The adhesive removal test: a sensitive method to assess sensorimotor deficits in mice

Decreased levels of phosphorylated synuclein in plasma are correlated with poststroke cognitive impairment

JOURNAL/nrgr/04.03/01300535-202509000-00022/figure1/v/2024-11-05T132919Z/r/image-tiff Poststroke cognitive impairment is a major secondary effect of ischemic stroke in many patients; however, few options are available for the early diagnosis and treatment of this condition. The aims of this study were to (1) determine the specific relationship between hypoxic and α-synuclein during the occur of poststroke cognitive impairment and (2) assess whether the serum phosphorylated α-synuclein level can be used as a biomarker for poststroke cognitive impairment. We found that the phosphorylated α-synuclein level was significantly increased and showed pathological aggregation around the cerebral infarct area in a mouse model of ischemic stroke. In addition, neuronal α-synuclein phosphorylation and aggregation were observed in the brain tissue of mice subjected to chronic hypoxia, suggesting that hypoxia is the underlying cause of α-synuclein-mediated pathology in the brains of mice with ischemic stroke. Serum phosphorylated α-synuclein levels in patients with ischemic stroke were significantly lower than those in healthy subjects, and were positively correlated with cognition levels in patients with ischemic stroke. Furthermore, a decrease in serum high-density lipoprotein levels in stroke patients was significantly correlated with a decrease in phosphorylated α-synuclein levels. Although ischemic stroke mice did not show significant cognitive impairment or disrupted lipid metabolism 14 days after injury, some of them exhibited decreased cognitive function and reduced phosphorylated α-synuclein levels. Taken together, our results suggest that serum phosphorylated α-synuclein is a potential biomarker for poststroke cognitive impairment.

Semaglultide targets Spp1+ microglia/macrophage to attenuate neuroinflammation following perioperative stroke

Peripheral surgery evokes neuroimmune activation in the central nervous system and modulates immune cell polarization in the ischemic brain. However, the phenotypic change of microglia and myeloid cells within post-surgical ischemic brain tissue remain poorly defined. Using an integrated approach that combines single-cell RNA sequencing with comprehensive biological analysis in a perioperative ischemic stroke (PIS) model, we identified a distinct Spp1-positive macrophage/microglia (Spp1+ Mac/MG) subgroup that exhibit enriched anti-inflammatory pathways with distinct lipid metabolic reprogrammed profile. Moreover, using immunofluorescence staining, we identified the expression of Glucagon-like peptide-1 receptor (GLP1R) in Spp1+F4/80+ cells and Spp1+Iba-1+ cells. Intraperitoneal administration of semaglutide, a GLP1R agonist clinically approved for the treatment of type 2 diabetes mellitus, resulted in a significant reduction of cerebral infarct volume in PIS mice compared to that in ischemic stroke (IS) mice. Meanwhile, semaglutide treatment also increased the proportion of Spp1+Edu+Iba-1+ cells 3 days after PIS. Using high-parameter flow cytometry, immunofluorescence staining and RNA sequencing, we demonstrated that semaglutide treatment significantly attenuated the expression of neuroinflammatory markers in mice following PIS. We also found that semaglutide treatment significantly ameliorated sensorimotor dysfunction up to 3 days after PIS in mice. Our current finding reveal a novel protective Spp1+Mac/MG subset after PIS and demonstrated that it can be upregulated by semaglutide. We propose that targeting Spp1+Mac/MG subsets using semaglutide could serve as a promising strategy to attenuate the exacerbated neuroinflammation in PIS.

Genetic Variation A118G in the OPRM1 Gene Underlies the Dimorphic Response to Epidural Opioid-Induced Itch

Neuraxial opioids, widely used in obstetric and perioperative pain management, often lead to unwanted itch, reducing patient satisfaction. While the μ-opioid receptor has been implicated in opioid-induced itch, the genetic basis for variable itch incidence remains unknown. This study examined 3616 patients receiving epidural opioids, revealing an itch occurrence of 26.55%, with variations among opioid types and gender. Analysis of the OPRM1 gene identified six single-nucleotide polymorphisms, notably rs1799971 (A118G), that correlated with opioid-induced itch. Mouse models with an equivalent A112G mutation showed reduced neuraxial opioid-induced itch and light touch-evoked itch, mirroring human findings. The 118G allele demonstrated an anti-itch effect without impacting analgesia, addiction, or tolerance, offering insights for risk stratification and potential anti-itch pretreatment strategies.

A minimally invasive thrombotic model to study stroke in awake mice

Experimental stroke models in rodents are essential for mechanistic studies and therapeutic development. However, these models have several limitations negatively impacting their translational relevance. Here we aimed to develop a minimally invasive thrombotic stroke model through magnetic particle delivery that does not require craniotomy, is amenable to reperfusion therapy, can be combined with in vivo imaging modalities, and can be performed in awake mice. We found that the model results in reproducible cortical infarcts within the middle cerebral artery (MCA) territory with cytologic and immune changes similar to that observed with more invasive distal MCA occlusion models. Importantly, the injury produced by the model was ameliorated by tissue plasminogen activator (tPA) administration. We also show that MCA occlusion in awake animals results in bigger ischemic lesions independent of day/night cycle. Magnetic particle delivery had no overt effects on physiologic parameters and systemic immune biomarkers. In conclusion, we developed a novel stroke model in mice that fulfills many requirements for modeling human stroke.

HPSE-mediated proinflammatory signaling contributes to neurobehavioral deficits following intranasal HSV-1 infection

Herpes simplex virus-1 (HSV-1) is a neurotropic virus that can infect the brain, and an uncontrolled infection can lead to a range of diseases, including chronic nerve pain, encephalitis, and neurobehavioral abnormalities. These outcomes are often severe and have lasting consequences, highlighting the need to identify host factors that contribute to disease severity. In this study, we report that intranasal HSV-1 infection in murine model, which promotes viral dissemination into the brain, implicates the host protein heparanase (HPSE) as a key mediator of neuroinflammation. Specifically, we observed that the HPSE activity during HSV-1 infection in naïve animals promotes the upregulation of proinflammatory cytokines, enhances microglial activity in the brain, and contributes to cognitive impairment, anxiety, and motor coordination deficits. Such effects are significantly less detectable in heparanase deficient (Hpse-/-) mice. Additionally, we found that moderate activation of toll-like receptors (TLRs), particularly in Hpse+/+ mice, may contribute to the activation of the inflammasome pathway. This, in turn, leads to the activation of caspase-1 (Casp1) and caspase-3 (Casp3), which may play a role in nerve function loss. Our findings position HPSE as a potential therapeutic target for mitigating virus-induced neuroinflammation and neurobehavioral defects.

IMPORTANCE

Herpes simplex virus-1 (HSV-1) infection in the brain can lead to severe and often permanent neurological consequences. Host factors influence disease outcomes in response to infection, and understanding these factors is crucial for developing effective therapies. This study identifies the host protein HPSE as a key mediator of neuroinflammation in response to HSV-1 infection. We demonstrate that the HPSE activity drives proinflammatory cytokine expression and microglial activation and promotes a signaling cascade involving toll-like receptors and caspase activation, potentially intensifying neuroinflammatory responses. These findings implicate HPSE as an important player in HSV-1 pathogenesis in the central nervous system and suggest that targeting HPSE could provide a novel therapeutic strategy to mitigate virus-induced neuroinflammation and neurobehavioral disturbance.

Neurotropic Effects of Cortexin on Models of Mental and Physical Developmental Delay

Objective: To evaluate the efficacy of the neurotropic action of cortexin in models of mental and physical developmental delays in rat offspring. Methods: The neurotropic properties of bovine brain cortex polypeptides were studied using two models of mental and physical developmental delays in rats: toxic CNS damage (oral administration of ethanol during the last week of pregnancy) and neonatal trauma (ischemia-hypoxia). The drug was administered intramuscularly or rectally as suppositories for 20 days. Treatment efficacy was evaluated using the mNSS scale, open field, rotarod, and adhesive removal tests. A histological examination of the brain was subsequently performed. In a separate series of experiments in mice, the concentration of the test drug cortexin and the reference drug cerebrolysin was determined in blood and brain tissue samples using radioactive iodine (Na125I) labeling of these preparations. Results: Modeling developmental delay in rat offspring (due to the toxic effect of ethanol in late pregnancy or neonatal trauma) led to pronounced neurological deficits, manifested by decreased motor activity, and sensorimotor, and coordination disorders. Administration of cortexin in all forms reduced the severity of neurological deficits as measured by mNSS scores, improved motor activity in the Open Field test, enhanced performance in the Adhesive Removal and Rotarod tests, and decreased structural changes in brain tissues. Histological examination revealed reduced neuronal damage in multiple cortical regions, with a significant increase in normal, unchanged neurons compared to placebo groups. Comparison of the blood concentrations of labeled Na125I cortexin depending on the type of administration showed similar distribution profiles in brain tissues, primarily dependent on its blood concentration, which was influenced by the route of administration. Conclusions: The results indicate that brain polypeptides (cortexin), administered either intramuscularly or rectally, can reach the systemic circulation and cross the blood-brain barrier, as demonstrated by our distribution studies using radiolabeled preparations. These polypeptides exert comparable neurotropic effects in models of mental and physical developmental delays in offspring caused by neonatal trauma or the toxic effect of ethanol in late pregnancy in rats.

