Focal Cerebral Ischemic Injury Research Articles

USP18 Overexpression Protects against Focal Cerebral Ischemia Injury in Mice by Suppressing Microglial Activation

The activation of inflammatory cytokines following stroke leads to neuron apoptosis and microglial activation, both of which are involved in ischemic brain damages. The ubiquitin-specific protease 18 (USP18) negatively regulated the expression of inflammatory cytokines and suppresses microglial activation. This study aims to determine whether USP18 expression protects against brain damage in ischemic models of stroke. We investigated USP18 expression, overexpression, and knockout under ischemic conditions in vitro and in vivo. Using BV2 microglial cells under oxygen and glucose deprivation (OGD) and 60 min transient middle cerebral artery occlusion (MCAO) in mice as models of ischemia, we assessed the infarct volume, the extent of neurogenesis, the expression of proinflammatory cytokines and Janus Kinases(JAKs)/Signal Transducer and Activator of Transcription (STAT) pathway members. BV2 cells under OGD for 0, 6, 12, or 24 h exhibited decreased USP18 expression and increased expression of the proinflammatory cytokines including interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor (TNF)-α, and interferon (INF)-γ. Lentiviral overexpression of USP18 in MCAO mice significantly decreased the infarct volume and significantly increased the number of new neurons that coexpressed bromodeoxyuridine (BrdU)/neuronal nuclei (NeuN). Additionally, microglial activation was inhibited, including the suppression of the JAK/STAT pathway and the proinflammatory cytokines expression. In vitro experiments demonstrated that USP18 inhibited BV2 microglial activity and reduced the mRNA and protein levels of NF-κB, JAK1, p-JAK1, STAT1, and p-STAT1 in BV2 microglial cells. USP18 overexpression decreased ischemic brain injury through the suppression of microglial activation by negatively regulating the release of proinflammatory cytokines.

Salvinorin A moderates postischemic brain injury by preserving endothelial mitochondrial function via AMPK/Mfn2 activation

Salvinorin A (SA) is a highly selective kappa opioid receptor (KOR) agonist that has significant protective effects on cerebrovascular function after ischemic stroke, but its underlying mechanism is still unclear. This study aimed to investigate whether KOR activation improves the morphology and function of intracellular mitochondria to protect endothelial cells after cerebral ischemia. A transient ischemic brain damage was generated by establishing middle cerebral artery occlusion (MCAO) model in male Sprague-Dawley rats and oxygen glucose deprivation (OGD) model in human brain microvascular endothelial cells (HBMECs). In vivo findings revealed that SA significantly reduced the infarct size, brain edema and Evans blue effusion after MCAO. In vitro findings revealed that SA improved the cell viability and decreased the apoptotic rates in HBMECs OGD model. SA also protected membrane potential and morphology of mitochondria, reduced the ROS level after OGD. SA function was blocked by KOR inhibitor norbinaltorphimine (NB). SA upregulated the phosphorylation levels of AMPK, and Mfn2 expression. Our findings suggest that SA effectively mitigated focal cerebral ischemic injury by activating KOR which potentially preserved mitochondrial function by up-regulating AMPK/Mfn2 in endothelial cells.

Forsythiaside A protects against focal cerebral ischemic injury by mediating the activation of the Nrf2 and endoplasmic reticulum stress pathways.

Ischemic stroke is a common type of stroke with a high mortality and morbidity rate. Preventing and controlling cerebral ischemic injury is particularly important. Forsythiaside A (FA) has been reported to have anti‑inflammatory and antioxidant activities. The aim of the present study was to explore the impact of FA on middle cerebral artery occlusion (MCAO)‑induced cerebral ischemic injury in rats. The results indicated that FA markedly increased the percent survival and decreased the neurological deficit score in rats with cerebral ischemic injury. Furthermore, cell apoptosis was significantly inhibited by FA administration, which was accompanied by decreased caspase‑3 and caspase‑9 expression. A marked increase in the expression levels of nuclear factor‑erythroid 2‑related factor 2 (Nrf2), NAD(P)H quinone dehydrogenase 1 and glutathione‑s‑transferase was detected in FA‑treated rats. In addition, treatment with FA reduced malonaldehyde expression, and enhanced the expression of superoxide dismutase and glutathione. Furthermore, endoplasmic reticulum (ER) stress was vastly alleviated by FA treatment, as evidenced by the increased expression of B‑cell lymphoma 2, apoptosis regulator and the downregulated expression of phosphorylated (phospho)‑protein kinase RNA‑like ER kinase (PERK)/PERK, phospho‑inositol‑requiring enzyme 1 (IRE1α)/IRE1α and CCAAT‑enhancer‑binding proteins homologous protein. Taken together, the present study demonstrated that FA attenuated cerebral ischemic damage via mediation of the activation of Nrf2 and ER stress pathways. These data may provide ideas for novel treatment strategies of cerebral ischemic damage.

