Astrocytes Research Articles

Glymphatic imaging and modulation of the optic nerve.

Optic nerve health is essential for proper function of the visual system. However, the pathophysiology of certain neurodegenerative disease processes affecting the optic nerve, such as glaucoma, is not fully understood. Recently, it was hypothesized that a lack of proper clearance of neurotoxins contributes to neurodegenerative diseases. The ability to clear metabolic waste is essential for tissue homeostasis in mammals, including humans. While the brain lacks the traditional lymphatic drainage system identified in other anatomical regions, there is growing evidence of a glymphatic system in the central nervous system, which structurally includes the optic nerve. Named to acknowledge the supportive role of astroglial cells, this perivascular fluid drainage system is essential to remove toxic metabolites from the central nervous system. Herein, we review existing literature describing the physiology and dysfunction of the glymphatic system specifically as it relates to the optic nerve. We summarize key imaging studies demonstrating the existence of a glymphatic system in the optic nerves of wild-type rodents, aquaporin 4-null rodents, and humans; glymphatic imaging studies in diseases where the optic nerve is impaired; and current evidence regarding pharmacological and lifestyle interventions that may help promote glymphatic function to improve optic nerve health. We conclude by highlighting future research directions that could be applied to improve imaging detection and guide therapeutic interventions for diseases affecting the optic nerve.

Short-term consumption of alcohol (vodka) mixed with energy drink (AMED) attenuated alcohol-induced cerebral capillary disturbances and neuroinflammation in adult wild-type mice

ABSTRACT Background: The ingestion of combinatory Alcohol Mixed with Energy Drink (AMED) beverages continues to increase markedly, particularly among young adults. Some studies suggest detrimental health effects related to the combination of alcohol with energy drink formulations; however, the consumption of AMED has not been investigated in context of the cerebral microvasculature or neuroinflammation. We hypothesized that cerebral capillary integrity and glial cells are particularly vulnerable to the combination of AMED. Methods:12-week old wild-type C57BL/6J mice were orally gavaged with either vehicle (water), alcohol (vodka), an energy drink (MotherTM), or a combination AMED, daily for five days. Thereafter, mice were sacrificed, blood alcohol concentrations were analysed and cryosections of brain specimens were subjected to confocal immunofluorescent analysis for measures of cerebral capillary integrity via immunoglobulin G (IgG), and markers of neuroinflammation, ionized-calcium-binding-adaptor-molecule 1 (Iba1) and Glial-Fibrillary-Acidic-Protein (GFAP). Proinflammatory cytokines, IL-2, IL-17A, IFN-ϒ, and anti-inflammatory cytokines, IL-4, IL-6 and IL-10, were also measured in serum. Results: Consistent with previous studies, cerebral capillary dysfunction and astroglial cell activation were markedly greater in the alcohol-only group (AO); however, the AO-induced effects were profoundly attenuated with the AMED combination. Mice maintained on AO and AMED interventions exhibited a moderate increase in microglial recruitment. There were no significant changes in pro-inflammatory nor anti-inflammatory cytokines in ED or AMED treated mice. Conclusion: This study suggests that paradoxically the acute detrimental effects of alcohol on cerebral capillary integrity and astrogliosis are counteracted with the co-provision of an ED, rich in caffeine and taurine and containing B-group vitamins.

Levetiracetam promoted rat embryonic neurogenesis via NMDA receptor-mediated mechanism in vitro

