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[Display omitted] • A new molecular mechanism affecting neuron apoptosis is proposed in this study. • Neuron apoptosis along with astrocyte activation take place in Alzheimer's disease. • BAI1′s expression is downregulated and astrocyte activation upregulated in rat AD models. • In vitro results prove that BAI1 inhibits astrocyte activation and neuron apoptosis. • The STAT3/EZH2 axis regulates BAI1 expression in astrocytes. Alzheimer's disease (AD) is a common neurodegenerative disease. Previous studies have identified the critical role of astrocytes in the progression of AD. The focus of this study revolves around clarifying the regulatory mechanism of the STAT3/EZH2/BAI1 axis in astrocytes in AD. We successfully developed a rat model of AD, and measured the learning and cognitive ability of the rats by Morris water maze experiment. HE and Nissl's staining were used for histomorphological identification of the rat hippocampus. Meanwhile, immunofluorescence and immunohistochemistry were used to detect astrocyte activation and brain-specific angiogenesis inhibitor-1 (BAI1) expression in rat hippocampal tissue, respectively. The role of STAT3/EZH2/BAI1 regulating axis in astrocyte activation and neuronal cell apoptosis was verified by establishing the co-culture system of astrocytes and neuronal cells in vitro. Western Blot (WB) was used to detect the expression of associated proteins, and enzyme-linked immunosorbent assay (ELISA) was used to detect astrocyte neurotrophic factor secretion. Hochest/PI staining and flow cytometry were used to observe neuronal apoptosis. Compared with the sham group, AD rats showed significantly decreased cognitive and learning abilities, noticeable hippocampal tissue damage, and significantly low levels of BAI1 expression. In in vitro models, BAI1 was found to inhibit astrocyte activation and enhance the secretion of neurotrophins, resulting in decrease of neurone apoptosis. The regulation of BAI1 by the STAT3/EZH2 axis was shown to affect astrocyte activation and neuronal cell apoptosis. In conclusion, this study represents the pioneering discovery that regulated by the STAT3/EZH2 axis, BAI1 suppresses astrocyte activation, thus reducing neuronal apoptosis. [ABSTRACT FROM AUTHOR]

Ischemic stroke is characterized by high morbidity and mortality and a lack of effective therapeutic interventions. Leptin plays an important role in regulating oxidative stress, angiogenesis, hematopoiesis, etc. Although recent studies have found a neuroprotective effect of leptin, little is known about its role in cerebral ischemia. This study explores the possible roles and potential preventative mechanisms of leptin in cerebral ischemia-reperfusion injury (CIRI). An in vivo middle cerebral artery occlusion/reperfusion (MCAO/R) mouse model was used to replicate the CIRI model, low (0.5 mg/kg), medium (1 mg/kg) and high (2 mg/kg) concentrations of leptin were injected intraperitoneally immediately after inserting the embolic line. After 1.5 h of ischemia and 24 h of reperfusion, we examined the neural function of the mice, collected brain tissue for histological examination, and screened for the optimal concentrations of leptin intervention. On this basis, we observed the changes of cortical apoptosis injury, intracellular calcium fluorescence intensity and astrocyte glial fibrillary acidic protein (GFAP) expression and morphological changes. In addition, we also tested the expression of transporters and metabolism-related enzymes (VGLUT-1, VGLUT-2, GLAST, GLT-1, GS, ATP1α1), the expression of inflammatory factors and the content of glutamate (Glu). Compared with the I/R group, we found that leptin improved neurological deficits, reduced the area of infarcts, maintained the normal morphology of astrocytes (AST), downregulated the expression of VGLUT-1, and upregulates the expression of GLT-1 and GLAST, thereby reducing the content of Glu in the synaptic cleft. Our studies suggest that leptin may have a neuroprotective effect by decreasing the excitotoxicity of glutamate., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

[Display omitted] • Glial activation and neurodegeneration contribute to the epilepsy associated cognitive impairment. • Metformin improved the TLE associated cognitive impairment by inhibiting neuroinflammation and neurodegeneration in rats. • Metformin inhibited the microglial and astroglial activation in epileptic rats. • Metformin holds promise as a therapeutic intervention for cognitive impairment associated with epilepsy. Cognitive impairment is a prevalent co-morbidity associated with epilepsy. Emerging studies indicate that neuroinflammation could be a possible link between epilepsy and its comorbidities, including cognitive impairment. In this context, the roles of glial activation, proinflammatory mediators, and neuronal death have been well studied and correlated with epilepsy-associated cognitive impairment in animal studies. While recent reports have demonstrated the anti-epileptogenic and anti-convulsant actions of metformin, its effect on epilepsy associated cognitive deficit remains unknown. Therefore, the current study investigated the effect of metformin treatment on neuroinflammation, neurodegeneration, and cognitive deficits after inducing status epilepticus (SE) with lithium-pilocarpine in rats. Metformin treatment improved the hippocampal-dependent spatial and recognition memory in Morris water maze and Novel object recognition tasks, respectively. Further, metformin treatment attenuated microglial and astroglial activation, accompanied by reduced IL-1β, COX-2 and NF-ĸβ gene expression. Additionally, metformin conferred neuroprotection by inhibiting the neuronal death as assessed by Nissl staining and transmission electron microscopy. These findings suggest that metformin holds promise as a therapeutic intervention for cognitive impairment associated with epilepsy, possibly through its modulation of glial activation and neuronal survival. Further research is needed to elucidate the precise mechanisms and to assess the long-term effect of metformin in epilepsy-associated cognitive impairment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Human astrocyte-specific genes were identified by statistical algorithm. • Shared astrocytic genes with significantly differential expression comparing samples of patients with temporal lobe epilepsy (TLE) and normal brains in two human datasets were identified. • Multiple changes of astrocyte-associated functions in the context of epilepsy were enriched. • Hub astrocyte genes (ERBB2, GFAP, NOTCH2, ITGAV, ABCA1, AQP4, LRP1, GJA1, and YAP1) were identified with a protein–protein interaction (PPI) network and cytoHubba analysis. • Upstream transcription factors of hub genes were predicted. • Five hub astrocytic genes positively paralleled with seizure frequency were identified, and preliminary explored the correlation between hub genes and epileptic phenotypes, including inflammatory mediators, complement factors, and glutamate excitotoxicity using Spearman correlation analysis. Epilepsy is a prevalent chronic neurological disorder characterized by recurrent seizures and brain dysfunction. Existing antiepileptic drugs (AEDs) mainly act on neurons and provide symptomatic control of seizures, but they do not modify the progression of epilepsy and may cause serious adverse effects. Increasing evidence suggests that reactive astrogliosis is critical in the pathophysiology of epilepsy. However, the function of reactive astrocytes in epilepsy has not been thoroughly explored. To provide a new perspective on the role of reactive astrocytes in epileptogenesis, we identified human astrocyte-specific genes and found 131 of these genes significantly differentially expressed in human temporal lobe epilepsy (TLE) datasets. Multiple astrocytic functions, such as cell adhesion, cell morphogenesis, actin filament-based process, apoptotic cell clearance and response to oxidative stress, were found to be promoted. Moreover, multiple altered astrocyte-specific genes were enriched in phagocytosis, perisynaptic astrocyte processes (PAPs), plasticity, and synaptic functions. Nine hub genes (ERBB2, GFAP, NOTCH2, ITGAV, ABCA1, AQP4, LRP1, GJA1, and YAP1) were identified by protein–protein interaction (PPI) network analysis. The correlation between the expression of these hub genes and seizure frequency, as well as epilepsy-related factors, including inflammatory mediators, complement factors, glutamate excitotoxicity and astrocyte reactivity, were analyzed. Additionally, upstream transcription factors of the hub genes were predicted. Finally, astrogliosis and the expression of the hub genes were validated in an epileptic rat model. Our findings reveal the various changes in astrocyte function associated with epilepsy and provide candidate astrocyte-specific genes that could be potential antiepileptogenic targets. [ABSTRACT FROM AUTHOR]