Electroacupuncture attenuated cerebral ischemic injury and neuroinflammation through \u03b17nAChR-mediated inhibition of NLRP3 inflammasome in stroke rats

BackgroundOur previous research confirmed that electroacupuncture (EA) stimulus elicits neuroprotective effects against cerebral ischemic injury through α7 nicotinic acetylcholine receptor (α7nAChR)-mediated inhibition of high-mobility group box 1 release mechanism. This study investigated whether the signal transducer of α7nAChR and inhibition of NLRP3 inflammasome are involved in the neuroprotective effects of EA stimulus.MethodsIn adult male Sprague-Dawley rats, the focal cerebral ischemic injury was induced by middle cerebral artery occlusion (MCAO) models for 1.5 h. The expression of NLRP3 inflammasome in the penumbral tissue following reperfusion was assessed by western blotting and immunoflourescent staining. The infarct size, neurological deficit score, TUNEL staining and the expression of proinflammatory factors or anti-inflammatory cytokines were evaluated at 72 h after reperfusion in the presence or absence of either α7nAChR antagonist (α-BGT) or agonist (PHA-543,613).ResultsThe contents of inflammasome proteins were gradually increased after cerebral ischemia/reperfusion (I/R). EA stimulus attenuated NLRP3 inflammasome mediated inflammatory reaction and regulated the balance between proinflammatory factors and anti-inflammatory cytokines. The agonist of α7nAChR induced similar neuroprotective effects as EA stimulus. In contrast, α7nAChR antagonist reversed not only the neuroprotective effects, but also the inhibitory effects of NLRP3 inflammasome and the regulatory effects on the balance between proinflammatory factors and anti-inflammatory cytokines.ConclusionsThese results provided compelling evidence that α7nAChR played a pivotal role in regulating the activation and expression of NLRP3 inflammasome in neurons after cerebral I/R. These findings highlighted a novel anti-inflammatory mechanism of EA stimulus by α7nAChR modulating the inhibition of NLRP3 inflammasome, suggesting that α7nAChR-dependent cholinergic anti-inflammatory system and NLRP3 inflammasome in neurons might act as potential therapeutic targets in EA induced neuroprotection against cerebral ischemic injury.

Sestrin2 overexpression attenuates focal cerebral ischemic injury in rat by increasing Nrf2/HO-1 pathway-mediated angiogenesis

Sestrin2 (Sesn2) is a stress response protein which expresses neuroprotective characteristics in some neurodegenerative disorders. However, the impact of Sesn2 on the clinical outcome of stroke is unclear. The nuclear factor-erythroid 2 related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway is a key factor in angiogenesis, which aids in attenuating cerebral ischemia damage. In this study the investigators examine the effects of Sesn2 on cerebral ischemia damage by increasing angiogenesis through the Nrf2/HO-1 signaling pathway. Healthy adult Sprague–Dawley (SD) rats were exposed to photochemical cerebral ischemia while AAV injection was used to overexpress Sesn2. At 5 days after photochemical embolization, the investigators observed a reduction in neurological problems, decreased infarct volume, and diminished neuronal injury in the Sesn2 overexpression samples compared to the controls. To further explore these defensive mechanisms, the investigators also silenced Nrf2. While Sesn2, Nrf2, HO-1, and VEGF were significantly increased following cerebral ischemia, overexpression of Sesn2 further increased their expression. After silencing Nrf2, the opposite effect was observed. These results imply that Sestrin2 may activate the Nrf2 / HO-1 pathway, leading to enhanced angiogenesis following photothrombotic cerebral ischemia.

Liraglutide protects against diabetes mellitus complicated with focal cerebral ischemic injury by activating mitochondrial ATP-sensitive potassium channels.

