Expression Of Bcl-2 In Neurons Research Articles

Synthesis of oxymatrine hydrazone and its preventive action against sevoflurane induced neuron damage through ERK pathway up-regulation.

Exposure of patients undergoing multiple surgeries to anesthetic compounds leads to harmful side effects such as memory loss and impaired cognition. The current study was aimed to synthesize and investigate the effect of oxymatrine hydrazone on neuronal toxicity induced by sevoflurane in rats. Incubation with oxymatrine hydrazone was followed by exposure to sevoflurane for 48 h and determination of proliferation by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) assay. Apoptosis was detected by flow cytometry using Annexin V‑FITC and propydium iodide staining. Western blot analysis was used for determination of changes in protein expression. Sevoflurane exposure significantly (P<0.05) reduced proliferation of neurons by activation of cell apoptosis. However, pretreatment of neurons with oxymatrine hydrazone prevented reduction of proliferative potential induced on exposure with sevoflurane. Pre-treatment of neurons with 5.0 µM doses of oxymatrine hydrazone significantly prevented apoptosis induction by sevoflurane. Moreover, oxymatrine hydrazone pretreatment inhibited BCL2 Associated-X (BAX) and cleaved caspase-3 levels induced by sevoflurane exposure in neurons. Phosphorylation of extracellular signal‑regulated protein kinase (ERK1/2) and expression of BCL-2 in neurons exposed to sevoflurane were markedly promoted on pretreatment with oxymatrine hydrazone. Additionally, U0126 (ERK ½ activation inhibitor) treatment of sevoflurane exposed neurons inhibited promotion of ERK1/2 phosphorylation by oxymatrine hydrazone pre-treatment. In summary, cytotoxicity of sevoflurane in neurons was prevented on pretreatment with oxymatrine hydrazone. Pretreatment of sevoflurane exposed neurons with oxymatrine hydrazone inhibited apoptosis, suppressed BAX/caspase-3 and elevated BCL-2. Moreover, oxymatrine hydrazone pre-treatment promoted ERK1/2 phosphorylation in sevoflurane exposed neurons. Therefore, oxymatrine hydrazone has a great potential for prevention of neurotoxicity induced by sevoflurane.

IL-37: Novel neuroprotective effects after brain ischemia and reperfusion

Interleukin-1 (IL-1) is a central mediator of innate immunity and inflammation. IL-37 (IL-37), a newly described member of the IL-1 family, functions as a fundamental inhibitor of innate inflammation and immunity. The purpose of the present study was to determine the effects of interleukin-37 on neuron cells and on brain inflammation induced by brain ischemia/reperfusion (I/R). A transgenic mouse strain was generated to express human IL-37 (hIL-37Tg) and WT mice were subjected to (60 min) brain ischemia and followed by reperfusion (24 h), by using a mice model of transient focal cerebral ischemia induced by advancing a nylon mono-filament to occlude the middle cerebral artery (MCA). Infarct size was determined by triphenyltetrazolium chloride staining. The morphology of neurons in brain sections were examined by Nissl staining and cytokines/chemokines measured by ELIZA. IL-37Tg significantly reduced infarct size by 65.4% (P&lt;0.05) compared with WT after I/R. Reduced inflammation was associated with decreased leukocyte recruitment, and reduced release of IL-1β and TNFα, macrophage inflammatory protein-2 (MIP-2), MCP-1 and keratinocyte chemokine (KC) compared with WT (P&lt;0.05), whereas IL-10 was increased eight fold (P&lt;0.05). IL-37 significantly reduced cell death and increased Bcl-2 expression in neurons. Thus, IL-37 emerges as a key modulator of brain inflammation and has important translational implications for both the prevention and treatment of patients suffering from brain ischemia.

Changes in the Expression of Bcl-2 Protein in Neurons in the Hippocampal Fields after Use of Ischemic Postconditioning of the Brain

The expression of Bcl-2 protein in pyramidal neurons in hippocampal fields CA1, CA2, CA3, and CA4 was studied in Mongolian gerbils (Meriones unguiculatus) in the early (two days) and late (seven days) reperfusion periods after 7-min ischemia of the forebrain, after use of ischemic postconditioning (IPostC) and in sham-operated animals (n = 60). The highest level of Bcl-2 expression in the latter group was seen in neurons in field CA4 and the lowest in neurons in field CA1 (p < 0.01). Reversible ischemic injury led to an increase in the deficit of morphologically unaltered neurons in the hippocampus at the later period of reperfusion and a significant decrease in neuronal Bcl-2 expression at the early reperfusion period, this decrease being significantly smaller in the late reperfusion period. IPostC consisting of three episodes of reperfusion-ischemia (15/15 sec) promoted a significant increase in the number of morphologically unaltered neurons in fields CA1 and CA3 in the early reperfusion period. An increase in the level of Bcl-2 expression was seen in the cytoplasm of morphologically unaltered neurons in all hippocampal fields. In the late reperfusion period after IPostC, the number of unaltered neurons was increased in fields CA1, CA3, and CA4 (p < 0.05); only hippocampal field CA1 neurons showed a significant increase in Bcl-2 expression (by 12.7%, p < 0.01). These results lead to the conclusion that the cytoporotective effect of IPostC for hippocampal field CA1 is mediated by a mechanism leading to an increase in Bcl-2 expression, i.e., via blockade of apoptosis.

