Death Of Cortical Neurons Research Articles

Necroptosis contributes to methamphetamine-induced cytotoxicity in rat cortical neurons

Necroptosis, a programmed necrosis, is involved in various types of neurodegenerative diseases. In this study, we investigated whether necroptosis contributed to neuronal damage in a methamphetamine injury model. Methods: Primary cultures of embryonic cortical neurons from Sprague-Dawley rats were subjected to different doses of methamphetamine with/without pre-treatment with a specific necroptosis inhibitor, Necrostatin-1. Necrosis was assessed by determining lactate dehydrogenase release and by Annexin V/propidium iodide double staining, while the neuronal ultra-structure was examined by electron microscopy. Tumor necrosis factor-α protein levels were determined by enzyme-linked immunosorbent assay. Results: At early stages (12h) of post-treatment with methamphetamine, significant necrosis occurred and the viability of neurons decreased in a dose- and time-dependent manner in this model of acute neuronal injury. Pretreatment with Necrostatin-1 led to significant neuronal preservation compared with the methamphetamine-treated groups. Furthermore, tumor necrosis factor-α expression increased in a dose-dependent manner following methamphetamine exposure. Conclusion: Methamphetamine induced necrosis in rat cortical neurons in vitro, both time and dose dependently, and necroptosis may be an important newly identified mode of cortical neuronal death caused by single high-dose methamphetamine administration.

Glycine confers neuroprotection through microRNA-301a/PTEN signaling.

BackgroundGlycine is known to protect against neuronal death. However, the underlying mechanism remains to be elucidated. The microRNA-301a is involved in both biological and pathological processes. But it is not known whether microRNA-301a has a neuroprotective property. In this study, we aimed to determine whether glycine-induced neuroprotection requires microRNA-301a-dependent signaling.ResultsWe provided the first evidence that glycine increased the expression of microRNA-301a in cultured rat cortical neurons and protected against cortical neuronal death through up-regulation of microRNA-301a after oxygen-glucose deprivation. MicroRNA-301a directly bound the predicted 3′UTR target sites of PTEN and reduced PTEN expression in cortical neurons. We revealed that PTEN down-regulation by microRNA-301a mediated glycine-induced neuroprotective effect following oxygen-glucose deprivation.ConclusionsOur results suggest that 1) microRNA-301a is neuroprotective in oxygen-glucose deprivation-induced neuronal injury; 2) glycine is an upstream regulator of microRNA-301a; 3) glycine confers neuroprotection through microRNA-301a/PTEN signal pathway.

Transcranial Direct Current Stimulation Modulates Cortical Neuronal Activity in Alzheimer's Disease.

Quantitative electroencephalography (qEEG) showed that Alzheimer's disease (AD) is characterized by increased theta power, decreased alpha and beta power, and decreased coherence in the alpha and theta band in posterior regions. These abnormalities are thought to be associated with functional disconnections among cortical areas, death of cortical neurons, axonal pathology, and cholinergic deficits. Since transcranial Direct Current Stimulation (tDCS) over the temporo-parietal area is thought to have beneficial effects in patients with AD, in this study we aimed to investigate whether tDCS benefits are related to tDCS-induced changes in cortical activity, as represented by qEEG. A weak anodal current (1.5 mA, 15 min) was delivered bilaterally over the temporal-parietal lobe to seven subjects with probable AD (Mini-Mental State Examination, MMSE score >20). EEG (21 electrodes, 10–20 international system) was recorded for 5 min with eyes closed before (baseline, t0) and 30 min after anodal and cathodal tDCS ended (t1). At the same time points, patients performed a Word Recognition Task (WRT) to assess working memory functions. The spectral power and the inter- and intra-hemispheric EEG coherence in different frequency bands (e.g., low frequencies, including delta and theta; high frequencies, including alpha and beta) were calculated for each subject at t0 and t1. tDCS-induced changes in EEG neurophysiological markers were correlated with the performance of patients at the WRT. At baseline, qEEG features in AD patients confirmed that the decreased high frequency power was correlated with lower MMSE. After anodal tDCS, we observed an increase in the high-frequency power in the temporo-parietal area and an increase in the temporo-parieto-occipital coherence that correlated with the improvement at the WRT. In addition, cathodal tDCS produced a non-specific effect of decreased theta power all over the scalp that was not correlated with the clinical observation at the WRT. Our findings disclosed that tDCS induces significant modulations in the cortical EEG activity in AD patients. The abnormal pattern of EEG activity observed in AD during memory processing is partially reversed by applying anodal tDCS, suggesting that anodal tDCS benefits in AD patients during working memory tasks are supported by the modulation of cortical activity.

