Deep rTMS Mitigates Behavioral and Neuropathologic Anomalies in Cuprizone-Exposed Mice Through Reducing Microglial Proinflammatory Cytokines

Evaluation of microglia activation related markers following a clinical course of TBS: A non-human primate study

While the applicability and popularity of theta burst stimulation (TBS) paradigms remain, current knowledge of their neurobiological effects is still limited, especially with respect to their impact on glial cells and neuroinflammatory processes. We used a multimodal imaging approach to assess the effects of a clinical course of TBS on markers for microglia activation and tissue injury as an indirect assessment of neuroinflammatory processes. Healthy non-human primates received continuous TBS (cTBS), intermittent TBS (iTBS), or sham stimulation over the motor cortex at 90% of resting motor threshold. Stimulation was delivered to the awake subjects 5 times a week for 3-4 weeks. Translocator protein (TSPO) expression was evaluated using Positron Emission Tomography and [11C]PBR28, and myo-inositol (mI) and N-acetyl-aspartate (NAA) concentrations were assessed with Magnetic Resonance Spectroscopy. Animals were then euthanized, and immunofluorescence staining was performed using antibodies against TSPO. Paired t-tests showed no significant changes in [11C]PBR28 measurements after stimulation. Similarly, no significant changes in mI and NAA concentrations were found. Post-mortem TSPO evaluation showed comparable mean immunofluorescence intensity after active TBS and sham delivery. The current study suggests that in healthy brains a clinical course of TBS, as evaluated with in-vivo imaging techniques (PET and MRS), did not measurably modulate the expression of glia related markers and metabolite associated with neural viability.

Preliminary Observations of Personalized Repetitive Magnetic Stimulation (PrTMS) Guided by EEG Spectra for Concussion

There are no FDA-approved treatments for the chronic sequelae of concussion. Repetitive magnetic transcranial stimulation (rTMS) has been explored as a therapy but outcomes have been inconsistent. To address this we developed a personalized rTMS (PrTMS) protocol involving continual rTMS stimulus frequency adjustment and progressive activation of multiple cortical sites, guided by spectral electroencephalogram (EEG)-based analyses and psychological questionnaires. We acquired pilot clinical data for 185 symptomatic brain concussion patients who underwent the PrTMS protocol over an approximate 6 week period. The PrTMS protocol used a proprietary EEG spectral frequency algorithm to define an initial stimulation frequency based on an anteriorly graded projection of the measured occipital alpha center peak, which was then used to interpolate and adjust regional stimulation frequency according to weekly EEG spectral acquisitions. PrTMS improved concussion indices and normalized the cortical alpha band center frequency and peak EEG amplitude. This potentially reflected changed neurotransmitter, cognitive, and perceptual status. PrTMS may be a promising treatment choice for patients with persistent concussion symptoms. This clinical observational study was limited in that there was no control group and a number of variables were not recorded, such as time since injury and levels of depression. While the present observations are indeed preliminary and cursory, they may suggest further prospective research on PrTMS in concussion, and exploration of the spectral EEG as a concussion biomarker, with the ultimate goals of confirmation and determining optimal PrTMS treatment parameters.

Repetitive transcranial magnetic stimulation and fluoxetine reverse depressive-like behavior but with differential effects on Olig2-positive cells in chronically stressed mice

Depression is a mood disorder coursing with several behavioral, cellular, and neurochemical alterations. The negative impact of chronic stress may precipitate this neuropsychiatric disorder. Interestingly, downregulation of oligodendrocyte-related genes, abnormal myelin structure, and reduced numbers and density of oligodendrocytes in the limbic system have been identified in patients diagnosed with depression, but also in rodents exposed to chronic mild stress (CMS). Several reports have emphasized the importance of pharmacological or stimulation-related strategies in influencing oligodendrocytes in the hippocampal neurogenic niche. Repetitive transcranial magnetic stimulation (rTMS) has gained attention as an intervention to revert depression. Here, we hypothesized that 5 Hz (Hz) of rTMS or Fluoxetine (Flx) would revert depressive-like behaviors by influencing oligodendrocytes and revert neurogenic alterations caused by CMS in female Swiss Webster mice. Our results showed that 5 Hz rTMS or Flx revert depressive-like behavior. Only rTMS influenced oligodendrocytes by increasing the number of Olig2-positive cells in the hilus of the dentate gyrus and the prefrontal cortex. However, both strategies exerted effects on some events of the hippocampal neurogenic processes, such as cell proliferation (Ki67-positive cells), survival (CldU-positive cells), and intermediate stages (doublecortin-positive cells) along the dorsal-ventral axis of this region. Interestingly, the combination of rTMS-Flx exerted antidepressant-like effects, but the increased number of Olig2-positive cells observed in mice treated only with rTMS was canceled. However, rTMS-Flx exerted a synergistic effect by increasing the number of Ki67-positive cells. It also increased the number of CldU- and doublecortin-positive cells in the dentate gyrus. Our results demonstrate that 5 Hz rTMS has beneficial effects, as it reverted depressive-like behavior by increasing the number of Olig2-positive cells and reverting the decrement in hippocampal neurogenesis in CMS-exposed mice. Nevertheless, the effects of rTMS on other glial cells require further investigation.