Cerebral infarction is a common disease that threatens the health of humankind worldwide. Diabetes is one of the important causes of cerebral ischemic (CI) injury. CI complicated with diabetes has a worse prognosis and lacks effective treatment. Our preliminary study demonstrated that liraglutide mitigates CI injuries in diabetic rats. However, the essential mechanism underlying this effect remained to be fully investigated. Recent research has shown that damaged mitochondrial ATP-sensitive potassium channels (mitoKATP) play a critical role in diabetes-aggravated CI injury. Therefore, we hypothesized that liraglutide may confer therapeutic effects against CI with diabetes by activating mitoKATP channels. In this study, liraglutide, but not insulin, significantly improved ischemia-induced neurological deficits and decreased infarct volumes following CI in diabetic rats, down-regulated the expression of myeloperoxidase and up-regulated the expression of superoxide dismutase and two subunits of the mitoKATP channel (SUR1 and Kir6.2). However, these effects were weakened by the mitoKATP antagonist 5-hydroxydecanoic acid. Our study demonstrated that the neuroprotective effects of liraglutide on CI injury with diabetes, which occurs by reducing oxidative stress and the inflammatory response, are associated with the activation of the mitoKATP channel.

CKLF1 Aggravates Focal Cerebral Ischemia Injury at Early Stage Partly by Modulating Microglia/Macrophage Toward M1 Polarization Through CCR4.

CKLF1 is a chemokine with increased expression in ischemic brain, and targeting CKLF1 has shown therapeutic effects in cerebral ischemia model. Microglia/macrophage polarization is a mechanism involved in poststroke injury expansion. Considering the quick and obvious response of CKLF1 and expeditious evolution of stroke lesions, we focused on the effects of CKLF1 on microglial/macrophage polarization at early stage of ischemic stroke (IS). The present study is to investigate the CKLF1-mediated expression of microglia/macrophage phenotypes in vitro and in vivo, discussing the involved pathway. Primary microglia culture was used in vitro, and mice transient middle cerebral artery occlusion (MCAO) model was adopted to mimic IS. CKLF1 was added to the primary microglia for 24h, and we found that CKLF1 modulated primary microglia skew toward M1 phenotype. In mice transient IS model, CKLF1 was stereotactically microinjected to the lateral ventricle of ischemic hemisphere. CKLF1 aggravated ischemic injury, accompanied by promoting microglia/macrophage toward M1 phenotypic polarization. Increased expression of pro-inflammatory cytokines and decreased expression of anti-inflammatory cytokines were observed in mice subjected to cerebral ischemia and administrated with CKLF1. CKLF1-/- mice were used to confirm the effects of CKLF1. CKLF1-/- mice showed lighter cerebral damage and decreased M1 phenotype of microglia/macrophage compared with the WT control subjected to cerebral ischemia. Moreover, NF-κB activation enhancement was detected in CKLF1 treatment group. Our results demonstrated that CKLF1 is an important mediator that skewing microglia/macrophage toward M1 phenotype at early stage of cerebral ischemic injury, which further deteriorates followed inflammatory response, contributing to early expansion of cerebral ischemia injury. Targeting CKLF1 may be a novel way for IS therapy.

Identification and functional analysis of microRNAs in rats following focal cerebral ischemia injury

MicroRNA sequencing (miRNA-seq) was performed in the present study to investigate miRNA expression profiles in infarcted brain areas following focal cerebral ischemia induced by middle cerebral artery occlusion in rats. In total, 20 miRNAs were identified to be upregulated and 17 to be downregulated in the infarct area. The expression levels of six differentially expressed miRNAs (DEmiRs), miR-211-5p, miR-183-5p, miR-10b-3p, miR-182, miR-217-5p and miR-96-5p, were examined by reverse transcription-quantitative polymerase chain reaction. Subsequently, a miRNA-mRNA network was constructed. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to investigate the functions of the mRNAs targeted by these DEmiRs. The present study aimed to investigate the association between miRNAs and cerebral ischemia to provide potential insight into the molecular mechanisms underlying ischemic stroke.

Activation of the Omega-3 Fatty Acid Receptor GPR120 Protects against Focal Cerebral Ischemic Injury by Preventing Inflammation and Apoptosis in Mice.