AimsLevetiracetam (LEV) is a broad-spectrum antiepileptic drug with neuroprotective properties and novel mechanisms of action. Some evidence suggests that LEV may impact adult neurogenesis, but the results are controversial. The present study was aimed to evaluate the effects of LEV on the proliferation and differentiation of rat embryonic neural stem cells (NSCs) and to explore the role of GABAB or NMDA receptors. Main methodsNSCs were isolated from rat fetal ganglionic eminence at embryonic day 14.5. The effects of LEV on viability, proliferation, neurosphere formation, and neuronal or astroglial differentiation of NSCs were assessed using resazurin, BrdU incorporation, immunocytochemistry, quantitative real-time PCR, and western blotting. Additionally, we addressed the relationship between treatment with NMDA and GABAB receptor antagonists (MK801 and saclofen, respectively) in combination with LEV on these parameters. Key findingsThe data showed that LEV (50 μM) significantly increased the number (p < 0.01) and diameter of neurospheres (p < 0.05), enhanced proliferation (p < 0.01), and promoted neuronal differentiation, as revealed by significantly increased expressions of DCX and NeuN. The expressions of astroglial markers, GFAP and Olig2, were markedly reduced. The addition of MK801 (10 μM) significantly diminished neurospheres growth (p < 0.001), decreased the number of proliferating cells (p < 0.01), and reduced the number of new neurons (p < 0.001) but increased the astroglial cells (p < 0.001) induced by LEV. Co-treatment with saclofen (25 μM) did not significantly affect LEV-induced NSCs proliferation and differentiation. SignificanceOur findings suggest that LEV may enhance rat embryonic neurogenesis mainly through an NMDA receptor-mediated mechanism.

The cAMP Inducers Modify N-Acetylaspartate Metabolism in Wistar Rat Brain.

Neuronal N-acetylaspartate production appears in the presence of aspartate N-acetyltransferase (NAT8L) and binds acetyl groups from acetyl-CoA with aspartic acid. Further N-acetylaspartate pathways are still being elucidated, although they seem to involve neuron-glia crosstalk. Together with N-acetylaspartate, NAT8L takes part in oligoglia and astroglia cell maturation, myelin production, and dopamine-dependent brain signaling. Therefore, understanding N-acetylaspartate metabolism is an emergent task in neurobiology. This project used in in vitro and in vivo approaches in order to establish the impact of maturation factors and glial cells on N-acetylaspartate metabolism. Embryonic rat neural stem cells and primary neurons were maturated with either nerve growth factor, trans-retinoic acid or activators of cAMP-dependent protein kinase A (dibutyryl-cAMP, forskolin, theophylline). For in vivo, adult male Wistar rats were injected with theophylline (20 mg/kg b.w.) daily for two or eight weeks. Our studies showed that the N-acetylaspartate metabolism differs between primary neurons and neural stem cell cultures. The presence of glia cells protected N-acetylaspartate metabolism from dramatic changes within the maturation processes, which was impossible in the case of pure primary neuron cultures. In the case of differentiation processes, our data points to dibutyryl-cAMP as the most prominent regulator of N-acetylaspartate metabolism.

Calcitonin gene-related peptide induces the histone H3 lysine 9 acetylation in astrocytes associated with neuroinflammation in rats with neuropathic pain.

AimsCalcitonin gene‐related peptide (CGRP) as a regulator of astrocyte activation may facilitate spinal nociceptive processing. Histone H3 lysine 9 acetylation (H3K9ac) is considered an important regulator of cytokine and chemokine gene expression after peripheral nerve injury. In this study, we explored the relationship between CGRP and H3K9ac in the activation of astrocytes, and elucidated the underlying mechanisms in the pathogenesis of chronic neuropathic pain.MethodsAstroglial cells (C6) were treated with CGRP and differentially enrichments of H3K9ac on gene promoters were examined using ChIP‐seq. A chronic constriction injury (CCI) rat model was used to evaluate the role of CGRP on astrocyte activation and H3K9ac signaling in CCI‐induced neuropathic pain. Specific inhibitors were employed to delineate the involved signaling.ResultsIntrathecal injection of CGRP and CCI increased the number of astrocytes displaying H3K9ac in the spinal dorsal horn of rats. Treatment of CGRP was able to up‐regulate H3K9ac and glial fibrillary acidic protein (GFAP) expression in astroglial cells. ChIP‐seq data indicated that CGRP significantly altered H3K9ac enrichments on gene promoters in astroglial cells following CGRP treatment, including 151 gaining H3K9ac and 111 losing this mark, which mostly enriched in proliferation, autophagy, and macrophage chemotaxis processes. qRT‐PCR verified expressions of representative candidate genes (ATG12, ATG4C, CX3CR1, MMP28, MTMR14, HMOX1, RET) and RTCA verified astrocyte proliferation. Additionally, CGRP treatment increased the expression of H3K9ac, CX3CR1, and IL‐1β in the spinal dorsal horn. CGRP antagonist and HAT inhibitor attenuated mechanical and thermal hyperalgesia in CCI rats. Such analgesic effects were concurrently associated with the reduced levels of H3K9ac, CX3CR1, and IL‐1β in the spinal dorsal horn of CCI rats.ConclusionOur findings highly indicate that CGRP is associated with the development of neuropathic pain through astrocytes‐mediated neuroinflammatory responses via H3K9ac in spinal dorsa horn following nerve injury.This study found that CGRP act on their astrocytic receptors and lead to H3K9 acetylation (H3K9ac), which are mainly associated with proliferation‐, autophagy‐, and inflammation‐related gene expression. The number of astrocytes with H3K9ac expression is increased after nerve injury. Inhibition of CGRP attenuates the development of neuropathic pain, which was accompanied by the suppression of H3K9ac, CX3CR1, and IL‐1β expression in CCI rats.

