Ibudilast prevents oxygen-glucose deprivation-induced oligodendroglial injury]

Previously we have demonstrated that ibudilast, which is used clinically for treating patients with asthma and cerebrovascular diseases, prevents excitotoxicity of oligodendroglial lineage mediated by Ca2+ influx via non-N-methyl-D-aspartate (NMDA) glutamate receptor (GluR) channels. We here present a finding that ibudilast prevents oxygen-glucose deprivation (OGD)-induced oligodendroglial injury. The oligodendrocyte-like cells (OLC), differentiated from the CG-4 cell line established from rat oligodendrocyte-type-2 astrocyte (O-2A) progenitor cells, were exposed to hypoxia in the absence of glucose for 12 h and subsequent reoxygenation for 2 h. Cell damage was evaluated by measuring activity of lactate dehydrogenase (LDH) released into the culture medium. OGD for 12 h induced 30 to 50% LDH release into the medium. OLC damage induced by deprivation of oxygen and glucose was prevented by ibudilast at concentrations of > or = 50 microM. The protection given by ibudilast against OGD-induced injury was enhanced by prostacyclin (PGI2). OGD-induced OLC injury was prevented by 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX), an inhibitor of non-NMDA GluR or deprivation of Ca2+ from culture medium. While ibudilast increased intracellular cAMP at concentrations of > or = 10 microM, at least 100 microM concentrations were needed to increase intracellular cGMP. Therefore, we concluded that ibudilast prevented OGD-induced oligodendroglial injury possibly by increasing intracellular cAMP which modulates Ca2+ influx via non-NMDA GluR channels.     

Exercise intensity influences cell injury in rat hippocampal slices exposed to oxygen and glucose deprivation

We evaluated the effects of two levels of daily forced exercise intensity (moderate and high) in the treadmill over cell susceptibility to oxygen and glucose deprivation (OGD) in hippocampal slices from Wistar rats. Moderate exercise decreased lactate dehydrogenase (LDH) release after OGD, while a significant increase in LDH release was observed in the high intensity group submitted to OGD. Our data corroborate the hypothesis that higher training intensity exacerbates brain damage, while a moderate intensity reduces the injury caused by in vitro ischemia.     

Reduced neuronotrophic activity of fibroblasts from individuals with dysautonomia in cultures of newborn mouse sensory ganglion cells

The neuronotrophic activity of human skin fibroblast cell lines from two normal individuals and 3 individuals with Familial Dysautonomia (FD) was compared in terms of their ability to support neuron survival and neurite regeneration in cultures of newborn mouse sensory neurons. Neuronotrophic activity was assayed by culturing dissociated sensory neurons from newborn mice: (1) on fibroblast 'cell beds' consisting of monolayer cultures of living fibroblasts, (2) with medium that had been conditioned by monolayer fibroblast cultures and (3) with extracts of the cultured fibroblasts. Neurite regeneration was compared by determining the percentage of neurons that had regenerated neurites after 24 or 48 h in culture. Neuron survival was determined by counts at 48 h, 7 days and 14 days after culture initiation. Neurite regeneration and neuron survival was found to be significantly less on FD cell beds or with FD-conditioned medium than in replicate cultures with normal fibroblasts or their conditioned medium. The reduced neuronotrophic activity of FD fibroblasts or conditioned medium was still observed in the presence of antibody sufficient to block the neuronotrophic effects of purified nerve growth factor (NGF). Thus, fibroblasts from individuals with FD exhibit reduced neuronotrophic activity for newborn mouse sensory neurons that appears to be due to factor(s) other than NGF.     