Extracellular signal–regulated kinase 1/2 is involved in a tamoxifen neuroprotective effect in a lateral fluid percussion injury rat model

BackgroundThe aim of the present study was to determine whether tamoxifen (TMX) causes attenuation of traumatic brain injury (TBI) induced by fluid percussion injury. Materials and methodsImmediately after the onset of fluid percussion TBI, anesthetized male Sprague-Dawley rats were divided into three major groups and intraperitoneally administered the vehicle solution (1 mL/kg), TMX (1 mg/kg), or TMX (1 mg/kg) plus the extracellular signal–regulated kinase 1/2 antagonist SL327 (30 mg/kg). Another group of rats were used as sham-operated controls. The functional outcomes, such as motor outcomes, were evaluated using an incline plane. The cellular infarction volume was evaluated by triphenyltetrazolium chloride staining. Neuronal loss, apoptosis, and p-ERK1/2 and Bcl2 expression in neuronal cortex cells were evaluated by immunofluorescence methods. All the parameters were assessed on day 4 after injury. ResultsCompared with the sham-operated controls, the TBI-induced motor deficits and cerebral infarction after TBI were significantly attenuated by TMX therapy. The TBI-induced neuronal loss and apoptosis were also significantly reduced by TMX therapy. The numbers of Bcl2- and phospho-ERK1/2-positive neuronal cells in the ischemic cortex after TBI were significantly increased by TMX therapy. These TMX effects were significantly blocked by SL327 administration. ConclusionsOur results suggest that intravenous injection of TMX may ameliorate TBI in rats by increasing neuronal p-ERK1/2 expression, which might lead to an increase in neuronal Bcl2 expression and a decrease in neuronal apoptosis and cell infarction volume, and it might represent one mechanism by which functional recovery occurred. TMX may be a promising TBI treatment strategy.

Facial paralysis induced by herpes simplex virus type 1 and the study of facial neurons apoptosis in mice

To study the apoptosis of facial motor neurons and the expression of apoptosis-related genes, Bcl-2 and Bax, in the animal model of viral facial paralysis. Total of 84 Balb/c mice were divided into viral inoculation group and nerve transaction group. The animals were executed 1, 3, 7, 10, 15, 20 and 30 days after being operated respectively. The histopathological features of facial neurons in brain stem were observed by HE and Nissl stain. The changes of facial neuronal apoptosis were observed by TUNEL. The changes of expression of Bcl-2 and Bax genes in facial neurons were observed by immunohistochemistry staining. After nerve transection, increased apoptotic cells were found in homolateral facial motor nucleus and the peak appeared at 10 and 15 days. The level of Bcl-2 expression in neurons declined while the expression of Bax increased gradually. Correspondingly, the ratio of Bcl-2/Bax declined. In the viral inoculation group, no visible change of apoptosis and Bax expression, but the level of Bcl-2 and the ratio of Bcl-2/Bax increased gradually. Comparing to axotomy, facial motor nucleus in HSV-1 infective animal model are free of apoptosis. Both the mild form of lesion and the ability to block apoptosis of HSV-1 are likely to be involved into the phenomenon. Bcl-2 and Bax might interfere with the apoptotic response.

Bcl-2 Prolongs neuronal survival during hypoxia-induced apoptosis

In vivo models of hypoxic–ischemic brain injury have shown altered expression of a number of genes that are important in regulating neuronal survival. However, it is not clear as to whether hypoxia alone can alter the expression of genes regulating neuronal survival. We hypothesized that (1) hypoxia alone alters the expression of bcl-2 in neurons, (2) the severity and duration of hypoxia influence bcl-2 expression, and (3) the alteration of bcl-2 expression has an important role in regulating neuronal survival during hypoxia. Embryonic rat neocortical neurons cultured for 7–10 days were exposed to 0.1, 1, or 3% oxygen for various durations and were removed for analyses at 24-h intervals. Under all hypoxic conditions, neurons exhibited morphologic changes, as assessed by electron microscopy and Annexin V staining, consistent with apoptosis. Immunoblot and immunofluorescence analyses revealed an increase in neuronal bcl-2 protein during hypoxic exposure. Quantitative immunofluorescence analyses of bcl-2 immunostained neurons indicated that expression of bcl-2 was altered by the duration and severity of hypoxia. Attenuation of bcl-2 expression by antisense oligonucleotides decreased the proportion of surviving neurons by ∼50% after 48 h of exposure to 0.1% oxygen. We conclude that observed increase in bcl-2, in part, plays an important role in neuronal survival during exposure to hypoxia.