A developmental stage- and Kidins220-dependent switch in astrocyte responsiveness to brain-derived neurotrophic factor.

Astroglial cells are key to maintain nervous system homeostasis. Neurotrophins are known for their pleiotropic effects on neuronal physiology but also exert complex functions to glial cells. Here, we investigated (i) the signaling competence of mouse embryonic and postnatal primary cortical astrocytes exposed to brain-derived neurotrophic factor (BDNF) and, (ii) the role of kinase D-interacting substrate of 220 kDa (Kidins220), a transmembrane scaffold protein that mediates neurotrophin signaling in neurons. We found a shift from a kinase-based response in embryonic cells to a response predominantly relying on intracellular Ca2+ transients [Ca2+]i within postnatal cultures, associated with a decrease in the synthesis of full-length BDNF receptor TrkB, with Kidins220 contributing to the BDNF-activated kinase and [Ca2+]i pathways. Finally, Kidins220 participates in the homeostatic function of astrocytes by controlling the expression of the ATP-sensitive inward rectifier potassium channel 10 (Kir4.1) and the metabolic balance of embryonic astrocytes. Overall, our data contribute to the understanding of the complex role played by astrocytes within the central nervous system, and identify Kidins220 as a novel actor in the increasing number of pathologies characterized by astrocytic dysfunctions. This article has an associated First Person interview with the first authors of the paper.

Astroglial and Microglial Purinergic P2X7 Receptor as a Major Contributor to Neuroinflammation during the Course of Multiple Sclerosis.

Multiple sclerosis (MS) is an autoimmune inflammatory disease of the central nervous system that leads to the progressive disability of patients. A characteristic feature of the disease is the presence of focal demyelinating lesions accompanied by an inflammatory reaction. Interactions between autoreactive immune cells and glia cells are considered as a central mechanism underlying the pathology of MS. A glia-mediated inflammatory reaction followed by overproduction of free radicals and generation of glutamate-induced excitotoxicity promotes oligodendrocyte injury, contributing to demyelination and subsequent neurodegeneration. Activation of purinergic signaling, in particular P2X7 receptor-mediated signaling, in astrocytes and microglia is an important causative factor in these pathological processes. This review discusses the role of astroglial and microglial cells, and in particular glial P2X7 receptors, in inducing MS-related neuroinflammatory events, highlighting the importance of P2X7R-mediated molecular pathways in MS pathology and identifying these receptors as a potential therapeutic target.

Monoallelic IDH1 R132H Mutation Mediates Glioma Cell Response to Anticancer Therapies via Induction of Senescence.