Non-N-methyl-D-aspartate glutamate receptors mediate oxygen--glucose deprivation-induced oligodendroglial injury

Cells of oligodendroglial lineage are susceptible to oxygen and glucose deprivation. When oligodendrocyte-like cells differentiated from CG-4-immortalized rat O-2A progenitor cells were exposed to hypoxia alone or glucose deprivation alone for 48 h, release of lactate dehydrogenase (LDH) into the culture medium did not increase. However, when cells were deprived of both oxygen and glucose for 6 or 12 h preceding reoxygenation for 2 h, LDH release increased. Adding glucose to the medium protected against cell death and increased lactate production in a concentration-dependent manner. Cell damage induced by deprivation of oxygen and glucose was prevented by calcium-free medium or by non-N-methyl-D-aspartate glutamate receptor (GluR) antagonists, such as 6-cyano-7-nitroquinoxaline-2,3-dione or LY293558, but not by the voltage-dependent calcium channel blocker, nimodipine, or by the N-methyl-D-aspartate GluR antagonist, MK-801. The glutamate concentration in the medium from cells exposed to oxygen-glucose deprivation for 12 h was 49.70+/-3.04 microM/l, which is sufficient to activate GluRs during deprivation of oxygen and glucose. Apoptotic cells detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end-labeling (TUNEL) or Hoechst 33258 staining did not increase in cells exposed to oxygen-glucose deprivation for 12 h and subsequent reoxygenation for 2 h. No DNA laddering was detected by agarose gel electrophoresis from cells exposed to deprivation of oxygen and glucose. Neither acetyl-YVAD-CHO, an inhibitor of caspase-1-like proteases, nor acetyl-DEVD-CHO, an inhibitor of caspase-3-like proteases, prevented oxygen-glucose deprivation-induced injury. Thus, oxygen and glucose deprivation causes calcium-influx-induced necrotic cell damage in cells of oligodendroglial lineage via non-N-methyl-D-aspartate GluR channels.     

Fructose-1,6-bisphosphate protects astrocytes from hypoxic damage

To determine the effects of glucose and fructose-1,6-bisphosphate (FDP) on hypoxic cell damage, primary cultures of astrocytes were incubated for 18 h in an air-tight chamber that had been flushed with 95% N2/5% CO2 for 15 min before it was sealed. Cultures containing 7.5 mM glucose without FDP or FDP without glucose showed evidence of significant cell injury after 18 h of hypoxia (increased lactate dehydrogenase content in the culture medium; cell edema and disruption by phase-contrast microscopy). Cultures exposed to glucose + FDP had normal lactate dehydrogenase concentrations and appeared normal microscopically. Maximal protection of hypoxic cells occurred at 6.0 mM FDP. Lactate concentrations of the culture medium of hypoxic cells increased 2.5 times above normoxic control values when glucose was present, but neither FDP alone nor glucose + FDP caused the lactate concentrations to increase further. This implies that anaerobic glycolysis was not increased by adding FDP to the medium. Cell volumes (water space) measured with [14C]-3-0-methyl-D-glucose were normal with glucose + FDP in the culture medium of hypoxic cells but were significantly larger than normal when glucose alone was present. Increases in cell volume paralleled changes in lactate dehydrogenase in the culture medium. Uptake of [14C]FDP occurred rapidly in normoxic cells and was maximal after 5 min of incubation. The data indicate that the presence of glucose + FDP in the culture medium protects primary cultures of hypoxic astrocytes from cell damage.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neurotoxic activity in HTLV-I carrier lymphocyte culture

