Continuous theta-burst stimulation enhances and sustains neurogenesis following ischemic stroke

A core scientific problem in the treatment of central nervous system diseases: newborn neurons

It has long been asserted that failure to recover from central nervous system diseases is due to the system's intricate structure and the regenerative incapacity of adult neurons. Yet over recent decades, numerous studies have established that endogenous neurogenesis occurs in the adult central nervous system, including humans'. This has challenged the long-held scientific consensus that the number of adult neurons remains constant, and that new central nervous system neurons cannot be created or renewed. Herein, we present a comprehensive overview of the alterations and regulatory mechanisms of endogenous neurogenesis following central nervous system injury, and describe novel treatment strategies that target endogenous neurogenesis and newborn neurons in the treatment of central nervous system injury. Central nervous system injury frequently results in alterations of endogenous neurogenesis, encompassing the activation, proliferation, ectopic migration, differentiation, and functional integration of endogenous neural stem cells. Because of the unfavorable local microenvironment, most activated neural stem cells differentiate into glial cells rather than neurons. Consequently, the injury-induced endogenous neurogenesis response is inadequate for repairing impaired neural function. Scientists have attempted to enhance endogenous neurogenesis using various strategies, including using neurotrophic factors, bioactive materials, and cell reprogramming techniques. Used alone or in combination, these therapeutic strategies can promote targeted migration of neural stem cells to an injured area, ensure their survival and differentiation into mature functional neurons, and facilitate their integration into the neural circuit. Thus can integration replenish lost neurons after central nervous system injury, by improving the local microenvironment. By regulating each phase of endogenous neurogenesis, endogenous neural stem cells can be harnessed to promote effective regeneration of newborn neurons. This offers a novel approach for treating central nervous system injury.

Physical Exercise Counteracts Aging-Associated White Matter Demyelination Causing Cognitive Decline

In the central nervous system, oligodendrocytes wrap around neuronal axons to form myelin, an insulating layer or sheath that allows for the efficient conductance of action potentials. In addition to structural insulation, myelin provides encased axons with nutrient, metabolic and defensive support. Demyelination, or myelin loss, can therefore cause axonal dysfunction, leading to neurological impairment and disease. In Alzheimer's disease (AD), progressive white matter demyelination is acknowledged as one of the earliest pathologies preceding symptom onset. Unfortunately, current pharmacotherapy for slowing demyelination or promoting remyelination in AD is nonexistent. Exercise is recognized for its wide-ranging benefits to human health, including improved mental health and the prevention of lifestyle-related diseases. Mounting evidence suggests the contribution of physical activity in delaying the progression of dementia in elderly populations. Recent mechanistic studies have shown that exercise facilitates myelination in the brain through the vitalization of intrinsic pro-myelination cues, such as increased neurotrophic factors and electrical activity. In this review, we summarize and discuss the potential of physical exercise on counteracting aging-associated white matter demyelination, which causes cognitive decline in AD. We highlight the need of further basic and clinical research investigations on this topic to establish novel approaches for healthy and improved brain aging.

Transcranial direct current stimulation enhances the protective effect of isoflurane preconditioning on cerebral ischemia/reperfusion injury: A new mechanism associated with the nuclear protein Akirin2

AIMS

Ischemic stroke is a major cause of disability and mortality worldwide. Transcranial direct current stimulation (tDCS) and isoflurane (ISO) preconditioning exhibit neuroprotective properties. However, it remains unclear whether tDCS enhances the protective effect of ISO preconditioning on ischemic stroke, and the underlying mechanisms are yet to be clarified.

METHOD

A model of middle cerebral artery occlusion (MCAO), a rat ischemia-reperfusion (I/R) injury model, and an in vitro oxygen-glucose deprivation/re-oxygenation (O/R) model of ischemic injury were developed. ISO preconditioning and tDCS were administered daily for 7 days before MCAO modeling. Triphenyltetrazolium chloride staining, modified neurological severity score, and hanging-wire test were conducted to assess infarct volume and neurological outcomes. Untargeted metabolomic experiments, adeno-associated virus, lentiviral vectors, and small interfering RNA techniques were used to explore the underlying mechanisms.