Heterozygous isocitrate dehydrogenase (IDH) R132H mutation (IDH1R132H/WT) is an early event during gliomagenesis. Clinically, patients with glioma carrying mutant IDH1 respond better to antitumor therapies. However, the mechanism by which IDH1 mutations contribute to gliomagenesis and therapeutic response remains elusive. Here we report that senescence is involved in the improved therapeutic responses of mutant IDH1 glioma cells. Knocking-in IDH1R132H/WT in glioma cells significantly enhanced gliomas cell senescence in response to temozolomide and radiation via a DNA-damage mediated mechanism. We further asked if senescence plays a role in IDH1R132H/WT-induced gliomagenesis. Together with ATRX knockout and p53/RB loss, IDH1R132H/WT transformed nonneoplastic human astroglial cells to form tumors in mouse brains. In-depth characterization revealed that a subset of these precancerous cells underwent senescence-like phenotypic changes, including flat and enlarged-cell morphology, increased senescence marker expression, decreased cell proliferation, and cell-cycle arrest at the G2-M phase. Mechanistic studies indicated that the combination of glioma driver genes (p53/RB/IDH1/ATRX) dramatically increased DNA damage and activated DNAdamage response (DDR) pathways ATR/ATR and Chk1/Chk2 in senescent cells. To determine how senescent cells drive tumor formation, we investigated non-cell-autonomous mechanisms such as senescence-associated secretory phenotype (SASP), a panel of proinflammatory and tissue-remodeling factors implicated in a tumor-permissive microenvironment. We found that astroglial cells carrying p53/RB/ATRX loss and IDH1R132H/WT upregulated key factors in SASP via an epigenetic-mediated mechanism. Our work suggests that drugs that specifically eliminate senescent cells could help kill precancerous cells and senescent tumor cells following antitumor therapies. IMPLICATIONS: The mechanisms by which IDH1 mutations contribute to gliomagenesis and therapeutic responses remain incompletely characterized; this work reveals senescence as a novel mechanism of IDH-mutant-mediated biological impact and describes new therapeutic opportunities concerning IDH1-mutant gliomas.

Chronic Stress Alters Astrocyte Morphology in Mouse Prefrontal Cortex.

BackgroundNeuromorphological changes are consistently reported in the prefrontal cortex of patients with stress-related disorders and in rodent stress models, but the effects of stress on astrocyte morphology and the potential link to behavioral deficits are relatively unknown.MethodsTo answer these questions, transgenic mice expressing green fluorescent protein (GFP) under the glial fibrillary acid protein (GFAP) promotor were subjected to 7, 21, or 35 days of chronic restraint stress (CRS). CRS-induced behavioral effects on anhedonia- and anxiety-like behaviors were measured using the sucrose intake and the PhenoTyper tests, respectively. Prefrontal cortex GFP+ or GFAP+ cell morphology was assessed using Sholl analysis, and associations with behavior were determined using correlation analysis.ResultsCRS-exposed male and female mice displayed anxiety-like behavior at 7, 21, and 35 days and anhedonia-like behavior at 35 days. Analysis of GFAP+ cell morphology revealed significant atrophy of distal processes following 21 and 35 days of CRS. CRS induced similar decreases in intersections at distal radii for GFP+ cells accompanied by increased proximal processes. In males, the number of intersections at the most distal radius step significantly correlated with anhedonia-like behavior (r = 0.622, P < .05) for GFP+ cells and with behavioral emotionality calculated by z-scoring all behavioral measured deficits (r = −0.667, P < .05). Similar but not significant correlations were observed in females. No correlation between GFP+ cell atrophy with anxiety-like behavior was found.ConclusionChronic stress exposure induces a progressive atrophy of cortical astroglial cells, potentially contributing to maladaptive neuroplastic and behavioral changes associated with stress-related disorders.

Inhibitors of Venezuelan Equine Encephalitis Virus Identified Based on Host Interaction Partners of Viral Non-Structural Protein 3.