Adenosine kinase facilitated astrogliosis-induced cortical neuronal death in traumatic brain injury.

Adenosine kinase (ADK) plays a pivotal role in regulating brain function by regulating adenosine level, and ADK inhibition protects against neuronal damage in cerebral ischemia and epilepsy; however, the effects of ADK in traumatic brain injury (TBI) have not been investigated. For exploring its effects, we generated a blade-induced rat focal brain injury model. Western blot analysis, immunohistochemistry and immunofluorescent staining suggested that ADK was up-regulated after TBI, and it was temporally and spatially associated with astrogliosis. Terminal deoxynucleotidyl transferase-mediated biotinylated-dUTP nick-end labeling showed that neuronal apoptosis was paralleled with TBI-induced ADK up-regulation and astrogliosis. For further investigating the role of ADK in astrogliosis-induced neuronal death, primary cultured astrocytes and neurons were utilized, lipopolysaccharide (LPS) was employed to mediate astrogliosis, and condition medium (CM) of reactive astrocytes was used to treat neurons. The results showed that astrocytes increased iNOS expression and secreted pro-inflammatory cytokines after LPS treatment, and CM of reactive astrocytes resulted neuronal death. Additionally, ADK knock-down didn't ameliorate LPS-induced astrocyte proliferation, but it protected against neuronal death by reducing iNOS expression, tumor necrosis factor α and interleukin 1β secretion of reactive astrocytes. Taken together, ADK was associated with astrogliosis after TBI, its inhibition in reactive astrocytes ameliorated astrogliosis-induced neuronal death. Our findings extended the current knowledge on the role of ADK in astrogliosis, and also provided new evidence for the TBI treatment.

Age-Related Changes in D-Aspartate Oxidase Promoter Methylation Control Extracellular D-Aspartate Levels and Prevent Precocious Cell Death during Brain Aging.

The endogenous NMDA receptor (NMDAR) agonist D-aspartate occurs transiently in the mammalian brain because it is abundant during embryonic and perinatal phases before drastically decreasing during adulthood. It is well established that postnatal reduction of cerebral D-aspartate levels is due to the concomitant onset of D-aspartate oxidase (DDO) activity, a flavoenzyme that selectively degrades bicarboxylic D-amino acids. In the present work, we show that d-aspartate content in the mouse brain drastically decreases after birth, whereas Ddo mRNA levels concomitantly increase. Interestingly, postnatal Ddo gene expression is paralleled by progressive demethylation within its putative promoter region. Consistent with an epigenetic control on Ddo expression, treatment with the DNA-demethylating agent, azacitidine, causes increased mRNA levels in embryonic cortical neurons. To indirectly evaluate the effect of a putative persistent Ddo gene hypermethylation in the brain, we used Ddo knock-out mice (Ddo(-/-)), which show constitutively suppressed Ddo expression. In these mice, we found for the first time substantially increased extracellular content of d-aspartate in the brain. In line with detrimental effects produced by NMDAR overstimulation, persistent elevation of D-aspartate levels in Ddo(-/-) brains is associated with appearance of dystrophic microglia, precocious caspase-3 activation, and cell death in cortical pyramidal neurons and dopaminergic neurons of the substantia nigra pars compacta. This evidence, along with the early accumulation of lipufuscin granules in Ddo(-/-) brains, highlights an unexpected importance of Ddo demethylation in preventing neurodegenerative processes produced by nonphysiological extracellular levels of free D-aspartate.

Effects of BET inhibitor JQ1 on neurotoxicity in rat primary cortical neurons: A potential therapeutic approach in Alzheimer's disease