Alpha‑Asarone Ameliorates Neuronal Injury After Ischemic Stroke and Hemorrhagic Transformation by Attenuating Blood-Brain Barrier Destruction, Promoting Neurogenesis, and Inhibiting Neuroinflammation

Recombinant tissue-type plasminogen activator (rt-PA), the primary drug for acute ischemic stroke (IS), has a narrow therapeutic window and carries a potential risk of hemorrhagic transformation (HT). Without rt-PA administration, patients may suffer permanent cerebral ischemia. Alpha-asarone (ASA), a natural compound derived from Acorus tatarinowii Schott, exhibits diverse neuropharmacological effects. This study aims to investigate whether ASA could improve outcomes in IS and be used to mitigate HT induced by rt-PA. We employed models of permanent middle cerebral artery occlusion (pMCAO) and photothrombotic cortical injury (PCI) to investigate both the therapeutic efficacy and underlying mechanisms of ASA during the acute and recovery periods following IS, respectively. Additionally, Sprague-Dawley rats were subjected to rt-PA treatment at 6-h post-PCI to mimic HT (rt-PA-HT). Our results revealed three key findings: (1) ASA demonstrated therapeutic effects in the acute phase of pMCAO rats by alleviating blood-brain barrier damage through inhibition of glial cell-mediated neuroinflammation; (2) administration of ASA 24 h after stroke ameliorated the neurological damage during the recovery phase in PCI mice by promoting neurogenesis via activation of the BDNF/ERK/CREB signaling pathway; (3) ASA attenuated rt-PA-HT injury by modulating the NLRP3/Caspase1/IL-1β and IL-18 pathways. Overall, our findings suggest that ASA mitigates neuronal injury following IS and HT, positioning it as a promising candidate for treating these conditions.

T cell receptor activation contributes to brain damage after intracerebral hemorrhage in mice

BACKGROUND

Our previous studies demonstrated that activated T cells accumulate in perihematomal regions following intracerebral hemorrhage (ICH) and exacerbate hemorrhagic brain injury. In the present study, we aimed to explore the mechanisms underlying brain-infiltrating T cell activation and the associated pathophysiological effects in neurological outcomes following ICH.

METHODS

We employed standardized collagenase injection-induced and autologous blood injection models of ICH in male C57BL/6J mice. T cell receptor (TCR) activation, immune cell infiltration, and cytokine production were quantified through immunostaining, flow cytometry, and cytokine arrays at 1- and 3-days post-ICH. Brain edema volume was measured at 3 days post-ICH and neurobehavioral assessments were conducted up to 14 days post-ICH. Pharmacological inhibition of TCR activation was achieved using the TCR-specific inhibitor AX-024, administered intraperitoneally at a dosage of 10 mg/kg 1-hour post-ICH.

RESULTS

Flow cytometry and immunostaining detected TCR activation of brain-infiltrating T cells. Specific TCR activation inhibitor AX-024 administration markedly reduced TCR activation and the production of pro-inflammatory cytokines in the brain at 1- and 3-days post-ICH. Moreover, AX-024 administration led to a significant reduction in the infiltration of other leukocyte populations, and significantly reduced brain edema while improved long-term sensorimotor and cognitive outcomes up to 14 days post-ICH.

DISCUSSION

Our findings underscore the critical role of TCR activation in the mobilization and activation of brain-infiltrating T cells post-ICH. Inhibition of TCR activation via AX-024 administration might be developed as a promising therapeutic strategy to improve neurological outcomes following ICH. However, further research is necessary to thoroughly explore the complex pathophysiological processes involved.

Tie2-Dependent Mechanisms Promote Leptomeningeal Collateral Remodeling and Reperfusion Following Stroke

Leptomeningeal collaterals are distal pial arterial anastomotic vessels that provide an alternative route for redistributing cerebral blood flow following arterial obstruction, thereby limiting tissue damage. However, the regulatory mechanisms and strategies to enhance this adaptive response remain under investigation. This study explored the pharmacological effects of Tie2 receptor activation, using the peptide agonist Vasculotide, following permanent middle cerebral artery occlusion (pMCAO). Vasculotide improved collateral growth and remodeling, which correlated with reduced infarct volume, enhanced blood flow, and functional recovery within 24hrs post-pMCAO. In contrast, collateral growth was attenuated in Tie2 and EphA4/Tie2 double knockdown mice, while the loss of EphA4 increased Tie2 and Ang-1 expression and mimicked the positive effects of Vasculotide following stroke. Furthermore, bulk RNA sequencing of meningeal tissue identified key transcriptomic changes, including alterations in AJ-associated transcripts, such as Krt5 , Krt14 , and Col17a1 , in the ipsilateral meninges of both endothelial cell-specific EphA4 knockout and Vasculotide-treated mice. Krt5 expression was found upregulated on meningeal arterial vascular network in injured KO mice, highlighting a potential new mediator of meningeal vascular remodeling. These findings illustrate that EphA4 and Tie2 play opposing roles in collateral remodeling, including the regulation of Krt5. Modulating their activity could potentially enhance the collateral response to stroke.

M4 Positive Allosteric Modulator VU0467154 Impacts Amphetamine Sensitization and Spontaneous Locomotion in Male Mice

This study investigates the effects of the muscarinic acetylcholine receptor subtype 4 (M4) positive allosteric modulator (PAM) VU0467154 on the development, incubation, and expression of amphetamine sensitization in mice, the expression of immediate early genes in the medial prefrontal cortex after induction and expression of sensitization, as well as on spontaneous locomotion and several aspects of sensorimotor function. Mice were pretreated with VU0467154 during the induction phase, before the challenge test, or both. A separate cohort was treated during the incubation period. Tests of spontaneous locomotion and sensorimotor function were conducted after VU0467154 administration to evaluate potential side effects. Treatment with VU0467154 inhibited the development and expression of amphetamine sensitization. This was paralleled by effects on immediate early gene expression in the medial prefrontal cortex. Additionally, previous pretreatment with VU0467154 during the induction phase attenuated the expression of sensitization after a two-week incubation period. However, treatment with VU0467154 during the incubation period did not affect the expression of a sensitized response. VU0467154 significantly reduced spontaneous locomotion without impairing other aspects of sensorimotor function, as assessed by the mesh, adhesive removal, horizontal bar, and negative geotaxis tests. Global M4 knockout mice confirmed that the inhibitory effect on spontaneous locomotion was specific to M4 receptors. Our findings provide new insights into the therapeutic potential of M4 PAMs in modulating the neuroadaptations associated with psychostimulant abuse. Collectively, these results suggest that activation of M4 receptors could be a promising strategy for modulating dopaminergic signaling and reducing some behaviors associated with substance use disorder.

hESC-derived extracellular vesicles enriched with MFGE-8 and the GSH redox system act as senotherapeutics for neural stem cells in ischemic stroke

Human embryonic stem cells (hESCs) and their extracellular vesicles (EVs) hold significant potential for tissue repair and regeneration. Neural stem cells (NSCs) in the adult brain often acquire senescent phenotypes after ischemic injuries, releasing neurodegenerative senescence-associated secretory phenotype factors. In this study, we investigated the senotherapeutic effects of hESC-EVs on NSCs and confirmed their neuroprotective effects in neurons via rejuvenation of NSC secretions. Proteomic profiling of hESC-EVs identified MFGE-8 as a critical bridging molecule to NSCs. We also found that the glutathione (GSH) redox system is a key contributor to the therapeutic antioxidant activity of hESC-EVs. Additionally, EVs produced by the hypoxic preconditioning of hESCs (hESC-HypoxEVs) exhibited reinforced GSH redox capacity and further enhanced the senotherapeutic effects on NSCs compared to naïve hESC-EVs. We also demonstrated that administration of hESC-HypoxEVs, precoated with MFGE-8, significantly increased the populations of NSCs and newborn neurons in the subventricular zone of the brain and improved sensorimotor functions in a rat model of ischemic stroke. Our study suggests that combining hESC-HypoxEVs with MFGE-8 may serve as an effective therapeutic modality for reversing senescence and enhancing the neurogenic potential of NSCs to treat neurodegenerative diseases.

Strychni Semen and its active compounds promote axon regeneration following peripheral nerve injury by suppressing myeloperoxidase in the dorsal root ganglia

OBJECTIVE

Treating peripheral nerve injury (PNI) presents a clinical challenge due to limited axon regeneration. Strychni Semen, a traditional Chinese medicine, is clinically used for numbness and hemiplegia. However, its role in promoting functional recovery after PNI and the related mechanisms have not yet been systematically studied.

METHODS

A mouse model of sciatic nerve crush (SNC) injury was established and the mice received drug treatment via intragastric gavage, followed by behavioral assessments (adhesive removal test, hot-plate test and Von Frey test). Transcriptomic analyses were performed to examine gene expression in the dorsal root ganglia (DRGs) from the third to the sixth lumbar vertebrae, so as to identify the significantly differentially expressed genes. Immunofluorescence staining was used to assess the expression levels of superior cervical ganglia neural-specific 10 protein (SCG10). The ultra-trace protein detection technique was used to evaluate changes in gene expression levels.

RESULTS

Strychni Semen and its active compounds (brucine and strychnine) improved functional recovery in mice following SNC injury. Transcriptomic data indicated that Strychni Semen and its active compounds initiated transcriptional reprogramming that impacted cellular morphology and extracellular matrix remodeling in DRGs after SNC, suggesting potential roles in promoting axon regeneration. Imaging data further confirmed that Strychni Semen and its active compounds facilitated axon regrowth in SNC-injured mice. By integrating protein-protein interaction predictions, ultra-trace protein detection, and molecular docking analysis, we identified myeloperoxidase as a potentially critical factor in the axon regenerative effects conferred by Strychni Semen and its active compounds.

CONCLUSION

Strychni Semen and its active compounds enhance sensory function by promoting axonal regeneration after PNI. These findings establish a foundation for the future applications of Strychni Semen and highlight novel therapeutic strategies and drug targets for axon regeneration. Please cite this article as: Zhang Y, Zhao XY, Liu MT, Zhou ZC, Cheng HB, Jiang XH, Zheng YR, Chen Z. Strychni Semen and its active compounds promote axon regeneration following peripheral nerve injury by suppressing myeloperoxidase in the dorsal root ganglia. J Integr Med. 2025; 23(2): 169-181.