A close association between human T-lymphotropic virus type I (HTLV-I) infection and a group of chronic myelopathies of unknown etiology has recently been established and the name "HTLV-I associated myelopathy" (HAM) has been coined. Although the mechanism of neural tissue damage in HAM remains virtually unknown, several lines of evidence suggest the involvement of a soluble factor(s) including cytokines and viral proteins in the disease process. In this study, we examined cytopathic effects of the supernatants from 6 HTLV-I carrier human T lymphocyte cell lines on 4 human and one murine neuroblastoma cell lines, and 2 human glioma cell lines. Among 6 lymphocyte cell culture supernatants, only 1 from MT-2 cell culture repeatedly exerted cytopathic effects on human neuroblastoma cells, particularly on IMR-32 cells: marked retraction of neurites leading to cellular clumping. This activity was neither abolished by treatment of the medium at 80 degrees C for 30 min or by UV-irradiation, nor was it neutralized by anti-HTLV-I antibodies. The MT-2 supernatant also induced mild cytopathic changes in 2 other human neuroblastoma cell lines and 2 human glioma cell lines. This activity was abolished by treatment of the medium at 80 degrees C for 30 min but not at 56 degrees C for 30 min. Myelinated murine cerebellum explants and other cell lines showed no morphological changes when incubated with the MT-2 supernatant. In addition, the growth of THP-1 cells, a monocyte/macrophage lineage cell line, was remarkably suppressed when maintained in the MT-2 conditioned medium, accompanied by enhancement of phagocytic activity. The THP-1 conditioned medium, on the other hand, suppressed tumor necrosis factor (TNF) activity detected in the MT-2 culture. These observations suggest that HTLV-I induced cytokines may directly act on neural cells, but their action appears to be regulated by the intricate interactions of lymphocytic and monocytic cells.     

Quenching of intracellular ROS generation as a mechanism for oleate-induced reduction of endothelial activation and early atherogenesis

We previously showed that the exposure of vascular endothelium to oleate results in reduced endothelial activation. We now investigate possible mechanisms for this effect in relation to generation of reactive oxygen species (ROS). We stimulated several types of endothelial cells with cytokines or lipopolysaccharide, with or without preincubation with 10-100 mumol/L oleate. Oleate preincubation reduced VCAM-1 expression in all cell types, as well as macrophage-colony stimulating factor release. We simultaneously measured the concentration of intracellular glutathione (GSH), the activity of GSH-related antioxidant enzymes and the production of intracellular ROS. Stimulation of endothelial cells caused a decrease of GSH and an increase in intracellular ROS. The addition of oleate before stimulation, prevented the depletion of GSH and partially prevented stimuli-induced increase of intracellular ROS. This occurred without any change in the activity of GSH-related antioxidant enzymes, superoxide dismutase and catalase. Furthermore, in a cell-free superoxide anion-generating system, oleate quenched the generation of ROS. These results indicate that oleate may exert direct vascular atheroprotective effects by inhibiting endothelial activation through a quenching of stimuli-induced increase in ROS.     

Ionic modulation of triethyllead neurotoxicity in cerebellar granule cell culture

While the molecular mechanism underlying triethyllead (TEL) neurotoxicity is unknown, we hypothesize that triethyllead mediates an accelerated Cl-/OH exchange across neuronal membranes leading to prolonged depolarization and neuronal cell injury. As a test of this hypothesis we have investigated the effect of external ion modulation on triethyllead neurotoxicity in cerebellar granule cell culture. Cultures were prepared from neonatal rats and used 10-20 days in vitro. Cytotoxicity was assessed by lactate dehydrogenase (LDH) release and trypan blue exclusion. A slow, dose-dependent (1-30 microM TEL) release of LDH occurred after a variable latent period dependent upon [TEL]. External replacement of [Cl-]e by Na isothionate dramatically shifted the dose response curve to the left reflecting an accelerated stimulation of LDH release, while replacement of extracellular [Na+]e with equimolar choline chloride had a minimal protective effect. Similarly, high [Mg2+]e or low [Ca2+]e did not protect or potentiate TEL cytotoxicity. The low [Cl-]e accelerated TEL cytotoxicity was dependent on medium pH: alkaline pH potentiated the cytotoxicity. Low [Cl-]e had no significant effect on culture ATP over 5 hrs. ATP reduction was markedly stimulated by TEL in low Cl- medium in contrast to the minimal decline in [ATP] in the control medium. The reduction of ATP in the low [Cl-]e medium occurred prior to LDH or trypan blue staining release confirming that such reduction in [ATP] was not secondary to cell damage. Substituting K sulfate or Na sulfate for the Cl(-)-free medium revealed marked loss of ATP without LDH release in control and TEL supplemented cultures. These observations provide supporting evidence for the role of an abnormal Cl- flux in mediating TEL-induced neurotoxic injury. Specifically, the membrane depolarization is proportional to the gradient imposed by Cl- efflux/OH influx, stimulated by low [Cl-]e. The rapid loss in ATP appeared early, was not a secondary reflection of neuronal damage but a result of a combination of increased ion flux at the plasma membrane, stimulation of Na+/K+ ATPase and direct TEL-induced inhibition of mitochondrial oxidative phosphorylation.     

