Activation of A1 reactive astrocytes in the medullary dorsal horn of rats participates in the chronification of trigeminal neuralgia. / å¤§é¼ å»¶é«“èƒŒè§’A1åž‹ååº”æ€§æ˜Ÿå½¢èƒ¶è´¨ç»†èƒžæ¿€æ´»å‚ä¸Žä¸‰å‰ç¥žç»ç—›æ ¢æ€§åŒ–.

OBJECTIVES: The activation of astrocytes is an important process in the formation of chronic pain. This study aims to observe the activation of A1 reactive astrocytes in the medullary dorsal horn in the rat model of trigeminal neuralgia, and to explore the mechanism of central sensitization caused by A1 reactive astrocyte. METHODS: The adult male rats were randomly divided into a sham group and a chronic constriction injury of infraorbital nerve (ION-CCI) group. The facial mechanical pain threshold and thermal withdrawal latency were measured before the operation and on the 1st, 3rd, 7th, 10th, and 14th day after the operation. After pain behavior observation, the expression of glial fibrillary acidic protein (GFAP) in the medullary dorsal horn was observed by immunohistochemistry and immunofluorescence colocalization of GFAP, complement 3 (C3)/S100A10, and 4', 6-diamidino-2-phenylindole (DAPI) was analyzed. Primary astrocytes were cultured and randomly divided into a naive group and a DHK group. The DHK group was treated with 1 mmol/L of astrocyte activation inhibitor dihydrokainic acid (DHK). Fura-2/AM was used to stain the astrocytes and the calcium wave of the 2 groups under the stimulation of high potassium was recorded and compared. The expression of C3 was detected by Western blotting. RESULTS: The facial mechanical pain threshold and thermal withdrawal latency of the ION-CCI group were significantly lower than those of the sham group (both P<0.05). There were a large number of GFAP positive astrocytes in the medullary dorsal horn of the ION-CCI group. The fluorescence intensity of GFAP in the ION-CCI group was higher than that in the sham group (P<0.05). GFAP and C3/S100A10 were co-expressed in astrocytes. Compared with the sham group, the fluorescence intensity of C3 and the protein expression of C3 in the ION-CCI group were increased (both P<0.05). The expression of C3 in ION-CCI group was significantly increased (P<0.05). Compared with the naive group, the C3 protein expression was significantly decreased in the DHK group (P<0.05). The intensity of calcium fluorescence was increased after high potassium stimulation in both groups. Furthermore, the peak and increase amplitude of calcium fluorescence in the naive group were much higher than those in the DHK group (both P<0.05). CONCLUSIONS: A1 reactive astrocytes in the medullary dorsal horn of trigeminal neuralgia model rats are increased significantly, which may participate in central sensitization of trigeminal neuralgia by impacting astrocyte calcium wave.

Taurine ameliorates sensorimotor function by inhibiting apoptosis and activating A2 astrocytes in mice after subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a form of severe acute stroke with very high mortality and disability rates. Early brain injury (EBI) and delayed cerebral ischemia (DCI) contribute to the poor prognosis of patients with SAH. Currently, some researchers have started to focus on changes in amino acid metabolism that occur in brain tissues after SAH. Taurine is a sulfur-containing amino acid that is semi-essential in animals, and it plays important roles in various processes, such as neurodevelopment, osmotic pressure regulation, and membrane stabilization. In acute stroke, such as cerebral hemorrhage, taurine plays a neuroprotective role. However, the role of taurine after subarachnoid hemorrhage has rarely been reported. In the present study, we established a mouse model of SAH. We found that taurine administration effectively improved the sensorimotor function of these mice. In addition, taurine treatment alleviated sensorimotor neuron damage and reduced the proportion of apoptotic cells. Furthermore, taurine treatment enhanced the polarization of astrocytes toward the neuroprotective phenotype while inhibiting their polarization toward the neurotoxic phenotype. This study is the first to reveal the relationship between taurine and astrocyte polarization and may provide a new strategy for SAH research and clinical treatment.

