Traumatic brain injury (TBI) is a neurological disease that seriously endangers human life and has a poor prognosis. In particular, neuroinflammation during secondary injury after TBI affects the course of TBI, and interleukin-33 (IL-33) plays an important regulatory role in neuroinflammation after TBI. Meanwhile, the Yes-associated protein (YAP) can influence the prognosis after TBI. In this study, we explored whether the upregulation of YAP in astrocytes can enhance the protective effect of IL-33 against neuroinflammation after TBI. In the current study, the markers of microglial proinflammatory/anti-inflammatory responses both in vivo and in vitro were assessed after the administration of exogenous IL-33. Adeno-associated virus targeting astrocytes in vivo and lentivirus transfecting astrocytes in vitro were used to overexpress YAP, and the expression and localization of proteins were evaluated by Western blotting and immunofluorescence staining. Chromatin immunoprecipitation-quantitative Polymerase Chain Reaction (qPCR) assays were performed to confirm that YAP transcriptionally regulates the IL33 gene by binding directly to its promoter region. Astegolimab was administered to block Growth Stimulation Express Gene 2 Protein (ST2) receptors in vivo and in vitro . Morris water maze and Y-maze tests were employed to assess cognitive function after TBI. The results demonstrated that the expression levels of both YAP and IL-33 were significantly decreased during the early phase of TBI. Concurrently, the anti-inflammatory marker CD206 in microglia was also markedly reduced in the acute stage post-TBI. Importantly, YAP was found to enhance IL-33 secretion by binding to its gene promoter, thereby activating the IL-33/ST2 signaling pathway. This activation promoted anti-inflammatory responses in microglia, which were mediated through the NF-κB signaling pathway, and ultimately led to improved cognitive function. These beneficial effects were effectively reversed by the administration of astegolimab, confirming the specificity of the YAP/IL-33/ST2 mechanism. Above all, we found that YAP produced by astrocytes regulates microglial anti-inflammatory responses through the IL-33/ST2 pathway, thereby improving cognitive function after TBI.

Brain endothelial cell (bEC) dysfunction is the main factor of blood-brain barrier (BBB) breakdown, which triggers a vicious cycle of aggravating traumatic brain injury (TBI) pathogenesis. Previous studies have revealed that neutrophil extracellular traps (NETs) released by neutrophils can lead to BBB disruption, but there is a lack of research on the underlying mechanisms after TBI. Here, excessive NETs were found in both contused brain tissue and circulation following TBI. We found that NETs could activate the TLR4/NF-κB pathway to induce bEC pyroptosis, which led to BBB disruption after TBI. During this process, ninjurin-1 (NINJ1) was activated in pyroptotic bECs, and it mediated the release of high mobility group box 1 protein (HMGB1) via plasma membrane rupture (PMR) to promote NET formation. NINJ1-mediated release of HMGB1 aggravated NET accumulation by forming a vicious circle following TBI. Knockdown of NINJ1 rescued NET formation, attenuated BBB leakage, and improved neurological outcomes after TBI. NINJ1 may represent a promising target for alleviating NET-induced BBB destruction and other related injuries after TBI.