Protective effects of ginkgo biloba leaves extract on peroxide-induced oxidative stress damage in PC12 cells

BACKGROUND: Extracts of ginkgo biloba leaves (EGB) and its metabolites have been reported to enhance brain function and nerve behavior. It has also been hypothesized that they can protect neurons from oxidative stress. OBJECTIVE: To investigate protective effects of EGB on peroxide (H2O2)-induced oxidative stress damage in PC12 cells. DESIGN: Observational contrast study. SETTING: Department of Pathophysiology, Guangdong Pharmacological College. MATERIALS: EGB was provided by Xi'an Fujie Biotechnological Development Company; 1640 culture medium, methylthiazolyl tetrazolium (MTT), trypsin and dimathyl sulfoxide (DMSO) by Sigma Company; PC12 cell strain by Cell Center of Medical College of Zhongshan University; calf serum by Hangzhou Sijiqing Bioengineering Company; lactate dehydrogenase (LDH) kit by Nanjing Jiancheng Bioengineering Research Institute. METHODS: The experiment was carried out in Department of Cell Biology of Guangdong Pharmacological College from June to December 2005. ① Cell culture: PC12 cells were cultured in 1640 medium containing 200 g/L fetal calf serum. The cells were diluted to 1×107 L–1 and washed every two days. Those cells were used to experiment until they grew in logarithm on solid wall. ② Grouping and intervention: PC12 cells (1×108 L–1) were plated in 96-well plates with the density of 200 μL/hole and divided into three groups: normal control group (routinely adding media), H2O2 group (treating with media and H2O2 for 20 hours) and EGB group (adding media, 100 μmol/L EGB and 100 μmol/L H2O2). ③ MTT assay: PC12 cells (1× 108 L–1) were plated in 96-well plates and divided into three groups with 8 holes for each group. Under sterile condition, cells were added with 5 g/L MTT (100 μL) and cultured for 4 hours. And then, 200 μL DMSO fluid was added and shaken for 30 minutes until blue crystal products formed were dissolved soundly. ④ Experimental evaluation: Absorbance (A) at 630 nm was measured and LDH activity was measured at the same time. MAIN OUTCOME MEASURES: Results of MTT assay and LDH activity. RESULTS: ① Results of MTT assay: A value was lower in the H2O2 group than that in the normal control group (P < 0.01), while A value was higher in the EGB group than that in the H2O2 group (P < 0.01). ② LDH activity: LDH activity was higher in the H2O2 group than that in the normal control group (P < 0.01), while LDH activity was lower in the EGB group than that in the H2O2 group (P < 0.01). CONCLUSION: EGB can inhibit H2O2-induced oxidative stress damage in PC12 cells possibly by preventing damage to the cell membrane.     

Non-N-methyl- -aspartate glutamate receptors mediate oxygen–glucose deprivation-induced oligodendroglial injury