Preparation of Healthy Single Neuron or Astrocyte Suspension from Adult Mouse Brain for RNA-seq.

Single-cell RNA sequencing (scRNA-seq) has been widely applied in neuroscience research, enabling the investigation of cellular heterogeneity at the transcriptional level, the characterization of rare cell types, and the detailed analysis of the stochastic nature of gene expression. Isolation of single nerve cells in good health, especially from the adult rodent brain, is the most difficult and critical process for scRNA-seq. Here, we describe methods to optimize protease digestion of brain slices, which enable yield of millions of cells in good health from the adult brain.

Multicore fiber optic imaging reveals that astrocyte calcium activity in the mouse cerebral cortex is modulated by internal motivational state.

Astrocytes are a direct target of neuromodulators and can influence neuronal activity on broad spatial and temporal scales in response to a rise in cytosolic calcium. However, our knowledge about how astrocytes are recruited during different animal behaviors remains limited. To measure astrocyte activity calcium in vivo during normative behaviors, we utilize a high-resolution, long working distance multicore fiber optic imaging system that allows visualization of individual astrocyte calcium transients in the cerebral cortex of freely moving mice. We define the spatiotemporal dynamics of astrocyte calcium changes during diverse behaviors, ranging from sleep-wake cycles to the exploration of novel objects, showing that their activity is more variable and less synchronous than apparent in head-immobilized imaging conditions. In accordance with their molecular diversity, individual astrocytes often exhibit distinct thresholds and activity patterns during explorative behaviors, allowing temporal encoding across the astrocyte network. Astrocyte calcium events were induced by noradrenergic and cholinergic systems and modulated by internal state. The distinct activity patterns exhibited by astrocytes provides a means to vary their neuromodulatory influence in different behavioral contexts and internal states.

Conversion of Astrocyte Cell Lines to Oligodendrocyte Progenitor Cells Using Small Molecules and Transplantation to Animal Model of Multiple Sclerosis.

Astrocytes, the most prevalent cells in the central nervous system (CNS), can be transformed into neurons and oligodendrocyte progenitor cells (OPCs) using specific transcription factors and some chemicals. In this study, we present a cocktail of small molecules that target different signaling pathways to promote astrocyte conversion to OPCs. Astrocytes were transferred to an OPC medium and exposed for five days to a small molecule cocktail containing CHIR99021, Forskolin, Repsox, LDN, VPA and Thiazovivin before being preserved in the OPC medium for an additional 10 days. Once reaching the OPC morphology, induced cells underwent immunocytofluorescence evaluation for OPC markers while checked for lacking the astrocyte markers. To test the in vivo differentiation capabilities, induced OPCs were transplanted into demyelinated mice brains treated with cuprizone over 12 weeks. Two distinct lines of astrocytes demonstrated the potential of conversion to OPCs using this small molecule cocktail as verified by morphological changes and the expression of PDGFR and O4 markers as well as the terminal differentiation to oligodendrocytes expressing MBP. Following transplantation into demyelinated mice brains, induced OPCs effectively differentiated into mature oligodendrocytes. The generation of OPCs from astrocytes via a small molecule cocktail may provide a new avenue for producing required progenitors necessary for myelin repair in diseases characterized by the loss of myelin such as multiple sclerosis.

Effect of total flavonoids of Dracocephalum moldavica L. On neuroinflammation in Alzheimer's disease model amyloid-ß (Aß1-42)-peptide-induced astrocyte activation.