The secretion and cargo selection of extracellular vesicles is regulated by SUMOylation in astrocytes and HeLa cells. Stimulation of SUMOylation (via SUMO over-expression or corticosterone treatment) leads to an increased protein content per secreted sEV. In contrast, inhibition of SUMOylation using 2-D08 significantly increases the number of sEVs that cells produce but these vesicles contain a decreased quantity of total proteins. In turn, CORT stimulation increases the loading of selective proteins when compared to 2-D08 (such as AldoA and EF-2), which are potential SUMO targets. [Display omitted] • The secretion and protein cargo is regulated by SUMOylation in astrocytes and HeLa cell derived extracellular vesicles (EVs) • SUMOylation (by SUMO over-expression or corticosterone treatment) facilitates the loading of transcription and translation-related proteins into EVs. • EVs produced by astrocytes under SUMOylation-favorable conditions increase the protein synthesis in target neurons. Emerging evidence highlights the relevance of the protein post-translational modification by SUMO (Small Ubiquitin-like Modifier) in the central nervous system for modulating cognition and plasticity in health and disease. In these processes, astrocyte-to-neuron crosstalk mediated by extracellular vesicles (EVs) plays a yet poorly understood role. Small EVs (sEVs), including microvesicles and exosomes, contain a molecular cargo of lipids, proteins, and nucleic acids that define their biological effect on target cells. Here, we investigated whether SUMOylation globally impacts the sEV protein cargo. For this, sEVs were isolated from primary cultures of astrocytes by ultracentrifugation or using a commercial sEV isolation kit. SUMO levels were regulated: 1) via plasmids that over-express SUMO, or 2) via experimental conditions that increase SUMOylation, i.e., by using the stress hormone corticosterone, or 3) via the SUMOylation inhibitor 2-D08 (2′,3′,4′-trihydroxy-flavone, 2-(2,3,4-Trihydroxyphenyl)-4H-1-Benzopyran-4-one). Corticosterone and 2-D08 had opposing effects on the number of sEVs and on their protein cargo. Proteomic analysis showed that increased SUMOylation in corticosterone-treated or plasmid-transfected astrocytes increased the presence of proteins related to cell division, transcription, and protein translation in the derived sEVs. When sEVs derived from corticosterone-treated astrocytes were transferred to neurons to assess their impact on protein synthesis using the fluorescence non-canonical amino acid tagging assay (FUNCAT), we detected an increase in protein synthesis, while sEVs from 2-D08-treated astrocytes had no effect. Our results show that SUMO conjugation plays an important role in the modulation of the proteome of astrocyte-derived sEVs with a potential functional impact on neurons. [ABSTRACT FROM AUTHOR]

The cerebellar cortex contains several classes of GABAergic neurons. Previous studies have shown that most GABAergic neurons in this region possess the capacity for gamma-aminobutyric acid (GABA) uptake. The present study determined the postnatal expression of two GABA transporters, GAT-1 and GAT-3, in the cerebellar cortex and deep nuclei of the rat by using immunocytochemistry. Immunoreactivity for GAT-1 and GAT-3 appears at postnatal day 7 (P7), emerges centroperipherally across the cerebellum during the following 2 weeks and reaches an adult-like pattern by P30. The mature patterns are fully established by P45, which for GAT-1 is characterized by immunolabeled profiles localized exclusively to neuropil, mostly in the molecular layer and the pinceaux deep to the Purkinje cell bodies, and for GAT-3 as immunoreactivity distributed in the neuropil of mainly the granular layer. Before the adult patterns are completed, GAT-1 immunoreactivity is present in the somata of Purkinje, Golgi, basket and stellate cells between P7 and P21, while GAT-3 immunoreactivity is distinct in astrocytic somata which are organized in regularly spaced clusters. During this period, there is also a banding pattern in the sagittal plane of GAT-1 immunoreactivity in developing Purkinje cells. The postnatal development of GAT-1 and GAT-3 in the rat cerebellar cortex shares a similar spatiotemporal pattern with other GABAergic parameters, including the GABA synthesizing enzyme, GABA content and uptake. Specifically, the transient expression of GAT-1 in the somata and dendrites of cerebellar GABAergic neurons appears to correlate with the supra-adult levels of whole-tissue GABA uptake capability during development. Further, GAT-1 expression in immature Purkinje cells may play a unique role in regulating GABA's function during development, since mature Purkinje cells do not express GAT-1 or take up GABA.

• Culture medium from OGD preconditioned astrocytes ameliorates OGD-induced neuron injury. • Exosomes derived from preconditioned astrocytes can be internalized into neurons. • OGD preconditioning promotes the production of exosomal miR-92b-3p from astrocytes. • MiR-92b-3p mimic as same as exosomes from preconditioned astrocytes exerts protective effects on neurons after OGD. Ischemic preconditioning (IPC) exerts protective effects against ischemic cerebral injury. In the present study, an in vitro model of cerebral ischemia (oxygen and glucose deprivation, OGD) was established to investigate the neuroprotective mechanism of IPC. We found that conditioned medium (C.M.) from astrocytes rather than neurons nor microglia cell line BV2 exerted neuroprotection. Moreover, exosomes derived from OGD preconditioned astrocytes can be taken up by neurons and attenuated OGD-induced neuron death and apoptosis. High-throughput microRNA (miRNA) sequencing revealed that miR-92b-3p levels in exosomes released from preconditioned astrocytes were increased. Overexpression of miR-92b-3p in neurons with miR-92b-3p mimic achieved the same protective effects as C.M. from astrocytes. Thus, we propose that the mechanism of IPC may associate with astrocytes, and that exosome-mediated miR-92b-3p shuttle from preconditioned astrocytes to neurons participate in these process. [ABSTRACT FROM AUTHOR]

Highlights • OGD upregulates CYP4A expression and 20-HETE production in astrocytes. • Conditioned media from stimulated astrocytes promotes angiogenesis through 20-HETE. • HET0016 suppresses angiogenesis and worsens neurological outcomes 14 days poststroke. • 20-HETE mediates OGD activated VEGF and HIF-1α via JNK pathway in astrocytes. • HET0016 decreases VEGF and HIF-1α by inhibiting JNK pathway in ischemic brains. Abstract 20-Hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P450 4A (CYP4A) metabolite of arachidonic acid, is one of the primary eicosanoids in most of microcirculatory beds. Studies have indicated that 20-HETE has important functions in the modulation of vascular tone, ion transport, inflammation reaction, and cellular proliferation. Both we and others have demonstrated that 20-HETE plays an important role in acute phase of ischemic stroke. However, little is known about the effect of 20-HETE on recovery phase of stroke. Crosstalk between the cells within the neurovascular unit is increasingly suspected of playing critical roles in stroke recovery. We found that CYP4A is upregulated in astrocytes exposed to oxygen-glucose deprivation (OGD), which increases the production of 20-HETE that promotes endothelial cell proliferation, tube formation and migration. siRNA suppression of CYP4A or 20-HETE inhibitor prevents this effect. In a mouse model of transient focal cerebral ischemia, inhibition of CYP4A reduces peri-infact angiogenesis and worsens neurological deficits 14 days after stroke. We further showed that ischemia injury increases VEGF and HIF-1α expression in cell cultures and ischemic brains, which is negated by a 20-HETE inhibitor-HET0016. Lastly, we showed that JNK signaling pathway is a component of 20-HETE regulated ischemic angiogenesis after stroke. Taken together, we demonstrated a positive influence of 20-HETE in angiogenesis in later stage of stroke. These molecular and in vivo findings also support a previously undescribed mechanism of crosstalk between reactive astrocytes and endothelial cells wherein 20-HETE promotes neurovascular remodeling and functional recovery after ischemic stroke. [ABSTRACT FROM AUTHOR]

Highlights • Granulovacuolar inclusions were found in tau-transgenic but not APP-transgenic mice. • Granulovacuolar inclusions increase with tau-pathology in human tau transgenic mice. • The ESCRTIII proteins CHMP2B and VPS4a are present in granulovacuolar inclusions. • AT8-positive astrocytes in ARTAG cases are strongly CHMP2B-immunoreactive. Abstract Charged multivesicular body protein 2b (CHMP2B) is a subunit of the endosomal sorting complex required for transport (ESCRT)-III that mediates scission of budded membranes. Neurons with CHMP2B-positive granulovacuolar inclusions in the cytoplasm are much more frequent in hippocampi of cases with Alzheimer's disease when compared with controls. We analyzed immunolabeled brain sections from tau-transgenic mice, APP-transgenic mice, non-transgenic mice, and human hippocampi to investigate the relation between CHMP2B and tau and plaque pathology that are major histopathological features of Alzheimer's disease. Neurons undergoing granulovacuolar degeneration (GVD) were found in human hippocampi and old tau-trangenic mice but not in the APP-transgenic strains. 57% of neurons with GVD displayed GVD-granules double-labeled for CHMP2B and the GVD-marker casein kinase 1δ in 24 months-old tau-transgenic mice and 5.7% of neurons with tau hyper-phosphorylated at Thr212 and Ser214 (immunoreactive with antibody AT100) displayed CHMP2B-positive GVD-granules, in human hippocampi it was 100% and 46% respectively. The number of neurons with GVD-inclusions increased in tau-transgenic mice with the number of AT100-positive neurons, suggesting a link between tau-pathology and GVD. GVD-granules in human hippocampi also displayed immunoreactivity for Vps4a, another protein component of ESCRT-III. In cases with aging-related tau astrogliopathy (ARTAG), astrocytes containing hyper-phosphorylated tau immunoreactive with antibody AT8 displayed strong CHMP2B immunoreactivity. The results suggest dysregulation of CHMP2B together with tau-pathology and possibly a disturbance of the regulation of vesicular compartments. The absence of combined Aβ- and tau-associated pathology in the transgenic mice may account for the difference in CHMP2B-immunoreactivity between the transgenic mice and human hippocampus. [ABSTRACT FROM AUTHOR]