RESULTS

tDCS/DCS enhanced the protective effects of ISO pretreatment on I/R injury-induced brain damage. This was evidenced by reduced infarct volume and improved neurological outcomes in rats with MCAO, as well as decreased cortical neuronal death after O/R injury. Untargeted metabolomic experiments identified oxidative phosphorylation (OXPHOS) as a critical pathological process for ISO-mediated neuroprotection from I/R injury. The combination of tDCS/DCS with ISO preconditioning significantly inhibited I/R injury-induced OXPHOS. Mechanistically, Akirin2, a small nuclear protein that regulates cell proliferation and differentiation, was found to decrease in the cortex of rats with MCAO and in cortical primary neurons subjected to O/R injury. Akirin2 functions upstream of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). tDCS/DCS was able to further upregulate Akirin2 levels and activate the Akirin2/PTEN signaling pathway in vivo and in vitro, compared with ISO pretreatment alone, thereby contributing to the improvement of cerebral I/R injury.

CONCLUSION

tDCS treatment enhances the neuroprotective effects of ISO preconditioning on ischemic stroke by inhibiting oxidative stress and activating Akirin2-PTEN signaling pathway, highlighting potential of combination therapy in ischemic stroke.

Astrocyte modulation in cerebral ischemia-reperfusion injury: A promising therapeutic strategy

Cerebral ischemia-reperfusion injury (CIRI) poses significant challenges for drug development due to its complex pathogenesis. Astrocyte involvement in CIRI pathogenesis has led to the development of novel astrocyte-targeting drug strategies. To comprehensively review the current literature, we conducted a thorough analysis from January 2012 to December 2023, identifying 82 drugs aimed at preventing and treating CIRI. These drugs target astrocytes to exert potential benefits in CIRI, and their primary actions include modulation of relevant signaling pathways to inhibit neuroinflammation and oxidative stress, reduce cerebral edema, restore blood-brain barrier integrity, suppress excitotoxicity, and regulate autophagy. Notably, active components from traditional Chinese medicines (TCM) such as Salvia miltiorrhiza, Ginkgo, and Ginseng exhibit these important pharmacological properties and show promise in the treatment of CIRI. This review highlights the potential of astrocyte-targeted drugs to ameliorate CIRI and categorizes them based on their mechanisms of action, underscoring their therapeutic potential in targeting astrocytes.

Molecular Changes in the Ischemic Brain as Non-Invasive Brain Stimulation Targets-TMS and tDCS Mechanisms, Therapeutic Challenges, and Combination Therapies

Ischemic stroke is one of the leading causes of death and disability. As the currently used neurorehabilitation methods present several limitations, the ongoing research focuses on the use of non-invasive brain stimulation (NIBS) techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). NIBS methods were demonstrated to modulate neural excitability and improve motor and cognitive functioning in neurodegenerative diseases. However, their mechanisms of action are not fully elucidated, and the clinical outcomes are often unpredictable. This review explores the molecular processes underlying the effects of TMS and tDCS in stroke rehabilitation, including oxidative stress reduction, cell death, stimulation of neurogenesis, and neuroprotective phenotypes of glial cells. A highlight is put on the newly emerging therapeutic targets, such as ferroptotic and pyroptotic pathways. In addition, the issue of interindividual variability is discussed, and the role of neuroimaging techniques is investigated to get closer to personalized medicine. Furthermore, translational challenges of NIBS techniques are analyzed, and limitations of current clinical trials are investigated. The paper concludes with suggestions for further neurorehabilitation stroke treatment, putting the focus on combination and personalized therapies, as well as novel protocols of brain stimulation techniques.

Salidroside directly activates HSC70, revealing a new role for HSC70 in BDNF signalling and neurogenesis after cerebral ischemia