Oxidative stress is a major pathological factor in acute brain injury, such as traumatic brain injury (TBI). As highly branched cells, the transport of lysosomes plays a crucial role in neuronal homeostasis. However, the effects and mechanisms of oxidative damage on axonal lysosome transport remain unknown. In this study, we demonstrated that the downregulation of the membrane lipid orchestrator oxysterol-binding protein (OSBP) induced by oxidative stress alters the subcellular distribution of lysosomes in neurons through regulating lysosomal phosphatidylinositol-4-monophosphate (PI(4)P)/phosphatidylinositol-3-monophosphate (PI(3)P) contents, thus disrupting lysosomal transport. The results of the cell experiments confirmed the occurrence of an autophagic pressure burst, disordered anterograde lysosome transport, and an imbalance in the PI(4)P/PI(3)P ratio in neurons after H2O2 treatment. Mechanistically, oxidative damage reduced neuronal OSBP protein levels, thus contributing to lysosomal PI(4)P storage. Furthermore, a protein‒liposome binding assay revealed that compared with liposomes containing PI(4)P, liposomes containing PI(3)P or cholesterol presented decreased coprecipitation of Arl8. The overexpression of OSBP restored the PI(4)P/PI(3)P content, improved the binding ability of Arl8 to bind to lysosomes, increased lysosome localization in neurites, and promoted axonal injury repair. Finally, overexpression of neuronal OSBP through adeno-associated virus intervention in vivo alleviated dendritic damage and improved the neurological function of mice with TBI. Taken together, these findings suggest that disturbance of OSBP induced by oxidative stress results in abnormal lysosomal distribution and contributes to neuronal malfunction in TBI, and OSBP could be a potential target to promote neuronal repair and regeneration by regulating lysosomal lipid composition and axonal localization.

BACKGROUND:Externally caused traumatic brain injury (TBI) poses a woeful worldwide health concern, bringing about disability, death, and prolonged neurological impairment. Increased galectin-3 levels have been linked to unfavorable outcomes in several neurological conditions. This study explores the role of galectin-3 in TBI, specifically examining its contribution to neuroinflammation. METHODS:BV2 microglia cells treated with lipopolysaccharide (LPS) and a mouse model of TBI were applied to investigate the impact of galectin-3 on neuroinflammation following TBI. Western blotting and immunofluorescence labeling were applied for evaluating protein levels and colocalization. Adeno-associated virus (AAV) that targets microglia was used to knock down galectin-3 in microglia. Nissl staining and the modified neurologic severity score were employed in evaluating neural survival and neurological function, and the cognitive impairment following TBI was assessed by the Y-Maze and Morri water maze test. RESULTS:Galectin-3 expression was shown to rise dramatically after TBI, peaking between days five and seven. In vitro, BV2 cells treated with LPS showed reduced NOD-like receptor thermal protein domain associated protein 3 (NLRP3) inflammasome activation when galectin-3 was inhibited. In LPS-activated microglia, galectin-3 inhibition specifically decreased the expression of Toll-like receptor 4 (TLR4), nuclear factor-κB (NF-κB), p-NF-κB, NLRP3, Apoptosis-associated speck-like protein containing a CARD (ASC), caspase-1, and Gasdermin D (GSDMD). Injection with AAV containing siRNA to knock down galectin-3 in microglia was operated on mice in vivo. Following TBI, this knockdown led to reduced NLRP3 inflammasome activation, neuronal death, neurological impairments and cognitive impairment. CONCLUSIONS:Our foundings indicate that modulating microglia-derived galectin-3 following TBI to reduce neuroinflammation could serve as a promising therapeutic strategy.

Subarachnoid hemorrhage (SAH) is characterized by the extravasation of blood into the subarachnoid space, in which erythrocyte lysis is the primary contributor to cell death and brain injuries. New evidence has indicated that meningeal lymphatic vessels (mLVs) are essential in guiding fluid and macromolecular waste from cerebrospinal fluid (CSF) into deep cervical lymph nodes (dCLNs). However, the role of mLVs in clearing erythrocytes after SAH has not been completely elucidated. Hence, we conducted a cross-species study. Autologous blood was injected into the subarachnoid space of rabbits and rats to induce SAH. Erythrocytes in the CSF were measured with/without deep cervical lymph vessels (dCLVs) ligation. Additionally, prior to inducing SAH, we administered rats with vascular endothelial growth factor C (VEGF-C), which is essential for meningeal lymphangiogenesis and maintaining integrity and survival of lymphatic vessels. The results showed that the blood clearance rate was significantly lower after dCLVs ligation in both the rat and rabbit models. DCLVs ligation aggravated neuroinflammation, neuronal damage, brain edema, and behavioral impairment after SAH. Conversely, the treatment of VEGF-C enhanced meningeal lymphatic drainage of erythrocytes and improved outcomes in SAH. In summary, our research highlights the indispensable role of the meningeal lymphatic pathway in the clearance of blood and mediating consequences after SAH.