Highlights • We examined production of non-canonical nucleotides by brain cells. • In microglia, oxidative stress increased extracellular 2'-AMP by ∼16-fold. • In astrocytes and neurons, oxidative stress did not increase extracellular 2'-AMP. • In microglia, extracellular 2'-AMP and adenosine were correlated. • 2'-AMP may regulate microglia via adenosine. Abstract Background Microglia metabolize exogenous 2'-AMP and 3'-AMP (non-canonical nucleotides) to adenosine and exogenous 2'-AMP and 3'-AMP (via conversion to adenosine) inhibit the production of inflammatory cytokines by microglia. This suggests that if microglia release endogenous 2'-AMP and/or 3'-AMP in response to injurious stimuli, this would complete an autocrine/paracrine mechanism that attenuates the over-activation of microglia during brain injury. Here we investigated in microglia (and for comparison astrocytes and neurons) the effects of injurious stimuli on extracellular and intracellular levels of 2',3'-cAMP (2'-AMP and 3'-AMP precursor), 2'-AMP, and 3'-AMP. Methods Experiments were conducted in primary cultures of rat microglia, astrocytes, and neurons. Cells were exposed to oxygen/glucose deprivation, iodoacetate plus 2,4-dinitrophenol (metabolic inhibitors), glutamate, or H 2 O 2 for one hour, and extracellular and intracellular 2',3'-cAMP, 2'-AMP, and 3'-AMP were measured by UPLC-MS/MS. Key results In microglia, H 2 O 2 increased extracellular levels of 2'-AMP, but not 3'-AMP, by ∼16-fold (from 0.17 ± 0.11 to 2.78 ± 0.27 ng/106 cells; n = 13; mean ± SEM; P < 0.000005). H 2 O 2 also induced oxidative changes in cellular proteins as detected by an increased number of carbonyl groups in protein side chains. In contrast, oxygen/glucose deprivation, metabolic inhibitors, or glutamate had no effect on either extracellular 2'-AMP or 3'-AMP levels. In astrocytes and neurons, none of the injurious stimuli increased extracellular 2'-AMP or 3'-AMP. Conclusions Oxidative stress (but not oxygen/glucose deprivation, energy deprivation, or excitotoxicity) induces microglia (but not astrocytes or neurons) to release 2'-AMP, but not 3'-AMP. The 2',3'-cAMP/ 2'-AMP /adenosine pathway mechanism may serve to prevent over-activation of microglia in response to oxidative stress. [ABSTRACT FROM AUTHOR]

Highlights • NEUROG2/ASCL1 instruct different neuronal fates in NPCs and reprogrammed astroglia. • Origin of astroglia affects the acquisition of final neuronal phenotype of iNs. • Reprogramming of astroglia is a powerful tool to probe neuronal fate specification. Abstract The adult mammalian brain contains an enormous variety of neuronal types, which are generally categorized in large groups, based on their neurochemical identity, hodological properties and molecular markers. This broad classification has allowed the correlation between individual neural progenitor populations and their neuronal progeny, thus contributing to probe the cellular and molecular mechanisms involved in neuronal identity determination during central nervous system (CNS) development. In this review, we discuss the contribution of the proneural genes Neurogenin2 (Neurog2) and Achaete-scute homolog 1 (Ascl1) for the specification of neuronal phenotypes in the developing neocortex, cerebellum and retina. Then, we revise recent data on astroglia cell lineage reprogramming into induced neurons using the same proneural proteins to compare the neuronal phenotypes obtained from astroglial cells originated in those CNS regions. We conclude that Ascl1 and Neurog2 have different contributions to determine neuronal fates, depending on the neural progenitor or astroglial population expressing those proneural factors. Finally, we discuss some possible explanations for these seemingly conflicting effects of Ascl1 and Neurog2 and propose future approaches to further dissect the molecular mechanisms of neuronal identity specification. [ABSTRACT FROM AUTHOR]

Highlight • MHY908 attenuated MPTP-induced motor deficits and dopaminergic neuronal death. • MHY908 also ameliorated MPTP-induced glial activation in the STR and SN. • MHY908 pretreatment protected SH-SY5Y neuroblastoma cells against MPP+ toxicity. • Pretreatment of MHY908 inhibited MPP+-induced ROS generation. • MHY908 treatment attenuated MPP+-induced primary astrocyte activation and nuclear translocation of NF-κB. Abstract Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are considered promising therapeutic targets in several neurodegenerative diseases. A number of PPAR agonists have been shown to have neuroprotective properties in the presence of oxidative stress, neuroinflammatory response, and apoptosis in various neurodegenerative disease. MHY908 is a novel PPAR α/γ dual agonist, which has been shown to suppress inflammatory response and attenuate insulin resistance in aged rats and db/db mice. Here, we evaluated the neuroprotective effects of MHY908 in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. Pretreatment with MHY908 attenuated MPTP-induced dopaminergic neuronal loss and motor deficit. MPTP-induced glial activations were mitigated by MHY908 in the nigrostriatal pathway, and MHY908 effectively blocked 1-methyl-4-phenylpyridinium (MPP+)-induced cell death and ROS production in SH-SY5Y neuroblastoma cells. Further study revealed MHY908 inhibited MPP+-induced astroglial activation by suppressing NF-κB signaling in primary astrocytes. Taken together, the present study suggests that PPAR α/γ dual agonists be considered potentially useful preventions for PD and other neurodegenerative diseases associated with neuroinflammation. [ABSTRACT FROM AUTHOR]

Highlights • HFD induces astrocyte activation in the hippocampus. • HFD represses the process arborization of the hippocampal astrocytes. • HFD downregulates the hippocampal expression of astrocytic glutamate transporters. • HFD induces depression-like behaviors in mice. Abstract Metabolic disorders induce adverse effects on brain functions. The hippocampus is one of the most vulnerable regions to metabolic disorders. Disrupted neuroplasticity is a major cause of hippocampus-related behavioral impairments, including memory loss, anxiety, and depression. Astrocytes support processes of neuroplasticity. However, whether metabolic disorders induce changes in astrocytes and their roles in affective disorders is relatively unclear. To answer this question, we fed 8-week-old male C57BL/6 mice with a high-fat diet (HFD) for 12 weeks to induce metabolic disruption and then examined their performance of hippocampus-related memory, and anxiety- and depression-like behaviors. The morphology of astrocytes and the expression of astrocytic neuroplasticity-related proteins in the hippocampus were also assessed. The results showed that HFD led to obesity, systemic insulin resistance and dysregulated lipid metabolism in mice. HFD induced depression-like behaviors, but not anxiety or memory impairment. Furthermore, HFD increased the expression of GFAP, shortened the processes of GFAP+ cells, and downregulated the expression of astrocytic neuroplasticity-related protein, GLAST, GLT-1, and connexin-43 in the hippocampi. In conclusion, HFD disturbs the function of hippocampal astrocytes and induces depression-like behaviors in mice. A decrease of hippocampal glutamate transporters may play a critical role in the pathogenesis of metabolic disorder-related depression. [ABSTRACT FROM AUTHOR]

Highlights • Astrocytes express all adenosine receptor subtypes. • ARA1 has superior adenosine binding ability. • Function of immune suppressive in CNS. Abstract The four kinds of adenosine receptor subtypes (ARs), named as ARA1, ARA2A, ARA2B and ARA3, have multiple biological functions. ARs are differently distributed across the body and have distinguished ability of binding adenosine. We try to figure out how these ARs were expressed in astrocytes and which one has the first priority of utilizing adenosine. Firstly, mRNA expressions and membrane localization of all ARs were evaluated by qPCR and western blot. After the membrane localization of all ARs in astrocytes was being confirmed their individual adenosine binding ability was determined by radio-active ligand binding assay respectively. It was revealed that ARA1 had much superior adenosine binding ability than other AR subtypes. Functional study demonstrated that ARA1 potentially mediated an immune suppressive effect in astrocytes. The activation of ARA1 signaling lead to decreased IL-12 and IL-23 production, and decreased chemokine production, including CCL2, CXCL8 and IP-10. When interacted with CD4 cells ARA1 agonist pre-treated astrocytes showed hindered ability of stimulating CD4 cells to secret IL-17 and IFN-γ and inducing CD4 cells' chemo taxi. Finally, in vivo experiment confirmed that local administration of ARA1agonist ameliorated EAE in wild type B6 recipients, but not Ara1 -/- recipients. As a conclusion, this paper suggested that adenosine receptor A1 subtype predominantly binds adenosine in astrocytes and mediates an immunosuppressive effect. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Superior sagittal sinus occlusion in rats induces subacute venous infarction. • Cerebral venous thrombosis (CVT) causes MMP9 mediated BBB breakdown. • CVT induces neuroinflammation and microglia activation. • CVT causes NLRP3 inflammasome activation and caspase-1 mediated cell death. Abstract Cerebral venous thrombosis (CVT) is a rare form of cerebral stroke that causes a variety of symptoms, ranging from mild headache to severe morbidity or death in the more severe forms. The use of anti-coagulant or thrombolytic agents is the classical treatment for CVT. However, the development of new therapies for the treatment of the condition has not been the focus. In this study, we aimed to analyze the pathophysiology of CVT and to identify the pathways associated with its pathology. Moreover, mechanisms that are potential drug targets were identified. Our data showed the intense activation of immune cells, particularly the microglia, along with the increase in macrophage activity and NLRP3 inflammasome activation that is indicated by NLRP3, IL-1β, and IL-18 gene and caspase-1 upregulation and cleavage as well as pyroptotic cell death. Leukocytes were observed in the brain parenchyma, indicating a role in CVT-induced inflammation. In addition, astrocytes were activated, and they induced glial scar leading to parenchymal contraction during the subacute stage and tissue loss. MMP9 was responsible primarily for the BBB breakdown after CVT and it is mainly produced by pericytes. MMP9 activation was observed before inflammatory changes, indicating that BBB breakdown is the initial driver of the pathology of CVT. These results show an inflammation driven pathophysiology of CVT that follows MMP9-mediated BBB breakdown, and identified several targets that can be targeted by pharmaceutical agents to improve the neuroinflammation that follows CVT, such as MMP9, NLRP3, and IL-1β. Some of these pharmaceutical agents are already in clinical practice or under clinical trials indicating a good potential for translating this work into patient care. [ABSTRACT FROM AUTHOR]