IntroductionThe neuropathological features of Alzheimer's disease (AD) are deposition of amyloid plaques, neurofibrillary tangles and neuro-inflammation. Among these, neuro-inflammation is a common pathological substrate of neurodegenerative disease, such as AD, and Parkinson disease.AimsHerein, we tested whether the inhibition of bromodomain and extra-terminal domain (BET) protein, a critical regulators of transcription in neurons, could attenuate the neuronal cell death and amyloid beta aggregation using rat primary cortical neurons. We also investigated whether a BET inhibitor could prevent the inflammatory processes and cognitive decline in an animal model of AD.MethodsThe effects of BET inhibition on neuronal cell death were assessed in the followings:– cell viability and reactive oxygen species generation;– enzyme activity of tPA/PAI-1 measured by casein zymography;– the signal pathways including BDNF/CREB and MAPKs using western blotting;– the effects on inflammatory responses in an animal model of AD using immunohistochemistry.ResultsJQ1, an inhibitor of Brd2/4 protein, significantly decreased the neuronal cell death in mixed cortical neurons in concentration-dependent manner but not in pure neurons. JQ1 increased the enzyme activity of tPA, which decreased the expression of Brd2 protein. JQ1 also decreased the ROS generation and decreased cleaved caspase-3 expression. Moreover, Brd2 inhibition by transfection of Brd2 siRNA reduced amyloid beta aggregation.ConclusionOur results suggested that BET inhibition might have therapeutic potential for AD. That is, Brd2 inhibition by JQ1 can prevent the neuronal cell death and neuroinflammation as well as amyloid beta aggregation through regulation of tPA/PAI-1 system.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Lysosomal membrane permeabilization is involved in oxidative stress-induced apoptotic cell death in LAMP2-deficient iPSCs-derived cerebral cortical neurons

Patients with Danon disease may suffer from severe cardiomyopathy, skeletal muscle dysfunction as well as varying degrees of mental retardation, in which the primary deficiency of lysosomal membrane-associated protein-2 (LAMP2) is considerably associated. Owing to the scarcity of human neurons, the pathological role of LAMP2 deficiency in neural injury of humans remains largely elusive. However, the application of induced pluripotent stem cells (iPSCs) may shed light on overcoming such scarcity.In this study, we obtained iPSCs derived from a patient carrying a mutated LAMP2 gene that is associated with Danon disease. By differentiating such LAMP2-deficient iPSCs into cerebral cortical neurons and with the aid of various biochemical assays, we demonstrated that the LAMP2-deficient neurons are more susceptible to mild oxidative stress-induced injury.The data from MTT assay and apoptotic analysis demonstrated that there was no notable difference in cellular viability between the normal and LAMP2-deficient neurons under non-stressed condition. When exposed to mild oxidative stress (10μM H2O2), the LAMP2-deficient neurons exhibited a significant increase in apoptosis. Surprisingly, we did not observe any aberrant accumulation of autophagic materials in the LAMP2-deficient neurons under such stress condition.Our results from cellular fractionation and inhibitor blockade experiments further revealed that oxidative stress-induced apoptosis in the LAMP2-deficient cortical neurons was caused by increased abundance of cytosolic cathepsin L. These results suggest the involvement of lysosomal membrane permeabilization in the LAMP2 deficiency associated neural injury.

Pathogenetic approaches to treatment of cognitive disorders in patients with diabetes mellitus

The article presents the currents concepts on the mechanisms of brain lesions and development of cognitive impairment in diabetes mellitus (DM) including DM type 2. Metabolic and vascular mechanisms, oxidative stress, hyperglycemia, glutamate excitotoxicity, insulin insufficiency and brain insulin resistance, general vascular and microcirculatory disturbances, death of cortical neurons, decrease in the newly synthesized acetylcholine, activation of lipid peroxidation are considered. A review of the main domestic and international drugs used in clinical practice for treatment of cognitive impairment in patients with DM is presented.

Gains and losses on the road to understanding Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder and the most common cause for dementia, which affects approximately 120 thousand people in Switzerland and 35 million worldwide. Aging is a major risk factor for developing AD and thus, as our societies are growing older, we face great challenges to find treatment strategies. The disease is characterised by loss of memory, deposition of extracellular amyloid plaques containing Aβ peptides and intraneuronal tangles of the tau protein. To date, there is no effective treatment and the cause of the disease is still debated. The Schweizerische Alzheimervereinigung states that we need "continuous manifold research" into all possible causes of AD to find a cure for this disease. Fitting this proposition, a recent publication by Xia et al. (2015) described a novel mouse model that for the first time reproduces cortical neuron death as observed in human AD cases. At the same time, this publication questions the major theory of AD pathogenesis and points towards different treatment avenues that should be followed to find a cure for AD.