Intravenous administration of muse cells improves cerebral ischemia outcome via immunomodulation in the spleen

Ischemic stroke is a leading cause of disability and death globally. Stem cell therapies are emerging as a frontier for enhancing post-stroke recovery, with Muse cells-a subclass of pluripotent stem cells-demonstrating considerable promise. Muse cells are notable not only for their potential in cell replacement but also for their role in modulating immune responses following cerebral infarction. In the present study, we administered Muse cells intravenously to mice after inducing a stroke via distal middle cerebral artery occlusion. We evaluated motor outcomes, splenocyte populations, cytokine profiles, and gene expression 2 weeks after inducing stroke. Additionally, comparisons were drawn between outcomes in splenectomized mice and those receiving adoptive splenocyte transfer to discern the specific influence of the spleen on treatment efficacy. Our findings revealed that Muse cell therapy facilitates motor recovery, an effect that is compromised in the absence of the spleen. Spleens in treated mice exhibited a shift in neutrophil counts, increased cytokine activity, and a notable uptick in the expression of genes related to protein folding. These insights affirm the potential therapeutic effect of Muse cells in post-stroke treatment strategies, with their efficacy attributed, at least in part, to immunomodulatory pathways involving the spleen.

A microglial kinase ITK mediating neuroinflammation and behavioral deficits in traumatic brain injury

Microglia-mediated neuroinflammation has been implicated in the neuropathology of traumatic brain injuries (TBI). Recently, the expression of interleukin-2-inducible T-cell kinase (ITK) has been detected in brain microglia, regulating their inflammatory activities. However, the role of microglial ITK in TBI has not been investigated. In this study, we demonstrate that ITK expression and activation are upregulated in microglia following an injury caused by controlled cortical impact (CCI) - a mouse model of TBI. Pharmacological inhibition of ITK protein or knockdown of microglial ITK gene expression using adeno-associated virus mitigates neuroinflammation and improves neurological outcomes in the CCI model. Additionally, ITK mRNA expression was found to be increased in the brains of patients with chronic traumatic encephalopathy. An ITK inhibitor reduced the activation of inflammatory responses in both human and mouse microglia in vitro. Collectively, these results suggest that microglial ITK plays a pivotal role in neuroinflammation and mediating behavioral deficits following TBI. Thus, targeting the signaling pathway of microglial ITK may exert protective effects by alleviating neuroinflammation associated with TBI.

Conditioning Electrical Nerve Stimulation Enhances Functional Rewiring in a Mouse Model of Nerve Transfer to Treat Chronic Spinal Cord Injury

BACKGROUND/OBJECTIVES

Nerve transfer surgery is a state-of-the-art surgical approach to restore hand and arm function in individuals living with tetraplegia, significantly impacting daily life. While nearly a third of all individuals with chronic spinal cord injury may benefit from this intervention, variability in outcomes can limit the functional impact. A bedside to bench approach was taken to address the variable response of tetraplegic individuals to nerve transfer surgery.

METHODS

We used a hierarchical multiple factor analysis to evaluate the effects of conditioning electrical stimulation (CES) on outcomes in a mouse model of nerve transfer to treat chronic cervical spinal cord injury.

RESULTS

We found that CES of donor nerves one week prior to nerve transfer surgery enhanced anatomical and functional measures of innervation of targeted muscles. Furthermore, CES increased the rate of recovery of naturalistic behavior.

CONCLUSIONS

While the model has some limitations due to the small size of the rodent, our results support the use of CES as an effective approach to improve outcomes in clinical nerve repair settings.

THBS1 in macrophage-derived exosomes exacerbates cerebral ischemia-reperfusion injury by inducing ferroptosis in endothelial cells

Macrophages play a critical role in the development of acute ischemic stroke (AIS). Cerebral ischemia-reperfusion injury (CIRI) is a pivotal pathological process that exacerbates AIS, with exosomes act as crucial mediators. However, the effects and mechanisms of action of macrophage-derived exosomes on CIRI remain unclear. This study demonstrated that macrophage-derived exosomes induce endothelial ferroptosis and barrier disruption during CIRI. Through proteomic sequencing and the reanalysis of transcriptomic and single-cell sequencing data, thrombospondin-1 (THBS1) was identified as a key exosomal molecule. Elevated THBS1 was observed in exosomes and monocytes from the peripheral blood of patients with AIS in oxygen-glucose deprivation/reoxygenation (OGD/R)-stimulated THP-1 and RAW264.7, in their secreted exosomes, and in macrophages within the brains of transient middle cerebral artery occlusion (tMCAO) mice. Additionally, THBS1 expression in exosomes was positively correlated with vascular barrier injury biomarkers, including MMP-9 and S100B. Modulation of THBS1 in macrophage-derived exosomes affected exosome-induced ferroptosis in endothelial cells. The mechanism by which THBS1 binds directly to OTUD5 and promotes GPX4 ubiquitination was elucidated using RNA interference, adeno-associated virus transfection, and endothelial-specific Gpx4 knockout mice. High-throughput screening of small-molecule compounds targeting THBS1 was performed. Molecular docking, molecular dynamics simulations, and cellular thermal shift assays further confirmed that salvianolic acid B (SAB) has a potent binding affinity for THBS1. SAB treatment inhibited the interaction between THBS1 and OTUD5, leading to reduced GPX4 ubiquitination. Further research revealed that SAB treatment enhanced the cerebral protective effects of THBS1 inhibition. In conclusion, this study explored the role of exosome-mediated signaling between macrophages and cerebral vascular endothelial cells in CIRI, highlighting the THBS1-OTUD5-GPX4 axis as a driver of endothelial ferroptosis and brain injury. Targeting this signaling axis represents a potential therapeutic strategy for treating CIRI.

The efficacy of an allosteric modulator of the alpha 7 nicotinic acetylcholine receptor in a murine model of stroke

Introduction

Ischemic strokes contribute significantly to cardiovascular-related deaths in the U.S., with current interventions limited to thrombolytic agents. However, these agents present challenges such as a limited therapeutic window, incomplete reperfusion rates, risk of transformation, reperfusion-induced inflammation, and a lack of promoting neuroprotection. We investigated an additional strategy in which prior studies indicated a neuroprotective role. Using a murine transient middle cerebral artery occlusion (tMCAO) model, we sought to evaluate the neurotherapeutic efficacy of a positive allosteric modulator of the alpha7 nicotinic acetylcholine receptor (α7-nAChR), PNU-120596 (PNU), specifically examining whether PNU would modulate stroke-induced neurological dysfunction and neuropathology, with modulation of neuroinflammation as a possible mechanism.

Methods

Young male C57BL/6J mice received a subcutaneous injection of 20mg/kg of vehicle (DMSO) or PNU-120596 immediately after reperfusion, and infarct area and Bederson score were analyzed 24 hours post-stroke. In the 72-hour post-stroke study, the animals were injected with 20mg/kg of PNU or vehicle subcutaneously immediately after reperfusion, followed by two additional doses of 10mg/kg of PNU or vehicle at 24 and 48 hours post-tMCAO. Seventy-two hours later, behavior function and infarct area were assessed.

Results

In contrast to previous rat studies that demonstrated improvements in clinical outcomes, a single administration of PNU following stroke induction led to a reduction in acute neuropathology but did not produce a significant improvement in motor outcomes. Prolonged treatment showed no significant changes in acute neuropathology or sensorimotor function. Additionally, an assessment of neuroinflammation revealed no changes in CD4 T-cell cellularity or phenotype.

Discussion

These findings, alongside prior studies, suggest that the therapeutic efficacy of PNU may be contingent upon the timing of administration, dosage, and pharmacokinetics.

Deferiprone ameliorates cisplatin induced peripheral neurotoxicity via ferritinophagy adjustment

Cisplatin-induced neurotoxicity is one of the limiting factors to its use especially in tumors that demand high drug dosage. One of the Cisplatin pathways is ferritinophagy which may end up in ferroptosis. So, we aimed to use iron chelator as a new strategy based on an anti-ferroptotic mechanism and to evaluate its neuroprotective effect against polyneuropathy in Cisplatin-treated rats. Twenty-four male Wistar albino rats were arranged into four groups: (I) Control group, rats were given vehicle; (II) Def group, rats received deferiprone (200 mg/kg orally once daily for 10 days); (III) Cis group, rats were injected by Cis 2 mg/Kg once daily for 3 consecutive days i.p.; and (IV) Cis + Def group, rats received deferiprone (200 mg/kg orally once daily for 10 days, rats were injected with Cis in the 4th, 5th, and 6th days). Cis increased and upregulated ferritinophagy inducers significantly including MDA, NCOA4, and IREB1 as compared to the control group. On the other hand, GSH, GPX4, SLCA11 and FTH1 were decreased and down regulated significantly compared to the control group. In addition to significant deterioration in the histopathological and immunological nerve tissue assessment using silver stain and PNCA. Embracing the cisplatin dosage with deferiprone reversed cisplatin-induced neuropathy, in which the physiological function significantly improved along with the immune and histopathology of nerve tissue. This was accompanied by down regulation of ferritinophagy inducers and enhancing ferritinophagy inhibitors. The current results concluded that rapping cisplatin with deferiprone can mitigate neurotoxicity induced by cisplatin in experimental animals through ferritinophagy pathway adjustment.

1,4-dihydroxy-2-naphthoic acid prevents 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced motor function deficits

Parkinson's disease (PD), characterized by death of dopaminergic neurons in the substantia nigra, is the second most prevalent progressive neurodegenerative disease. However, the etiology of PD is largely elusive. This study employed the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) rodent model to examine the effectiveness of 1,4-dihydroxy-2-naphthoic acid (1,4-DHNA), an aryl hydrocarbon receptor (AhR) active gut bacteria-derived metabolite, in mitigating MPTP's motoric deficits, and the role of AhR in mediating these effects. Male C57BL/6 mice were fed daily with vehicle, 20 mg/kg 1,4-DHNA, or AhR-inactive isomer 3,7-DHNA, for 3 weeks before administration of 80 mg/kg MPTP or vehicle. Four weeks later, mice were assessed for motoric functions. Both 1,4-DHNA and 3,7-DHNA prevented MPTP-induced deficits in the motor pole test and in the adhesive strip removal test. Additionally, 1,4-DHNA improved balance beam performance and completely prevented MPTP-induced reduction in stride length. In contrast, 3,7-DHNA, an AhR-inactive compound, did not improve balance beam performance and had only a partial effect on stride length. This study suggests that natural metabolites of gut microbiota, such as 1,4-DHNA, could be beneficial to counteract the development of motor deficits observed in PD. Thus, this study further supports the hypothesis that pathological and mitigating processes in the gut could play an essential role in PD development. Moreover, this indicates that 1,4-DHNA's ability to combat various motor deficits is likely mediated via multiple underlying molecular mechanisms. Specifically, AhR is involved, at least partially, in control of gait and bradykinesia, but it likely does not mediate the effects on fine motor skills.