Highlights • Fibrinogen (Fg) dose-dependently activates astrocytes. • Fg-activated astrocytes overexpress ICAM-1 and TrkB, result in TrkB phosphorylation. • Fg may bind the activated astrocytes via ICAM-1. Abstract Fibrinogen (Fg)-containing plaques are associated with memory loss during various inflammatory neurodegenerative diseases such as Alzheimer's disease, multiple sclerosis, stroke, and traumatic brain injury. However, mechanisms of its action in neurovascular unit are not clear. As Fg is a high molecular weight blood protein and cannot translocate far from the vessel after extravasation, we hypothesized that it may interact with astrocytes first causing their activation. Cultured mouse cortical astrocytes were treated with Fg in the presence or absence of function-blocking anti-mouse intercellular adhesion molecule 1 (ICAM-1) antibody, or with medium alone (control). Expressions of ICAM-1 and tyrosine receptor kinase B (TrkB) as markers of astrocyte activation, and phosphorylation of TrkB (pTrkB) were assessed. Fg dose-dependently increased activation of astrocytes defined by their shape change, retraction of processes, and enhanced expressions of ICAM-1 and TrkB, and increased pTrkB. Blocking of ICAM-1 function ameliorated these Fg effects. Data suggest that Fg interacts with astrocytes causing overexpression of ICAM-1 and TrkB, and TrkB phosphorylation, and thus, astrocyte activation. Since TrkB is known to be involved in neurodegeneration, interaction of Fg with astrocytes and the resultant activation of TrkB can be a possible mechanism involved in memory reduction, which were observed in previous studies and were associated with formation of complexes of Fg deposited in extravascular space with proteins such as Amyloid beta or prion, the proteins involved in development of dementia. [ABSTRACT FROM AUTHOR]

Highlights • Independent validation of differential methylation of the APOE gene in AD brain. • Application of FANS to separate neuronal and glial nuclei from postmortem brain. • Altered APOE DNA methylation in the AD brain occurs in glial cells. Abstract The apolipoprotein E gene (APOE) is the strongest genetic risk factor for developing Alzheimer’s disease (AD). Our recent identification of altered APOE DNA methylation in AD postmortem brain (PMB) prompted this follow-up study. Our goals were to (i) validate the AD-differential methylation of APOE in an independent PMB study cohort and (ii) determine the cellular populations (i.e., neuronal vs. non-neuronal) of AD PMB that contribute to this differential methylation. Here, we obtained an independent cohort of 57 PMB (42 AD and 15 controls) and quantified their APOE methylation levels from frontal lobe and cerebellar tissue. We also applied fluorescence-activated nuclei sorting (FANS) to separate neuronal nuclei from non-neuronal nuclei within the tissue of 15 AD and 14 control subjects. Bisulfite pyrosequencing was used to generate DNA methylation profiles of APOE from both bulk PMB and FANS nuclei. Our results provide independent validation that the APOE CGI holds lower DNA methylation levels in AD compared to control in frontal lobe but not cerebellar tissue. Our data also indicate that the non-neuronal cells of the AD brain, which are mainly composed of glia, are the main contributors to the lower APOE DNA methylation observed in AD PMB. Given that astrocytes are the primary producers of ApoE in the brain our results suggest that alteration of epigenetically regulated APOE expression in glia could be an important part of APOE ’s strong effect on AD risk. [ABSTRACT FROM AUTHOR]

Alzheimer’s disease (AD) is one of the leading causes of dementia that induced by aggregation of amyloid-beta (Aβ) in brain tissue. With high structural and functional plasticity, hippocampus plays fundamental roles in cognitive regulation. Moreover, impaired hippocampal functions present during early onset of AD. Hence, targeting on improving hippocampal plasticity would be recognized as the effective strategy in AD therapy. Physical exercise is widely encouraged healthy life style. However, whether exercise could reserve the neural dysfunctions in AD model and the possible neurobiological mechanism still need for better understanding. In current study, we created the AD model by intra-hippocampal injection of Aβ. Afterward, mice were administrated with treadmill running to mimic the physical exercise. Our results show that physical exercise prevented the Aβ-induced cognitive deficits in object recognition task and the Morris water maze. Morphological studies reveal physical exercise increased the adult neurogenesis and release the immune-response in hippocampal dentate gyrus (DG) region. In addition, physical exercise released the immune-response by decreasing the level of cytokines and population of astrocytes that elevated by injection of Aβ. We also found that physical exercise changed the modification of ERK, p38 and JNK, which recognized as the representative MAPK signaling involving with hippocampal neural functions. In conclusion, exercise serves as a potential strategy to prevent the development of AD by regulating adult neurogenesis and brain immune-activity via controlling MAPK signaling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Lipocalin-2 is upregulated in high glutamate-stimulated astrocyte enriched cultures. • Metabotropic glutamate receptor 3 in astrocytes is involved in the increase of Lcn2. • Lcn2 expression is increased in murine astrocytes after pilocarpine-induced seizure. • Lcn2 expression is increased in human cerebrospinal fluid after status epilepticus. Glutamate-induced excitotoxicity is mainly mediated by neuronal NMDA receptors; however, it is unclear how astrocytes are involved in this phenomenon. This study aimed to explore the effects of excess glutamate on astrocytes both in vitro and in vivo. We used astrocyte-enriched cultures (AECs), in which microglia were removed from mixed glial cultures, to investigate the effects of extracellular glutamate on these cells by microarray, quantitative PCR, ELISA, and immunostaining. We also examined the production of lipocalin-2 (Lcn2) by immunohistochemistry in the brains of mice after status epilepticus induced by pilocarpine and by ELISA in the cerebrospinal fluid (CSF) of patients characterised by status epilepticus. Microarray analysis identified Lcn2 as a factor upregulated in AECs by excess glutamate; glutamate addition increased Lcn2 in the cytoplasm of astrocytes and AECs released Lcn2 in a concentration-dependent manner. Lcn2 production was reduced by chemical inhibition of metabotropic glutamate receptor or siRNA knockdown of metabotropic glutamate receptor 3. Furthermore, Lcn2 was increased in the astrocytes of a status epilepticus mouse model and in the CSF of human patients. These results indicate that astrocytes stimulate Lcn2 production via metabotropic glutamate receptor 3 in response to high concentrations of glutamate. [ABSTRACT FROM AUTHOR]

• Spinal astrocytes in Stress-induced gastric mucosal damage in rat. • Astrocytic toxin L-a-aminoadipate (L-AA) prevented the stress-induced gastric damage. • Astrocytes contributed to the stress-induced gastric damage via CX43. Rat restraint water-immersion stress (RWIS) is a compound stress of high intensity and is widely used to study the pathological mechanisms of stress gastric ulcers. The spinal cord, as a part of the central nervous system, plays a dominant role in the gastrointestinal tract, but whether the spinal cord is involved in rat restraint water-immersion stress (RWIS)-induced gastric mucosal damage has not been reported. In this study, we examined the expression of spinal astrocytic glial fibrillary acidic protein (GFAP), neuronal c-Fos, connexin 43 (Cx43), and p-ERK1/2 during RWIS by immunohistochemistry and Western blotting. In addition, we intrathecally injected the astrocytic toxin L-a-aminoadipate (L-AA), gap junction blocker carbenoxolone (CBX), and ERK1/2 signaling pathway inhibitor PD98059 to explore the role of astrocytes in the spinal cord in RWIS-induced gastric mucosal damage and its possible mechanism in rats. The results showed that the expression of GFAP, c-Fos, Cx43, and p-ERK1/2 was significantly elevated in the spinal cord after RWIS. Intrathecal injection of both the astrocyte toxin L-AA and the gap junction blocker CBX significantly attenuated RWIS-induced gastric mucosal damage and decreased the activation of astrocytes and neurons induced in the spinal cord. Meanwhile, the ERK1/2 signaling pathway inhibitor PD98059 significantly inhibited gastric mucosal damage, gastric motility and RWIS-induced activation of spinal cord neurons and astrocytes. These results suggest that spinal astrocytes may regulate the RWIS-induced activation of neurons via CX43 gap junctions and play a critical role in RWIS-induced gastric mucosa damage through the ERK1/2 signaling pathway. [ABSTRACT FROM AUTHOR]