Totarol prevents neuronal injury in vitro and ameliorates brain ischemic stroke: Potential roles of Akt activation and HO-1 induction

The natural product totarol, a phenolic diterpenoid and a major constituent isolated from the sap of Podocarpus totara, has been reported to have a potent antimicrobial activity. In this study, we determined whether totarol possessed an additional neuroprotective activity in vitro and in vivo. We found that totarol prevented glutamate- and oxygen and glucose deprivation-induced neuronal death in primary rat cerebellar granule neuronal cells and cerebral cortical neurons. Totarol increased Akt and GSK-3β phosphorylation, Nrf2 and heme oxygenase-1 (HO-1) protein expressions and suppressed oxidative stress by increasing GSH and SOD activities. The PI3K/Akt inhibitor LY294002 prevented totarol neuroprotective effect by suppressing the totarol-induced changes in HO-1 expression and the activities of GSH and SOD. The HO-1 inhibitor ZnPPIX also prevented totarol-increased GSH and SOD activities. In a model of acute cerebral ischemic injury in Sprague–Dawley rats, produced by occlusion of the middle cerebral artery for 2h followed by 22h or 46h of reperfusion, totarol significantly reduced infarct volume and improved the neurological deficit. In this model, totarol increased HO-1 expression and the activities of GSH and SOD. These observations suggest that totarol may be a novel activator of the Akt/HO-1 pathway protecting against ischemic stroke through reduction of oxidative stress.

Target of HIV-1 Envelope Glycoprotein gp120-Induced Hippocampal Neuron Damage: Role of Voltage-Gated K(+) Channel Kv2.1.

Human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein 120 (gp120) has been reported to be toxic to the hippocampal neurons, and to be involved in the pathogenesis of HIV-1-associated neurocognitive disorders (HAND). Accumulating evidence has demonstrated that voltage-gated potassium (Kv) channels, especially the outward delayed-rectifier K(+) (Ik) channels, play a critical role in gp120-induced cortical neuronal death in vitro. However, the potential mechanisms underlying the hippocampal neuronal injury resulted from gp120-mediated neurotoxicity remain poorly understood. Using whole-cell patch clamp recording in cultured hippocampal neurons, this study found that gp120 significantly increased the outward delayed-rectifier K(+) currents (Ik). Meanwhile, Western blot assay revealed that gp120 markedly upregulated Kv2.1 protein levels, which was consistent with the increased Ik density. With Western blot and terminal deoxynucleotidyl transferase dUTP nick end labeling assays, it was discovered that gp120-induced neuronal injury was largely due to activation of Kv2.1 channels and resultant apoptosis mediated by caspase-3 activation, as the pharmacological blockade of Kv2.1 channels largely attenuated gp120-induced cell damage and caspase-3 expression. Moreover, p38 MAPK was demonstrated to participate in gp120-induced hippocampal neural damage, since p38 MAPK antagonist (SB203580) partially abrogated gp120-induced Kv2.1 upregulation and neural apoptosis. Taken together, these results suggest that gp120 induces hippocampal neuron apoptosis by enhancement of the Ik, which might be associated with increased Kv2.1 expression via the p38 MAPK pathway.

Resveratrol via sirtuin-1 downregulates RE1-silencing transcription factor (REST) expression preventing PCB-95-induced neuronal cell death

Resveratrol (3,5,4′-trihydroxystilbene) (RSV), a polyphenol widely present in plants, exerts a neuroprotective function in several neurological conditions; it is an activator of class III histone deacetylase sirtuin1 (SIRT1), a crucial regulator in the pathophysiology of neurodegenerative diseases. By contrast, the RE1-silencing transcription factor (REST) is involved in the neurotoxic effects following exposure to polychlorinated biphenyl (PCB) mixture A1254. The present study investigated the effects of RSV-induced activation of SIRT1 on REST expression in SH-SY5Y cells. Further, we investigated the possible relationship between the non-dioxin-like (NDL) PCB-95 and REST through SIRT1 to regulate neuronal death in rat cortical neurons. Our results revealed that RSV significantly decreased REST gene and protein levels in a dose- and time-dependent manner. Interestingly, overexpression of SIRT1 reduced REST expression, whereas EX-527, an inhibitor of SIRT1, increased REST expression and blocked RSV-induced REST downregulation. These results suggest that RSV downregulates REST through SIRT1. In addition, RSV enhanced activator protein 1 (AP-1) transcription factor c-Jun expression and its binding to the REST promoter gene. Indeed, c-Jun knockdown reverted RSV-induced REST downregulation. Intriguingly, in SH-SY5Y cells and rat cortical neurons the NDL PCB-95 induced necrotic cell death in a concentration-dependent manner by increasing REST mRNA and protein expression. In addition, SIRT1 knockdown blocked RSV-induced neuroprotection in rat cortical neurons treated with PCB-95. Collectively, these results indicate that RSV via SIRT1 activates c-Jun, thereby reducing REST expression in SH-SY5Y cells under physiological conditions and blocks PCB-95-induced neuronal cell death by activating the same SIRT1/c-Jun/REST pathway.