Salidroside, a principal bioactive component of Rhodiola crenulata, is neuroprotective across a wide time window in stroke models. We investigated whether salidroside induced neurogenesis after cerebral ischemia and aimed to identify its primary molecular targets. Rats, subjected to transient 2 h of middle cerebral artery occlusion (MCAO), received intraperitoneal vehicle or salidroside ± intracerebroventricular HSC70 inhibitor VER155008 or TrkB inhibitor ANA-12 for up to 7 days. MRI, behavioural tests, immunofluorescent staining and western blotting measured effects of salidroside. Reverse virtual docking and enzymatic assays assessed interaction of salidroside with purified recombinant HSC70. Salidroside dose-dependently decreased cerebral infarct volumes and neurological deficits, with maximal effects by 50 mg/kg/day. This dose also improved performance in beam balance and Morris water maze tests. Salidroside significantly increased BrdU+/nestin+, BrdU+/DCX+, BrdU+/NeuN+, BrdU-/NeuN+ and BDNF+ cells in the peri-infarct cortex, with less effect in striatum and no significant effect in the subventricular zone. Salidroside was predicted to bind with HSC70. Salidroside dose-dependently increased HSC70 ATPase and HSC70-dependent luciferase activities, but it did not activate HSP70. HSC70 immunoreactivity concentrated in the peri-infarct cortex and was unchanged by salidroside. However, VER155008 prevented salidroside-dependent increases of neurogenesis, BrdU-/NeuN+ cells and BDNF+ cells in peri-infarct cortex. Salidroside also increased BDNF protein and p-TrkB/TrkB ratio in ischemic brain, changes prevented by VER155008 and ANA-12, respectively. Additionally, ANA-12 blocked salidroside-dependent neurogenesis and increased BrdU-/NeuN+ cells in the peri-infarct cortex. Salidroside directly activates HSC70, thereby stimulating neurogenesis and neuroprotection via BDNF/TrkB signalling after MCAO. Salidroside and similar activators of HSC70 might provide clinical therapies for ischemic stroke.

The role of neuroglial cells communication in ischemic stroke

Ischemic stroke is one of the leading causes of death and disability globally, but its treatment options are limited due to therapeutic window and reperfusion injury constraints. Microglia, astrocytes, and oligodendrocytes are the major components of the neurovascular unit, and there is substantial evidence suggesting their contributions to maintaining homeostasis in the central nervous system. Neuroglial cells participate in neuronal physiological functions and the repair of damaged neurons through various communication methods, including gap junctions, chemical signaling, and extracellular vesicles, in conjunction with other components of the neurovascular unit. Ischemia-induced microglia and astrocytes polarize into "M1/M2" and "A1/A2" phenotypes and exert neurotoxic or neuroprotective effects by releasing soluble factors, secreting extracellular vesicles, and forming syncytia networks in the acute (<72 h), subacute (>72 h), and chronic phases (>6 weeks). Apoptosis of oligodendrocytes due to ischemic hypoxia leads to white matter injury, causing long-term cognitive dysfunction, and promoting oligodendrogenesis is a crucial direction for achieving functional recovery in ischemic stroke. In this article, we summarize the cellular interactions following cerebral ischemia, analyze the roles of neuroglial cells through gap junctions, chemical signaling, and extracellular vesicles in different stages of ischemic stroke, and further explore strategies for intervening in ischemic stroke.

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.

A polypeptide derived from pilose antler ameliorates CUMS-induced depression-like behavior by SENP2-PLCβ4 signaling axis

Neurogenesis is known to be closely associated with depression. We aimed to investigate whether a polypeptide monomer derived from pilose antler (polypeptide sequence LSALEGVFYP, PAP) exerts an antidepressant effect by influencing neurogenesis, and to elucidate the mechanism of its antidepressant action. Behavioral tests were performed to observe the antidepressant effect of PAP. Neurogenesis in the dentate gyrus (DG) region of hippocampus was observed by immunofluorescence. The expression of key proteins of Sentrin/SUMO-specific proteases 2 (SENP2)- Phosphoinositide-specific phospholipase C beta 4 (PLCβ4) pathway was accessed by co-immunoprecipitation (Co-IP), and the calcium homeostasis associated proteins were observed via Western blot (WB). Subsequently, temozolomide (TMZ) pharmacologically blocked neurogenesis to verify the antidepressant effect of PAP on neurogenesis. The mechanism of PAP antidepressant effect was verified by constructing a sh-SENP2 virus vector to silence SENP2 protein. Finally, corticosterone (CORT)-induced PC12 cell model was used to verify whether PAP was involved in the process of deconjugated PLCβ4 SUMOylated. The results showed that PAP improved depression-like behavior and neurogenesis induced by chronic unpredictable mild stimulation (CUMS). In addition, PAP acted on SENP2-PLCβ4 pathway to deconjugate the SUMOylation of PLCβ4 and affect calcium homeostasis. Pharmacological blockade of neurogenesis by TMZ treatment impaired the antidepressant efficacy of PAP. Knockout of SENP2 in the CUMS model attenuated the antidepressant response of PAP, and the impaired neurogenesis was not ameliorated by PAP treatment. In summary, PAP acted on the SENP2-PLCβ4 signaling pathway to inhibit the SUMOylation of PLCβ4 and maintain calcium homeostasis, thereby protecting neurogenesis and playing an antidepressant role.