The two most studied polyphenolic compounds, curcumin (Cur) and resveratrol (Res), have been reported to protect oxidative damage of astrocytes. The present study is designed to examine the comparative anti-oxidative effect of Cur and Res on astrocytes by studying their potential to protect H 2 O 2 induced oxidative stress at 4 h and 24 h time exposure. The effect of Cur and Res on cell viability, ROS production, inflammation and astrogliosis was compared. The effect of these two on Nrf2 expression and its translocation to nuclear compartment was investigated. The results showed that both Cur and Res significantly increase astrocytes survival after oxidative stress at both time points, however, Res demonstrated better effect on cell viability than the Cur. Res, showing significant inhibition of ROS production at both time points. Cur displayed significant inhibition of ROS production at 4 h, suggesting that Cur is more active on ROS inhibition in the earlier phase of insult. Comparing the expression of NF-κB, Cur showed better anti-inflammatory action on NF-κB while Res did not have any effect of NF-κB expression at 4 h. Interestingly, Cur showed an upregulation of nuclear Nrf2 expression at 24 h whereas Res displayed no effect after 24 h incubation. Both Cur and Res inhibited the H 2 O 2 induced translocation of Nrf2 into nucleus. In conclusion, based on our observation, we found that Cur and Res both protected astrocytes from oxidative stress. In addition, we observed that Cur is most effective in early hours of insult while Res is effective in late hours suggesting that Res may or may not have immediate effect on astrocytes. [ABSTRACT FROM AUTHOR]

Background Microglia are the main resident immunological cells of the central nervous system (CNS) that are functionally equivalent to macrophages. However, due to the cellular heterogeneity of the brain, it is technically challenging to obtain highly specific, healthy microglia with the desired phenotype in sufficient yield for in vivo experiments. New method This study presents a new and easy method for the isolation of microglia cells from mouse pups (P1-P3). This method consists of a 20-day protocol, divided in three sections: mixed cell culture, culture maintaining (astrocytes growing), and isolation after astrocytes confluence. Results This procedure produces microglia with no astrocyte, neuron and oligodendrocyte precursors cells contamination that are functionally active to answer inflammatory responses based on the measurement of cell and inflammatory markers. This technique requires approximately three hours for the isolation of neonatal mixed cell culture, 20 to 22 days for microglia growing and two days before starting experiments from pure and healthy microglia. Comparison with existing methods and conclusions This study presents an isolation protocol that is adapted from existing methods and is economic, rapid, not tedious, with little manipulation time and work. This method also allows to isolate large amount of high specific microglia cells with no specific phenotype and with great reproducibility and efficiently. This study provides a detailed description of the methods that is routinely used in our laboratory for the isolation and the culture of microglia, with emphasis on the steps that are deemed most critical for obtaining large amount of pure and healthy cultures. [ABSTRACT FROM AUTHOR]

Enriched environment (EE) has been shown to promote post-stroke neurogenesis and functional recovery. However, the underlying molecular mechanisms remains poorly understood. Male C57BL/6 mice underwent 60-min middle cerebral artery occlusion (MCAO) followed by reperfusion, after which mice were housed in either standard environment (SE) or EE. We found that post-ischemic EE exhibited reduced protein level of nuclear factor κB (NF-κB)/p65 in cytoplasm and increased its expression correspondingly in nucleus at 28 days post-ischemia (dpi). However, post-ischemic EE had no effects on terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL)-positive cells in ischemic hemisphere at 28dpi. EE mice treated with NF-kB inhibitor Bay11-7082 had decreased subventricular zone (SVZ) neural precursor cells (NPCs) proliferation, neuronal differentiation and subsequent functional recovery after stroke at 28dpi. Bay11-7082 treatment attenuated the promoting effects of post-ischemic EE on interleukin 17A (IL-17A) messenger RNA (mRNA) and protein expression at 28dpi. Furthermore, our in vitro data revealed that in primary astrocyte cultures addition of Bay11-7082 markedly decreased the expression of IL-17A in both the cell lysate and culture supernatant of activated astrocytes. Blockade of IL-17A with neutralizing antibody abrogated the promoting role of EE in NPCs proliferation derived from SVZ, neuronal differentiation and subsequent functional recovery after stroke. Thus, our results reveal a previously uncharacterized property of NF-κB/IL-17A signaling pathway in EE-mediated neurogenesis and functional recovery after ischemic stroke. [ABSTRACT FROM AUTHOR]

Maladaptive alterations of astrocytic plasticity may cause brain edema in the acute stage of stroke and glial scar formation in the recovery stage. The present study was designed to investigate the potential regulation of limb remote ischemic post-conditioning (RIPC) on astrocytic plasticity in experimental cerebral ischemia-reperfusion injury. Cerebral ischemia was induced by transient middle cerebral artery occlusion (tMCAO) for 1 h in C57BL/6 mice, who were treated with RIPC immediately after reperfusion. The results showed that RIPC decreased hemispheric swelling, infarct volume and brain atrophy, and increased neurological function recovery and survival rates of ischemic mice at 3 and 14 d after cerebral ischemia-reperfusion, respectively. Moreover, the proportion of astrocyte subtypes was adjusted by RIPC treatment, demonstrated by decreased expression of the fibrous type (glial fibrillary acidic protein, GFAP) and increased expression of the protoplasmic type (glutamine synthetase, GS) in the ipsilateral side of the mouse brain at 14 d after cerebral ischemia-reperfusion. RIPC treatment adjusted the proportion of GFAP subtypes by downregulating the protein level of GFAPα, as well as upregulating the GFAPδ/GFAPα ratio in the ipsilateral side at 3 and 14 d after reperfusion. Notably, RIPC inhibited the phosphorylation of signal transducer and activators of transcriptions 3 (p-STAT3) in the ipsilateral side at 3 and 14 d after cerebral ischemia-reperfusion. Taken together, the results show that RIPC treatment could regulate reactive astrocytic plasticity and inhibition of STAT3 phosphorylation to promote neurological function recovery following ischemic stroke. [ABSTRACT FROM AUTHOR]

Lysophosphatidic acid (LPA) and cyclic phosphatidic acid (cPA) are one of the lipid mediators regulating cell proliferation and differentiation through the activation of LPA receptors. An LPA receptor-mediated signal is important for the development of the central nervous system, while it has been demonstrated that LPA caused microglial activation and astroglial dysfunction. Previously, we have reported that cPA and carba analog of cPA, 2- O -carba-cPA (2ccPA), protected neural damage caused by transient ischemia. However, little is known about the target cell of cPA/2ccPA in the central nervous system s . Here, we examined the effect of 2ccPA on glial proliferation and differentiation using the primary astrocytes and oligodendrocyte precursor cells (OPCs) cultures. 2ccPA increased the DNA synthesis of astrocytes and OPCs, but it did not reduce the formazan production in the mitochondria. Further, 2ccPA increased the cell number and cell survival against oxidative stress. The inhibition of LPA receptors by ki16425 abolished 2ccPA-induced DNA synthesis. Extracellular signal-regulated kinase (ERK) was activated by 2ccPA, which contributed to the astroglial DNA synthesis. These results suggest that 2ccPA is a beneficial regulator of glial population through the activation of LPA receptor without reduction of mitochondrial activity. [ABSTRACT FROM AUTHOR]

In Alzheimer’s disease (AD), dementia severity correlates most strongly with decreased synapse density in the hippocampus and cerebral cortex. Although studies in rodents have established that hippocampal long-term potentiation (LTP) is inhibited by soluble oligomers of beta-amyloid (Aβ), the synaptic mechanisms remain unclear. Here, field excitatory postsynaptic potentials (fEPSP) recordings were made in the CA1 region of mouse hippocampal slices. The medium of APP-expressing CHO cells, which contain soluble forms of Aβ including small oligomers, inhibited LTP and facilitated long-term depression (LTD), thus making the LTP/LTD curve shift toward the right. This phenomenon could be mimicked by the non-selective glutamate transporter inhibitor, DL-TBOA. More specifically, the Aβ impaired LTP and facilitated LTD were occluded by the selective astrocytic glutamate transporter inhibitors, TFB-TBOA. In cultured astrocytes, the Aβ oligomers also decrease astrocytic glutamate transporters (EAAT1, EAAT2) expression. We conclude that soluble Aβ oligomers decrease the activation of astrocytic glutamate transporters, thereby impairing synaptic plasticity. [ABSTRACT FROM AUTHOR]