Neuronal activity and NIBS in developmental myelination and remyelination - current state of knowledge

Oligodendrocytes are responsible for myelinating central nervous system (CNS) axons. and rapid electrical transmission through saltatory conduction of action potentials. Myelination and myelin repair rely partially on oligodendrogenesis, which comprises. oligodendrocyte precursor cell (OPC) migration, maturation, and differentiation into. oligodendrocytes (OL). In multiple sclerosis (MS), demyelination occurs due to an. inflammatory cascade with auto-reactive T-cells. When oligodendrogenesis fails, remyelination becomes aberrant and conduction impairments are no longer restored. Although current disease modifying therapies have achieved results in modulating the. faulty immune response, disease progression continues because of chronic. inflammation, neurodegeneration, and failure of remyelination. Therapies have been. tried to promote remyelination. Modulation of neuronal activity seems to be a very. promising strategy in preclinical studies. Additionally, studies in people with MS. (pwMS) have shown symptom improvement following non-invasive brain stimulation. (NIBS) techniques. The aforementioned mechanisms are yet unknown and probably. involve both the activation of neurons and glial cells. Noting neuronal activity. contributes to myelin plasticity and that NIBS modulates neuronal activity; we argue. that NIBS is a promising research horizon for demyelinating diseases. We review the. hypothesized pathways through which NIBS may affect both neuronal activity in the. CNS and how the resulting activity can affect oligodendrogenesis and myelination.

Repetitive transcranial magnetic stimulation regulates neuroinflammation in neuropathic pain

Neuropathic pain (NP) is a frequent condition caused by a lesion in, or disease of, the central or peripheral somatosensory nervous system and is associated with excessive inflammation in the central and peripheral nervous systems. Repetitive transcranial magnetic stimulation (rTMS) is a supplementary treatment for NP. In clinical research, rTMS of 5-10 Hz is widely placed in the primary motor cortex (M1) area, mostly at 80%-90% RMT, and 5-10 treatment sessions could produce an optimal analgesic effect. The degree of pain relief increases greatly when stimulation duration is greater than 10 days. Analgesia induced by rTMS appears to be related to reestablishing the neuroinflammation system. This article discussed the influences of rTMS on the nervous system inflammatory responses, including the brain, spinal cord, dorsal root ganglia (DRG), and peripheral nerve involved in the maintenance and exacerbation of NP. rTMS has shown an anti-inflammation effect by decreasing pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α, and increasing anti-inflammatory cytokines, including IL-10 and BDNF, in cortical and subcortical tissues. In addition, rTMS reduces the expression of glutamate receptors (mGluR5 and NMDAR2B) and microglia and astrocyte markers (Iba1 and GFAP). Furthermore, rTMS decreases nNOS expression in ipsilateral DRGs and peripheral nerve metabolism and regulates neuroinflammation.

High frequency repetitive transcranial magnetic stimulation improves cognitive performance parameters in patients with Alzheimer's disease - an exploratory pilot study

BACKGROUND

Currently available medication for Alzheimer's disease (AD) may slows cognitive decline only transitory, but has failed to bring about long term positive effects. For this slowly progressive neurodegenerative disease so far no disease modifying therapy exists.

OBJECTIVE

To find out if non-pharmacologic non-ivasive neuromodulatory repetitive transcranial magnetic stimulation (rTMS) may offer a new alternative or an add on therapeutic strategy against loss of cognitive functions.

METHODS

In this exploratory intervention study safety and symptom development before and after frontopolar cortex stimulation (FPC) using intermittent theta burst stimulation (iTBS) at 10 subsequent working days was monitored as add-on treatment in 28 consecutive patients with AD. Out of these, 10 randomly selected patients received sham stimulation as a control. In addition, ​serum concentrations of neurotransmitter precursor amino acids, of immune activation and inflammation markers, of brain derived neurotrophic factor (BDNF) as well as of nitrite were measured.

RESULTS

Treatment was well tolerated, no serious adverse effects were observed. Improvement of cognition was detected by an increase of Mini Mental State Examination score (MMSE; p<0.01, paired rank test) and also by an increase in a modified repeat address phrase test, part of the 6-item cognitive ​impairment test (p < 0.01). A trend to an increase in the clock drawing test (CDT; p = 0.08) was also found in the verum treated group. Furtheron, in 10 of the AD patients with additional symptoms of depression treated with iTBS, a significant decrease in the HAMD-7 scale (p <0.01) and a trend to lower serum phenylalanine concentrations (p = 0.08) was seen. No changes of the parameters tested were found in the sham treated patients.