Subarachnoid hemorrhage (SAH) is a life-threatening neurological disease that usually has a poor prognosis. Neurogenesis is a potential therapeutic target for brain injury. Ketone metabolism also plays neuroprotective roles in many neurological disorders. OXCT1 (3-Oxoacid CoA-Transferase 1) is the rate-limiting enzyme of ketone body oxidation. In this study, we explored whether increasing ketone oxidation by upregulating OXCT1 in neurons could promote neurogenesis after SAH, and evaluated the potential mechanism involved in this process. The β-hydroxybutyrate content was measured using an enzymatic colorimetric assay. Adeno-associated virus targeting neurons was injected to overexpress OXCT1, and the expression and localization of proteins were evaluated by western blotting and immunofluorescence staining. Adult hippocampal neurogenesis was evaluated by dual staining with doublecortin and 5-Ethynyl-2′-Deoxyuridine. LY294002 was intracerebroventricularly administered to inhibit Akt activity. The Morris water maze and Y-maze tests were employed to assess cognitive function after SAH. The results showed that OXCT1 expression and hippocampal neurogenesis significantly decreased in the early stage of SAH. Overexpression of OXCT1 successfully increased hippocampal neurogenesis via activation of Akt/GSK-3β/β-catenin signaling and improved cognitive function, both of which were reversed by administration of LY294002. OXCT1 regulated hippocampal ketone body metabolism and increased neurogenesis through mechanisms mediated by the Akt/GSK-3β/β-catenin pathway, improving cognitive impairment after SAH.

Background: Subarachnoid hemorrhage (SAH) is a life -threatening neurological disease that usually has a poor prognosis. Neurogenesis is a potential therapeutic target for brain injury. Ketone metabolism also plays neuroprotective roles in many neurological disorders. OXCT1 (3-Oxoacid CoA-Transferase 1) is the rate -limiting enzyme of ketone body oxidation. In this study, we explored whether increasing ketone oxidation by upregulating OXCT1 in neurons could promote neurogenesis after SAH, and evaluated the potential mechanism involved in this process. Methods: The 8-hydroxybutyrate content was measured using an enzymatic colorimetric assay. Adeno-associated virus targeting neurons was injected to overexpress OXCT1, and the expression and localization of proteins were evaluated by western blotting and immunofluorescence staining. Adult hippocampal neurogenesis was evaluated by dual staining with doublecortin and 5-Ethynyl-2 '-Deoxyuridine. LY294002 was intracerebroventricularly administered to inhibit Akt activity. The Morris water maze and Y -maze tests were employed to assess cognitive function after SAH. Results: The results showed that OXCT1 expression and hippocampal neurogenesis significantly decreased in the early stage of SAH. Overexpression of OXCT1 successfully increased hippocampal neurogenesis via activation of Akt/GSK-38/8-catenin signaling and improved cognitive function, both of which were reversed by administration of LY294002. Conclusions: OXCT1 regulated hippocampal ketone body metabolism and increased neurogenesis through mechanisms mediated by the Akt/GSK-38/8-catenin pathway, improving cognitive impairment after SAH.