One of the main pathological features noted in Alzheimer's disease (AD) is the presence of plagues of aggregated ß-amyloid (Aß1-42)-peptides. Excess deposition of amyloid-ß oligomers (AßO) are known to promote neuroinflammation. Sequentially, following neuroinflammation astrocytes become activated with cellular characteristics to initiate activated astrocytes. The purpose of this study was to determine whether total flavonoids derived from Dracocephalum moldavica L. (TFDM) inhibited Aß1-42-induced damage attributed to activated C8-D1A astrocytes. Western blotting and ELISA were used to determine the expression of glial fibrillary acidic protein (GFAP), and complement C3 to establish the activation status of astrocytes following induction from exposure to Aß1-42. Data demonstrated that stimulation of C8-D1A astrocytes by treatment with 40 µM Aß1-42 for 24 hr produced significant elevation in protein expression and protein levels of acidic protein (GFAP) and complement C3 accompanied by increased expression and levels of inflammatory cytokines. Treatment with TFDM or the clinically employed drug donepezil in AD therapy reduced production of inflammatory cytokines, and toxicity initiated following activation of C8-D1A astrocytes following exposure to Aß1-42. Therefore, TFDM similar to donepezil inhibited inflammatory secretion in reactive astrocytes, suggesting that TFDM may be considered as a potential compound to be utilized in AD therapy.

Neuroprotective role of lactate in a human in vitro model of the ischemic penumbra.

In patients suffering from cerebral ischemic stroke, there is an urgent need for treatments to protect stressed yet viable brain cells. Recently, treatment strategies that induce neuronal activity have been shown to be neuroprotective. Here, we hypothesized that neuronal activation might maintain or trigger the astrocyte-to-neuron lactate shuttle (ANLS), whereby lactate is released from astrocytes to support the energy requirements of ATP-starved hypoxic neurons, and this leads to the observed neuroprotection. We tested this by using a human cell based in vitro model of the ischemic penumbra and investigating whether lactate might be neuroprotective in this setting. We found that lactate transporters are involved in the neuroprotective effect mediated by neuronal activation. Furthermore, we showed that lactate exogenously administered before hypoxia correlated with neuroprotection in our cellular model. In addition, stimulation of astrocyte with consequent endogenous production of lactate resulted in neuroprotection. To conclude, here we presented evidence that lactate transport into neurons contributes to neuroprotection during hypoxia providing a potential basis for therapeutic approaches in ischemic stroke.

Neuroprotective effects of methanolic extract from Chuanxiong Rhizoma in mice with middle cerebral artery occlusion-induced ischemic stroke: suppression of astrocyte- and microglia-related inflammatory response.

BACKGROUND: In traditional Asian medicine, dried rhizomes of Ligusticum chuanxiong Hort. (Chuanxiong Rhizoma [CR]) have long been used to treat pain disorders that affect the head and face such as headaches. Furthermore, they have been used primarily for blood circulation improvement or as an analgesic and anti-inflammatory medicine. This study aimed to investigate the neuroprotective effects of a methanol extract of CR (CRex) on ischemic stroke in mice caused by middle cerebral artery occlusion (MCAO). METHODS: C57BL/6 mice were given a 1.5-h transient MCAO (MCAO control and CRex groups); CRex was administered in the mice of the CRex group at 1,000-3,000 mg/kg either once (single dose) or twice (twice dose) before MCAO. The mechanism behind the neuroprotective effects of CRex was examined using the following techniques: brain infarction volume, edema, neurological deficit, novel object recognition test (NORT), forepaw grip strength, and immuno-fluorescence staining. RESULTS: Pretreating the mice with CRex once at 1,000 or 3,000 mg/kg and twice at 1,000 mg/kg 1 h before MCAO, brought about a significantly decrease in the infarction volumes. Furthermore, pretreating mice with CRex once at 3,000 mg/kg 1 h before MCAO significantly suppressed the reduction of forepaw grip strength of MCAO-induced mice. In the MCAO-induced group, preadministration of CRex inhibited the reduction in the discrimination ratio brought on by MCAO in a similar manner. CRex exhibited these effects by suppressing the activation of astrocytes and microglia, which regulated the inflammatory response. CONCLUSIONS: This study proposes a novel development for the treatment of ischemic stroke and provides evidence favoring the use of L. chuanxiong rhizomes against ischemic stroke.

Cx43 hemichannels and panx1 channels contribute to ethanol-induced astrocyte dysfunction and damage.