Hypoxic Postconditioning Offers Neuroprotection Against Transient Cerebral Ischemia via Down-Regulation of rno_piR_011022

BACKGROUND

Piwi-interacting RNAs (piRNAs) are differentially expressed after cerebral ischemia. However, little is known about their roles in transient global cerebral ischemia (tGCI). Herein, we aim to elucidate the roles and the underlying molecular mechanisms of piRNAs in tGCI and cerebral ischemic tolerance induced by hypoxic postconditioning (HPC).

METHODS

The male rat models of tGCI and HPC were established in vivo. Oxygen-glucose deprivation/reoxygenation (OGD/R) was developed from primary hippocampal neurons in vitro. RNA-sequencing, fluorescence in situ hybridization, and quantitative real-time PCR were used for detecting piRNA expression. Immunohistochemistry, TUNEL staining, CCK8 assay, etc., were used to evaluate neuronal damage. Western blot was used to measure protein levels of NR2B, PSD95, and cleaved-caspase 3.

RESULTS

The expression profiles of piRNAs in CA1 were significantly changed after tGCI. HPC downregulated the expression of the top 5 piRNAs associated with synaptic function. Notably, the knockdown of rno_piR_011022 not only alleviated neuronal apoptosis and enhanced synaptic plasticity after tGCI and OGD/R but also reduced methyl-D-aspartate (NMDA) receptor 2B (NR2B) expression and inhibited NR2B-postsynaptic density 95 (PSD95) interaction following tGCI. HPC enhanced these inhibitory effects.

CONCLUSION

This innovative study indicated that the down-regulation of rno_piR_011022 plays an important role in HPC-mediated neuroprotection against tGCI through inhibiting the NR2B-PSD95 interaction.

Neuroplasticity therapy using glia-like cells derived from human mesenchymal stem cells for the recovery of cerebral infarction sequelae

Despite a dramatic increase in ischemic stroke incidence worldwide, effective therapies for attenuating sequelae of cerebral infarction are lacking. This study investigates the use of human mesenchymal stem cells (hMSCs) induced toward glia-like cells (ghMSCs) to ameliorate chronic sequelae resulting from cerebral infarction. Transcriptome analysis demonstrated that ghMSCs exhibited astrocytic characteristics, and assessments conducted ex vivo using organotypic brain slice cultures demonstrated that ghMSCs exhibited superior neuroregenerative and neuroprotective activity against ischemic damage compared to hMSCs. The observed beneficial effects of ghMSCs were diminished by pre-treatment with a CXCR2 antagonist, indicating a direct role for CXCR2 signaling. Studies conducted in rats subjected to cerebral infarction demonstrated that ghMSCs restored neurobehavioral functions and reduced chronic brain infarction in a dose-dependent manner when transplanted at the subacute-to-chronic phase. These beneficial impacts were also inhibited by a CXCR2 antagonist. Molecular analyses confirmed that increased neuroplasticity contributed to ghMSCs' neuroregenerative effects. These data indicate that ghMSCs hold promise for treating refractory sequelae resulting from cerebral infarction by enhancing neuroplasticity and identify CXCR2 signaling as an important mediator of ghMSCs' mechanism of action.

Prophylactic use of probiotics as an adjunctive treatment for ischemic stroke via the gut-spleen-brain axis

A growing body of research has focused on the role of spleen in orchestrating brain injury through the peripheral immune system following stroke, highlighting the brain-spleen axis as a potential target for mitigating neuronal damage during stroke. The gut microbiota plays a pivotal role in the bidirectional communication between the gut and the brain. Several studies have suggested that probiotic supplements hold promise as a strategic approach to maintaining a balanced intestinal microecology, reducing the apoptosis of intestinal epithelial cells, protecting the intestinal mucosal and blood-brain barrier (BBB), enhancing both intestinal and systemic immune functions, and thereby potentially affecting the pathogenesis and progression of ischemic stroke. In this study, we aimed to clarify the neuroprotective effects of supplementation with Lactobacillus, specifically Limosilactobacillus reuteri GMNL-89 (G89) and Lacticaseibacillus paracasei GMNL-133 (G133) on ischemic stroke and investigate how G89 and G133 modulate the communication mechanisms between the gut, brain, and spleen following ischemic stroke. We explored the neuroprotection and the underlying mechanisms of Lactobacillus supplementation in C57BL/6 mice subjected to permanent middle cerebral artery occlusion. Our results revealed that oral treatment with G89 or G133 alone, as well as oral administration combining G89 and G133, significantly decreased the infarct volume and improved the neurological function in mice with ischemic stroke. Moreover, G89 treatment alone preserved the tight junction integrity of gut barrier, while G133 alone and the combined treatment of G89 and G133 would significantly decreased the BBB permeability, and thereby significantly attenuated stroke-induced local and systemic inflammatory responses. Both G89 and G133 regulated cytotoxic T cells, and the balance between T helper 1 cells and T helper 2 cells in the spleen following ischemic stroke. Additionally, the combined administration of G89 and G133 improved the gut dysbiosis and significantly increased the concentration of short-chain fatty acids. In conclusion, our findings suggest that G89 and G133 may be used as nutrient supplements, holding promise as a prospective approach to combat ischemic stroke by modulating the gut-spleen-brain axis.

Electroacupuncture Pretreatment Reduces Ischemic Brain Injury by Inhibiting the Lactate Production and Its Derived Protein Lactylation Formation

AIM

Given that electroacupuncture (EA) pretreatment inhibits lactate production and lactate-derived lysine lactation (Kla) aggravates ischemic brain injury, we aimed to investigate whether the formation of Kla protein is involved in EA pretreatment to alleviate ischemic brain injury.

METHODS

EA was performed on the Baihui acupoint (GV20) of male C57BL/6J mice before receiving the permanent middle cerebral artery occlusion (pMCAO) surgery. Western blot and immunofluorescent staining were used to observe neuronal survival, astrocyte activation, and protein Kla levels, and the lactate levels in ischemic brains were assayed with a commercial kit. TTC staining and neurological function scores are performed to evaluate the brain damage in mice.

RESULTS

We found that the increased lactate content and protein Kla levels were significantly decreased in ischemic brain tissue of mice after receiving EA pretreatment, and accompanied by the reduction of astrocyte activation and neuronal injury and death. Meantime, we found that EA pretreatment was effective in reversing the worsening of ischemic brain injury caused by lactate supplementation. However, EA pretreatment did not further reduce the lactate content and protein Kla levels and ameliorate brain injury in ischemic stroke mice after inhibition of glycolysis.

CONCLUSION

Our study reveals that EA pretreatment reduced ischemic brain damage by inhibiting lactate production and its derived protein Kla formation in mice with ischemic stroke.

Novel mouse model of alternating hemiplegia of childhood exhibits prominent motor and seizure phenotypes

Pathogenic variants in ATP1A3 encoding the neuronal Na/K-ATPase cause a spectrum of neurodevelopmental disorders including alternating hemiplegia of childhood (AHC). Three recurrent ATP1A3 variants are associated with approximately half of known AHC cases and mouse models of two of these variants (p.D801N, p.E815K) replicated key features of the human disorder, which include paroxysmal hemiplegia, dystonia and seizures. Epilepsy occurs in 40-50 % of individuals affected with AHC, but detailed investigations of seizure phenotypes were limited in the previously reported mouse models. Using gene editing, we generated a novel AHC mouse expressing the third most recurrent ATP1A3 variant (p.G947R) to model neurological phenotypes of the disorder. Heterozygous Atp1a3-G947R (Atp1a3G947R) mice on a pure C57BL/6J background were born at a significantly lower frequency than wildtype (WT) littermates, but in vitro fertilization or outcrossing to a different strain (C3HeB/FeJ) generated offspring at near-Mendelian genotype ratios, suggesting a defect in reproductive fitness rather than embryonic lethality. Heterozygous mutant mice were noticeably smaller and exhibited premature lethality, hyperactivity, anxiety-like behaviors, severe motor dysfunction including low grip strength, impaired coordination with abnormal gait and balance, reduced REM sleep, and cooling-induced hemiplegia and dystonia. We also observed a prominent seizure phenotype with lower thresholds to chemically (flurothyl, kainic acid) and electrically induced seizures, post-handling seizures, sudden death following seizures, and abnormal EEG activity. Together, our findings support face validity of a novel AHC mouse model with quantifiable traits including co-morbid epilepsy that will be useful as an in vivo platform for investigating pathophysiology and testing new therapeutic strategies for this rare neurodevelopmental disorder.

Electroacupuncture suppresses NK cell infiltration and activation in the ischemic mouse brain through STAT3 inhibition

AIMS

Electroacupuncture (EA) at Shuigou (GV26) and Baihui (GV20) has shown therapeutic benefits for stroke patients. Given that natural killer (NK) cell infiltration into the brain significantly contributes to the exacerbation of cerebral ischemic injury, this study investigated the impact of EA at Shuigou (GV26) and Baihui (GV20) on post-ischemic brain infiltration and activation of NK cells.

METHODS

Neurological deficit score, rotarod test, adhesive removal test, and TTC staining were used to evaluate the beneficial effects of EA in middle cerebral artery occlusion (MCAO) mice. The inhibitory effect of EA on STAT3 activation was assessed using Western blot. Flow cytometry was used to explore the impact of EA on post-ischemic brain infiltration of NK cells, as well as the activating receptor NKG2D expression and interferon-γ (IFN-γ) production by these infiltrated NK cells.