Cells of oligodendroglial lineage are susceptible to oxygen and glucose deprivation. When oligodendrocyte-like cells differentiated from CG-4-immortalized rat O-2A progenitor cells were exposed to hypoxia alone or glucose deprivation alone for 48 h, release of lactate dehydrogenase (LDH) into the culture medium did not increase. However, when cells were deprived of both oxygen and glucose for 6 or 12 h preceding reoxygenation for 2 h, LDH release increased. Adding glucose to the medium protected against cell death and increased lactate production in a concentration-dependent manner. Cell damage induced by deprivation of oxygen and glucose was prevented by calcium-free medium or by non-N-methyl- -aspartate glutamate receptor (GluR) antagonists, such as 6-cyano-7-nitroquinoxaline-2,3-dione or LY293558, but not by the voltage-dependent calcium channel blocker, nimodipine, or by the N-methyl- -aspartate GluR antagonist, MK-801. The glutamate concentration in the medium from cells exposed to oxygen–glucose deprivation for 12 h was 49.70±3.04 μM/l, which is sufficient to activate GluRs during deprivation of oxygen and glucose. Apoptotic cells detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end-labeling (TUNEL) or Hoechst 33258 staining did not increase in cells exposed to oxygen–glucose deprivation for 12 h and subsequent reoxygenation for 2 h. No DNA laddering was detected by agarose gel electrophoresis from cells exposed to deprivation of oxygen and glucose. Neither acetyl-YVAD-CHO, an inhibitor of caspase-1-like proteases, nor acetyl-DEVD-CHO, an inhibitor of caspase-3-like proteases, prevented oxygen–glucose deprivation-induced injury. Thus, oxygen and glucose deprivation causes calcium-influx-induced necrotic cell damage in cells of oligodendroglial lineage via non-N-methyl- -aspartate GluR channels.     

In vitro protection of 3-nitropropionic acid-induced toxicity of astrocytes by basic fibroblast growth factor and thrombin

The protective action of basic fibroblast growth factor (bFGF) and thrombin on cultured cortical astrocytes in vitro to the toxic effects of 3-nitropropionic acid (3-NPA) was examined. 3-NPA produced concentration- and time-dependent astrocyte loss as indicated by decrease in the number of glial fibrillary acidic protein (GFAP) positive cells and increase in lactate dehydrogenase (LDH) level of the culture medium. The 3-NPA-induced cellular loss was apparent within 12 h and was maximal at 24 h. The presence of bFGF (10 ng/ml) by itself increased the number of astrocytes at various time intervals, and attenuated the 3-NPA-induced cell loss significantly at various concentrations (0.017–1.7 mM), in 24 and 48 h of exposure. Lower concentrations of thrombin (up to 1 nM) had no effect on the number of astrocytes but higher concentrations (10–100 nM) produced greater cell loss. Thrombin (1 nM) prevented the 3-NPA-induced decrease in GFAP positive cells at both 24 and 48 h intervals. This was further substantiated by the fact that thrombin as low as 0.01 nM attenuated the 3-NPA-induced increase of LDH activity at 24 and 48 h exposure times. But, with 1 nM of thrombin, the attenuation of the LDH activity was seen only at 24 h. The results indicate that 3-NPA produced acute astrocyte toxicity and was attenuated by bFGF and lower concentrations of thrombin.     

Glutamate enhances the surface distribution and release of Munc18 in cerebral cortical neurons

Objective

Munc18 is considered as an intracellular protein that plays an important role in exocytosis of neurotransmitters. Previous studies have demonstrated the presence of autoantibodies against Munc18 in a subgroup of Rasmussen’s encephalitis patients. However, the machinery of Munc18 autoimmunity is still elusive. The present study was aimed to investigate Munc18 release from primary cultured neurons, Munc18 distribution on the outer plasma membrane of neurons, and the neurotoxicity of Munc18 antibody.

Methods

The cerebral cortical neurons from embryonic day 17 Sprague-Dawley rats were prepared and cultured in neurobasal medium. The proteins in culture medium were precipitated with 10% trichloroacetic acid, and analyzed by immunoblotting. The proteins on neuronal surface were biotinylated with EZ-Link-sulfo-NHS-LC-Biotin, and collected with avidin-conjugated agarose beads followed by immunoblotting analysis. For cell surface immunofluorescent staining, the living neurons were labeled with anti-Munc18 antibody at 4 °C. Neuronal injury was assessed by lactate dehydrogenase(LDH) release.

