of Bcl-2, and enhanced the phosphorylation of Akt on Ser473. Blockage of PI3K activity by wortmannin not only abolished the BCP-induced decreases in infarct volume and neurologic deficit score, but also dramatically abrogated the enhancement of AKt phosphorylation. Our results suggested that BCP pre-treatment protects against I/R injury partly by suppressing apoptosis via PI3K/AKt signaling pathway activation.

Neuroprotective effects of polydatin against mitochondrial-dependent apoptosis in the rat cerebral cortex following ischemia/reperfusion injury

The neuroprotective effect of polydatin (PD) against hemorrhagic shock-induced mitochondrial injury has been described previously, and mitochondrial dysfunction and apoptosis were reportedly involved in ischemic stroke. In the present study the neuroprotective effect of PD in preventing apoptosis was evaluated following induction of focal cerebral ischemia by middle cerebral artery occlusion (MCAO) in rats. PD (30 mg/kg) was administered by caudal vein injection 10 min prior to ischemia/reperfusion (I/R) injury. 24 h following I/R injury, ameliorated modified neurological severity scores (mNSS) and reduced infarct volume were observed in the PD treated group. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining and Annexin V/propidium iodide assays demonstrated the anti-apoptotic effect of PD in the ischemic cortex. In addition, PD improved I/R injury‑induced mitochondrial dysfunction, reflected by morphological observations and measurements of mitochondrial membrane potential and intracellular ATP measurement. Western blot analysis revealed an increase in B‑cell lymphoma 2 apoptosis regulator (Bcl-2) expression, and a decrease in Bcl‑2‑associated protein X apoptosis regulator expression in the PD group in comparison with the vehicle treated group. PD treatment also prevented the release of cytochrome c from mitochondria into the cytoplasm, and blunted the activities of caspase‑9 and caspase‑3. Furthermore, PD treatment decreased the levels of reactive oxygen species in neurons isolated from the ischemic cortex. The findings of this study, therefore, suggest that PD has a dual effect, ameliorating both oxidative stress and mitochondria‑dependent apoptosis, making it a promising new therapy for the treatment of ischemic stroke.

Non-Invasive Brain Stimulation to Enhance Post-Stroke Recovery

Brain plasticity after stroke remains poorly understood. Patients may improve spontaneously within the first 3 months and then more slowly in the coming year. The first day, decreased edema and reperfusion of the ischemic penumbra may possibly account for these phenomena, but the improvement during the next weeks suggests plasticity phenomena and cortical reorganization of the brain ischemic areas and of more remote areas. Indeed, the injured ischemic motor cortex has a reduced cortical excitability at the acute phase and a suspension of the topographic representation of affected muscles, whereas the contralateral motor cortex has an increased excitability and an enlarged somatomotor representation; furthermore, contralateral cortex exerts a transcallosal interhemispheric inhibition on the ischemic cortex. This results from the imbalance of the physiological reciprocal interhemispheric inhibition of each hemisphere on the other, contributing to worsening of neurological deficit. Cortical excitability is measurable through transcranial magnetic stimulation (TMS) and prognosis has been established according to the presence of motor evoked potentials (MEP) at the acute phase of stroke, which is predictive of better recovery. Conversely, the lack of response to early stimulation is associated with a poor functional outcome. Non-invasive stimulation techniques such as repetitive TMS (rTMS) or transcranial direct current stimulation (tDCS) have the potential to modulate brain cortical excitability with long lasting effects. In the setting of cerebrovascular disease, around 1000 stroke subjects have been included in placebo-controlled trials so far, most often with an objective of promoting motor recovery of the upper limb. High frequency repetitive stimulation (>3 Hz) rTMS, aiming to increase excitability of the ischemic cortex, or low frequency repetitive stimulation (≤1 Hz), aiming to reduce excitability of the contralateral homonymous cortex, or combined therapies, have shown various effects on the functional disability score and neurological scales of treated patients and on the duration of the treatment. We review here the patients’ characteristics and parameters of stimulation that could predict a good response, as well as safety issues. At last, we review what we have learnt from experimental studies and discuss potential directions to conduct future studies.