WITHDRAWN: Sevoflurane post-conditioning protects primary rat cortical neurons against oxygen–glucose deprivation/resuscitation via down-regulation in mitochondrial apoptosis axis of Bid, Bim, Puma–Bax and Bak mediated by Erk1/2

Temporal post-conditioning helps provide neuroprotection against brain injury secondary to ischemia-reperfusion and is considered an effective intervention, but the exact mechanism of sevoflurane post-conditioning is unclear. The essential axis involves activator Bid, Bim, Puma (BH3s), Bax, and Bak; activates the mitochondrial death program; and might be involved in a cell death signal. Extracellular signal-related kinases 1/2 (Erk1/2) play a pivotal role in cell growth and proliferation. We hypothesized that sevoflurane post-conditioning might inhibit Bid, Bim, Puma, Bax, and Bak expression and is activated by phosphor-Erk1/2 to decrease neuronal death. To test this hypothesis, we exposed primary cortical neuron cultures to oxygen-glucose deprivation for 1h, along with resuscitation for 24h (OGD/R). MTT assays, propidium iodide uptake (PI), JC-1 fluorescence, and Western blot indicated the following: decreased cell viability (P<0.05); increased cell death (P<0.05); decreased mitochondrial membrane potential (P<0.05); and decreased Bid, Bim, Puma, Bax, and Bak expression with OGD/R exposure. Inhibition of Erk1/2 phosphorylation could attenuate sevoflurane post-conditioning that mediated an increase in neuronal viability and mitochondrial membrane potential, as well as a decrease in cell death and Bid, Bim, Puma, Bax, and Bak expression after OGD/R treatment. The results demonstrated that sevoflurane post-conditioning caused a marked decrease in cortical neuronal death secondary to OGD/R exposure through the downregulation of the mitochondrial apoptosis axis involving Bid, Bim, Puma, Bax, and Bak that was mediated by the phosphorylation/activation of Erk1/2.

Sigma-1 receptor is a molecular target for novel neuroprotectant T-817MA

T-817MA is an orally available agent, which is in the phase 2 clinical trial for Alzheimer's disease (AD) in the US and Japan. T-817MA demonstrated a neuroprotective activity against the toxicity induced by amyloid β or oxidative stress in vitro. T-817MA also promoted the neurite outgrowth in vitro. The molecular mechanisms underlying these effects by T-817MA are not fully understood. T-817MA showed the highest binding to σ1 receptor among other central receptors. σ1 receptor is reportedly involved in oxidative stress resistance and neuritogenesis, and therefore implicated in neurological and psychiatric disorders. In the present study, we investigated that σ1 receptor is involved in the neuroprotective effects of T-817MA in vitro. Binding affinity: Affinity of T-817MA to human σ1 receptor was determined by the inhibition of the binding of radiolabeled (+)-pentazocine to Jurkat cell membrane. Neuroprotection assay: Cortical neurons were prepared from embryos of Wistar/ST rat at 8 days in vitro (DIV), and treated with sodium nitroprusside (SNP). T-817MA or σ1 receptor ligand was added to neurons 24 hr before SNP. Cell viability and intracellular reactive oxygen species (ROS) were determined 20 to 28 hr after SNP by WST-8 and dihydrorhodamine 123, respectively. Neurite outgrowth assay: Rat cortical neurons in reaggregation culture were treated with T-817MA or σ1 receptor ligand at 4 DIV. Neurons were fixed at 6 DIV and stained with Coomassie Brilliant Blue. Neurite lengths in the respective aggregates were measured using software Image J. T-817MA bound to σ1 receptor with Ki value of 16 nM, which is smaller than the plasma concentration achieved in ongoing clinical studies. A structurally close analog to T-817MA, lacking neuroprotection, did not bind to σ1 receptor. SNP-induced cell death and ROS generation in rat cortical neurons were blocked by T-817MA and those effects were negated by concomitant treatment with a σ1 receptor antagonist BD1047. T-817MA and a σ1 receptor agonist SA4503 promoted the neurite outgrowth in reaggregation culture of rat cortical neurons.