MiR-30d has been demonstrated to regulate autophagy in human cancer cells. However, the role of miR-30d in astrocytes exposed to hypoxia-ischemia is not clear. In this study, we established model of oxygen and glucose deprivation (OGD) with rat primary astrocytes and evaluated the role of miR-30d in the cross-talk between autophagy and apoptosis in astrocytes after OGD. We found that miR-30d inhibited Beclin1 expression in astrocytes. Inhibition of miR-30d by antagomir significantly increased cell autophagy but decreased cell apoptosis in astrocytes exposed to OGD. Knockdown of Beclin1 reversed the upregulation of autophagy and downregulation of apoptosis induced by miR-30d inhibition in astrocytes subjected to OGD. These results strongly indicated that miR-30d played critical roles in the cross-talk between autophagy and apoptosis of astrocytes subjected to OGD by targeting Beclin1. MiR-30d is a novel target to attenuate cell injury under hypoxia-ischemia condition. [ABSTRACT FROM AUTHOR]

Schizophrenia is a highly heritable disorder with a heterogeneous symptomatology. Research increasingly indicates the importance of the crucial and often overlooked glial perturbations within schizophrenia. Within this study, we examined an isoform of quaking (a gene encoding an RNA-binding protein that is exclusively expressed in glial cells), known as QKI6B , and a prototypical astrocyte marker, glial fibrillary acidic protein ( GFAP ), postulated to be under the regulation of QKI . The expression levels of these genes were quantified across post-mortem brain samples from 55 schizophrenic individuals, and 55 healthy controls, using real-time PCR. We report, through an analysis of covariance (ANCOVA) model, an upregulation of both QKI6B , and GFAP in the prefrontal cortex of brain samples of schizophrenic individuals, as compared to control samples. Previous research has suggested that the QKI protein directly regulates the expression of several genes through interaction with a motif in the target’s sequence, termed the Quaking Response Element (QRE). We therefore examined if QKI6B expression can predict the outcome of GFAP , and several oligodendrocyte-related genes, using a multiple linear regression approach. We found that QKI6B significantly predicts the expression of GFAP , but does not predict oligodendrocyte-related gene outcome, as previously seen with other QKI isoforms. [ABSTRACT FROM AUTHOR]

Transglutaminase 2 (TG2) is a multifunctional protein that can contribute to cell death and cell survival processes in a variety of disease contexts. Within the brain, TG2 has been shown to promote cell death in ischemic injury when expressed in astrocytes ( Colak and Johnson, 2012 ). However, the specific functions and characteristics of astrocytic TG2 that mediate this effect are largely unknown. Therefore, the goal of this study was to investigate the role of astrocytic TG2 in mediating cellular viability processes in the context of ischemic injury, with a specific focus on its contributions to intracellular signaling cascades. We show that, in response to oxygen/glucose deprivation (OGD), acute lentiviral-mediated knockdown of TG2, as well as inhibition with an irreversible TG2 inhibitor, enhances cell survival. We also show that TG2 depletion increases nuclear factor-κB (NF-κB) signaling, whereas inhibition reduces NF-κB activity. Despite its clear contribution to NF-κB signaling, however, TG2 modulation of NF-κB signaling is not likely to be a major contributor to its ability to mediate astrocytic viability in this context. Overall, the results of this study provide insight into the role of TG2 in astrocytes and suggest possible avenues for future study of the relationship between astrocytic TG2 and ischemic injury. [ABSTRACT FROM AUTHOR]

Interferon (IFN)-stimulated genes (ISGs) exert multiple functions in immune system. IFN-induced protein 35 (IFI35) is a member of ISGs, and has been suggested to regulate innate immune reaction. However, the physiological functions and pathological roles of IFI35 in the central nervous system are not characterized well. In the present study, we found that the expression of IFI35 was induced by a Toll-like receptor 3 (TLR3) ligand polyinosinic-polycytidylic acid (poly IC) in U373MG human astrocytoma cells. Knockdown of IFI35 using RNA interference resulted in increased expression of IFN-β, phosphorylated STAT1 (P-STAT1), retinoic acid-inducible gene-I (RIG-I), CXCL10 and CCL5 induced by poly IC. Poly IC-induced expression of CXCL10 and CCL5 was decreased by knockdown of RIG-I. These results suggest that IFI35 may negatively regulate the TLR3-IFN-β-P-STAT1-RIG-I-CXCL10/CCL5 axis in U373MG cells, and IFI35 may play a role at least partially in the regulation of innate immune reactions in astrocytes. [ABSTRACT FROM AUTHOR]

Motoneuron degeneration is the hallmark of amyotrophic lateral sclerosis (ALS). The cause and predisposing factors for sporadic ALS are still unknown. Exposure to a specific environmental risk factors in subjects with a susceptibility genotype may increase the risk of the disease. The role of physical activity and the use of anabolic steroids are still debated in epidemiological studies on patients and murine models of ALS. To assess at the cellular level the role (beneficial or detrimental) of physical exercise and the use of anabolic steroid, we here investigated, in SOD1(G93A) (mSOD1) mice and wild-type littermates, changes in the ventral horn after regular exercise, treatment with the anabolic androgenic steroid 19-nortestosterone (nandrolone), and their combination, compared with matched control sedentary mice. The experiments were pursued for several weeks until symptom onset in mSOD1 mice. Lumbar motoneurons, astrocytes and microglia were analyzed. In wild-type mice, cytological alterations of motoneurons were observed especially after nandrolone treatment. The following main findings were observed in treated mSOD1 mice versus untreated ones: i ) nandrolone treatment markedly enhanced motoneuron loss; this detrimental effect was reverted by the combination with exercise, resulting in increased motoneuron survival; ii ) astrocytic activation was most marked after nandrolone treatment when motoneuron damage was most severe; iii ) microglia activation was most marked after physical exercise when motoneuron damage was less severe. The results indicate a vulnerability of mSOD1 motoneurons to nandrolone treatment, a potential neuroprotective effect of physical exercise, and a modulation by glial cells in the ALS murine model in the examined paradigms. [ABSTRACT FROM AUTHOR]

The ability to accurately and systematically evaluate the cellular mechanisms underlying human neurodegenerative disorders such as Alzheimer׳s disease (AD) should lead to advancements in therapeutics. Recent developments in human induced pluripotent stem cells (iPSCs) have afforded the opportunity to use human neurons and glia to study cellular changes involved in neurological diseases. iPSCs have the potential to be differentiated into AD-relevant cell types, including forebrain neurons, astrocytes, and microglia. This permits the evaluation of individual cell types in isolation or in concert, thus modeling the interdependence of cell types within the brain. When discussing the potential of modeling AD with iPSCs, it is important to remember that the umbrella diagnosis of “Alzheimer׳s disease” represents a disease that is heterogeneous in terms of age of onset, underlying causes, and at times precise pathology. The ability of iPSCs to be derived from an array of AD patients allows for a closer examination of the mechanism of disease progression in particular subsets of subjects, who may have different mutations and allelic variants affecting their risk for disease. Disease mechanisms can be probed both by the genetic manipulation of iPSCs and by modifications to the cellular environment by chemical treatment. These studies may lead not only to the refinement of known pathways implicated in AD, but also to the identification of novel pathways heretofore unaffiliated with disease pathology. In this review, we describe the potential of iPSC models to transform our understanding of AD and to lead to valuable advancements in therapeutics. This article is part of a Special Issue entitled SI: Exploiting human neurons . [ABSTRACT FROM AUTHOR]