G protein-coupled receptor 120 (GPR120) has been shown to negatively regulate inflammation and apoptosis, but its role in cerebral ischemic injury remains unclear. Using an in vivo model of middle cerebral artery occlusion (MCAO) and an in vitro model of oxygen-glucose deprivation (OGD), we investigated the potential role and molecular mechanisms of GPR120 in focal cerebral ischemic injury. Increased GPR120 expression was observed in microglia and neurons following MCAO-induced ischemia in wild type C57BL/6 mice. Treatment with docosahexaenoic acid (DHA) inhibited OGD-induced inflammatory response in primary microglia and murine microglial BV2 cells, whereas silencing of GPR120 strongly exacerbated the inflammation induced by OGD and abolished the anti-inflammatory effects of DHA. Mechanistically, DHA inhibited OGD-induced inflammation through GPR120 interacting with β-arrestin2. In addition to its anti-inflammatory function, GPR120 also played a role in apoptosis as its knockdown impaired the antiapoptotic effect of DHA in OGD-induced rat pheochromocytoma (PC12) cells. Finally, using MCAO mouse model, we demonstrated that GPR120 activation protected against focal cerebral ischemic injury by preventing inflammation and apoptosis. Our study indicated that pharmacological targeting of GPR120 may provide a novel approach for the treatment of patients with ischemic stroke.

Abstract WP349: L-Glutamine Induces Heat Shock Protein 70 Expression & Attenuates Brain Ischemic Injury in Mice

Introduction: Oxidative stress plays an important role in ischemic stroke pathogenesis. L-glutamine (L-GLN) was shown to have antioxidant activity and was approved by the FDA in July 2017 for the treatment of sickle cell disease. In this study, we aim to investigate the effect of L-GLN in attenuating ischemic brain injury using a mouse middle cerebral artery occlusion (tMCAO) model. Methods: Ninety-minute tMCAO was used to induce a focal cerebral ischemic injury. Animals (n=135) were divided into four groups: (1) Sham, (2) Saline, (3) L-GLN, and (4) L-GLN plus HSP70 ATPase activity inhibitor Apoptozole (Az). Treatments were delivered intraperitoneally once daily for the first three days after ischemic surgery. Neurobehavioral tests were performed before tMCAO and at 1, 3, 7, and 14 days after tMCAO using the modified neurological severity score (mNSS), elevated body swing test (EBST), and rotarod test. Infarction volume was assessed by cresyl violet staining of brain sections. The expression levels of heat shock proteins and its signaling pathway related proteins were evaluated by Western Blot and real time-PCR. The level of oxidative stress was evaluated by malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) assays. Astrocyte and neuron cell cultures and oxygen glucose deprivation (OGD) model was used to further examine the molecular pathways involved in the protective effects by L-GLN. Results: L-GLN reduced brain infarct volume and promoted neurobehavioral recovery in mice suffering from ischemic injury. Such beneficial effect was abolished by the coadministration of AZ. L-GLN induced the up-regulation of HSP70, reduced oxidative stress level, and reduced the expression of IL-1beta and IL-6 in ischemic mice brain. In L-GLN group, SOD and GSH-PX activities are significantly increased compared to the Saline group. Nrf2 was upregulated in the L-GLN group while co-treatment with AZ abolished this upregulation. Cell culture experiments revealed that the conditioned media from astrocytes cultured with the presents of L-GLN attenuated the apoptosis of neurons after OGD. Conclusion: L-GLN attenuates ischemic brain injury in part through HSP70 related pathways and holds potential in post-stroke treatment.

Hypothermia: Impact on plasticity following brain injury.

Therapeutic hypothermia (TH) is a potent neuroprotectant against multiple forms of brain injury, but in some cases, prolonged cooling is needed. Such cooling protocols raise the risk that TH will directly or indirectly impact neuroplasticity, such as after global and focal cerebral ischemia or traumatic brain injury. TH, depending on the depth and duration, has the potential to broadly affect brain plasticity, especially given the spatial, temporal, and mechanistic overlap with the injury processes that cooling is used to treat. Here, we review the current experimental and clinical evidence to evaluate whether application of TH has any adverse or positive effects on postinjury plasticity. The limited available data suggest that mild TH does not appear to have any deleterious effect on neuroplasticity; however, we emphasize the need for additional high-quality preclinical and clinical work in this area.

Intranasal Calcitonin Gene-Related Peptide Protects Against Focal Cerebral Ischemic Injury in Rats Through the Wnt/β-Catenin Pathway.