Venezuelan equine encephalitis virus (VEEV) is a new world alphavirus and a category B select agent. Currently, no FDA-approved vaccines or therapeutics are available to treat VEEV exposure and resultant disease manifestations. The C-terminus of the VEEV non-structural protein 3 (nsP3) facilitates cell-specific and virus-specific host factor binding preferences among alphaviruses, thereby providing targets of interest when designing novel antiviral therapeutics. In this study, we utilized an overexpression construct encoding HA-tagged nsP3 to identify host proteins that interact with VEEV nsP3 by mass spectrometry. Bioinformatic analyses of the putative interactors identified 42 small molecules with the potential to inhibit the host interaction targets, and thus potentially inhibit VEEV. Three inhibitors, tomatidine, citalopram HBr, and Z-VEID-FMK, reduced replication of both the TC-83 strain and the Trinidad donkey (TrD) strain of VEEV by at least 10-fold in astrocytoma, astroglial, and microglial cells. Further, these inhibitors reduced replication of the related New World (NW) alphavirus Eastern equine encephalitis virus (EEEV) in multiple cell types, thus demonstrating broad-spectrum antiviral activity. Time-course assays revealed all three inhibitors reduced both infectious particle production and positive-sense RNA levels post-infection. Further evaluation of the putative host targets for the three inhibitors revealed an interaction of VEEV nsP3 with TFAP2A, but not eIF2S2. Mechanistic studies utilizing siRNA knockdowns demonstrated that eIF2S2, but not TFAP2A, supports both efficient TC-83 replication and genomic RNA synthesis, but not subgenomic RNA translation. Overall, this work reveals the composition of the VEEV nsP3 proteome and the potential to identify host-based, broad spectrum therapeutic approaches to treat new world alphavirus infections.

SOX9 Defines Distinct Populations of Cells in SHH Medulloblastoma but Is Not Required for Math1-Driven Tumor Formation.

Medulloblastoma is the most common malignant pediatric brain tumor and there is an urgent need for molecularly targeted and subgroup-specific therapies. The stem cell factor SOX9, has been proposed as a potential therapeutic target for the treatment of Sonic Hedgehog medulloblastoma (SHH-MB) subgroup tumors, given its role as a downstream target of Hedgehog signaling and in functionally promoting SHH-MB metastasis and treatment resistance. However, the functional requirement for SOX9 in the genesis of medulloblastoma remains to be determined. Here we report a previously undocumented level of SOX9 expression exclusively in proliferating granule cell precursors (GCP) of the postnatal mouse cerebellum, which function as the medulloblastoma-initiating cells of SHH-MBs. Wild-type GCPs express comparatively lower levels of SOX9 than neural stem cells and mature astroglia and SOX9low GCP-like tumor cells constitute the bulk of both infant (Math1Cre:Ptch1lox/lox ) and adult (Ptch1LacZ/+ ) SHH-MB mouse models. Human medulloblastoma single-cell RNA data analyses reveal three distinct SOX9 populations present in SHH-MB and noticeably absent in other medulloblastoma subgroups: SOX9 + MATH1 + (GCP), SOX9 + GFAP + (astrocytes) and SOX9 + MATH1 + GFAP + (potential tumor-derived astrocytes). To functionally address whether SOX9 is required as a downstream effector of Hedgehog signaling in medulloblastoma tumor cells, we ablated Sox9 using a Math1Cre model system. Surprisingly, targeted ablation of Sox9 in GCPs (Math1Cre:Sox9lox/lox ) revealed no overt phenotype and loss of Sox9 in SHH-MB (Math1Cre:Ptch1lox/lox;Sox9lox/lox ) does not affect tumor formation. IMPLICATIONS: Despite preclinical data indicating SOX9 plays a key role in SHH-MB biology, our data argue against SOX9 as a viable therapeutic target.

Neurotensin receptor 2 is induced in astrocytes and brain endothelial cells in relation to neuroinflammation following pilocarpine-induced seizures in rats.