NF-κB Upregulates Type 5 Phosphodiesterase in N9 Microglial Cells: Inhibition by Sildenafil and Yonkenafil

Our previous studies showed that the phosphodiesterase-5 (PDE5) inhibitor sildenafil inhibited the microglial activation induced by lipopolysaccharide (LPS). However, whether yonkenafil, a novel PDE5 inhibitor, also inhibits microglial activation and the underlying mechanism of inhibition remain elusive. Here we found that yonkenafil significantly suppressed the production of NO, interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) and the protein expression of inducible NO synthase (iNOS) induced by LPS in microglial cells in a concentration-dependent manner. Knockdown of PDE5 inhibits NO and iNOS protein expression in LPS-stimulated N9 microglia. Moreover, we observed that the nuclear factor-κB (NF-κB) transcriptionally upregulated PDE5 expression, which was inhibited by sildenafil and yonkenafil in LPS-stimulated N9 microglia. Therefore, sildenafil and yonkenafil may exert their inhibitory effects on microglial activation by reducing the expression of PDE5. Furthermore, sildenafil and yonkenafil increased the cyclic guanosine monophosphate (cGMP) level in N9 microglia, and 8-Br-cGMP, an analogue of cGMP, downregulates extracellular signal-regulated kinases 1 and 2 (ERK1/2)/the NF-κB pathway, suggesting that sildenafil and yonkenafil inhibit microglial activation by decreasing PDE5 expression and increasing the cGMP level. Importantly, sildenafil and yonkenafil significantly alleviated the death of SH-SY5Y neuroblastoma cells and primary cortical neurons induced by the conditioned medium from activated microglia. Together, these findings position PDE5 as a potential therapy target for the treatment of neuroinflammation accompanied by microglial activation.

Sevoflurane Post-conditioning Protects Primary Rat Cortical Neurons Against Oxygen-Glucose Deprivation/Resuscitation: Roles of Extracellular Signal-Regulated Kinase 1/2 and Bid, Bim, Puma.

Temporal post-conditioning to induce neuroprotection against brain ischemia-reperfusion injury insult is considered to be an effective intervention, but the exact mechanisms of sevoflurane post-conditioning are poorly understood. Extracellular signal-related kinases 1/2 (Erk1/2) play a pivotal role in the cell growth and proliferation. The essential axis of activator Bid, Bim, Puma (BH3s) and BAX, BAK in activating the mitochondrial death program might offer common ground for cell death signal. We hypothesized that, sevoflurane post-conditioning might inhibit the expression of Bid, Bim and Puma and is activated by phosphor-Erk1/2 to reduce neuronal death. To test this hypothesis, we exposed primary cultured cortical neurons to oxygen-glucose deprivation for 1 h and resuscitation for 24 h (OGD/R). The assays of MTT, propidium iodide uptake, JC-1 fluorescence and western blot demonstrated that OGD/R exposure reduced cell viability, increased cell death, decreased mitochondrial membrane potential and the expressions of Bid, Bim, and Puma. Inhibition of Erk1/2 phosphorylation could partially attenuate 2 % of sevoflurane post-conditioning mediated increase in neuronal viability and mitochondrial membrane potential, and also a decrease in cell death and expression of Bid, Bim and Puma after OGD/R treatment. The results demonstrated that, the protection of sevoflurane post-conditioning markedly reducing death of cortical neurons exposed to OGD/R could be correlated with down-regulation of Bid, Bim and Puma expression mediated by phosphorylation/activation of Erk1/2.

Striatal neuronal death mediated by astrocytes from the Gcdh-/- mouse model of glutaric acidemia type I.