BackgroundIntranasal calcitonin gene-related peptide (CGRP) delivery offers a noninvasive method of bypassing the blood-brain barrier for the delivery of CGRP to the brain. Here, we first reported the therapeutic benefits of intranasal CGRP delivery in rats following middle cerebral artery occlusion (MCAO).Material/MethodsReal-time quantitative polymerase chain reaction (RT-qPCR) assay, enzyme-linked immunosorbent assay (ELISA), rat MCAO model, TTC (2, 3, 5-triphenyltetrazolium chloride) staining, hematoxylin and eosin (H & E) staining, Morris water maze test, TUNEL assay, immunofluorescence, and western blot assay were used to investigate the role of CGRP in rats. Cell Counting Kit-8 assay, colony formation assay, cell cycle assay, apoptosis assay, western blot assay, and TOP/FOP assay were used to investigate the role of CGRP in normal human astrocytes (NHA) cells.ResultsThe CGRP-MCAO-NDDS (nasal drug delivery system) group showed a significant reduction in the infarct volume and improvement in neurologic deficit tests of motor, sensory, reflex and vestibulo-motor functions compared to those rats in the CGRP-MCAO-IV group. CGRP markedly inhibited apoptosis and increased the expression of vascular endothelial growth factor (VEGF) and bFGF and decreased the expression of GAP43 in the cortex of MCAO rats. CGRP promoted cell proliferation and cell cycle process and inhibited cell apoptosis through the Wnt/β-catenin pathway in NHA cells.ConclusionsThis noninvasive, simple, and cost-effective method is a potential treatment strategy for focal cerebral ischemic injury.

TOM7 silencing exacerbates focal cerebral ischemia injury in rat by targeting PINK1/Beclin1-mediated autophagy

Activated autophagy has been intensively observed in cerebrovascular diseases, including focal cerebral ischemia injury, but its molecular mechanisms remain unclear. TOM7, which is a component of the protein translocase of the outer mitochondrial membrane (TOM) complex, may modulate assembly of the TOM complex. However, an understanding of how TOM7 affects cerebral ischemia injury is limited. In this study, we demonstrate that the expression of TOM7 is up-regulated after a photothrombotic cerebral ischemic model in rats, peaking at 3 days. In addition, TOM7 knockdown may aggravate cerebral ischemic injury and inhibit autophagy after ischemic stroke. Mechanically, TOM7 may regulate autophagy through the PINK1/Beclin1 pathway after cerebral ischemia injury. These results demonstrate that TOM7 silencing may aggravate cerebral ischemia injury through inhibiting PINK1/Beclin1 pathway- mediated autophagy.

An Antioxidant Role by Minocycline Via Enhancing the Activation of LKB1/AMPK Signaling in the Process of Cerebral Ischemia Injury.

LKB1/AMPK signaling pathway, as a metabolic checkpoint, is involved in the pathogenesis of cerebral ischemia injury. Minocycline, a tetracycline derivative, protects against cerebral ischemia via reducing inflammation, oxidative stress, and apoptosis. The aim of the study was to evaluate the influence of minocycline on oxidative biomarkers and LKB1/AMPK signaling pathway in Wistar rats with focal cerebral ischemia injury and to clarify the neuroprotective mechanism of minocycline against focal cerebral ischemia injury. The focal cerebral ischemia injury of Wistar rats was established by inserting a thread into the left middle cerebral artery. 2,3,5-Triphenyltetrazolium chloride (TTC) staining was used to label infarct volume. The levels of MDA and LPO were measured with a biochemical assay. All other items were determined by Western blotting. Minocycline decreased cerebral infarct volume, but had no effects on neurological scores. Minocycline improved the biological activity of GPx-1/2, GSS and GR, while limited the GGT1 activity in the hippocampus of cerebral ischemia-reperfusion rats. Minocycline also elevated the biological activity of SOD and counteracted lipid peroxidation. Minocycline enhanced the activity of both LKB1 and the levels of the three AMPK subunits in the hippocampus of cerebral ischemia-reperfusion rats. Minocycline effectively inhibits oxidative stress via modulating antioxidative enzymes and activating the LKB1/AMPK signaling pathway in the process of acute cerebral infarct.

Retigabine attenuates focal cerebral ischemic injury through inhibiting mitochondria-dependent apoptotic pathway.