Neurotensin (NT) acts as a primary neurotransmitter and neuromodulator in the CNS and has been involved in a number of CNS pathologies including epilepsy. NT mediates its central and peripheral effects by interacting with the NTSR1, NTSR2, and Sort1/NTSR3 receptor subtypes. To date, little is known about the precise expression of the NT receptors in brain neural cells and their regulation in pathology. In the present work, we studied the cellular distribution of the NTSR2 protein in the rat hippocampus and questioned whether its expression was modulated in conditions of neuroinflammation using a model of temporal lobe epilepsy induced by pilocarpine. This model is characterized by a rapid and intense inflammatory reaction with reactive gliosis in the hippocampus. We show that NTSR2 protein is expressed in hippocampal astrocytes and its expression increases together with astrocyte reactivity following induction of status epilepticus. NTSR2 immunoreactivity is also increased in astrocytes proximal to blood vessels and their end-feet, and in endothelial cells. Proinflammatory factors such as IL1β and LPS induced NTSR2 mRNA and protein in cultured astroglial cells. Antagonizing NTSR2 with SR142948A decreased NTSR2 expression as well as astroglial reactivity. Together, our results suggest that NTSR2 is implicated in astroglial and gliovascular inflammation and that targeting the NTSR2 receptor may open new avenues in the regulation of neuroinflammation in CNS diseases.

Metaball skinning of synthetic astroglial morphologies into realistic mesh models for visual analytics and in silico simulations.

MotivationAstrocytes, the most abundant glial cells in the mammalian brain, have an instrumental role in developing neuronal circuits. They contribute to the physical structuring of the brain, modulating synaptic activity and maintaining the blood–brain barrier in addition to other significant aspects that impact brain function. Biophysically, detailed astrocytic models are key to unraveling their functional mechanisms via molecular simulations at microscopic scales. Detailed, and complete, biological reconstructions of astrocytic cells are sparse. Nonetheless, data-driven digital reconstruction of astroglial morphologies that are statistically identical to biological counterparts are becoming available. We use those synthetic morphologies to generate astrocytic meshes with realistic geometries, making it possible to perform these simulations.ResultsWe present an unconditionally robust method capable of reconstructing high fidelity polygonal meshes of astroglial cells from algorithmically-synthesized morphologies. Our method uses implicit surfaces, or metaballs, to skin the different structural components of astrocytes and then blend them in a seamless fashion. We also provide an end-to-end pipeline to produce optimized two- and three-dimensional meshes for visual analytics and simulations, respectively. The performance of our pipeline has been assessed with a group of 5000 astroglial morphologies and the geometric metrics of the resulting meshes are evaluated. The usability of the meshes is then demonstrated with different use cases.Availability and implementationOur metaball skinning algorithm is implemented in Blender 2.82 relying on its Python API (Application Programming Interface). To make it accessible to computational biologists and neuroscientists, the implementation has been integrated into NeuroMorphoVis, an open source and domain specific package that is primarily designed for neuronal morphology visualization and meshing.Supplementary informationSupplementary data are available at Bioinformatics online.

Influence of Simulated Deep Brain Stimulation on the Expression of Inflammatory Mediators by Human Central Nervous System Cells In Vitro

Deep brain stimulation (DBS) seems to modulate inflammatory processes. Whether this modulation leads to an induction or suppression of inflammatory mediators is still controversially discussed. Most studies of the influence of electrical stimulation on inflammation were conducted in rodent models with direct current stimulation and/or long impulses, both of which differ from the pattern in DBS. This makes comparisons with the clinical condition difficult. We established an in-vitro model that simulated clinical stimulation patterns to investigate the influence of electrical stimulation on proliferation and survival of human astroglial cells, microglia, and differentiated neurons. We also examined its influence on the expression of the inflammatory mediators C-X-C motif chemokine (CXCL)12, CXCL16, CC-chemokin-ligand-2 (CCL)2, CCL20, and interleukin (IL)-1β and IL-6 by these cells using quantitative polymerase chain reaction. In addition, protein expression was assessed by immunofluorescence double staining. In our model, electrical stimulation did not affect proliferation or survival of the examined cell lines. There was a significant upregulation of CXCL12 in the astrocyte cell line SVGA, and of IL-1β in differentiated SH-SY5Y neuronal cells at both messenger RNA and protein levels. Our model allowed a valid examination of chemokines and cytokines associated with inflammation in human brain cells. With it, we detected the induction of inflammatory mediators by electrical stimulation in astrocytes and neurons.