Physical exercise can induce brain plasticity and reduce the cognitive decline observed in type 1 diabetes mellitus (T1DM). We investigated the effects of physical exercise to prevent or reverse spatial memory deficits produced by diabetes and some biochemical and immunohistochemical changes in hippocampal astrocytes of T1DM model. In this study, 56 male Wistar rats were divided in four groups: trained control (TC), non-trained control (NTC), trained diabetic (TD) and non-trained diabetic (NTD). 27 days after streptozotocin-induced (STZ) diabetes, the exercise groups were submitted to 5 weeks of aerobic exercise. All groups were assessed in place recognition (PR) test before and after training. The glial fibrillary acidic protein (GFAP) positive astrocytes were evaluated using planar morphology, optical densitometry and Sholl's concentric circles method. Glucose and glutamate uptake, reduced glutathione (GSH) and glutamine synthetase (GS) levels were measured using biochemical assays. Our main results are: 1-Exercise reverses spatial memory impairments generated by T1DM; 2-Exercise increases GSH and GS in TC but not in TD rats; 3-Exercise increases density of GFAP positive astrocytes in the TC and TD groups and increases astrocytic ramification in TD animals. Our findings indicate that physical exercise reverses the cognitive deficits present in T1DM and induces important biochemical and immunohistochemical astrocytic changes. [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) leads to glial scar formation by astrocytes, which severely hinders neural regeneration. Curcumin (cur) can inhibit glial scar formation, but the underlying mechanism is not fully understood. Using both in vivo and in vitro experiments, the current study investigated the phenotypic transformation of astrocytes following cur and siRNA intervention during the processes of inflammation and fibrosis and determined details of the relationship between cur treatment and the glial scar components GFAP and CSPG. We found that cur and NF-κb p65 siRNA could inhibit astrocyte activation through suppressing NF-κb signaling pathway, which led to down-regulate the expression of chemokines MCP-1, RANTES and CXCL10 released by astrocytes and decreased macrophage and T-cell infiltration, thus reducing the inflammation in the glial scar. In addition, silencing SOX-9 may reduce the deposition of extracellular matrix CSPG; whereas its over-expression could increase the CSPG expression. Cur suppressedSOX-9-inducedCSPG deposition, reduced α-SMA (an important symbol of fibrosis) expression in astrocytes, altered astrocyte phenotype, and inhibited glial scar formation by regulating fibrosis. This study confirmed that cur could regulate both the NF-κb and SOX9 signaling pathways and reduce the expression of intracellular and extracellular glial scar components through dual-target regulating both inflammation and fibrosis after SCI in the rat. This study provides an important hypothesis centered on the dual inhibition of intracellular and extracellular glial scar components as a treatment strategy for SCI. [ABSTRACT FROM AUTHOR]

Voltage-gated Ca 2+ channels (VGCCs) are comprised of α1, α 2 /δ, β, and γ subunits. The pore-forming α1 subunit is essential for the proper functioning of Ca 2+ channels, while the α 2 /δ subunit interacts with components of the extracellular matrix. The α 2 /δ subunit is related in many neuropathological symptoms, including epilepsy and cerebellar ataxia. We previously reported that the mutant Cav.2.1α1 subunit has protective effects following brain injury. The present study aimed to investigate the effects of the α 2 /δ subunit inhibition alone and in combination with the inhibition of the Cav.2.1α1 subunit following brain injury by injecting Gabapentin using Cav.2.1α1 mutant heterozygous rolling Nagoya ( rol /+) and wild-type (+/+) mice. Gabapentin binds to the α 2 /δ subunit and leads to Ca 2+ flow disturbance. A cryogenic method was used to induce brain injury. The mice pretreated with 100 mg/kg Gabapentin exhibited a decrease in lesion size, while the 40 mg/kg Gabapentin injection was effective in rol /+ mice but not +/+ mice. The administration of 100 mg/kg Gabapentin also attenuated reactive astrocyte activity and neuronal degeneration; the pattern of results was similar to that for lesion size. An analysis of phosphorylated p38 (pp38) expression revealed that Gabapentin suppressed the p38 mitogen-activated protein kinase (MAPK) signaling cascade by interrupting glutamate-signaling induced by the inhibition of VGCCs. The present findings demonstrated that the administration of the α 2 /δ subunit inhibitor, Gabapentin, had neuroprotective effects following brain injury. [ABSTRACT FROM AUTHOR]

[Display omitted] • EPO increases glutamate uptake in astrocytes undergoing ischemia. • EPO preserves Na,K-ATPase function in ischemic astrocytes. • EPO restores intracellular pH in astrocytes via an effect on NHE. • EPO have beneficial effects on energy production in astrocytes and neurons. Erythropoietin (EPO) has neuroprotective effects in central nervous system injury models. In clinical trials EPO has shown beneficial effects in traumatic brain injury (TBI) as well as in ischemic stroke. We have previously shown that EPO has short-term effects on astrocyte glutamatergic signaling in vitro and that administration of EPO after experimental TBI decreases early cytotoxic brain edema and preserves structural and functional properties of the blood-brain barrier. These effects have been attributed to preserved or restored astrocyte function. Here we explored the effects of EPO on astrocytes undergoing oxygen-glucose-deprivation, an in vitro model of ischemia. Measurements of glutamate uptake, intracellular pH, intrinsic NADH fluorescence, Na,K-ATPase activity, and lactate release were performed. We found that EPO within minutes caused a Na,K-ATPase-dependent increase in glutamate uptake, restored intracellular acidification caused by glutamate and increased lactate release. The effects on intracellular pH were dependent on the sodium/hydrogen exchanger NHE. In neuron-astrocyte co-cultures, EPO increased NADH production both in astrocytes and neurons, however the increase was greater in astrocytes. We suggest that EPO preserves astrocyte function under ischemic conditions and thus may contribute to neuroprotection in ischemic stroke and brain ischemia secondary to TBI. [ABSTRACT FROM AUTHOR]

Nectins are Ca 2+ -independent immunoglobulin-like cell–cell adhesion molecules. In the nervous system, among four members (nectin-1, -2, -3, and -4), nectin-1 and -3 are asymmetrically localized at puncta adherentia junctions formed between the mossy fiber terminals and the dendrites of CA3 pyramidal neurons in the mouse hippocampus and heterophilic trans -interactions between nectin-1 and nectin-3 are involved in the selective interaction of axons and dendrites of cultured neurons. By contrast, nectin-2, which has two splicing variants, nectin-2α and -2δ, has not been well characterized in the brain. We showed here that nectin-2α was expressed in both cultured mouse neurons and astrocytes whereas nectin-2δ was selectively expressed in the astrocytes. Nectin-2δ was localized at the adhesion sites between adjacent cultured astrocytes, but in the brain it was localized on the plasma membranes of astrocytic perivascular endfoot processes facing the basement membrane of blood vessels. Genetic ablation of nectin-2 caused degeneration of astrocytic perivascular endfoot processes and neurons in the cerebral cortex. These results uncovered for the first time the localization and critical functions of nectin-2 in the brain. [ABSTRACT FROM AUTHOR]

This study was undertaken to examine the function of extracellular signal–regulated kinase (ERK) signaling pathway on the proliferation and activation of microglia/macrophage and astrocytes after brain injury in mice. The result of Western blot showed that p-ERK was immediately activated after injury (<4 h), but the duration was short (<4 days). According to immunofluorescence double staining, it was found that at 4 and 8 h after injury, p-ERK was expressed in microglia/macrophages, and that more cells were co-expressed by p-ERK and IBA-1 (microglia/macrophage marker) at 8 h; at days 1 and 4, p-ERK was expressed in astrocytes, and more cells were co-expressed by p-ERK and GFAP (astrocyte marker) at day 4. After injury, the mice were injected with U0126 (MAPK/ERK signaling pathway inhibitor) via the femoral vein. Compared with those injected with DMSO, the cell number co-expressed by p-ERK and IBA-1 or GFAP significantly decreased ( P <0.05). The increase of microglia/macrophage and astrocyte caused by injury was remitted, and the positive cell number significantly decreased ( P <0.05). Western blot showed that the expression quantity of IBA-1 and GFAP significantly decreased ( P <0.05). Furthermore, the ERK signaling pathway was involved in the proliferation and activation of the two glial cells types and improved long-term neurobehavioral function after brain injury. Therefore, the exploration of the formation mechanism of glial scar after injury and further research on the therapeutic method of neural regeneration are essential. [ABSTRACT FROM AUTHOR]

Chronic traumatic encephalopathy (CTE) is caused by progressive neurodegeneration associated with repetitive head impacts. This disease is more common in professionals who practice contact sports, resulting in a concussion and subconcussive trauma. CTE is characterized by the accumulation of hyperphosphorylated tau protein in neurons, astrocytes, and frontotemporal lobe degeneration. Symptoms are usually nonspecific and overlap with other neurodegenerative diseases, such as Alzheimer's disease and frontotemporal dementia, making it difficult to provide drug treatment for patients with this comorbidity. Therefore, the objective of this article is to present an updated review of the pharmacological treatment of chronic traumatic encephalopathy and its challenges., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

[Display omitted] • Exposure to a fluid shear stimulus enhanced the astrocyte Ca2+ response hours later, the cells have a memory of the early mechanical event. • The memory effect is enhanced with multiple additional stimuli. • Inhibiting Ca2+ influx did not eliminate the stress potentiation, indicating that the cells' memory bears mechanical origin. Traumatic brain injury (TBI) is a major risk factor for development of neurodegenerative disorders later in life. Short, repetitive, mechanical impacts can lead to pathology that appears days or months later. The cells have a physical "memory" of mechanical events. The origin of this memory is not known. To examine the properties of this memory, we used a microfluidic chip to apply programmed fluid shear pulses to adherent adult rat astrocytes. These caused a transient rise in intracellular Ca2+. In response to repeated stimuli, 6 to 24 hrs apart, the Ca2+ response increased. This effect lasted longer than 24 hrs. The Ca2+ responses were more sensitive to the number of repetitions than to the rest time between stimuli. We found that inhibiting the Ca2+ influx during conditioning stimulus did not eliminate the stress potentiation, suggesting that mechanical deformation during the primary injury is accountable for the later response. The mechanical mechanism that triggers this long term "memory" may act by plastic deformation of the cytoskeleton. [ABSTRACT FROM AUTHOR]