BACKGROUND: Alcohol, a widely abused drug, significantly diminishes life quality, causing chronic diseases and psychiatric issues, with severe health, societal, and economic repercussions. Previously, we demonstrated that non-voluntary alcohol consumption increases the opening of Cx43 hemichannels and Panx1 channels in astrocytes from adolescent rats. However, whether ethanol directly affects astroglial hemichannels and, if so, how this impacts the function and survival of astrocytes remains to be elucidated. RESULTS: Clinically relevant concentrations of ethanol boost the opening of Cx43 hemichannels and Panx1 channels in mouse cortical astrocytes, resulting in the release of ATP and glutamate. The activation of these large-pore channels is dependent on Toll-like receptor 4, P2X7 receptors, IL-1ß and TNF-α signaling, p38 mitogen-activated protein kinase, and inducible nitric oxide (NO) synthase. Notably, the ethanol-induced opening of Cx43 hemichannels and Panx1 channels leads to alterations in cytokine secretion, NO production, gliotransmitter release, and astrocyte reactivity, ultimately impacting survival. CONCLUSION: Our study reveals a new mechanism by which ethanol impairs astrocyte function, involving the sequential stimulation of inflammatory pathways that further increase the opening of Cx43 hemichannels and Panx1 channels. We hypothesize that targeting astroglial hemichannels could be a promising pharmacological approach to preserve astrocyte function and synaptic plasticity during the progression of various alcohol use disorders.

The Impact of Treadmill Training on Tissue Integrity, Axon Growth, and Astrocyte Modulation.

Spinal cord injury (SCI) presents a complex challenge in neurorehabilitation, demanding innovative therapeutic strategies to facilitate functional recovery. This study investigates the effects of treadmill training on SCI recovery, emphasizing motor function enhancement, neural tissue preservation, and axonal growth. Our research, conducted on a rat model, demonstrates that controlled treadmill exercises significantly improve motor functions post-SCI, as evidenced by improved scores on the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale and enhanced electromyography readings. Notably, the training facilitates the preservation of spinal cord tissue, effectively reducing secondary damage and promoting the maintenance of neural fibers in the injured area. A key finding is the significant stimulation of axonal growth around the injury epicenter in trained rats, marked by increased growth-associated protein 43 (GAP43) expression. Despite these advancements, the study notes a limited impact of treadmill training on motoneuron adaptation and highlights minimal changes in the astrocyte and neuron-glial antigen 2 (NG2) response. This suggests that, while treadmill training is instrumental in functional improvements post-SCI, its influence on certain neural cell types and glial populations is constrained.

Pharmacological Activation of Piezo1 Channels Enhances Astrocyte-Neuron Communication via NMDA Receptors in the Murine Neocortex.

The Piezo1 mechanosensitive ion channel is abundant on several elements of the central nervous system including astrocytes. It has been already demonstrated that activation of these channels is able to elicit calcium waves on astrocytes, which contributes to the release of gliotransmitters. Astrocyte- and N-methyl-D-aspartate (NMDA) receptor-dependent slow inward currents (SICs) are hallmarks of astrocyte-neuron communication. These currents are triggered by glutamate released as gliotransmitter, which in turn activates neuronal NMDA receptors responsible for this inward current having slower kinetics than any synaptic events. In this project, we aimed to investigate whether Piezo1 activation and inhibition is able to alter spontaneous SIC activity of murine neocortical pyramidal neurons. When the Piezo1 opener Yoda1 was applied, the SIC frequency and the charge transfer by these events in a minute time was significantly increased. These changes were prevented by treating the preparations with the NMDA receptor inhibitor D-AP5. Furthermore, Yoda1 did not alter the spontaneous EPSC frequency and amplitude when SICs were absent. The Piezo1 inhibitor Dooku1 effectively reverted the actions of Yoda1 and decreased the rise time of SICs when applied alone. In conclusion, activation of Piezo1 channels is able to alter astrocyte-neuron communication. Via enhancement of SIC activity, astrocytic Piezo1 channels have the capacity to determine neuronal excitability.

Pulsating Extremely Low-Frequency Electromagnetic Fields Influence Differentiation of Mouse Neural Stem Cells towards Astrocyte-like Phenotypes: In Vitro Pilot Study.