Analysis of the Toxicity of a Cu2O Nanocomposite Encapsulated in a Polymer Matrix of Arabinogalactan

An analysis of the acute and subacute toxicity of a copper oxide nanocomposite (NC) encapsulated in natural polymeric matrix of arabinogalactan is presented. The study was carried out in two stages. At the first stage, the acute toxicity of the NC was studied. For this, white mice were orally administered one time with an aqueous solution of NC at a dose 2000 mg/kg. The study demonstrated that according to this parameter, NC belongs to low-toxicity substances of hazard class 5. At the second stage, the biological response of the white rats was evaluated with a subacute intragastric effect of Cu2ОAG NC at a dose of 500 µg/kg (based on Cu) body weight within 10 days. The study demonstrated an increase in the contents of copper in the brain tissue, liver, and kidneys compared with the control group. Morphological and neurophysiological changes were detected in white rats treated with this NC. A pronounced macrophage reaction consisting in an increase in the number of Kupffer cells in the organ sinusoids was observed in liver tissue. In the tissues of the sensorimotor cortex of the brain, a sharp decrease in the number of astroglia cells was detected, which indicates a selective cytotoxicity of this NC. When studying the bioelectric activity of the sensorimotor cortex of the brain in animals a decrease in β-2 rhythm of background electroencephalogram, as well as a decrease in the amplitude of the P2 and N2-P3 peaks of the visually evoked potentials, were observed. No genotoxic effects were detected under the influence of the NC.

Effect of Tongfu Xingshen capsule on the endogenous neural stem cells of experimental rats with intracerebral hemorrhage.

Intracerebral hemorrhage (ICH) can stimulate neural regeneration, promoting tissue repair and recovery of nerve function. Tongfu Xingshen capsule (TXC) is a Chinese medicinal formula used to treat ICH and has been shown to protect brain tissue and improve nerve function in clinical studies. However, the effect of TXC on endogenous neural stem cells (NSCs) remains elusive. To explore the mechanisms underlying TXC action, a rat model of ICH was established. The effects of TXC on the proliferation and differentiation of NSCs were assessed in the subventricular zone (SVZ). TXC significantly improved nerve function defects, decreased brain water content and restored blood-brain barrier integrity. Additionally, BrdU labeling showed that both high and low doses of TXC significantly increased the proportion of actively cycling NSCs positive for Nestin and glial fibrillary acidic protein, but did not affect the proliferation rates of NeuN-positive neurons. Finally, TXC also upregulated the mRNA levels of brain-derived neurotrophic factor and its receptor, TrκB, in affected brain tissues. Taken together, TXC accelerated neural repair and functional recovery after brain injury by potentially enhancing the proliferation and differentiation of endogenous NSCs into astroglial cells in the SVZ area.

Spinal interleukin-1β induces mechanical spinal hyperexcitability in rats: Interactions and redundancies with TNF and IL-6.

Both spinal tumor necrosis factor (TNF) and interleukin-6 (IL-6) contribute to the development of "mechanical" spinal hyperexcitability in inflammatory pain states. Recently, we found that spinal sensitization by TNF was significantly reduced by blockade of spinal IL-6 signaling suggesting that IL-6 signaling is involved in spinal TNF effects. Here, we explored whether spinal interleukin-1β (IL-1β), also implicated in inflammatory pain, induces "mechanical" spinal hyperexcitability, and whether spinal IL-1β effects are related to TNF and IL-6 effects. We recorded the responses of spinal cord neurons to mechanical stimulation of the knee joint in vivo and used cellular approaches on microglial and astroglial cell lines to identify interactions of IL-1β, TNF, and IL-6. Spinal application of IL-1β in anesthetized rats modestly enhanced responses of spinal cord neurons to innocuous and noxious mechanical joint stimulation. This effect was blocked by minocycline indicating microglia involvement, and significantly attenuated by interfering with IL-6 signaling. In the BV2 microglial cell line, IL-1β, like TNF, enhanced the release of soluble IL-6 receptor, necessary for spinal IL-6 actions. Different to TNF, IL-1β caused SNB-19 astrocytes to release interleukin-11. The generation of "mechanical" spinal hyperexcitability by IL-1β was more pronounced upon spinal TNF neutralization with etanercept, suggesting that concomitant TNF limits IL-1β effects. In BV2 cells, TNF stimulated the release of IL-1Ra, an endogenous IL-1β antagonist. Thus, spinal IL-1β has the potential to induce spinal hyperexcitability sharing with TNF dependency on IL-6 signaling, but TNF also limited IL-1β effects explaining the modest effect of IL-1β.