We explored the protective effect of retigabine (RTG) on focal cerebral ischemic injury and the potential molecular mechanism. A mouse model of middle cerebral artery occlusion (MCAO) was established to induce cerebral ischemic injury. Blood samples were collected for the measurement of malondialdehyde (MDA), superoxide dismutase (SOD) and reduced glutathione (GSH). The brain infarct volume was stained by triphenyltetrazolium chloride. The cell apoptosis was observed by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) staining. The expression of B-cell lymphoma-2 (Bcl-2), BCL2-Associated X (Bax), cleaved caspase 3, p-p38 and p-JNK, were determined by Western blot. RTG treatment reduced the MCAO-induced increase in brain infarct volume and neurological deficit scores. RTG treatment reduced the level of MDA and increased the activity of SOD and GSH. RTG treatment also decreased the Bax/Bcl-2 ratio and cleaved caspase 3 expression in the ischemic tissues. Further, RTG treatment decreased the phosphorylation levels of p38 and JNK in the ischemic tissues. RTG attenuated cerebral ischemic injury through reducing oxidative stress and mitochondria-mediated apoptosis via inhibiting p38 and JNK phosphorylation.

Ginsenoside Rb1 administration attenuates focal cerebral ischemic reperfusion injury through inhibition of HMGB1 and inflammation signals.

High-mobility group box 1 (HMGB1) is released after focal cerebral ischemia/reperfusion (I/R), and aggravates brain tissue damage. Ginsenoside Rb1 (Rb1), isolated from Panax ginseng, has been reported to inhibit I/R-induced cell death in the brain. The present study aimed to investigate the protective ability of GRb1 on focal cerebral I/R rats and to explore its further mechanisms. A middle cerebral artery occlusion (MCAO) rat model was established and treated with different doses of Rb1. The neurological deficits were examined after reperfusion, and TTC staining was applied to assess the infarct volume. Histology and TUNEL staining were performed to evaluate pathological changes and neuronal cell apoptosis in brain tissues. HMGB1 and levels of inflammatory factors and proteins, were examined by ELISA or western blotting. Rb1 treatment notably improved the neurological deficits in an MCAO model, accompanied by decreased infarct volume in the brain tissues. Histological examination revealed that the necrotic tissue area in MCAO rats was also diminished by Rb1 treatment. Apoptosis induced by cerebral I/R was also attenuated by Rb1 treatment via downregulation of cleaved caspase-3 and caspase-9 levels. HMGB1 release was inhibited by Rb1 treatment in MCAO rats, and the levels of nuclear factor-κB, tumor necrosis factor-α, interleukin-6, inducible nitric oxide synthase and nitric oxide were also decreased. The present study suggests that Rb1 serves a protective role in I/R-induced cerebral-neuron injury, due to the decreased cerebral infarct volume of brain tissue. The mechanisms underlying these effects may be associated with the inhibition of HMGB1 inflammatory signals.

Neuroprotective effects of Tongxinluo on focal cerebral ischemia and reperfusion injury in rats associated with the activation of the MEK1/2/ERK1/2/p90RSK signaling pathway

Ischemic stroke brings a huge family and social burden. Although the reperfusion of ischemic cerebral tissue is the most important way to rescue ischemic stroke, ischemia–reperfusion (I/R) injury further results in brain damage and even lead to death. Recent studies demonstrated that Tongxinluo (TXL) helps to protect the brain against focal cerebral I/R injury in rats by reducing neuronal apoptosis, and the MEK1/2/ERK1/2/90 ribosomal S6 kinase (p90RSK) pathway may be involved in this protective effect. Therefore, our present research was designed to identify the potential mechanisms involved. Adult male Sprague-Dawley rats (n = 108) were randomly divided into 4 groups: sham, cerebral ischemia and reperfusion (I/R), I/R plus TXL (TXL), and TXL plus U0126, a highly selective inhibitor of MEK 1 and MEK 2 (TXL + U0126). Brain edema was measured by T2-weighted magnetic resonance imaging (MRI). Pathological destruction of the blood brain barrier (BBB) ultrastructure was assessed by transmission electron microscopy, and proteins involved in the MEK1/2/ERK1/2/p90RSK pathway were detected by immunofluorescence and Western blotting. Our results indicated that TXL significantly improved neurological function, reduced brain edema, ameliorated the destruction of the BBB ultrastructure and markedly reduced neuronal injury. However, these benefits were diminished when the MEK1/2/ERK1/2/p90RSK pathway was inhibited by U0126. We also found that TXL upregulated the expression levels of p-MEK1/2, p-ERK1/2, p-p90RSK and p-bad, which were all significantly reversed by U0126. Collectively, our data demonstrate that TXL provides neuroprotection against cerebral I/R injury and neuronal injury, and that these effects are mediated, in part, by activation of the MEK1/2/ERK1/2/p90RSK pathway.