BACKGROUND:Apoptosis and pyroptosis are two types of programmed cell death related to the neuroinflammatory reaction after subarachnoid hemorrhage (SAH). Research indicates that triggering receptor expressed on myeloid cells 2 (TREM2) can regulate the SAH-induced inflammatory response. However, whether TREM2 regulates programmed cell death (apoptosis and pyroptosis) remains to be clarified. The purpose of the present study was to investigate the effects of TREM2 on cell death in SAH. METHODS:SAH was induced in adult male C57BL/6J mice by endovascular perforation. An in-vitro cellular model of SAH was established by treating cocultured BV2 microglia and HT22 neuronal cells with oxyhemoglobin. TREM2 overexpression or knockdown was carried out by intraventricular lentivirus injection at 7 d before SAH induction in mice or lentiviral transfection, respectively. Neurobehavioral tests as well as western blot, reverse transcription-quantitative polymerase chain reaction (RT-qPCR), immunofluorescence, Evans blue (EB) staining, Nissl staining, and flow cytometry assays were performed to investigate the neuroprotective role of TREM2 after SAH. RESULTS:After SAH, the TREM2 mRNA and protein levels were elevated in SAH mice, exhibiting a peak at 72 h. TREM2 overexpression improved the SAH-induced neurological deficits in mice, while TREM2 knockdown worsened them. In the brains of mice with TREM2 overexpression, less neuronal death and more neuronal survival were detected at 72 h post SAH. Meanwhile, TREM2 overexpression showed an inhibitory effect on microglial activation, neutrophil infiltration, and the expression of cell death marker proteins. Consistent results were obtained in vitro. CONCLUSIONS:Our research indicates the important role of TREM2 on cell death after SAH, suggesting that targeting TREM2 might be an effective approach for treating SAH.

Secondary brain injury after intracerebral hemorrhage (ICH) is the main cause of poor prognosis in ICH patients, but the underlying mechanisms remain less known. The involvement of Piezo1 in brain injury after ICH was studied in a mouse model of ICH. ICH was established by injecting autologous arterial blood into the basal ganglia in mice. After vehicle, Piezo1 blocker, GsMTx4, Piezo1 activator, Yoda-1, or together with mannitol (tail vein injection) was injected into the left lateral ventricle of mouse brain, Piezo1 level and the roles of Piezo1 in neuronal injury, brain edema, and neurological dysfunctions after ICH were determined by the various indicated methods. Piezo1 protein level in neurons was significantly upregulated 24 h after ICH in vivo (human and mice). Piezo1 protein level was also dramatically upregulated in HT22 cells (a murine neuron cell line) cultured in vitro 24 h after hemin treatment as an in vitro ICH model. GsMTx4 treatment or together with mannitol significantly downregulated Piezo1 and AQP4 levels, markedly increased Bcl2 level, maintained more neurons alive, considerably restored brain blood flow, remarkably relieved brain edema, substantially decreased serum IL-6 level, and almost fully reversed the neurological dysfunctions at ICH 24 h group mice. In contrast, Yoda-1 treatment achieved the opposite effects. In conclusion, Piezo1 plays a crucial role in the pathogenesis of brain injury after ICH and may be a target for clinical treatment of ICH.

Iron accumulation is one of the most essential pathological events after subarachnoid hemorrhage (SAH). Ferroportin1 (FPN1) is the only transmembrane protein responsible for exporting iron. Hepcidin, as the major regulator of FPN1, is responsible for its degradation. Our study investigated how the interaction between FPN1 and hepcidin contributes to iron accumulation after SAH. We found that iron accumulation aggravated after SAH, along with decreased FPN1 in neurons and increased hepcidin in astrocytes. After knocking down hepcidin in astrocytes, the neuronal FPN1 significantly elevated, thus attenuating iron accumulation. After SAH, p-Smad1/5 and Smad4 tended to translocate into the nucleus. Moreover, Smad4 combined more fragments of the promoter region of Hamp after OxyHb stimulation. By knocking down Smad1/5 or Smad4 in astrocytes, FPN1 level restored and iron overload attenuated, leading to alleviated neuronal cell death and improved neurological function. However, the protective role disappeared after recombinant hepcidin administration. Therefore, our study suggests that owing to the nuclear translocation of transcription factors p-Smad1/5 and Smad4, astrocyte-derived hepcidin increased significantly after SAH, leading to a decreased level of neuronal FPN1, aggravation of iron accumulation, and worse neurological outcome.

