Search

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 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., 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-3β/β-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-3β/β-catenin pathway, improving cognitive impairment after SAH., 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.)

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., Competing Interests: Declaration of competing interest The authors declare that they have no relevant financial or non-financial interests to disclose., (Copyright © 2023 Elsevier Inc. All rights reserved.)

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., 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 © 2023 Elsevier B.V. All rights reserved.)

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 H 2 O 2 kit to measure the H 2 O 2 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 H 2 O 2 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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Miao, Gao, Li, Zhuang, Wang, Li, Gao, Han, Qiu and Zhou.)

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 β 1 -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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wang, Deng, Gao, Li, Gao, Han, Zhuang, Qiu, Miao and Zhou.)

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 H 2 O 2 (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., 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 Inc. All rights reserved.)