RESULTS

EA significantly alleviated neurological functional deficits and reduced brain infarction in MCAO mice. Abundant NK cells infiltrated into the ischemic hemisphere, but this infiltration was significantly suppressed by EA. Furthermore, EA attenuated NKG2D levels and reduced production of IFN-γ by NK cells in the ischemic brain. Notably, EA's inhibitory effect on post-ischemic NK cell brain infiltration and activation was comparable to that of STAT3 inhibition. The combination of EA and STAT3 inhibition did not result in further enhancement of the inhibitory effect. Moreover, the protective effects of EA against MCAO injury were abolished when STAT3 was activated.

CONCLUSION

Our findings suggest that EA at Shuigou (GV26) and Baihui (GV20) inhibits the post-ischemic brain infiltration and activation of NK cells through STAT3 inhibition, significantly contributing to its therapeutic effects against brain ischemia.

Protein kinase N1 deficiency results in upregulation of cerebral energy metabolism and is highly protective in in vivo and in vitro stroke models

BACKGROUND AND AIM

We recently identified protein kinase N1 (PKN1) as a master regulator of brain development. However, its function in the adult brain has not been clearly established. In this study, we assessed the cerebral energetic phenotype of wildtype (WT) and global Pkn1 knockout (Pkn1-/-) animals under physiological and pathophysiological conditions.

METHODS

Cerebral energy metabolism was analyzed by 13C6-glucose tracing in vivo and real time seahorse analysis of extracellular acidification rates as well as mitochondrial oxygen consumption rates (OCR) of brain slice punches in vitro. Isolated WT and Pkn1-/- brain mitochondria were tested for differences in OCR with different substrates. Metabolite levels were determined by mass spectrometric analysis in brain slices under control and energetic stress conditions, induced by oxygen-glucose deprivation and reperfusion, an in vitro model of ischemic stroke. Differences in enzyme activities were assessed by enzymatic assays, western blotting and bulk RNA sequencing. A middle cerebral artery occlusion stroke model was used to analyze lesion volumes and functional recovery in WT and Pkn1-/- mice.

RESULTS

Pkn1 deficiency resulted in a remarkable upregulation of cerebral energy metabolism, in vivo and in vitro. This was due to two separate mechanisms involving an enhanced glycolytic flux and higher pyruvate-induced mitochondrial OCR. Mechanistically we show that Pkn1-/- brain tissue exhibits an increased activity of the glycolysis rate-limiting enzyme phosphofructokinase. Additionally, glucose-1,6-bisphosphate levels, a metabolite that increases mitochondrial pyruvate uptake, were elevated upon Pkn1 deficiency. Consequently, Pkn1-/- brain slices had more ATP and a greater accumulation of ATP degradation metabolites during energetic stress. This translated into increased phosphorylation and activity of adenosine monophosphate (AMP)-activated protein kinase (AMPK) during in vitro stroke. Accordingly, Pkn1-/- brain slices showed a post-ischemic transcriptional upregulation of energy metabolism pathways and Pkn1 deficiency was strongly protective in in vitro and in vivo stroke models. While inhibition of mitochondrial pyruvate uptake only moderately affected the protective phenotype, inhibition of AMPK in Pkn1-/- slices increased post-ischemic cell death in vitro.

CONCLUSION

This is the first study to comprehensively demonstrate an essential and unique role of PKN1 in cerebral energy metabolism, regulating glycolysis and mitochondrial pyruvate-induced respiration. We further uncovered a highly protective phenotype of Pkn1 deficiency in both, in vitro and in vivo stroke models, validating inhibition of PKN1 as a promising new therapeutic target for the development of novel stroke therapies.

Transcriptome Analysis Reveals Dynamic Microglial-Induced A1 Astrocyte Reactivity via C3/C3aR/NF-κB Signaling After Ischemic Stroke

Microglia and astrocytes are key players in neuroinflammation and ischemic stroke. A1 astrocytes are a subtype of astrocytes that are extremely neurotoxic and quickly kill neurons. Although the detrimental A1 astrocytes are present in many neurodegenerative diseases and are considered to accelerate neurodegeneration, their role in the pathophysiology of ischemic stroke is poorly understood. Here, we combined RNA-seq, molecular and immunological techniques, and behavioral tests to investigate the role of A1 astrocytes in the pathophysiology of ischemic stroke. We found that astrocyte phenotypes change from a beneficial A2 type in the acute phase to a detrimental A1 type in the chronic phase following ischemic stroke. The activated microglial IL1α, TNF, and C1q prompt commitment of A1 astrocytes. Inhibition of A1 astrocytes induction attenuates reactive gliosis and ameliorates morphological and functional defects following ischemic stroke. The crosstalk between astrocytic C3 and microglial C3aR contributes to the formation of A1 astrocytes and morphological and functional defects. In addition, NF-κB is activated following ischemic stroke and governs the formation of A1 astrocytes via direct targeting of inflammatory cytokines and chemokines. Taken together, we discovered that A2 astrocytes and A1 astrocytes are enriched in the acute and chronic phases of ischemic stroke respectively, and that the C3/C3aR/NF-κB signaling leads to A1 astrocytes induction. Therefore, the C3/C3aR/NF-κB signaling is a novel therapeutic target for ischemic stroke treatment.

Unveiling Smyd-2's Role in Cytoplasmic Nrf-2 Sequestration and Ferroptosis Induction in Hippocampal Neurons After Cerebral Ischemia/Reperfusion

SET and MYND Domain-Containing 2 (Smyd-2), a specific protein lysine methyltransferase (PKMT), influences both histones and non-histones. Its role in cerebral ischemia/reperfusion (CIR), particularly in ferroptosis-a regulated form of cell death driven by lipid peroxidation-remains poorly understood. This study identifies the expression of Smyd-2 in the brain and investigates its relationship with neuronal programmed cell death (PCD). We specifically investigated how Smyd-2 regulates ferroptosis in CIR through its interaction with the Nuclear Factor Erythroid-2-related Factor-2 (Nrf-2)/Kelch-like ECH-associated protein (Keap-1) pathway. Smyd-2 knockout protects HT-22 cells from Erastin-induced ferroptosis but not TNF-α + Smac-mimetic-induced apoptosis/necroptosis. This neuroprotective effect of Smyd-2 knockout in HT-22 cells after Oxygen-Glucose Deprivation/Reperfusion (OGD/R) was reversed by Erastin. Smyd-2 knockout in HT-22 cells shows neuroprotection primarily via the Nuclear Factor Erythroid-2-related Factor-2 (Nrf-2)/Kelch-like ECH-associated protein (Keap-1) pathway, despite the concurrent upregulation of Smyd-2 and Nrf-2 observed in both the middle cerebral artery occlusion (MCAO) and OGD/R models. Interestingly, vivo experiments demonstrated that Smyd-2 knockout significantly reduced ferroptosis and lipid peroxidation in hippocampal neurons following CIR. Moreover, the Nrf-2 inhibitor ML-385 abolished the neuroprotective effects of Smyd-2 knockout, confirming the pivotal role of Nrf-2 in ferroptosis regulation. Cycloheximide (CHX) fails to reduce Nrf-2 expression in Smyd-2 knockout HT-22 cells. Smyd-2 knockout suppresses Nrf-2 lysine methylation, thereby promoting the Nrf-2/Keap-1 pathway without affecting the PKC-δ/Nrf-2 pathway. Conversely, Smyd-2 overexpression disrupts Nrf-2 nuclear translocation, exacerbating ferroptosis and oxidative stress, highlighting its dual regulatory role. This study underscores Smyd-2's potential for ischemic stroke treatment by disrupting the Smyd-2/Nrf-2-driven antioxidant capacity, leading to hippocampal neuronal ferroptosis. By clarifying the intricate interplay between ferroptosis and oxidative stress via the Nrf-2/Keap-1 pathway, our findings provide new insights into the molecular mechanisms of CIR and identify Smyd-2 as a promising therapeutic target.

Site-specific drug release of monomethyl fumarate to treat oxidative stress disorders

Treatment of diseases of oxidative stress through activation of the antioxidant nuclear factor E2-related factor 2 (NRF2) is limited by systemic side effects. We chemically functionalize the NRF2 activator monomethyl fumarate to require Baeyer-Villiger oxidation for release of the active drug at sites of oxidative stress. This prodrug reverses chronic pain in mice with reduced side effects and could be applied to other disorders of oxidative stress.

Binding of α-synuclein to ACO2 promotes progressive mitochondrial dysfunction in Parkinson's disease models

The accumulation of α-synuclein (α-syn), a key protein in Parkinson's disease (PD), contributes to progressive neuronal damage associated with mitochondrial dysfunction and interactions with various proteins. However, the precise mechanism by which α-syn affects energy metabolism remains unclear. In our study, we used human α-syn (hα-syn) transgenic mice, which exhibit progressive neuronal decline. Through an immunoprecipitation assay specific to hα-syn, we identified an enzyme in the mitochondrial tricarboxylic acid (TCA) cycle as a binding partner-mitochondrial aconitase 2 (ACO2), which converts citrate to isocitrate. Hα-syn increasingly interacted with ACO2 in mitochondria as mice aged, correlating with a progressive decrease in ACO2 activity. The overexpression of ACO2 and the addition of isocitrate, a downstream metabolite of ACO2, were observed to alleviate hα-syn-induced mitochondrial dysfunction and cytotoxicity. Furthermore, we designed an interfering peptide to block the interaction between ACO2 and hα-syn, which showed therapeutic effects in reducing hα-syn toxicity in vitro and in vivo. Our research establishes a direct link between α-syn and the TCA cycle and identifies ACO2 as a promising therapeutic target for improving mitochondrial function and reducing α-syn neurotoxicity in PD.