Background: Erythrocytes and their breakdown products in the subarachnoid space (SAS) are the main contributors to the pathogenesis of subarachnoid hemorrhage (SAH). Dobutamine is a potent β1-adrenoreceptor agonist that can increase cardiac output, thus improving blood perfusion and arterial pulsation in the brain. In this study, we investigated whether the administration of dobutamine promoted the clearance of red blood cells (RBCs) and their degraded products via meningeal lymphatic vessels (mLVs), thus alleviating neurological deficits in the early stage post-SAH.Materials and methods: Experimental SAH was induced by injecting autologous arterial blood into the prechiasmatic cistern in male C57BL/6 mice. Evans blue was injected into the cisterna magna, and dobutamine was administered by inserting a femoral venous catheter. RBCs in the deep cervical lymphatic nodes (dCLNs) were evaluated by hematoxylin–eosin staining, and the hemoglobin content in dCLNs was detected by Drabkin’s reagent. The accumulation of RBCs in the dura mater was examined by immunofluorescence staining, neuronal death was evaluated by Nissl staining, and apoptotic cell death was evaluated by TUNEL staining. The Morris water maze test was used to examine the cognitive function of mice after SAH.Results: RBCs appeared in dCLNs as early as 3 h post-SAH, and the hemoglobin in dCLNs peaked at 12 h after SAH. Dobutamine significantly promoted cerebrospinal fluid (CSF) drainage from the SAS to dCLNs and obviously reduced the RBC residue in mLVs, leading to a decrease in neuronal death and an improvement in cognitive function after SAH.Conclusion: Dobutamine administration significantly promoted RBC drainage from cerebrospinal fluid in the SAS via mLVs into dCLNs, ultimately relieving neuronal death and improving cognitive function.

Glioblastoma (GBM) is an aggressive intracranial tumour, and current chemotherapy regimens have limited efficacy. Aloperine (ALO), a natural alkaline compound, has shown potential as an antitumor agent. However, the effect of ALO against GBM remains unclear. This study aimed to investigate the function of ALO in treating GBM. U87, A172, and GL261 cell lines were used for in vitro experiments, and GL261 was also used to establish in vivo models. The results showed that ALO inhibited the proliferation of GBM cells by cell cycle arrest and apoptosis. Furthermore, autophagy was found to play a critical role, suggested by observation of autophagosomes under the transmission electron microscopy. It was discovered for the first time that ALO targeted lysosomes directly in glioma cells, tested by fluo-rescence-labelled ALO and organelle-localizing probes. In addition, ALO inhibited late autophagy and induced paraptosis in GBM, verified by classical gene expression changes in qPCR and western blotting. Also, ALO inhibited tumour growth and acted synergistically with temozolomide in intracranial glioma mice models in vivo. Our findings suggest that ALO targets lysosomes to inhibit late autophagy in GBM, inducing cell cycle arrest, paraptosis, and apoptosis. ALO may therefore be a promising therapeutic agent for the treatment of GBM.

Background: Ketones are not only utilized to produce energy but also play a neuroprotective role in many neurodegenerative diseases. However, whether this process has an impact on secondary brain damage after traumatic brain injury (TBI) remains unknown. OXCT1 (3-Oxoacid CoA-Transferase 1) is the rate-limiting enzyme in the intra-neuronal utilization of ketones. In this study, we investigated whether reduced expression of OXCT1 after TBI could impact neuroprotective mechanisms and exacerbate neurological dysfunction. Materials and methods: Experimental TBI was induced by a modified version of the weight drop model, it is a model of severe head trauma. Expression of OXCT1 in the injured hippocampus of mice was measured at different time points using immunoblotting assays. The release of abnormal mitochondrial cytochrome c from neurons of the mouse injured lateral hippocampus was measured 1 week after TBI using immunoblotting assays. Neuronal death was assessed by Nissl staining and the level of reactive oxygen species (ROS) within the neurons of the injured lateral hippocampus was assessed by Dihydroethidium staining. Results: OXCT1 was overexpressed in hippocampal neurons by injection of adeno-associated virus into the lateral ventricle. OXCT1 expression levels decreased significantly 1 week post-TBI. After comparing the data obtained from different groups of mice, OXCT1 was found to significantly increase the expression of SIRT3 and reduce the proportion of acetylated SOD2, thus decreasing the production of ROS in the injured hippocampal neurons, reducing neuronal death, and improving cognitive function. Conclusions: OXCT1 has a critical previously unappreciated protective role in neurological impairment following TBI via the SIR3-SOD2 pathway. These findings highlight the potential of OXCT1 as a simple treatment for patients with TBI.