Neuroprotective Effect of Sirt2-specific Inhibitor AK-7 Against Acute Cerebral Ischemia is P38 Activation-dependent in Mice

Cerebral ischemia is the most common cause of stroke with high morbidity, disability and mortality. Sirtuin-2 (Sirt2), a vitally important NAD+-dependent deacetylase which has been widely researched in central nervous system diseases, has also been identified as a promising treatment target using its specific inhibitors such as AK-7. In this study, we found that P38 was specifically activated after focal cerebral ischemic injury, and it was also significantly activated after AK-7 administration in a concentration-dependent manner in vitro and in vivo. AK-7 decreased the infarction volume remarkably and promoted the recovery of neurological function efficiently in the mice evaluated by behavior tests. In contrast, pP38 inhibition increased the infarct volume and exacerbated the symptoms of paralysis. Herein, we suggest AK-7 improves the outcome of brain ischemia in dependence on the P38 activation in mice, which may serve as a strategy for the treatment of stroke.

Liraglutide Activates the Nrf2/HO-1 Antioxidant Pathway and Protects Brain Nerve Cells against Cerebral Ischemia in Diabetic Rats.

This study aimed to determine the effect of liraglutide pretreatment and to elucidate the mechanism of nuclear factor erythroid 2-related factor (Nrf2)/heme oxygenase-1 (HO-1) signaling after focal cerebral ischemia injury in diabetic rats model. Adult male Sprague-Dawley rats were randomly divided into the sham-operated (S) group, diabetes mellitus ischemia (DM + MCAO) group, liraglutide pretreatment normal blood glucose ischemia (NDM+MCAO+L) group, and liraglutide pretreatment diabetes ischemia (DM + MCAO + L) group. At 48 h after middle cerebral artery occlusion (MCAO), neurological deficits and infarct volume of brain were measured. Oxidative stress brain tissue was determined by superoxide dismutase (SOD) and myeloperoxidase (MPO) activities. The expression levels of Nrf2 and HO-1 of brain tissue were analyzed by western blotting. In the DM + MCAO + L group, neurological deficits scores and cerebral infarct volume seemed to decrease at 48 h after MCAO cerebral ischemia compared with those in DM + MCAO group (P < 0.05). In addition, the expression of Nrf2 and HO-1 increased in 48 h at liraglutide pretreatment groups after MCAO cerebral ischemia if compared with those in the DM + MCAO group (P < 0.05). Furthermore, the DM + MCAO + L group has no significant difference compared with the NDM + MCAO + L group (P > 0.05). To sum up, alleviating effects of liraglutide on diabetes complicated with cerebral ischemia injury rats would be related to Nrf2/HO-1 signaling pathway.

Dental Mesenchymal Stem/Stromal Cells and Their Exosomes.

Stem cells derived from human dental pulp tissue (DP-MSC) differ from the other mesenchymal stem cells prepared from bone marrow or adipose tissue due to their embryonic origin from the neural crest and are of special interest because of their neurotropic character. Furthermore, the therapeutic potential of DP-MSCs is realized through paracrine action of extracellularly released components, for which exosomes play an important role. In this review, we intend to explore the properties of these cells with an emphasis on exosomes. The therapeutic applicability of these cells and exosomes in dental practice, neurodegenerative diseases, and many other difficultly treatable diseases, like myocardial infarction, focal cerebral ischemia, acute lung or brain injury, acute respiratory distress syndrome, acute inflammation, and several others is concisely covered. The use of cellular exosomes as an important diagnostic marker and indicator of targeted cancer therapies is also discussed, while the importance of stem cells from human exfoliated deciduous teeth as a source of evolutionally young cells for future regenerative therapies is stressed. We conclude that exosomes derived from these cells are potent therapeutic tools for regenerative medicine in the near future as clinical administration of DP-MSC-conditioned medium and/or exosomes is safer and more practical than stem cells.