Pre- and post-treatments with escitalopram protect against experimental ischemic neuronal damage via regulation of BDNF expression and oxidative stress

Selective serotonin re-uptake inhibitors (SSRI) have been widely used in treatment of major depression because of their efficacy, safety, and tolerability. Escitalopram, an SSRI, is known to decrease oxidative stress in chronic stress animal models. In the present study, we examined the neuroprotective effects of pre- and post-treatments with 20 mg/kg and 30 mg/kg escitalopram in the gerbil hippocampal CA1 region (CA1) after transient cerebral ischemia. Pre-treatment with escitalopram protected against ischemia-induced neuronal death in the CA1 after ischemia/reperfusion (I/R). Post-treatment with 30 mg/kg, not 20 mg/kg, escitalopram had a neuroprotective effect against ischemic damage. In addition, 20 mg/kg pre- and 30 mg/kg post-treatments with escitalopram increased brain-derived neurotrophic factor (BDNF) protein levels in the ischemic CA1 compared to vehicle-treated ischemia animals. In addition, 20 mg/kg pre- and 30 mg/kg post-treatments with escitalopram reduced microglia activation and decreased 4-hydroxy-2-nonenal and Cu,Zn-superoxide dismutase immunoreactivity and their levels in the ischemic CA1 compared to vehicle-treated ischemia animals after transient cerebral ischemia. In conclusion, these results indicated that pre- and post-treatments with escitalopram can protect against ischemia-induced neuronal death in the CA1 induced by transient cerebral ischemic damage by increase of BDNF as well as decrease of microglia activation and oxidative stress.     

Chronic ethanol intake induces partial microglial activation that is not reversed by long-term ethanol withdrawal in the rat hippocampal formation

Neuroinflammation has been implicated in the pathogenesis of several disorders. Activation of microglia leads to the release of pro-inflammatory mediators and microglial-mediated neuroinflammation has been proposed as one of the alcohol-induced neuropathological mechanisms. The present study aimed to examine the effect of chronic ethanol exposure and long-term withdrawal on microglial activation and neuroinflammation in the hippocampal formation. Male rats were submitted to 6 months of ethanol treatment followed by a 2-month withdrawal period. Stereological methods were applied to estimate the total number of microglia and activated microglia detected by CD11b immunohistochemistry in the hippocampal formation. The expression levels of the pro-inflammatory cytokines TNF-α, COX-2 and IL-15 were measured by qRT-PCR. Alcohol consumption was associated with an increase in the total number of activated microglia but morphological assessment indicated that microglia did not exhibit a full activation phenotype. These data were supported by functional evidence since chronic alcohol consumption produced no changes in the expression of TNF-α or COX-2. The levels of IL-15 a cytokine whose expression is increased upon activation of both astrocytes and microglia, was induced by chronic alcohol treatment. Importantly, the partial activation of microglia induced by ethanol was not reversed by long-term withdrawal. This study suggests that chronic alcohol exposure induces a microglial phenotype consistent with partial activation without significant increase in classical cytokine markers of neuroinflammation in the hippocampal formation. Furthermore, long-term cessation of alcohol intake is not sufficient to alter the microglial partial activation phenotype induced by ethanol.     

CORM-3介导小胶质细胞ICAM-1抑制放射性脑损伤炎症反应

目的本研究旨在探讨水溶性一氧化碳分子释放剂(CORM-3)对放射性脑损伤炎症反应的影响及其分子机制。方法 BV2系小胶质细胞,随机分为正常对照组、单纯照射组和照射加CORM干预组,通过ELISA法测定各组照射后24 h炎症因子TNF-α、IL-1β的表达情况;采用免疫荧光法判断各组小胶质细胞激活形态,TUNEL染色比较各组共培养后原代神经元凋亡情况,并用Western blot法检测P38 MAPK通路对CORM干预放射后细胞间黏附分子1(ICAM-1)蛋白表达的影响。结果 BV2细胞放射后24 h TNF-α、IL-1β表达明显增高;CORM-3可减轻放射后小胶质细胞活化程度及炎症表达,降低了放射后TUNEL阳性细胞百分比;CORM-3抑制了放射后BV2细胞磷酸化P38及ICAM-1蛋白的表达增加,而P38抑制剂进一步下调放射后BV2细胞ICAM-1的表达。结论 CORM-3通过P38 MAPK-ICAM-1通路抑制内源性小胶质细胞活化和外源性白细胞趋化的双重调控方式改善放射后脑损伤炎症反应,进而减轻放射后炎症所致神经元损伤,这为改善鼻咽癌放疗后脑损伤的治疗提供了有潜在前景的新途径。     