Preconditioning Exercise Inhibits Neuron Ferroptosis and Ameliorates Brain Ischemia Damage by Skeletal Muscle-Derived Exosomes via Regulating miR-484/ACSL4 Axis

Aims: Although there is evidence that patients with stroke who exercise regularly before stroke have a better prognosis than those who do not exercise, the detailed mechanism remains unclear. Moreover, neuronal death plays a central role in neurological dysfunction caused by ischemic stroke. Thus, we investigated whether exercise could reduce stroke-induced neuronal death and its associated mediators in the current study. Results: Ferroptosis was the most dominant form of programmed cell death in neurons. Preconditioning exercise before stroke improved the neurological function and decreased the infarct area in rats with ischemic stroke. Preconditioning exercise attenuated stroke-induced ferroptosis by reducing lipid peroxidation (LPO) production, upregulating glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11), and downregulating acyl-CoA synthetase long-chain family member 4 (ACSL4). High-throughput sequencing and dual luciferase reporter assays revealed that exercise-induced exosomal miR-484 inhibits Acsl4 expression. Moreover, we showed that exercise-induced exosomal miR-484 is mainly derived from skeletal muscle, and the neuroprotective effect of preconditioning exercise is suppressed by inhibiting miR-484 production in skeletal muscle. Innovation: This study suggested that neuronal ferroptosis is the most dominant form of programmed cell death in a hypoxic environment. Moreover, we showed that the ferroptosis pathway is a potential therapeutic target in ischemic stroke and that preconditioning exercise could be an effective antioxidant intervention for cerebral ischemia. Conclusion: Our work revealed that preconditioning exercise before stroke exerts neuroprotective effects against brain ischemia by skeletal muscle-derived exosomal miR-484 via inhibiting ferroptosis. Antioxid. Redox Signal. 41, 769-792.

Cav3.2 channel regulates cerebral ischemia/reperfusion injury: a promising target for intervention

JOURNAL/nrgr/04.03/01300535-202419110-00028/figure1/v/2024-03-08T184507Z/r/image-tiff Calcium influx into neurons triggers neuronal death during cerebral ischemia/reperfusion injury. Various calcium channels are involved in cerebral ischemia/reperfusion injury. Cav3.2 channel is a main subtype of T-type calcium channels. T-type calcium channel blockers, such as pimozide and mibefradil, have been shown to prevent cerebral ischemia/reperfusion injury-induced brain injury. However, the role of Cav3.2 channels in cerebral ischemia/reperfusion injury remains unclear. Here, in vitro and in vivo models of cerebral ischemia/reperfusion injury were established using middle cerebral artery occlusion in mice and high glucose hypoxia/reoxygenation exposure in primary hippocampal neurons. The results showed that Cav3.2 expression was significantly upregulated in injured hippocampal tissue and primary hippocampal neurons. We further established a Cav3.2 gene-knockout mouse model of cerebral ischemia/reperfusion injury. Cav3.2 knockout markedly reduced infarct volume and brain water content, and alleviated neurological dysfunction after cerebral ischemia/reperfusion injury. Additionally, Cav3.2 knockout attenuated cerebral ischemia/reperfusion injury-induced oxidative stress, inflammatory response, and neuronal apoptosis. In the hippocampus of Cav3.2-knockout mice, calcineurin overexpression offset the beneficial effect of Cav3.2 knockout after cerebral ischemia/reperfusion injury. These findings suggest that the neuroprotective function of Cav3.2 knockout is mediated by calcineurin/nuclear factor of activated T cells 3 signaling. Findings from this study suggest that Cav3.2 could be a promising target for treatment of cerebral ischemia/reperfusion injury.

STING recognition of viral dsDNA by nociceptors mediates pain in mice

Pain is often one of the initial indicators of a viral infection, yet our understanding of how viruses induce pain is limited. Immune cells typically recognize viral nucleic acids, which activate viral receptors and signaling, leading to immunity. Interestingly, these viral receptors and signals are also present in nociceptors and are associated with pain. Here, we investigate the response of nociceptors to nucleic acids during viral infections, specifically focusing on the role of the viral signal, Stimulator of Interferon Genes (STING). Our research shows that cytosolic double-stranded DNA (dsDNA) from viruses, like herpes simplex virus 1 (HSV-1), triggers pain responses through STING expression in nociceptors. In addition, STING agonists alone can elicit pain responses. Notably, these responses involve the direct activation of STING in nociceptors through TRPV1. We also provided a proof-of-concept showing that STING and TRPV1 significantly contribute to the mechanical hypersensitivity induced by HSV-1 infection. These findings suggest that STING could be a potential therapeutic target for relieving pain during viral infections.

Stroke of Consistency: Streamlining Multicenter Protocols for Enhanced Reproducibility of Infarct Volumes in Preclinical Stroke Research

BACKGROUND

The discrepancy between experimental research and clinical trial outcomes is a persistent challenge in preclinical studies, particularly in stroke research. A possible factor contributing to this issue is the lack of standardization across experimental stroke models, leading to poor reproducibility in multicenter studies. This study addresses this gap by aiming to enhance reproducibility and the efficacy of multicenter studies through the harmonization of protocols and training of involved personnel.

METHODS

We established a set of standard operating procedures for various stroke models and the Neuroscore. These standard operating procedures were implemented across multiple research centers, followed by specialized, in-person training for all participants. We measured the variability in infarct volume both before and after the implementation of these standardized protocols and training sessions.

RESULTS

The standardization process led to a significant reduction in variability of infarct volume across different stroke models (40%-50% reduction), demonstrating the effectiveness of our harmonized protocols and training. Additionally, the implementation of the Neuroscore system across centers showed low variability and consistent results up to 28 days poststroke, underscoring its utility in chronic phase evaluations.

CONCLUSIONS

The harmonization of protocols and surgeon training significantly reduced variability in experimental outcomes across different centers. This improvement can increase the comparability of data between research groups and enhance the statistical power of multicenter studies. Our findings also establish the Neuroscore as a reliable tool for long-term assessment in stroke research, paving the way for more consistent and impactful multicenter preclinical studies.

CCL5 is essential for axonogenesis and neuronal restoration after brain injury

BACKGROUND

Traumatic brain injury (TBI) causes axon tearing and synapse degradation, resulting in multiple neurological dysfunctions and exacerbation of early neurodegeneration; the repair of axonal and synaptic structures is critical for restoring neuronal function. C-C Motif Chemokine Ligand 5 (CCL5) shows many neuroprotective activities.

METHOD

A close-head weight-drop system was used to induce mild brain trauma in C57BL/6 (wild-type, WT) and CCL5 knockout (CCL5-KO) mice. The mNSS score, rotarod, beam walking, and sticker removal tests were used to assay neurological function after mTBI in different groups of mice. The restoration of motor and sensory functions was impaired in CCL5-KO mice after one month of injury, with swelling of axons and synapses from Golgi staining and reduced synaptic proteins-synaptophysin and PSD95. Administration of recombinant CCL5 (Pre-treatment: 300 pg/g once before injury; or post-treatment: 30 pg/g every 2 days, since 3 days after injury for 1 month) through intranasal delivery into mouse brain improved the motor and sensory neurological dysfunctions in CCL5-KO TBI mice.

RESULTS

Proteomic analysis using LC-MS/MS identified that the "Nervous system development and function"-related proteins, including axonogenesis, synaptogenesis, and myelination signaling pathways, were reduced in injured cortex of CCL5-KO mice; both pre-treatment and post-treatment with CCL5 augmented those pathways. Immunostaining and western blot analysis confirmed axonogenesis and synaptogenesis related Semaphorin, Ephrin, p70S6/mTOR signaling, and myelination-related Neuregulin/ErbB and FGF/FAK signaling pathways were up-regulated in the cortical tissue by CCL5 after brain injury. We also noticed cortex redevelopment after long-term administration of CCL5 after brain injury with increased Reelin positive Cajal-Rerzius Cells and CXCR4 expression. CCL5 enhanced the growth of cone filopodia in a primary neuron culture system; blocking CCL5's receptor CCR5 by Maraviroc reduced the intensity of filopodia in growth cone and also CCL5 mediated mTOR and Rho signalling activation. Inhibiting mTOR and Rho signaling abolished CCL5 induced growth cone formation.

CONCLUSIONS

CCL5 plays a critical role in starting the intrinsic neuronal regeneration system following TBI, which includes growth cone formation, axonogenesis and synaptogensis, remyelination, and the subsequent proper wiring of cortical circuits. Our study underscores the potential of CCL5 as a robust therapeutic stratagem in treating axonal injury and degeneration during the chronic phase after mild brain injury.

The cerebellum modulates thirst

The cerebellum, a phylogenetically ancient brain region, has long been considered strictly a motor control structure. Recent studies have implicated the cerebellum in cognition, sensation, emotion and autonomic function, making it an important target for further investigation. Here, we show that cerebellar Purkinje neurons in mice are activated by the hormone asprosin, leading to enhanced thirst, and that optogenetic or chemogenetic activation of Purkinje neurons induces rapid manifestation of water drinking. Purkinje neuron-specific asprosin receptor (Ptprd) deletion results in reduced water intake without affecting food intake and abolishes asprosin's dipsogenic effect. Purkinje neuron-mediated motor learning and coordination were unaffected by these manipulations, indicating independent control of two divergent functions by Purkinje neurons. Our results show that the cerebellum is a thirst-modulating brain area and that asprosin-Ptprd signaling may be a potential therapeutic target for the management of thirst disorders.

Central IRF4/5 Signaling Are Critical for Microglial Activation and Impact on Stroke Outcomes

Microglia and monocytes play a critical role in immune responses to cerebral ischemia. Previous studies have demonstrated that interferon regulatory factor 4 (IRF4) and IRF5 direct microglial polarization after stroke and impact outcomes. However, IRF4/5 are expressed by both microglia and monocytes, and it is not clear if it is the microglial (central) or monocytic (peripheral) IRF4-IRF5 regulatory axis that functions in stroke. In this work, young (8-12 weeks) male pep boy (PB), IRF4 or IRF5 flox, and IRF4 or IRF5 conditional knockout (CKO) mice were used to generate 8 types of bone marrow chimeras, to differentiate the role of central (PB-to-IRF CKO) vs. peripheral (IRF CKO-to-PB) phagocytic IRF4-IRF5 axis in stroke. Chimeras generated from PB and flox mice were used as controls. All chimeras were subjected to 60-min middle cerebral artery occlusion (MCAO) model. Three days after the stroke, outcomes and inflammatory responses were analyzed. We found that PB-to-IRF4 CKO chimeras had more robust microglial pro-inflammatory responses than IRF4 CKO-to-PB chimeras, while ameliorated microglial response was seen in PB-to-IRF5 CKO vs. IRF5 CKO-to-PB chimeras. PB-to-IRF4 or IRF5 CKO chimeras had worse or better stroke outcomes respectively than their controls, whereas IRF4 or 5 CKO-to-PB chimeras had similar outcomes compared to controls. We conclude that the central IRF4/5 signaling is responsible for microglial activation and mediates stroke outcomes.