CONCLUSION

Our preliminary results may indicate that iTBS is effective in the treatment of AD. Also a slight influence of iTBS on the metabolism of phenylalanine was found after 10 iTBS sessions. An impact of iTBS to influence the enzyme phenylalanine hydroxylase (PAH), as found in previous series of treatment resistant depression, could not be seen in this our first observational trial in 10 AD patients with comorbidity of depression. Longer treatment periods for several weeks in a higher number of AD patients with depression could cause more intense and disease modifying effects visible in different neurotransmitter concentrations important in the pathogenesis of AD.

Microglia-mediated neuroinflammation and neuroplasticity after stroke

Stroke remains a major cause of long-term disability and mortality worldwide. The immune system plays an important role in determining the condition of the brain following stroke. As the resident innate immune cells of the central nervous system, microglia are the primary responders in a defense network covering the entire brain parenchyma, and exert various functions depending on dynamic communications with neurons, astrocytes, and other neighboring cells under both physiological or pathological conditions. Microglia activation and polarization is crucial for brain damage and repair following ischemic stroke, and is considered a double-edged sword for neurological recovery. Microglia can exist in pro-inflammatory states and promote secondary brain damage, but they can also secrete anti-inflammatory cytokines and neurotrophic factors and facilitate recovery following stroke. In this review, we focus on the role and mechanisms of microglia-mediated neuroinflammation and neuroplasticity after ischemia and relevant potential microglia-based interventions for stroke therapy.

Non-invasive Brain Stimulation for Central Neuropathic Pain

The research and clinical application of the noninvasive brain stimulation (NIBS) technique in the treatment of neuropathic pain (NP) are increasing. In this review article, we outline the effectiveness and limitations of the NIBS approach in treating common central neuropathic pain (CNP). This article summarizes the research progress of NIBS in the treatment of different CNPs and describes the effects and mechanisms of these methods on different CNPs. Repetitive transcranial magnetic stimulation (rTMS) analgesic research has been relatively mature and applied to a variety of CNP treatments. But the optimal stimulation targets, stimulation intensity, and stimulation time of transcranial direct current stimulation (tDCS) for each type of CNP are still difficult to identify. The analgesic mechanism of rTMS is similar to that of tDCS, both of which change cortical excitability and synaptic plasticity, regulate the release of related neurotransmitters and affect the structural and functional connections of brain regions associated with pain processing and regulation. Some deficiencies are found in current NIBS relevant studies, such as small sample size, difficulty to avoid placebo effect, and insufficient research on analgesia mechanism. Future research should gradually carry out large-scale, multicenter studies to test the stability and reliability of the analgesic effects of NIBS.

Repetitive Transcranial Magnetic Stimulation Improves Neurological Function and Promotes the Anti-inflammatory Polarization of Microglia in Ischemic Rats

Ischemic stroke (IS) is a severe neurological disease that is difficult to recovery. Previous studies have shown that repetitive transcranial magnetic stimulation (rTMS) is a promising therapeutic approach, while the exact therapy mechanisms of rTMS in improving neural functional recovery remain unclear. Furthermore, the inflammatory environment may influence the rehabilitation efficacy. Our study shows that long-term rTMS stimulation will significantly promote neurogenesis, inhibit apoptosis, and control inflammation. rTMS inhibits the activation of transcription factors nuclear factor kappa b (NF-κB) and signal transducer and activator of transcription 6 (STAT6) and promotes the anti-inflammatory polarization of microglia. Obvious promotion of anti-inflammatory cytokines production is observed both in vitro and in vivo through rTMS stimulation on microglia. In addition, neural stem cells (NSCs) cultured in conditioned medium (CM) from microglia treated with rTMS showed downregulation of apoptosis and upregulation of neuronal differentiation. Overall, our results illustrate that rTMS can modulate microglia with anti-inflammatory polarization variation, promote neurogenesis, and improve neural function recovery.

Transcranial magnetic stimulation in animal models of neurodegeneration

Brain stimulation techniques offer powerful means of modulating the physiology of specific neural structures. In recent years, non-invasive brain stimulation techniques, such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation, have emerged as therapeutic tools for neurology and neuroscience. However, the possible repercussions of these techniques remain unclear, and there are few reports on the incisive recovery mechanisms through brain stimulation. Although several studies have recommended the use of non-invasive brain stimulation in clinical neuroscience, with a special emphasis on TMS, the suggested mechanisms of action have not been confirmed directly at the neural level. Insights into the neural mechanisms of non-invasive brain stimulation would unveil the strategies necessary to enhance the safety and efficacy of this progressive approach. Therefore, animal studies investigating the mechanisms of TMS-induced recovery at the neural level are crucial for the elaboration of non-invasive brain stimulation. Translational research done using animal models has several advantages and is able to investigate knowledge gaps by directly targeting neuronal levels. In this review, we have discussed the role of TMS in different animal models, the impact of animal studies on various disease states, and the findings regarding brain function of animal models after TMS in pharmacology research.