Results

Munc18 was detected in culture medium by immunoblotting analysis. After treatment with 50 μmol/L glutamate for 1 h, Munc18 content in medium was increased. Meanwhile, β-actin and syntaxin1 were not detected in culture medium, and LDH release was not significantly increased. Moreover, glutamate enhanced Munc18 distribution on outer plasma membrane. Living neuron staining also demonstrated the localization of Munc18 on neuronal surface after glutamate treatment, especially at contacting regions between neurons. Glutamate-induced increase of surface Munc18 distribution was suppressed by NMDA receptor antagonist MK801, but not by AMPA receptor antagonist NBQX. Moreover, compared with c-Fos antibody, Munc18 antibody could induce neuronal injury, when culture medium contained the components of serum.

Conclusion

A portion of Munc18 can be released from neurons or distributed on neuronal surface, which can be enhanced by glutamate treatment via activation of NMDA receptors. Besides, Munc18 antibody-induced neuronal injury depends on the serum components.     

不同载体及年龄对大鼠视神经组织体外培养的影响

目的 探讨不同载体及年龄对大鼠视神经组织体外培养的影响. 方法 取出生4d和3月龄SD大鼠的视神经,分别使用鼠尾胶原玻片、多聚赖氨酸玻片和Bioeoat小室进行组织培养,观察组织生长情况.培养48 h后观察组织块贴壁率,培养5 d时使用图像分析仪测量细胞最大迁移距离.使用乳酸脱氢酶(LDH)试剂盒对Biocoat小室组不同年龄大鼠视神经组织培养液LDH活性进行动态比较.HE染色形态学观察,透射电镜观察组织块超微结构变化. 结果 Bioeoat小室组的组织贴壁率明显高于鼠尾胶原组、多聚赖氨酸组;在Bioeoat小室中培养的成年和新生大鼠视神经组织的细胞最大迁移距离均明显大于鼠尾胶原组和多聚赖氨酸组;在相同培养载体上.新生大鼠细胞迁移距离均明显高于成年大鼠,差异均有统计学意义(P<0.05).视神经组织培养液LDH活性在接种3 d后开始下降,成年大鼠LDH水平在培养9 d后再次上升.而新生大鼠在培养12 d时仍保持较低水平.视神经在培养早期即有细胞从组织块边缘游出,逐渐发出突起.新生大鼠较早出现细胞迁移.随着培养时间延长,组织出现结构紊乱和坏死.新生大鼠组织存活时间较成年大鼠明显延长. 结论 通过选择适宜的培养条件,视神经可以在体外较长时间存活.     

Brain glutathione peroxidase in neurodegenerative disorders

Glutathione peroxidase is an enzyme that couples the oxidation of reduced glutathione to the detoxification of peroxides. Alterations in the activity of this component of the glutathione oxygen scavenging system in brain have been reported in several conditions associated with oxidative challenge and/or cellular damage. We measured the activity of glutathione peroxidase in autopsied brain regions of neurologically normal adults and in brain of patients with primary degenerative disorder Alzheimer’s type (AD/SDAT), as well as two other neurodegenerative disorders, namely Huntington’s disease and striatonigral degeneration. No significant alterations in enzyme activity were observed in morphologically normal or abnormal brain regions. Our results suggest that in the three brain disorders studied, the neuronal cell loss is unlikely to result from reduced activity of brain glutathione peroxidase, and that a significant compensatory increase in this brain enzyme, consequent to the degenerative processes, does not occur.     

Long-term activation of adenosine A(2a) receptors blocks glutamate excitotoxicity in cultures of avian retinal neurons