Introduction Endothelial nitric oxide synthase (eNOS) uncoupling plays a significant role in acute vasoconstriction during early brain injury (EBI) after subarachnoid hemorrhage (SAH). Astrocytes in the neurovascular unit extend their foot processes around endothelia. In our study, we tested the hypothesis that increased nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) expression in astrocytes after SAH leads to eNOS uncoupling. Methods We utilized laser speckle contrast imaging for monitoring cortical blood flow changes in mice, nitric oxide (NO) kits to measure the level of NO, and a co-culture system to study the effect of astrocytes on endothelial cells. Moreover, the protein levels were assessed by Western blot and immunofluorescence staining. We used CCK-8 to measure the viability of astrocytes and endothelial cells, and we used the H2O2 kit to measure the H2O2 released from astrocytes. We used GSK2795039 as an inhibitor of NOX2, whereas lentivirus and adeno-associated virus were used for dihydrofolate reductase (DHFR) knockdown in vivo and in vitro. Results The expression of NOX2 and the release of H2O2 in astrocytes are increased, which was accompanied by a decrease in endothelial DHFR 12 h after SAH. Moreover, the eNOS monomer/dimer ratio increased, leading to a decrease in NO and acute cerebral ischemia. All of the above were significantly alleviated after the administration of GSK2795039. However, after knocking down DHFR both in vivo and in vitro, the protective effect of GSK2795039 was greatly reversed. Discussion The increased level of NOX2 in astrocytes contributes to decreased DHFR in endothelial cells, thus aggravating eNOS uncoupling, which is an essential mechanism underlying acute vasoconstriction after SAH.

中枢神经系统作为高级神经功能的基础解剖结构,对营养物质的运输和代谢废物的清除有着很高的要求.但是中枢神经系统缺乏淋巴循环的完整结构,脑内毛细血管内皮之间的紧密连接又限制了毛细血管的滤过作用,这些结构的特殊性导致了中枢神经系统液体运输的复杂性,而类淋巴系统的存在弥补了脑内微循环结构的缺失,保证了脑脊液和脑间质液的物质交换.完成交换的液体顺着静脉周围间隙重新进入蛛网膜下腔,进一步通过蛛网膜颗粒、硬脑膜淋巴管等途径进入外周循环.本文就中枢神经系统中液体运输的具体途径以及参与其中的分子机制的研究进展作一综述.

Endothelial malfunction is a major contributor to early or delayed vasospasm after subarachnoid hemorrhage (SAH). As a representative form of endothelial dysfunction, endothelial nitric oxide synthase (eNOS) uncoupling leads to a reduction in nitric oxide (NO) generated by endothelial cells. In this study, we investigated how the interaction between endothelial NOX4 (nicotinamide adenine dinucleotide phosphate oxidase 4) and DHFR (dihydrofolate reductase) contributes to eNOS uncoupling after SAH. Setanaxib and the adeno-associated virus (AAV) targeting brain vascular endothelia were injected through the tail vein and the expression and localization of proteins were examined by western blot and immunofluorescence staining. The NO content was measured using the NO assay kit, and laser speckle contrast imaging was used to assess cortical perfusion. ROS (reactive oxygen species) level was detected by DHE (dihydroethidium) staining, DCFH-DA (2',7'-dichlorofluorescin diacetate) staining and H2O2 (hydrogen peroxide) measurement. The Garcia score was employed to examine neurological function. Setanaxib is widely used for its preferential inhibition for NOX1/4 over other NOX isoforms. After endothelial NOX4 was inhibited by Setanaxib in a mouse model of SAH, the endothelial DHFR level was significantly elevated, which attenuated eNOS uncoupling, increased cortical perfusion, and improved the neurological function. The protective role of inhibiting endothelial NOX4, however, disappeared after knocking down endothelial DHFR. Our results suggest that endothelial DHFR decreased significantly because of the elevated level of endothelial NOX4, which aggravated eNOS uncoupling after SAH, leading to decreased cortical perfusion and worse neurological outcome.