Even though electromagnetic fields have been reported to assist endogenous neurogenesis, little is known about the exact mechanisms of their action. In this pilot study, we investigated the effects of pulsating extremely low-frequency electromagnetic fields on neural stem cell differentiation towards specific phenotypes, such as neurons and astrocytes. Neural stem cells isolated from the telencephalic wall of B6(Cg)-Tyrc-2J/J mouse embryos (E14.5) were randomly divided into three experimental groups and three controls. Electromagnetic field application setup included a solenoid placed within an incubator. Each of the experimental groups was exposed to 50Hz ELF-EMFs of varied strengths for 1 h. The expression of each marker (NES, GFAP, ß-3 tubulin) was then assessed by immunocytochemistry. The application of high-strength ELF-EMF significantly increased and low-strength ELF-EMF decreased the expression of GFAP. A similar pattern was observed for ß-3 tubulin, with high-strength ELF-EMFs significantly increasing the immunoreactivity of ß-3 tubulin and medium- and low-strength ELF-EMFs decreasing it. Changes in NES expression were observed for medium-strength ELF-EMFs, with a demonstrated significant upregulation. This suggests that, even though ELF-EMFs appear to inhibit or promote the differentiation of neural stem cells into neurons or astrocytes, this effect highly depends on the strength and frequency of the fields as well as the duration of their application. While numerous studies have demonstrated the capacity of EMFs to guide the differentiation of NSCs into neuron-like cells or ß-3 tubulin+ neurons, this is the first study to suggest that ELF-EMFs may also steer NSC differentiation towards astrocyte-like phenotypes.

Dysregulation of neuroprotective lipoxin pathway in astrocytes in response to cytokines and ocular hypertension​.

Glaucoma leads to vision loss due to retinal ganglion cell death. Astrocyte reactivity contributes to neurodegeneration. Our recent study found that lipoxin B4 (LXB4), produced by retinal astrocytes, has direct neuroprotective actions on retinal ganglion cells. In this study, we aimed to investigate how the autacoid LXB4 influences astrocyte reactivity in the retina under inflammatory cytokine-induced activation and during ocular hypertension. The protective activity of LXB4 was investigated in vivo using the mouse silicone-oil model of chronic ocular hypertension. By employing a range of analytical techniques, including bulk RNA-seq, RNAscope in-situ hybridization, qPCR, and lipidomic analyses, we discovered the formation of lipoxins and expression of the lipoxin pathway in rodents (including the retina and optic nerve), primates (optic nerve), and human brain astrocytes, indicating the presence of this neuroprotective pathway across various species. Findings in the mouse retina identified significant dysregulation of the lipoxin pathway in response to chronic ocular hypertension, leading to an increase in 5-lipoxygenase (5-LOX) activity and a decrease in 15-LOX activity. This dysregulation was coincident with a marked upregulation of astrocyte reactivity. Reactive human brain astrocytes also showed a significant increase in 5-LOX. Treatment with LXB4 amplified the lipoxin biosynthetic pathway by restoring and amplifying the generation of another member of the lipoxin family, LXA4, and mitigated astrocyte reactivity in mouse retinas and human brain astrocytes. In conclusion, the lipoxin pathway is functionally expressed in rodents, primates, and human astrocytes, and is a resident neuroprotective pathway that is downregulated in reactive astrocytes. Novel cellular targets for LXB4's neuroprotective action are inhibition of astrocyte reactivity and restoration of lipoxin generation. Amplifying the lipoxin pathway is a potential target to disrupt or prevent astrocyte reactivity in neurodegenerative diseases, including retinal ganglion cell death in glaucoma.

NF-κB and JAK/STAT Signaling Pathways as Crucial Regulators of Neuroinflammation and Astrocyte Modulation in Spinal Cord Injury.