Previous work showed the presence of adenosine receptors as well as adenosine uptake and release mechanisms in developing chick retinal neurons in culture. In the present work we show that exogenous glutamate or kainate promotes extensive cell death in these cultures which is blocked when the cultures are previously incubated with adenosine. Addition of glutamate or kainate to purified cultures of retinal neurons and photoreceptors induced massive death of cultured cells which was inhibited in both cases by preincubation with MK801, an NMDA antagonist, or DNQX, an AMPA/kainate antagonist. Cell death was also greatly attenuated by preincubation with adenosine plus EHNA, an adenosine deaminase inhibitor, NBI, an adenosine uptake blocker, the permeable cAMP analogs 8-Br cAMP and Sp cAMP and the A_2a agonists CGS 21680 and DPMA, but not with the A₁ receptor agonist CHA. Kinetic studies performed determining the intracellular LDH activity showed that maximal death was observed after 8 h and in concentrations of glutamate as low as 50 μM. We also observed a time-dependent protective effect of adenosine beginning after 1 h of preincubation and reaching a maximal effect after 24 h, indicating its association with changes in cellular metabolism induced by long-term exposure of cells to the nucleoside. The results show that adenosine inhibits glutamate toxicity in retinal neurons through a long-term activation of A_2a receptors and elevation of intracellular cyclic AMP levels.     

Glutamine synthetase activity and HSP70 levels in cultured rat astrocytes: effect of 1-octadecyl-2-methyl-rac-glycero-3-phosphocholine

The ether lipid 1-octadecyl-2-methyl-rac-glicero-3-phosphocholine (ET-18-OCH₃) is a membrane interactive drug selectively cytotoxic toward neoplastic cells compared to normal cells. It induces apoptosis in human leukemic HL-60, T-lymphoid and in U937 myeloid cell lines and stimulates NO biosynthesis in cultured rat astrocytes. We have found a double action of ET-18-OCH₃ in astrocytes which, at low doses, promotes a moderate induction of heat shock proteins of 70 kDa (HSP70) and the increase of glutamine synthetase (GS) activity. Conversely, at high doses, the drug shows toxic effects on astrocytes inducing decrease in GS activity, low molecular weight DNA formation, and release of lactic dehydrogenase (LDH) in the culture medium. Its analog compound platelet-activating factor (PAF) shares some of these biological aspects.     

Basic fibroblast growth factor rescues CNS neurons from cell death caused by high oxygen atmosphere in culture

In the present study, we cultured rat CNS neurons and tested the neurotrophic support provided by basic fibroblast growth factor (bFGF) to prevent the oxygen-induced neuronal cell death. When rat basal forebrain (septum and vertical limb of diagonal band of Broca) cells of embryonic day 20 were cultured in a serum-free medium containing 5 microM cytosine arabinoside in a 50% oxygen atmosphere, the neuronal cells, which were immunostained by an anti-microtubule-associated protein 2 (MAP2) antibody, gradually died after 1 day in culture. After 3.5 days in culture, only 2-5% of neuronal cells survived. This oxygen-induced cell death of cultured basal forebrain neurons was reversed by the addition of bFGF at a concentration of 100 ng/ml. This cell-saving effect was dose-dependent, and the ED50 value was 12 ng/ml. Nerve growth factor (NGF) and insulin-like growth factor II could not prevent cell death. The activity of choline acetyltransferase was also maintained when bFGF was present in the basal forebrain culture. Viable astroglial cells, which were immunostained by an anti-glial fibrillary acidic protein, accounted for a few percent of the total number of cells after 3 days in culture both with and without 100 ng/ml of bFGF. The survival-enhancing effect of bFGF was observed not only in basal forebrain neurons but also in neocortical and hippocampal neurons. However, the sensitivity to oxygen toxicity of cultured neurons from the 3 CNS regions varied greatly. The neocortical neurons were the most sensitive to oxidative stress, while the hippocampal neurons were the most resistant. These results suggest that bFGF plays an important role in saving neuronal cells from oxidative stress during their long life without division.     

Immature rat brain slices exposed to oxygen-glucose deprivation as an in vitro model of neonatal hypoxic-ischemic encephalopathy