BCL-2 Transduction, Using a Herpes Simplex Virus Amplicon, Protects Hippocampal Neurons from Transient Global Ischemia

Transient global ischemia results in selective neuronal damage of hippocampal CA1 neurons. Five minutes of bilateral common carotid artery occlusion, in the Mongolian gerbil, effectively restricts forebrain blood flow, resulting in a delayed neuronal death of CA1 pyramidal cells. While there is a delay of approximately 72 h in the appearance of cell death, markers related to the mechanism of ischemic death become apparent well before neurons die. Ischemia-induced increases in the cell-death-promoting protein, bax, may disrupt the bcl-2/bax ratio necessary for normal neuronal functioning and thus promote transient ischemic death. In order to locally maintain this critical bcl-2/bax ratio and thus protect CA1 neurons from delayed neuronal death, a herpes simplex viral (HSV) vector was used to selectively introduce human bcl-2, under the control of the herpes IE 4/5 promoter, into the CA1 region of the gerbil hippocampus. Twenty-four hours prior to ischemia surgery, 1 μl of HSVbcl-2 was infused unilaterally into the CA1 region at a rate of 2 nl/min. Seventy-two hours after ischemia the animals were sacrificed and processed using Nissl, silver degeneration, and immunohistochemical (anti-human bcl-2) staining. Immunohistochemistry demonstrated both glial and neuronal bcl-2 expression around the HSVbcl-2 infusion site. The evaluation following silver degeneration staining indicated a further degeneration of CA1 neurons in the immediate area of the viral vector infusion. This damage seems to be the result of cellular debris associated with the processing of the viral amplicons. Silver degeneration staining is not present in the areas that demonstrate bcl-2 staining. These neurons appear to have been rescued from ischemic damage. This result was confirmed using the Nissl staining. Therefore, by altering the local ratio of bcl-2/bax using the HSVbcl-2 vector one may protect CA1 pyramidal cell from the delayed neuronal death of transient global ischemia.

Effect of flupirtine on Bcl-2 and glutathione level in neuronal cells treated in vitro with the prion protein fragment (PrP106-126).

Flupirtine, trade name Katadolon, is a centrally acting nonopioid analgesic that has recently been found to display cytoprotective activity in vitro and in vivo on neurons induced to undergo apoptosis. This report shows that the PrP106-126 fragment of the prion protein, which is the likely etiological agent for a series of encephalopathies, is toxic to cortical neurons in vitro. Simultaneously, PrP106-126 influences the molecular GSH content and the bcl-2 expression in neurons. Significant toxicity (32% reduction in cell viability) was observed at a concentration of 50 microM of the peptide after 9 days of incubation, while at higher concentrations toxicity increased to 70%. Neurotoxicity was greatly reduced following coincubation with 1 to 3 microg/ml flupirtine. Concomitant with PrP106-126-mediated cytotoxicity, glutathione (GSH) content fell by > 70% with respect to untreated controls. This decrease in GSH level was strongly blocked by flupirtine under incubation conditions that reduce cell toxicity. In addition to normalizing GSH content, flupirtine induced the expression of the anti-apoptotically acting proto-oncogene bcl-2. Based on these in vitro data and on the favorable pharmacokinetic profile of the drug, we strongly suggest that flupirtine may prove useful for treatment of patients with prion disease.

Bcl-2 protein expression is widespread in the developing nervous system and retained in the adult PNS.

Cell death is a common feature of neural development in all vertebrates. The bcl-2 proto-oncogene has been shown to protect a variety of cell types from programmed cell death. We have examined the distribution of bcl-2 protein in the developing and adult nervous systems. bcl-2 protein is widespread during embryonic development. Proliferating neuroepithelial cells of ventricular zones as well as the postmitotic cells of the cortical plate, cerebellum, hippocampus and spinal cord express bcl-2. Postnatally, bcl-2 is principally retained in the granule cells of the cerebellum and dentate gyrus of the hippocampus. bcl-2 expression in the CNS declines with aging. In the peripheral nervous system, neurons and supporting cells of sympathetic and sensory ganglia retain substantial bcl-2 protein throughout life. The widespread expression of bcl-2 in CNS and PNS neurons during embryonic development and its selective retention in the adult PNS is consistent with a role for bcl-2 in regulating neuronal survival. In addition, the expression of bcl-2 in some neuronal populations beyond the recognized period of cell death is suggestive of a role for bcl-2 beyond simply protecting neurons from developmental cell death.