Repetitive Transcranial Magnetic Stimulation: A Potential Treatment for Obesity in Patients with Schizophrenia

Obesity is highly prevalent in patients with schizophrenia and, in association with metabolic syndrome, contributes to premature deaths of patients due to cardiovascular disease complications. Moreover, pharmacologic, and behavioral interventions have not stemmed the tide of obesity in schizophrenia. Therefore, novel effective interventions are urgently needed. Repetitive transcranial magnetic stimulation (rTMS) has shown efficacy for inducing weight loss in obese non-psychiatric samples but this promising intervention has not been evaluated as a weight loss intervention in patients with schizophrenia. In this narrative review, we describe three brain mechanisms (hypothalamic inflammation, dysregulated mesocorticolimbic reward system, and impaired prefrontal cortex function) implicated in the pathogenesis and pathophysiology of obesity and emphasize how the three mechanisms have also been implicated in the neurobiology of schizophrenia. We then argue that, based on the three overlapping brain mechanisms in obesity and schizophrenia, rTMS would be effective as a weight loss intervention in patients with schizophrenia and comorbid obesity. We end this review by describing how deep TMS, relative to conventional TMS, could potentially result in larger effect size for weight loss. While this review is mainly conceptual and based on an extrapolation of findings from non-schizophrenia samples, our aim is to stimulate research in the use of rTMS for weight loss in patients with schizophrenia.

Repetitive transcranial magnetic stimulation increases the brain's drainage efficiency in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease with high prevalence rate among the elderly population. A large number of clinical studies have suggested repetitive transcranial magnetic stimulation (rTMS) as a promising non-invasive treatment for patients with mild to moderate AD. However, the underlying cellular and molecular mechanisms remain largely uninvestigated. In the current study, we examined the effect of high frequency rTMS treatment on the cognitive functions and pathological changes in the brains of 4- to 5-month old 5xFAD mice, an early pathological stage with pronounced amyloidopathy and cognitive deficit. Our results showed that rTMS treatment effectively prevented the decline of long-term memories of the 5xFAD mice for novel objects and locations. Importantly, rTMS treatment significantly increased the drainage efficiency of brain clearance pathways, including the glymphatic system in brain parenchyma and the meningeal lymphatics, in the 5xFAD mouse model. Significant reduction of Aβ deposits, suppression of microglia and astrocyte activation, and prevention of decline of neuronal activity as indicated by the elevated c-FOS expression, were observed in the prefrontal cortex and hippocampus of the rTMS-treated 5xFAD mice. Collectively, these findings provide a novel mechanistic insight of rTMS in regulating brain drainage system and β-amyloid clearance in the 5xFAD mouse model, and suggest the potential use of the clearance rate of contrast tracer in cerebrospinal fluid as a prognostic biomarker for the effectiveness of rTMS treatment in AD patients.

Low field magnetic stimulation promotes myelin repair and cognitive recovery in chronic cuprizone mouse model

BACKGROUND

Multiple sclerosis (MS) is an inflammatory demyelinating disease featured with neuroinflammation, demyelination, and the loss of oligodendrocytes. Cognitive impairment and depression are common neuropsychiatric symptoms in MS that are poorly managed with the present interventions.

OBJECTIVE

This study aimed to investigate the effects of low field magnetic stimulation (LFMS), a novel non-invasive neuromodulation technology, on cognitive impairment and depressive symptoms associated with MS using a mouse model of demyelination.

METHODS

C57BL female mice were fed with a 0.2% cuprizone diet for 12 weeks to induce a chronic demyelinating model followed by 4 weeks of cuprizone withdrawal with either sham or LFMS treatment.

RESULTS

Improved cognition and depression-like behaviour and restored weight gain were observed in mice with LFMS treatment. Immunohistochemical and immunoblotting data showed enhanced myelin basic protein (MBP) and myelin oligodendrocyte glycoprotein expressions (MOG) in the prefrontal cortex of mice with LFMS treatment, supporting that myelin repair was promoted. LFMS also increased the protein expression of mature oligodendrocyte biomarker glutathione-S-transferase (GST-π). In addition, expression of TGF-β and associated receptors were elevated with LFMS treatment, implicating this pathway in the response.

CONCLUSION

Results from the present study revealed LFMS to have neuroprotective effects, suggesting that LFMS has potential therapeutic value for treating cognitive impairment and depression related to demyelination disorders.