Elabela ameliorates neuronal pyroptosis and mitochondrial fission via APJ/ZBP1 signaling in ischemic stroke

Pyroptosis signifies a significant form of programmed neuronal demise subsequent to ischemic stroke. In our prior investigations, we demonstrated that the Elabela (ELA)-Apelin receptor (APJ) axis alleviated neuronal death by improving collateral circulation and mitigating ferroptosis in a murine model of middle cerebral artery occlusion (MCAO). However, the connection between ELA and neuronal pyroptosis remains further elucidation. Here, we observed an upregulation of ELA and APJ expression in both murine brain specimens and cultured HT-22 hippocampal neurons exposed to experimental ischemic stroke. ELA administration markedly diminished the infarct size in comparison to controls. ELA treatment ameliorated neurological deficits and anxiety-like symptoms in mice with stroke, concurrently inhibiting pyroptosis and mitochondria fission in neurons. Conversely, ELA knockdown yielded the opposite effects. Utilizing RNA-sequencing analysis, we identified a candidate for pyroptosis priming, Z-DNA-binding protein 1 (ZBP1), which was suppressed in ELA-treated HT-22 neurons during oxygen-glucose deprivation/reperfusion (OGD/R). Subsequent co-immunoprecipitation analyses demonstrated the binding between APJ and ZBP1. Specifically, APJ suppressed ZBP1 to inhibit NLRP3 inflammasome activation and dynamin-related protein 1-mediated mitochondrial fission in neurons. In summary, our findings suggest that ELA functions as a stroke-induced signal limiting neuronal pyroptosis and mitochondrial fission via APJ/ZBP1 signaling, thereby underscoring ELA as a potential therapeutic target for ischemic stroke treatment.

Multistrain Probiotics with Fructooligosaccharides Improve Middle Cerebral Artery Occlusion-Driven Neurological Deficits by Revamping Microbiota-Gut-Brain Axis

Recent burgeoning literature unveils the importance of gut microbiota in the neuropathology of post-stroke brain injury and recovery. Indeed, ingestion of prebiotics/probiotics imparts positive effects on post-stroke brain injury, neuroinflammation, gut dysbiosis, and intestinal integrity. However, information on the disease-specific preference of selective prebiotics/probiotics/synbiotics and their underlying mechanism is yet elusive. Herein, we examined the effect of a new synbiotic formulation containing multistrain probiotics (Lactobacillus reuteri UBLRu-87, Lactobacillus plantarum UBLP-40, Lactobacillus rhamnosus UBLR-58, Lactobacillus salivarius UBLS-22, and Bifidobacterium breve UBBr-01), and prebiotic fructooligosaccharides using a middle cerebral artery occlusion (MCAO) model of cerebral ischemia in female and male rats. Three weeks pre-MCAO administration of synbiotic rescinded the MCAO-induced sensorimotor and motor deficits on day 3 post-stroke in rotarod, foot-fault, adhesive removal, and paw whisker test. We also observed a decrease in infarct volume and neuronal death in the ipsilateral hemisphere of synbiotic-treated MCAO rats. The synbiotic treatment also reversed the elevated levels/mRNA expression of the glial fibrillary acidic protein (GFAP), NeuN, IL-1β, TNF-α, IL-6, matrix metalloproteinase-9, and caspase-3 and decreased levels of occludin and zonula occludens-1 in MCAO rats. 16S rRNA gene-sequencing data of intestinal contents indicated an increase in genus/species of Prevotella (Prevotella copri), Lactobacillus (Lactobacillus reuteri), Roseburia, Allobaculum, and Faecalibacterium prausnitzii, and decreased abundance of Helicobacter, Desulfovibrio, and Akkermansia (Akkermansia muciniphila) in synbiotic-treated rats compared to the MCAO surgery group. These findings confer the potential benefits of our novel synbiotic preparation for MCAO-induced neurological dysfunctions by reshaping the gut-brain-axis mediators in rats.

Temporal expression of brainstem neurotrophic proteins following mild traumatic brain injury

BDNF, a neurotrophic factor, and its receptors have been implicated in the pathophysiology of mild traumatic brain injury (mTBI). The brainstem houses many vital functions, that are also associated with signs and symptoms of mTBI, but has been understudied in mTBI animal models. We determined the extent to which neurotrophic protein and associated receptor expression is affected within the brainstem of adult rats following mTBI. Their behavioral function was assessed and temporal expression of the 'negative' regulators of neuronal function (p75, t-TrkB, and pro-BDNF) and 'positive' neuroprotective (FL-TrkB and m-BDNF) protein isoforms were determined via western blot and immunohistochemistry at 1, 3, 7, and 14 post-injury days (PID) following mTBI or sham (control) procedure. Within the brainstem, p75 expression increased at PID 1 vs. sham animals. t-TrkB and pro-BDNF expression increased at PID 7 and 14. The 'positive' protein isoforms of FL-TrkB and m-BDNF expression were increased only at PID 7. The ratio of t-TrkB:FL-TrkB (negative:positive) was substantial across groups and time points, suggesting a negative impact of neurotrophic signaling on neuronal function. Additional NeuN experiments revealed cell death occurring within a subset of neurons within the medulla. While behavioral measures improved by PID 7-14, negative neurotrophic biochemical responses persisted. Despite the assertion that mTBI produces "mild" injury, evidence of cell death was observed in the medulla. Ratios of TrkB and BDNF isoforms with conflicting functions suggest that future work should specifically measure each subtype since they induce opposing downstream effects on neuronal function.

Impact of social isolation on corticosterone release and recovery after stroke in aged rats: A behavioral and biochemical analysis

Social isolation (SI) after stroke reduces recovery. The aim of this study was to evaluate the effects of SI on corticosterone release and recovery after stroke in aged rats. A total of 64 male Wistar rats (aged 24 months) were used in the present study. All rats were housed in pairs for two weeks. After two weeks, rats were randomly assigned to one of four groups: (1) rats underwent sham surgery and kept socially isolated (control/social isolated (CO/SI) group); (2) rats underwent sham surgery and kept pair housed (control/pair housed (CO/PH) group); (3) rats underwent middle cerebral artery occlusion (MCAO) surgery and kept socially isolated (stroke/isolated (ST/SI) group); (4) rats underwent MCAO surgery and kept pair housed (stroke/pair housed (ST/PH)) group. Behaviors were assessed using the adhesive removal test, rotarod test and social interaction test at 1st, 7th, 14th and 21st days after stroke. Serum biochemical analysis was also performed on the behavioral testing days. Results showed THAT serum corticosterone and MDA levels in CO/PH group were significantly lower than CO/SI group. Serum BDNF levels in CO/PH group was significantly higher than CO/SI group. Serum corticosterone and MDA levels in ST/PH group were lower than ST/SI group. In ST/PH group, serum Total antioxidant capacity (TAC) and BDNF levels were significantly higher than ST/SI group. Biochemical analysis of certain regions of the brain (hippocampus, striatum and cerebral cortex) was performed on 21st day after stroke. In the hippocampus of CO/PH group, BDNF and TAC levels were significantly higher than CO/SI group. The hippocampal MDA level of CO/PH group were significantly lower than CO/SI group. BDNF and TAC levels in the hippocampus, striatum and cerebral cortex of ST/PH group were significantly higher and MDA level was significantly lower as compared with ST/SI group. Both ischemic groups showed sensorimotor recovery over a 21-day period, but recovery of ST/PH group was significantly greater than ST/SI group. Total social interaction time in ST/PH group was significantly longer than ST/SI group. Based on the results of this study, social interaction after stroke enhances histologic and sensorimotor recovery through reduction of HPA activity and corticosterone release, leading to increased TAC and BDNF levels.

ATF5-Mediated Mitochondrial Unfolded Protein Response (UPRmt) Protects Neurons Against Oxygen-Glucose Deprivation and Cerebral Ischemia

BACKGROUND

The mitochondrial unfolded protein response (UPRmt) is an evolutionarily conserved mitochondrial response that is critical for maintaining mitochondrial and energetic homeostasis under cellular stress after tissue injury and disease. Here, we ask whether UPRmt may be a potential therapeutic target for ischemic stroke.

METHODS

We performed the middle cerebral artery occlusion and oxygen-glucose deprivation models to mimic ischemic stroke in vivo and in vitro, respectively. Oligomycin and meclizine were used to trigger the UPRmt. We used 2,3,5-triphenyltetrazolium chloride staining, behavioral tests, and Nissl staining to evaluate cerebral injury in vivo. The Cell Counting Kit-8 assay and the Calcein AM Assay Kit were conducted to test cerebral injury in vitro.

RESULTS

Inducing UPRmt with oligomycin protected neuronal cultures against oxygen-glucose deprivation. UPRmt could also be triggered with meclizine, and this Food and Drug Administration-approved drug also protected neurons against oxygen-glucose deprivation. Blocking UPRmt with siRNA against activating transcription factor 5 eliminated the neuroprotective effects of meclizine. In a mouse model of focal cerebral ischemia, pretreatment with meclizine was able to induce UPRmt in vivo, which reduced infarction and improved neurological outcomes.

CONCLUSIONS

These findings suggest that the UPRmt is important in maintaining the survival of neurons facing ischemic/hypoxic stress. The UPRmt mechanism may provide a new therapeutic avenue for ischemic stroke.