Spinal cord injury (SCI) leads to significant functional impairments below the level of the injury, and astrocytes play a crucial role in the pathophysiology of SCI. Astrocytes undergo changes and form a glial scar after SCI, which has traditionally been viewed as a barrier to axonal regeneration and functional recovery. Astrocytes activate intracellular signaling pathways, including nuclear factor κB (NF-κB) and Janus kinase-signal transducers and activators of transcription (JAK/STAT), in response to external stimuli. NF-κB and STAT3 are transcription factors that play a pivotal role in initiating gene expression related to astrogliosis. The JAK/STAT signaling pathway is essential for managing secondary damage and facilitating recovery processes post-SCI: inflammation, glial scar formation, and astrocyte survival. NF-κB activation in astrocytes leads to the production of pro-inflammatory factors by astrocytes. NF-κB and STAT3 signaling pathways are interconnected: NF-κB activation in astrocytes leads to the release of interleukin-6 (IL-6), which interacts with the IL-6 receptor and initiates STAT3 activation. By modulating astrocyte responses, these pathways offer promising avenues for enhancing recovery outcomes, illustrating the crucial need for further investigation into their mechanisms and therapeutic applications in SCI treatment.

Sustained Retinal Defocus Increases the Effect of Induced Myopia on the Retinal Astrocyte Template.

The aim of this article is to describe sustained myopic eye growth's effect on astrocyte cellular distribution and its association with inner retinal layer thicknesses. Astrocyte density and distribution, retinal nerve fiber layer (RNFL), ganglion cell layer, and inner plexiform layer (IPL) thicknesses were assessed using immunochemistry and spectral-domain optical coherence tomography on seventeen common marmoset retinas (Callithrix jacchus): six induced with myopia from 2 to 6 months of age (6-month-old myopes), three induced with myopia from 2 to 12 months of age (12-month-old myopes), five age-matched 6-month-old controls, and three age-matched 12-month-old controls. Untreated marmoset eyes grew normally, and both RNFL and IPL thicknesses did not change with age, with astrocyte numbers correlating to RNFL and IPL thicknesses in both control age groups. Myopic marmosets did not follow this trend and, instead, exhibited decreased astrocyte density, increased GFAP+ spatial coverage, and thinner RNFL and IPL, all of which worsened over time. Myopic changes in astrocyte density, GFAP+ spatial coverage and inner retinal layer thicknesses suggest astrocyte template reorganization during myopia development and progression which increased over time. Whether or not these changes are constructive or destructive to the retina still remains to be assessed.

Human Glial Cells as Innovative Targets for the Therapy of Central Nervous System Pathologies.

In vitro and preclinical in vivo research in the last 35 years has clearly highlighted the crucial physiopathological role of glial cells, namely astrocytes/microglia/oligodendrocytes and satellite glial cells/Schwann cells in the central and peripheral nervous system, respectively. Several possible pharmacological targets to various neurodegenerative disorders and painful conditions have therefore been successfully identified, including receptors and enzymes, and mediators of neuroinflammation. However, the translation of these promising data to a clinical setting is often hampered by both technical and biological difficulties, making it necessary to perform experiments on human cells and models of the various diseases. In this review we will, therefore, summarize the most relevant data on the contribution of glial cells to human pathologies and on their possible pharmacological modulation based on data obtained in post-mortem tissues and in iPSC-derived human brain cells and organoids. The possibility of an in vivo visualization of glia reaction to neuroinflammation in patients will be also discussed.

Nigrostriatal degeneration determines dynamics of glial inflammatory and phagocytic activity.