Clinically, the renin-angiotensin-aldosterone system is activated intensely in patients with moderate to severe traumatic brain injury (TBI). Increased angiotensin II in circulatory blood after TBI can enter the brain through the disrupted blood-brain barrier. Angiotensin-converting enzyme 2 (ACE2) is an enzyme that metabolizes angiotensin II into angiotensin (1-7), which has been shown to have neuroprotective results. The expression and role of ACE2 in the brain after TBI remains elusive, however. We found that ACE2 protein abundance was downregulated around the contusional area in the brains of both humans and mice. Endogenous ACE2 was expressed in neurons, astrocytes, and microglia in the cortex of the mouse brain. Administration of recombinant human ACE2 intracerebroventricularly alleviated neurological defects after TBI in mice. Treatment of recombinant human ACE2 suppressed TBI-induced increase of angiotensin II and the decrease of angiotensin (1-7) in the brain, mitigated neural cell death, reduced the activation of NLRP3 and caspase3, decreased phosphorylation of mitogen-activated protein kinases, and nuclear factor kappa B, and reduced inflammatory cytokines tumor necrosis factor alpha and interleukin-1 beta. Administration of ACE2 enzyme activator diminazene aceturate intraperitoneally rescued downregulation of ACE2 enzymatic activity and protein abundance in the brain. Diminazene aceturate treatment once per day in the acute stage after TBI alleviated long-term cognitive defects and neuronal loss in mice. Collectively, these results indicated that restoration of ACE2 alleviated neurological deficits after TBI by mitigation of pyroptosis and apoptosis.

Traumatic brain injury (TBI) causes neurotransmitter disturbances contributing to neuronal cell death and neurological deficits. In humans, brain injuries impair γ-aminobutyric acid (GABA) uptake and ultimately result in cognitive impairment. GABA transporter 3 (GAT3) is a vital approach of GABA reuptake and catabolism. The contribution of GAT3 in TBI-induced cognitive impairment and its underlying mechanisms remain unknown, which were explored in the present study. Here, we found that expression of GAT3 was downregulated to increase GABA concentration in the mouse brain after TBI. And GAT3 was detected in neurons and astrocytes after TBI unexpectedly, instead of merely expressed on astrocytes in physiological states. Subsequently, activated metabotropic glutamate receptor 5 (mGluR5) reduced GABA content by elevating the expression levels of GAT3. Then, increased mGluR5 activity obviously improved cognitive impairment. Mechanistically, mGluR5 was activated to evidently induce the expression of p-ERK, CREB, and p-CREB after TBI. The inhibition of CREB decreased the expression of CREB, p-CREB, and GAT3 elevated by active mGluR5. However, the CREB inhibitor increased GABA content. Furthermore, Rab11a regulating GAT3 trafficking by endocytosis was elevated after TBI. And Rab11a downregulated by active mGluR5 was reversed by CREB inhibitor. In summary our findings elucidated that activated mGluR5 ameliorated cognitive function by upregulating GAT3 in TBI. And mGluR5 possibly regulated GAT3 by ERK/CREB/Rab11a pathway. GAT3 could serve as a potential target for TBI cognitive treatment.