Amantadine and/or transcranial magnetic stimulation for fatigue associated with multiple sclerosis (FETEM): study protocol for a phase 3 randomised, double-blind, cross-over, controlled clinical trial

INTRODUCTION

Fatigue is one of the most disabling symptoms of multiple sclerosis (MS), and effective treatments are lacking. Amantadine is one of the most used treatments, although its efficacy is under debate. Transcranial magnetic stimulation (TMS) is a promising intervention that has shown positive effects in some preliminary investigations. We aim to investigate the effect of 6 weeks of amantadine and/or TMS in fatigue due to MS.

METHODS AND ANALYSIS

The study is a national, multicentre, phase 3, randomised, double-blind, cross-over, placebo-controlled and sham-controlled clinical trial. Adult patients with relapsing-remitting MS, Expanded Disability Status Scale score of 1.5-4.5 and Fatigue Severity Score>4 are eligible for the trial. Participants will be randomised to one of the sequences of the study. Each sequence consists of four periods of 6 weeks of treatment and three washout periods of 12-18 weeks. All patients will receive all the combinations of therapies. The primary outcome is the Modified Fatigue Impact Scale. The secondary outcomes are the Symbol Digit Modalities Test (cognition), Beck Depression Inventory-II (depressive symptoms) and Short-Survey 12 (quality of life). Safety and cost-effectiveness will also be evaluated. An exploratory substudy including MRI and blood biomarkers will be conducted.

ETHICS AND DISSEMINATION

The study is approved by the Ethics Committee of the Hospital Clinico San Carlos and the Spanish Agency of Medications and Medical Devices. All study findings will be published in scientific peer-reviewed journals and presented at relevant scientific conferences.

TRIAL REGISTRATION NUMBER

EudraCT 2021-004868-95; NCT05809414.

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.

Current evidence, clinical applications, and future directions of transcranial magnetic stimulation as a treatment for ischemic stroke

Transcranial magnetic stimulation (TMS) is a non-invasive brain neurostimulation technique that can be used as one of the adjunctive treatment techniques for neurological recovery after stroke. Animal studies have shown that TMS treatment of rats with middle cerebral artery occlusion (MCAO) model reduced cerebral infarct volume and improved neurological dysfunction in model rats. In addition, clinical case reports have also shown that TMS treatment has positive neuroprotective effects in stroke patients, improving a variety of post-stroke neurological deficits such as motor function, swallowing, cognitive function, speech function, central post-stroke pain, spasticity, and other post-stroke sequelae. However, even though numerous studies have shown a neuroprotective effect of TMS in stroke patients, its possible neuroprotective mechanism is not clear. Therefore, in this review, we describe the potential mechanisms of TMS to improve neurological function in terms of neurogenesis, angiogenesis, anti-inflammation, antioxidant, and anti-apoptosis, and provide insight into the current clinical application of TMS in multiple neurological dysfunctions in stroke. Finally, some of the current challenges faced by TMS are summarized and some suggestions for its future research directions are made.

Cerebral Hemodynamic Changes during Unaffected Handgrip Exercises in Stroke Patients: An fNIRS Study

This study aimed to assess the effect of the altered strength of the sound limb on the hemodynamics in the affected brain of stroke patients. We recruited 20 stroke patients to detect changes in the HbO concentrations in the bilateral prefrontal cortex (PFC), sensorimotor cortex (SMC), and occipital lobe (OL). We performed functional near-infrared spectroscopy (fNIRS) to detect changes in oxyhemoglobin (HbO) concentrations in regions of interest (ROIs) in the bilateral cerebral hemispheres of stroke patients while they performed 20%, 50%, and 80% maximal voluntary contraction (MVC) levels of handgrip tasks with the unaffected hands. The results suggest that when patients performed handgrip tasks with 50% of the MVC force, SMC in the affected cerebral hemisphere was strongly activated and the change in the HbO concentration was similar to that of the handgrip with 80% of MVC. When the force was 50% of MVC, the SMC in the affected hemisphere showed a more proportional activation than that at 80% MVC. Overall, this research suggests that stroke patients with a poor upper limb function should perform motor training with their sound hands at 50% of the MVC grip task to activate the ipsilesional hemisphere.