Glial cells are key players in the initiation of innate immunity in neurodegeneration. Upon damage, they switch their basal activation state and acquire new functions in a context and time-dependent manner. Since modulation of neuroinflammation is becoming an interesting approach for the treatment of neurodegenerative diseases, it is crucial to understand the specific contribution of these cells to the inflammatory reaction and to select experimental models that recapitulate what occurs in the human disease. Previously, we have characterized a region-specific activation pattern of CD11b+ cells and astrocytes in the α-synuclein overexpression mouse model of Parkinson´s disease (PD). In this study we hypothesized that the time and the intensity of dopaminergic neuronal death would promote different glial activation states. Dopaminergic degeneration was induced with two administration regimens of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), subacute (sMPTP) and chronic (cMPTP). Our results show that in the sMPTP mouse model, the pro-inflammatory phenotype of striatal CD11b+ cells was counteracted by an anti-inflammatory astrocytic profile. In the midbrain the roles were inverted, CD11b+ cells exhibited an anti-inflammatory profile and astrocytes were pro-inflammatory. The overall response generated resulted in decreased CD4 T cell infiltration in both regions. Chronic MPTP exposure resulted in a mild and prolonged neuronal degeneration that generated a pro-inflammatory response and increased CD4 T cell infiltration in both regions. At the onset of the neurodegenerative process, microglia and astrocytes cooperated in the removal of dopaminergic terminals. With time, only microglia maintained the phagocytic activity. In the ventral midbrain, astrocytes were the main phagocytic mediators at early stages of degeneration while microglia were the major phagocytic cells in the chronic state. In this scenario, we questioned which activation pattern recapitulates better the features of glial activation in PD. Glial activation in the cMPTP mouse model reflects many pathways of their corresponding counterparts in the human brain with advanced PD. Altogether, our results point toward a context-dependent cooperativity of microglia/myeloid cells and astrocytes in response to neuronal damage and the relevance of selecting the right experimental models for the study of neuroinflammation.

Enriched Environment Inhibits Neurotoxic Reactive Astrocytes via JAK2-STAT3 to Promote Glutamatergic Synaptogenesis and Cognitive Improvement in Chronic Cerebral Hypoperfusion Rats.

Chronic cerebral hypoperfusion (CCH) is a primary contributor to cognitive decline in the elderly. Enriched environment (EE) is proved to improve cognitive function. However, mechanisms involved remain unclear. The purpose of the study was exploring the mechanisms of EE in alleviating cognitive deficit in rats with CCH. To create a rat model of CCH, 2-vessel occlusion (2-VO) surgery was performed. All rats lived in standard or enriched environments for 4 weeks. Cognitive function was assessed using the novel object recognition test and Morris water maze test. The protein levels of glutamatergic synapses, neurotoxic reactive astrocytes, reactive microglia, and JAK2-STAT3 signaling pathway were measured using Western blot. The mRNA levels of synaptic regulatory factors, C1q, TNF-α, and IL-1α were identified using quantitative PCR. Immunofluorescence was used to detect glutamatergic synapses, neurotoxic reactive astrocytes, and reactive microglia, as well as the expression of p-STAT3 in astrocytes in the hippocampus. The results demonstrated that the EE mitigated cognitive impairment in rats with CCH and enhanced glutamatergic synaptogenesis. EE also inhibited the activation of neurotoxic reactive astrocytes. Moreover, EE downregulated microglial activation, levels of C1q, TNF-α and IL-1α and phosphorylation of JAK2 and STAT3. Our results suggest that inhibition of neurotoxic reactive astrocytes may be one of the mechanisms by which EE promotes glutamatergic synaptogenesis and improves cognitive function in rats with CCH. The downregulation of reactive microglia and JAK2-STAT3 signaling pathway may be involved in this process.

Transcriptomic alterations in cortical astrocytes following the development of post-traumatic epilepsy.

Post-traumatic epilepsy (PTE) stands as one of the numerous debilitating consequences that follow traumatic brain injury (TBI). Despite its impact on many individuals, the current landscape offers only a limited array of reliable treatment options, and our understanding of the underlying mechanisms and susceptibility factors remains incomplete. Among the potential contributors to epileptogenesis, astrocytes, a type of glial cell, have garnered substantial attention as they are believed to promote hyperexcitability and the development of seizures in the brain following TBI. The current study evaluated the transcriptomic changes in cortical astrocytes derived from animals that developed seizures as a result of severe focal TBI. Using RNA-Seq and ingenuity pathway analysis (IPA), we unveil a distinct gene expression profile in astrocytes, including alterations in genes supporting inflammation, early response modifiers, and neuropeptide-amidating enzymes. The findings underscore the complex molecular dynamics in astrocytes during PTE development, offering insights into therapeutic targets and avenues for further exploration.