木樨草素对脂多糖诱导的小胶质细胞炎性反应的抑制作用

目的:以脂多糖(LPS)刺激小胶质细胞BV-2,体外模拟神经退行性疾病的炎症模型,探讨木樨草素的抗炎作用和机制。方法:采用LPS(0.1μg/mL)刺激小胶质细胞建立炎症模型,MTT法检测木樨草素对BV-2细胞的毒性作用;硝酸还原酶法检测木樨草素对LPS刺激BV-2细胞一氧化氮(NO)表达量的影响;一氧化氮合酶分型法检测木樨草素对LPS刺激BV-2细胞一氧化氮合酶(iNOS)活性的影响;Western Blot法检测木樨草素对LPS刺激BV-2细胞TLR4蛋白表达影响。结果:木樨草素低、中、高剂量及阳性药物能抑制LPS诱导的BV-2炎性反应。结论:木樨草素能够抑制小胶质细胞活化产生的炎症反应,其抗炎作用的机制可能是通过抑制TLR4信号通路而发挥效用。     

针刺干预对肌萎缩侧索硬化症模型小鼠脑及脊髓中 IBA-1和TNF-α表达的影响

目的:探讨电针治疗肌萎缩侧索硬化症(ALS)的机制。方法:将SOD1^G93A转基因小鼠随机分为正常组、模型组、针刺组及利鲁唑治疗组,每组各8-10只。小鼠日龄30 d后,针刺组选取双侧天枢穴(ST25)及足三里穴(ST36)予以电针治疗。利鲁唑治疗组按照30 mg/(kg·d)的剂量予以90 d日龄小鼠灌胃治疗,1次/d。模型组及对照组常规饲养,不予干预。于小鼠电针治疗前及治疗后分别对4组进行体质量记录及行为学观察。采用免疫组化法检测各组小鼠脑干及脊髓中IBA-1和TNF-α表达变化。结果:正常组小鼠精神状态及运动功能良好,针刺组及利鲁唑组小鼠较模型组精神状态及运动功能明显改善;转棒实验结果显示针刺组及利鲁唑组小鼠潜伏期较模型组延长;免疫组化检测结果表明在模型组脑干IBA-1阳性细胞表达高于正常组(P<0.05);而利鲁唑组IBA-1阳性细胞表达虽有降低,但组间无统计学差异(P>0.05)。该结果与IBA-1阳性细胞在脊髓L_4-5节段表达趋于一致(P<0.05)。针刺治疗后脊髓中促炎因子TNF-α表达明显减少(P<0....     

Brain trauma induces expression of diacylglycerol kinase ζ in microglia

Diacylglycerol kinase (DGK) is an enzyme which phosphorylates a second messenger diacylglycerol and consists of a family of isozymes that differ in terms of structural motifs, enzymological property, and cell and tissue distribution. One of the isozymes, DGKζ was originally shown to be expressed in various kinds of neurons under physiological conditions. However, we unexpectedly found that under pathological conditions, such as cerebral infarction, DGKζ-immunoreactivity is detected in non-neuronal cells, although it remained to be elucidated in detail which cell types are responsible for the induced expression of DGKζ in this setting. To further elucidate functional implications of DGKζ in non-neuronal cells we performed detailed immunohistochemical analysis of DGKζ using rat brain cryoinjury model. As early as 1 h after cryoinjury, DGKζ-immunoreactivity was greatly decreased in the afflicted cerebral cortex and almost disappeared in the necrotic core. On day 7 after cryoinjury, however, DGKζ-immunoreactivity reappeared in this area. DGKζ-immunoreactivity was clearly detected in Iba1-immunoreactive cells of an oval or ameboid shape in the scar region, which represent activated microglia and/or macrophages. On the other hand, DGKζ-immunoreactivity was not detected in Iba1-immunoreactive, resting microglia of ramified and dendritic configuration in the intact cortex. Furthermore, DGKζ-immunoreactive cells were also positive for a microglia marker GLUT5 in the scar region, but never for an astrocyte marker GFAP. Taken together, the present study reveals that DGKζ is induced in activated microglia in brain trauma, suggesting the functional significance of DGKζ in this process.     