Toll-like receptors in neuroinflammation, neurodegeneration, and alcohol-induced brain damage.

Toll-like receptors (TLRs) or pattern recognition receptors respond to pathogen-associated molecular patterns (PAMPs) or internal damage-associated molecular patterns (DAMPs). TLRs are integral membrane proteins with both extracellular leucine-rich and cytoplasmic domains that initiate downstream signaling through kinases by activating transcription factors like AP-1 and NF-κB, which lead to the release of various inflammatory cytokines and immune modulators. In the central nervous system, different TLRs are expressed mainly in microglia and astroglial cells, although some TLRs are also expressed in oligodendroglia and neurons. Activation of TLRs triggers signaling cascades by the host as a defense mechanism against invaders to repair damaged tissue. However, overactivation of TLRs disrupts the sustained immune homeostasis-induced production of pro-inflammatory molecules, such as cytokines, miRNAs, and inflammatory components of extracellular vesicles. These inflammatory mediators can, in turn, induce neuroinflammation, and neural tissue damage associated with many neurodegenerative diseases. This review discusses the critical role of TLRs response in Alzheimer's disease, Parkinson's disease, ischemic stroke, amyotrophic lateral sclerosis, and alcohol-induced brain damage and neurodegeneration.

RNA methylation and neurovascular unit remodeling.

RNA methylation is of great significance in the regulation of gene expression, among which the more important methylation modifiers are N6-methyladenosine (m6A) and 5-methylcytosine (m5C). The methylation process is mainly regulated by 3 kinds of proteins: methyltransferase, demethylase, and reader. m6A, m5C, and their related proteins have high abundance in the brain, and they have important roles in the development of the nervous system and the repair and remodeling of the vascular system. The neurovascular unit (NVU) is a unit of brain structure and function composed of neurons, capillaries, astrocytes, supporting cells, and extracellular matrix. The local microenvironment for NVU has an important role in nerve cell function repair, and the remodeling of NVU is of great significance in the prognosis of various neurological diseases.

The features of the glymphatic system.

The glymphatic system creates a network of perivascular channels. It is made of astroglia cells, whose perikaryon extensions strongly express aquaporin-4 water channels (AQP4). The pathways of the glymphatic system ensure the transport of nutrients, including glucose, lipids, amino acids, neurotransmitters, antigens, and immune cells, as well as exchange of information via afferent and efferent immune pathways. Within the glymphatic system, convective exchange of cerebrospinal fluid (CSF) and interstitial fluid (ISF) components takes place, through aquaporin-4 water channels that facilitate fluid exchange. The proper functioning of the glymphatic system allows elimination and reabsorption of solutes, metabolites, pursuit of water and ionic balance, transport of lipid signaling molecules, regulation of intracranial pressure, cerebrospinal fluid pressure, and interstitial fluid pressure. The functions of the glymphatic system are primarily affected by the influence of the sympathetic and parasympathetic innervation, sleep and wakefulness cycle, the aging process, genetic factors, and body posture. Now, the glymphatic system shows weak activity during wakefulness, while its activity increases dramatically during sleep and the state of anesthesia. Changes occurring with age begin a number of factors that impair the function of the glymphatic system pathways. Dysfunction of the glymphatic pathways causes the aggregation of incorrectly formed proteins that underlie the development of neurodegenerative diseases. Harmful protein aggregates cause prolonged inflammation. All pathologies occurring within the central nervous system (CNS), both neurodegenerative diseases and injuries, disrupt the drainage of glymphatic pathways, which are important efflux of interstitial substances and byproducts of CNS metabolism.