The p75 neurotrophin receptor attenuates secondary thalamic damage after cortical infarction by promoting angiogenesis

BACKGROUND

Angiogenesis is crucial in neuroprotection of secondary thalamic injury after cortical infarction. The p75 neurotrophin receptor (p75NTR) plays a key role in activating angiogenesis. However, the effects of p75NTR on angiogenesis in the thalamus after cortical infarction are largely unknown. Herein we investigate whether p75NTR facilitates angiogenesis to attenuate secondary thalamic damage via activating hypoxia-inducible factor 1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway mediated by Von Hippel-Lindau (VHL) after distal middle cerebral artery occlusion (dMCAO).

METHODS

The male rat model of dMCAO was established. The effects of p75NTR on the angiogenesis was evaluated using RNA-sequencing, immunohistochemistry, western blot, quantitative real-time polymerase chain reaction, magnetic resonance imaging, behavior tests, viral and pharmacological interventions.

RESULTS

We found that the p75NTR and vessel density were decreased in ipsilateral thalamus after dMCAO. The p75NTR-VHL interaction was reduced, which promoted the ubiquitination degradation of HIF-1α and reduced VEGF expression after dMCAO. Notably, p75NTR overexpression restrained the ubiquitination degradation of HIF-1α by inhibiting VHL-HIF-1α interaction, further promoted angiogenesis, increased cerebral blood flow of ipsilateral thalamus and improved neurological function after dMCAO.

CONCLUSION

For the first time, we highlighted that the enhancement of p75NTR-VHL interaction promoted angiogenesis in attenuating secondary thalamic damage after dMCAO.

STZ-induced diabetes exacerbates neurons ferroptosis after ischemic stroke by upregulating LCN2 in neutrophils

Diabetic is a major contributor to the unfavorable prognosis of ischemic stroke. However, intensive hypoglycemic strategies do not improve stroke outcomes, implying that diabetes may affect stroke outcomes through other ways. Ferroptosis is a novel programmed cell death pathway associated with the development of diabetes and ischemic stroke. This study aimed to investigate the effect of streptozotocin (STZ)-induced diabetes on ferroptosis after stroke from the immune cell perspective, and to provide a theoretical foundation for the clinical management of ischemic stroke in patients with diabetes. The results revealed that STZ-induced diabetes not only facilitates the infiltration of neutrophils into the brain after stroke, but also upregulates the expression of lipocalin 2 (LCN2) in neutrophils. LCN2 promotes lipid peroxide accumulation by increasing intracellular ferrous ions, which intensify ferroptosis in major brain cell populations, especially neurons. Our findings suggest that STZ-induced diabetes aggravates ischemic stroke partially by mediating ferroptosis through neutrophil-derived LCN2. These data contribute to improved understanding of post-stroke immune regulation in diabetes, and offer a potentially novel therapeutic target for the management of acute-stage ischemic stroke complicated with diabetes.

A minimally invasive thrombotic stroke model to study circadian rhythm in awake mice

Experimental stroke models in rodents are essential for mechanistic studies and therapeutic development. However, these models have several limitations negatively impacting their translational relevance. Here we aimed to develop a minimally invasive thrombotic stroke model through magnetic particle delivery that does not require craniotomy, is amenable to reperfusion therapy, can be combined with in vivo imaging modalities, and can be performed in awake mice. We found that the model results in reproducible cortical infarcts within the middle cerebral artery (MCA) with cytologic and immune changes similar to that observed with more invasive distal MCA occlusion models. Importantly, the injury produced by the model was ameliorated by tissue plasminogen activator (tPA) administration. We also show that MCA occlusion in awake animals results in bigger ischemic lesions independent of day/night cycle. Magnetic particle delivery had no overt effects on physiologic parameters and systemic immune biomarkers. In conclusion, we developed a novel stroke model in mice that fulfills many requirements for modeling human stroke.

Peripheral gating of mechanosensation by glial diazepam binding inhibitor

We report that diazepam binding inhibitor (DBI) is a glial messenger mediating crosstalk between satellite glial cells (SGCs) and sensory neurons in the dorsal root ganglion (DRG). DBI is highly expressed in SGCs of mice, rats, and humans, but not in sensory neurons or most other DRG-resident cells. Knockdown of DBI results in a robust mechanical hypersensitivity without major effects on other sensory modalities. In vivo overexpression of DBI in SGCs reduces sensitivity to mechanical stimulation and alleviates mechanical allodynia in neuropathic and inflammatory pain models. We further show that DBI acts as an unconventional agonist and positive allosteric modulator at the neuronal GABAA receptors, particularly strongly affecting those with a high-affinity benzodiazepine binding site. Such receptors are selectively expressed by a subpopulation of mechanosensitive DRG neurons, and these are also more enwrapped with DBI-expressing glia, as compared with other DRG neurons, suggesting a mechanism for a specific effect of DBI on mechanosensation. These findings identified a communication mechanism between peripheral neurons and SGCs. This communication modulates pain signaling and can be targeted therapeutically.

A role for astrocytic insulin-like growth factor I receptors in the response to ischemic insult

Increased neurotrophic support, including insulin-like growth factor I (IGF-I), is an important aspect of the adaptive response to ischemic insult. However, recent findings indicate that the IGF-I receptor (IGF-IR) in neurons plays a detrimental role in the response to stroke. Thus, we investigated the role of astrocytic IGF-IR on ischemic insults using tamoxifen-regulated Cre deletion of IGF-IR in glial fibrillary acidic protein (GFAP) astrocytes, a major cellular component in the response to injury. Ablation of IGF-IR in astrocytes (GFAP-IGF-IR KO mice) resulted in larger ischemic lesions, greater blood-brain-barrier disruption and more deteriorated sensorimotor coordination. RNAseq detected increases in inflammatory, cell adhesion and angiogenic pathways, while the expression of various classical biomarkers of response to ischemic lesion were significantly increased at the lesion site compared to control littermates. While serum IGF-I levels after injury were decreased in both control and GFAP-IR KO mice, brain IGF-I mRNA expression show larger increases in the latter. Further, greater damage was also accompanied by altered glial reactivity as reflected by changes in the morphology of GFAP astrocytes, and relative abundance of ionized calcium binding adaptor molecule 1 (Iba 1) microglia. These results suggest a protective role for astrocytic IGF-IR in the response to ischemic injury.

Activation of Pedunculopontine Tegmental Nucleus Alleviates the Pain Induced by the Lesion of Midbrain Dopaminergic Neurons

The loss of midbrain dopaminergic (DA) neurons is the fundamental pathological feature of Parkinson's disease (PD). PD causes chronic pain in two-thirds of patients. Recent studies showed that the activation of the pedunculopontine tegmental nucleus (PPTg) can effectively relieve inflammatory pain and neuropathic pain. The PPTg is located in the pontomesencephalic tegmentum, a target of deep brain stimulation (DBS) treatment in PD, and is involved in motor control and sensory integration. To test whether the lesion of midbrain DA neurons induced pain hypersensitivity, and whether the chemogenetic activation of the PPTg could modulate the pain, the AAV-hM3Dq receptor was transfected and expressed into the PPTg neurons of 6-hydroxydopamine-lesioned mice. In this study, von Frey, open field, and adhesive tape removal tests were used to assess animals' pain sensitivity, locomotor activity, and sensorimotor function and somatosensory perception, respectively. Here, we found that the lesion of midbrain DA neurons induced a minor deficit in voluntary movement but did not affect sensorimotor function and somatosensory perception in the tape removal test. The results showed that lesion led to pain hypersensitivity, which could be alleviated both by levodopa and by the chemogenetic activation of the PPTg. Activating the PPTg may be a potential therapeutic strategy to relieve pain phenotypes in PD.

Hi1a Improves Sensorimotor Deficit following Endothelin-1-Induced Stroke in Rats but Does Not Improve Functional Outcomes following Filament-Induced Stroke in Mice

Activation of acid-sensing ion channel 1a (ASIC1a) plays a major role in mediating acidosis-induced neuronal injury following a stroke. Therefore, the inhibition of ASIC1a is a potential therapeutic avenue for the treatment of stroke. Venom-peptide Hi1a, a selective and highly potent ASIC1a inhibitor, reduces the infarct size and functional deficits when injected into the brain after stroke in rodents. However, its efficacy when administered using a clinically relevant route of administration remains to be established. Therefore, the current investigation aims to examine the efficacy of systemically administered Hi1a, using two different models of stroke in different species. Mice were subjected to the filament model of middle cerebral artery occlusion (MCAO) and treated with Hi1a systemically using either a single- or multiple-dosing regimen. 24 h poststroke, mice underwent functional testing, and the brain infarct size was assessed. Rats were subjected to endothelin-1 (ET-1)-induced MCAO and treated with Hi1a intravenously 2 h poststroke. Rats underwent functional tests prior to and for 3 days poststroke, when infarct volume was assessed. Mice receiving Hi1a did not show any improvements in functional outcomes, despite a trend toward reduced infarct size. This trend for reduced infarct size in mice was consistent regardless of the dosing regimen. There was also a trend toward lower infarct size in rats treated with Hi1a. More specifically, Hi1a reduced the amount of damage occurring within the somatosensory cortex, which was associated with an improved sensorimotor function in Hi1a-treated rats. Thus, this study suggests that Hi1a or more brain-permeable ASIC1a inhibitors are a potential stroke treatment.

Electroencephalographic monitoring of anesthesia during surgical procedures in mice using a modified clinical monitoring system

Monitoring brain activity and associated physiology during the administration of general anesthesia (GA) in mice is pivotal to guarantee postanesthetic health. Clinically, electroencephalogram (EEG) monitoring is a well-established method to guide GA. There are no established methods available for monitoring EEG in mice (Mus musculus) during surgery. In this study, a minimally invasive rodent intraoperative EEG monitoring system was implemented using subdermal needle electrodes and a modified EEG-based commercial patient monitor. EEG recordings were acquired at three different isoflurane concentrations revealing that surgical concentrations of isoflurane anesthesia predominantly contained burst suppression patterns in mice. EEG suppression ratios and suppression durations showed strong positive correlations with the isoflurane concentrations. The electroencephalographic indices provided by the monitor did not support online monitoring of the anesthetic status. The online available suppression duration in the raw EEG signals during isoflurane anesthesia is a straight forward and reliable marker to assure safe, adequate and reproducible anesthesia protocols.