Glutaric acidemia type I (GA-I) is an inherited neurometabolic childhood disorder caused by defective activity of glutaryl CoA dehydrogenase (GCDH) which disturb lysine (Lys) and tryptophan catabolism leading to neurotoxic accumulation of glutaric acid (GA) and related metabolites. However, it remains unknown whether GA toxicity is due to direct effects on vulnerable neurons or mediated by GA-intoxicated astrocytes that fail to support neuron function and survival. As damaged astrocytes can also contribute to sustain high GA levels, we explored the ability of Gcdh-/- mouse astrocytes to produce GA and induce neuronal death when challenged with Lys. Upon Lys treatment, Gcdh-/- astrocytes synthetized and released GA and 3-hydroxyglutaric acid (3HGA). Lys and GA treatments also increased oxidative stress and proliferation in Gcdh-/- astrocytes, both prevented by antioxidants. Pretreatment with Lys also caused Gcdh-/- astrocytes to induce extensive death of striatal and cortical neurons when compared with milder effect in WT astrocytes. Antioxidants abrogated the neuronal death induced by astrocytes exposed to Lys or GA. In contrast, Lys or GA direct exposure on Gcdh-/- or WT striatal neurons cultured in the absence of astrocytes was not toxic, indicating that neuronal death is mediated by astrocytes. In summary, GCDH-defective astrocytes actively contribute to produce and accumulate GA and 3HGA when Lys catabolism is stressed. In turn, astrocytic GA production induces a neurotoxic phenotype that kills striatal and cortical neurons by an oxidative stress-dependent mechanism. Targeting astrocytes in GA-I may prompt the development of new antioxidant-based therapeutical approaches.

Ишемические изменения в головном мозге белых крыс разного возраста после введения инсулина

The morphological changes in the brain tissue of Wistar rats of different ages after intramuscular insulin injection in the dose of 1 IU/kg are typical for the hypoxic lesions of nervous tissue. The brain of rats at the age of 1-2 months responds to increased deposition of glycogen, moderate swelling around the cells and blood vessels. The effect of insulin on the brain Mature rats at the age of 5-7 months leads to vasodilatation, more pronounced swelling around the cells and blood vessels, hypertrophy of cells, aggregation and diabetes of red blood cells. The severity of ischemic changes significantly increased in the brain of old rats at the age of 20-24 months. These old rats had the senile dendrites, the widespread hypertrophic degenerative changes, i.e. flask-shaped vasodilation, hyperemia. In most of the visual fields are detected capillaries with the presence of aggregation on the side erythrocytes, signs of micro thrombosis, hemorrhage areas. The authors note that there is a loss of tone and tortuosity of the small arterioles, widespread swelling around the cells and around the blood vessels. Morphological signs of brain reaction on insulin injection reflect the death of cortical neurons, marked swelling of the brain tissue, disruption of vascular permeability, the thrombus formation and hemorrhages.

The roles of Cdk5-mediated subcellular localization of FOXO1 in neuronal death.

Deficiency of cyclin-dependent kinase 5 (Cdk5) has been linked to the death of postmitotic cortical neurons during brain development. We now report that, in mouse cortical neurons, Cdk5 is capable of phosphorylating the transcription factor FOXO1 at Ser249 in vitro and in vivo. Cellular stresses resulting from extracellular stimulation by H2O2 or β-amyloid promote hyperactivation of Cdk5, FOXO1 nuclear export and inhibition of its downstream transcriptional activity. In contrast, a loss of Cdk5 leads to FOXO1 translocation into the nucleus: a shift due to decreased AKT activity but independent of S249 phosphorylation. Nuclear FOXO1 upregulates transcription of the proapoptotic gene, BIM, leading to neuronal death, which can be rescued when endogenous FOXO1 was replaced by the cytoplasmically localized form of FOXO1, FOXO1-S249D. Cytoplasmic, but not nuclear, Cdk5 attenuates neuronal death by inhibiting FOXO1 transcriptional activity and BIM expression. Together, our findings suggest that Cdk5 plays a novel and unexpected role in the degeneration of postmitotic neurons through modulation of the cellular location of FOXO1, which constitutes an alternative pathway through which Cdk5 deficiency leads to neuronal death.

Overexpression of nuclear FUS induces neuronal cell death

Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are neurodegenerative diseases that overlap clinically, genetically, and pathologically. Dysregulation of fused in sarcoma (FUS) has been hypothesized to cause ALS and FTLD in gain-of-function and/or loss-of-function manners. However, the link between the pathogenesis of ALS/FTLD and dysfunction of FUS has not been clearly determined. In this study, we found that overexpression of FUS, but not knocking-down of endogenous FUS expression, induces death in motor neuronal NSC34 cells and primary cortical neurons via the mitochondrial apoptotic pathway, possibly independently of transactive response DNA-binding protein-43. Furthermore, we found that nuclear FUS, but not cytoplasmic FUS, is responsible for FUS-induced neuronal cell death. These observations suggest that the gain-of-function of FUS in the nucleus contributes to the pathogenesis of FUS-linked neurodegenerative diseases.