Objective This study aimed to investigate whether β-amyloid (Aβ) was able to enhance neurocan expression in a Sox9 dependent manner in astrocytes. Methods and materials Astrocytes were incubated with Aβ at different concentrations, the expression of Sox9 and neurocan was detected by Western blot assay. Meanwhile, the viability and proliferation of astrocytes were assessed by MTT assay. Then, the Sox9 expression was silenced, and the expression of Sox9 and neurocan was examined. Results After incubation with Aβ, the viability of astrocytes was increased regardless silencing of Sox9 (all P<0.05). The proliferation of astrocytes was also gradually increased with the increase in the time of Aβ incubation (all P<0.05). With the increase in Aβ concentration, the expression of Sox9 and neurocan was also increased (all P<0.05). However, after silencing of Sox9 expression, the neurocan expression was significantly reduced as compared to control group and scra-siRNA group (all P<0.05). Conclusion Our study shows the viability and proliferation of astrocytes are significantly increased by Aβ in a dose dependent manner. Moreover, Aβ may effectively up-regulate the neurocan expression via regulating Sox9. [ABSTRACT FROM AUTHOR]

In 1969 a paper entitled Neuronal plasticity in the septal nuclei of the adult rat proposed that new synapses are formed in the adult brain after injury (Raisman, 1969). The quantitative electron microscopic study of the timed responses to selective partial denervation of the neuropil of the adult rat septal nuclei after distant transection of the hippocampal efferent axons in the fimbria showed that the new synapses arise by sprouting of surviving adjacent synapses which selectively take over the previously denervated sites and thus restore the number of synapses to normal. This article presents the evidence for the role of perisynaptic astrocytic processes in the removal and formation of synapses and considers its significance as one of the three major divisions of the astrocytic surface in terms of the axonal responses to injury and regeneration. This article is part of a Special Issue entitled SI:50th Anniversary Issue . [ABSTRACT FROM AUTHOR]

Background Angiotensin (Ang) II, a bio-peptide of the renin-angiotensin system (RAS), plays a pivotal role in biological systems. It has been well established that in the brain, astrocytes are the predominant source for angiotensinogen (AGT), which is the precursor molecule for Ang II. The primary objective of this study was to determine the effect of Ang II on AGT mRNA and protein expression levels in primary cultures of astrocytes isolated from the brainstem and cerebellum regions of spontaneously hypertensive rats (SHRs) and normotensive Wistar rats. Methods Astrocytes were treated with 100 nM Ang II and the effect of time and the receptors involved in AGT mRNA and protein expression were measured using qPCR, and western blotting techniques, respectively. Results Ang II significantly downregulated AGT mRNA levels and upregulated AGT protein levels in both SHR and Wistar rat astrocytes. Basal AGT mRNA levels in SHR samples were significantly lower as compared to Wistar astrocytes isolated from brainstem and cerebellum. There was no difference in the basal AGT protein levels when SHR and Wistar samples were compared. There was a tendency for higher Ang II-induced AGT protein levels in SHR samples compared to normotensive controls, but the difference was not significant. Ang II tended to decrease AGT mRNA levels of Wistar samples to a greater degree than SHR samples. The Ang AT 1 receptor mediated the actions of Ang II on AGT protein and mRNA levels. Conclusion These findings highlight the complexity of AGT regulation and show that AGT protein and mRNA levels are responsive to Ang II in both SHR and Wistar astrocytes. Most importantly, our findings suggest that this peptide can induce its own synthesis by positively regulating AGT protein synthesis, an effect that was more robust in SHR astrocytes. Thus, dysregulation of this system may be important in preserving the hypertensive phenotype in this model. [ABSTRACT FROM AUTHOR]

Bone morphogenetic protein-3 (BMP3) is a very unique member of the TGF-β superfamily, because it functions as an antagonist to both the canonical BMP and activin pathways and plays important roles in multiple biological events. Although BMP3 expression has been described in the early development of the kidney, intestine and bone, little information is available for BMP3 expression in the central nervous system (CNS). We, thus, investigated BMP3 expression in the adult rat CNS using immunohistochemistry. BMP3 was intensely expressed in most neurons and their axons. Furthermore, we found that astrocytes and ependymal cells also express BMP3 protein. These data indicate that BMP3 is widely expressed throughout the adult CNS, and its abundant expression in the adult brain strongly supports the idea that BMP3 plays important roles in the adult brain. [ABSTRACT FROM AUTHOR]

Inflammation is extremely important in the development of cerebral ischemia/reperfusion injury. Pannexin 1 (Panx1) channel has been reported to activate inflammasome in astrocytes and be involved in ischemic injury, but this damage effect is reversed by a Panx1 inhibitor—probenecid. However, the mechanism of probenecid protects against cerebral ischemia/reperfusion injury remains unclear. In present study, we hypothesized that probenecid protected astrocytes from ischemia/reperfusion injury in vitro by modulating the inflammasome. Primary cultured neocortical astrocytes were exposed to oxygen–glucose deprivation/reoxygenation (OGD/RX) and probenecid was added in this model. Viability and nuclear morphology of astrocytes, production of reactive oxygen species (ROS), protein expressions of NLRP3 (NOD-like receptor protein 3), caspase-1, and AQP4 (Aquaporins 4), as well as release of cellular HMGB1 and IL-1β were observed to evaluate the effect and mechanisms of probenecid on OGD/reoxygenated astrocytes. Probenecid did not affect cell viability at concentrations of 1, 5, 10, and 100 μM but induced significant astrocytes death at 500 μM. Probenecid inhibited cell death and ROS generation in astrocytes subjected to 6 h of OGD and 24 h of reoxygenation. The expression levels of NLRP3, caspase-1, and AQP4 increased after 6 h of OGD, but probenecid treatment attenuated this increase. Moreover, the extracellular release of IL-1β and HMGB1 from OGD/reoxygenated astrocytes increased significantly. However, treatment by probenecid resulted in substantial reduction of these proteins levels in extracellular space. In conclusion, The Panx1 inhibitor, probenecid, which was administered before OGD, provided protective effects on the OGD/reoxygenation model of cultured astrocytes by modulating inflammasome activity and downregulating AQP4 expression. [ABSTRACT FROM AUTHOR]

Little is known about the mechanisms of unconsciousness induced by general anesthetics. Previous studies have shown that the primary somatosensory cortex (S1) is a sensitive region to a variety of intravenous general anesthetics. Etomidate is a widely used intravenous anesthetic that can influence synaptic transmission. Recently, there are some evidences suggesting that astrocytes, a type of glia cell, also contribute to information transmission in the brain, and modulate synaptic function by releasing neuroactive substances. However, it is unknown whether astrocytes influence the effects of etomidate on information transmission in S1 pyramidal neurons. In the present study, the role of astrocytes in etomidate-induced unconsciousness was investigated by using the whole-cell patch clamp technique. We observed etomidate at clinically relevant concentrations inhibited the spontaneous postsynaptic currents (sPSCs) of rat S1 pyramidal neurons in a concentration-dependent manner, and the EC50 value of etomidate for inhibiting sPSCs from the concentration-effect curve was 6.9 μM. Furthermore, in the presence of fluorocitrate, a glia-selective metabolism inhibitor that blocks the aconitase enzyme, both the amplitude and frequency of sPSCs in rat S1 pyramidal neurons were reduced, and the inhibitory effects of etomidate on sPSCs amplitude was strengthened without affecting the effects of etomidate on frequency. From these data, we deduce that etomidate suppresses synaptic activity via presynaptic and postsynaptic components. Furthermore, astrocytes participate in synaptic transmission and influence the effects of etomidate on postsynaptic receptors. This study provides new insight into the role of astrocytes in etomidate-induced unconsciousness. [ABSTRACT FROM AUTHOR]

In the central nervous system, NG2-glia are the cells responsible for the generation of mature oligodendrocytes during development and adulthood. Some studies could show that NG2-glia can give origin also to astrocytes and neurons, a property that makes them similar to neural stem cells. Beside their important role as progenitors, NG2-glia are believed also to have more functions due to their unique interaction with neurons through synapses. It is however not clear whether these features are common to all NG2-glia or different subpopulations of NG2-glia devoted to different functions exist. Therefore the aim of this review is to highlight the state of the art on NG2-glia heterogeneity from development to adulthood and in different brain areas, and discuss the impact of it on our understanding of the glial neurobiology. This article is part of a Special Issue entitled SI:NG2-glia(Invited only) . [ABSTRACT FROM AUTHOR]