Neuronal-glial Interactions Define the Role of Nitric Oxide in Neural Functional Processes

Nitric oxide (NO) is a versatile cellular messenger performing a variety of physiologic and pathologic actions in most tissues. It is particularly important in the nervous system, where it is involved in multiple functions, as well as in neuropathology, when produced in excess. Several of these functions are based on interactions between NO produced by neurons and NO produced by glial cells, mainly astrocytes and microglia. The present paper briefly reviews some of these interactions, in particular those involved in metabolic regulation, control of cerebral blood flow, axonogenesis, synaptic function and neurogenesis. Aim of the paper is mainly to underline the physiologic aspects of these interactions rather than the pathologic ones.     

Differences in cytokine gene expression profile between acute and secondary injury in adult rat spinal cord

It is likely that the environment within the injured spinal cord influences the capacity of fetal spinal cord transplants to support axonal growth. We have recently demonstrated that fetal spinal cord transplants and neurotrophin administration support axonal regeneration after spinal cord transection, and that the distance and amount of axonal growth is greater when these treatments are delayed by several weeks after injury. In this study, we sought to determine whether differences in inflammatory mediators exist between the acutely injured spinal cord and the spinal cord after a second injury and re-section, which could provide a more favorable environment for the axonal re-growth. The results of this study show a more rapid induction of transforming growth factor (TGF) beta1 mRNA expression in the re-injured spinal cord than the acutely injured spinal cord and an attenuation of proinflammatory cytokine mRNA expression. Furthermore, there was a rapid recruitment of activated microglia/macrophages in the degenerating white matter rostral and caudal to the injury but fewer within the lesion site itself. These findings suggest that the augmentation of TGFbeta-1 gene expression and the attenuation of pro-inflammatory cytokine gene expression combined with an altered distribution of activated microglia/macrophages in the re-injured spinal cord might create a more favorable milieu for transplants and axonal regrowth as compared to the acutely injured spinal cord.     

The role of cyclo-oxygenase 1 and 2 activity in prostaglandin E(2) secretion by cultured human adult microglia: implications for Alzheimer's disease

Microglial cyclo-oxygenase (COX) expression is considered to be important in the pathogenesis of Alzheimer's disease (AD) and, therefore, constitutes a key target for therapeutic intervention. We investigated the influence of AD plaque associated factors on COX-1 and COX-2 expression and activity in adult human microglial cells in vitro. COX-2 immunoreactivity and mRNA were induced by lipopolysaccharide (LPS), not by AD plaque associated cytokines interleukin (IL)-1alpha, IL-1beta, IL-6, tumor necrosis factor (TNF)-alpha, or amyloid (A)beta(1-42). To assess functional COX activity, the release of PGE(2) into the culture medium was determined. LPS and also arachidonic acid (AA) dose-dependently stimulated PGE(2) release. The effects of AA are independent from induction of COX mRNA expression, or of de novo protein synthesis. No effects of either plaque-associated cytokines or Abeta(1-42) on PGE(2) secretion were seen, even when cells were co-stimulated with AA, to provide enough substrate. COX isotype selective inhibitors were used to discern relative contributions of COX-1 and COX-2 activities to microglial PGE(2) secretion. COX-2 and in part COX-1-selective inhibitors inhibited LPS-induced PGE(2) secretion, whereas the AA-induced PGE(2) secretion was reduced by COX-1-selective inhibitors only. Apparently, adult human microglia in vitro (1) constitutively express COX-1, and (2) do not express COX-2 upon exposure to either Abeta or plaque associated cytokines. In the light of microglial COX activity as a potential therapeutical target in AD, the data presented in this study suggest that classical NSAIDs, rather than selective COX-2 inhibitors, are more potent in reducing microglial prostaglandin secretion.     

视网膜小胶质细胞活化模型的建立

目的: 建立视网膜小胶质细胞培养、纯化和鉴定的方法,以观察视网膜小胶质细胞活化后的形态和功能变化,探讨活化的小胶质细胞在糖尿病视网膜病变时的可能作用. 方法: 以细菌内毒素脂多糖(LPS)活化小胶质细胞,通过免疫细胞化学及con-focal显微镜技术、流式细胞术、MTT、ELISA等方法观察视网膜小胶质细胞形态、数量和功能的变化. 结果: 视网膜小胶质细胞纯度在96%以上,LPS激活的小胶质细胞发生形态改变,CD11b表达上调,释放细胞因子TNF-α,而细胞数量无明显改变. 结论: 从细胞免疫表型、纯度、形态学和分泌功能等方面都证明,本方法是一种稳定、高效的小胶质细胞分离纯化方法.