To analyze whether exposure to oxygen-glucose deprivation (OGD) of immature rat brain slices might reproduce the main pathophysiologic events leading to neuronal death in neonatal hypoxic-ischemic encephalopathy (NHIE), 500 microm-thick brain slices were obtained from 7-day-old Wistar rats, and incubated in oxygenated physiological solution. In OGD group, oxygen and glucose were removed from the medium for 10-30 min (n = 25); then, slices were re-incubated in normal medium. In control group the medium composition remained unchanged (CG, n = 30). Medium samples were obtained every 30 min for 3 h. To analyze neuronal damage, slices were stained with Nissl and CA1 area of hippocampus and cortex were observed under microscopy. In addition, neuronal death was quantified as LDH released to the medium determined by spectrophotometry. Additionally, medium glutamate (Glu) levels were determined by HPLC and those of TNFalpha by ELISA, whereas inducible nitric oxide synthase expression was determined by Western blot performed on slices homogenate. Optimal OGD time was established in 20 min. After OGD, a significant decrease in the number of neurones in hippocampus and cortex was observed. LDH release was maximal at 30 min, when it was five-fold greater than in CG. Furthermore, medium Glu concentrations were 200 times greater than CG levels at the end of OGD period. A linear relationship between Glu and LDH release was demonstrated. Finally, 3 h after OGD a significant induction of iNOS as well as an increase in TNFalpha release were observed. In conclusion, OGD appears as a feasible and reproducible in vitro model, leading to a neuronal damage, which is physiopathologically similar to that found in NHIE.     

乌司他丁对缺氧诱导PC12细胞神经损伤的保护作用研究

目的 探讨乌司他丁对缺氧诱导PC12细胞神经损伤的作用及分子机制。方法 PC12细胞分为对照组、缺氧组、缺氧+乌司他丁低、中、高剂量组、缺氧+miR-NC组、缺氧+miR-190组、缺氧+乌司他丁+anti-miR-NC组、缺氧+乌司他丁+anti-miR-190组。检测培养液中乳酸脱氢酶（LDH）漏出率及细胞中超氧化物歧化酶（SOD）活性、丙二醛（MDA）含量；流式细胞术检测细胞凋亡；蛋白质印迹法（Western blotting）检测蛋白表达；实时荧光定量聚合酶链反应（qRT-PCR）检测miR-190表达水平。结果 与缺氧组比较，缺氧+乌司他丁低、中、高剂量组PC12细胞中LDH漏出率降低，SOD活性升高，MDA含量降低，细胞凋亡率降低，Bcl-2相对表达量升高，Bax相对表达量降低，miR-190相对表达量升高，且呈剂量依赖性（均P<0.05）。miR-190过表达后，LDH漏出率降低，SOD活性升高，MDA含量降低，细胞凋亡率降低，Bcl-2相对表达量升高，Bax相对表达量降低（均P<0.05）。抑制miR-190表达能逆转乌司他丁对缺氧诱导的PC12细胞损伤的作用。结论 乌司他丁可能通过上调miR-190表达对缺氧诱导PC12细胞神经损伤起保护作用。     

Effects of ischemia-like conditions on cultured neurons: protection by low Na+, low Ca2+ solutions

An in vitro system was used to mimic several aspects of ischemia, including low oxygen pressure, low nutrient levels, and the accumulation of cellular products thought to contribute to damage during ischemia. We replaced normal culture medium from 3-week-old basal ganglia cultures with oxygen-depleted, nutrient-deficient medium. After incubation in an atmosphere of 94% N2, 6% CO2 for 5 hr at 37 degrees C, the cultures were returned to normal medium. After a 24 hr recovery period, cell viability was assessed in terms of cell number, electrophysiological properties, and immunohistochemical markers. When the medium used during the ischemic period was a normal balanced salt solution, more than 70% of the cells were damaged by the low-oxygen, low-glucose stress. Loss of cell processes and cell swelling were the most evident signs of damage. The majority of the cells remaining viable were astrocytes. Neuronal damage was observed only when both glucose and oxygen were deficient. Some damage was evident even at oxygen tensions of 60 mm Hg when glucose was absent from the medium; much more extensive damage was observed at tensions below 1.0 mm Hg. Lowering both extracellular sodium and calcium resulted in more than a 2-fold increase in survival (70 vs 28%). These results indicate that damage to neurons during conditions of extreme energy deprivation such as ischemia may be mediated by the influx of calcium and/or sodium.