Age and duration of inflammatory environment differentially affect the neuroimmune response and catecholaminergic neurons in the midbrain and brainstem

Neuroinflammation and degeneration of ascending catecholaminergic systems occur early in the neurodegenerative process. Age and the duration of a pro-inflammatory environment induced by continuous intraventricular lipopolysaccharide (LPS) differentially affect the expression profile of pro- and anti-inflammatory genes and proteins as well as the number of activated microglia (express major histocompatibility complex II; MHC II) and the integrity and density of ascending catecholaminergic neural systems originating from the locus coeruleus (LC) and substantia nigra pars compacta (SNpc) in rats. LPS infusion increased gene expression and/or protein levels for both pro- and anti-inflammatory biomarkers. Although LPS infusion stimulated a robust increase in IL-1ß gene and protein expression, this increase was blunted with age. LPS infusion also increased the density of activated microglia cells throughout the midbrain and brainstem. Corresponding to the development of a pro-inflammatory environment, LC and SNpc neurons immunopositive for tyrosine-hydroxylase (the rate-limiting synthetic enzyme for dopamine and norepinephrine) decreased in number, along with a decrease in tyrosine-hydroxylase gene expression in the midbrain and/or brainstem region. Our data support the concept that continuous exposure to a pro-inflammatory environment drives exaggerated changes in the production and release of inflammatory mediators that interact with age to impair functional capacity of the SNpc and LC.     

Microglial responses to dopamine in a cell culture model of Parkinson's disease

Activated microglia appear to selectively attack dopamine (DA) neurons in the Parkinson's disease (PD) substantia nigra. We investigated potential mechanisms using culture models. As targets, human SH-SY5Y cells were left undifferentiated (UNDIFF) or were differentiated with retinoic acid (RA) or RA plus brain-derived neurotrophic factor (RA/BDNF). RA/BDNF-treated cells were immunoreactive for tyrosine hydroxylase and the DA transporter, took up exogenous DA, and released DA after K(+) stimulation. Undifferentiated and RA-treated cells lacked these characteristics of a DA phenotype. Co-culture of target cells with human elderly microglia resulted in elevated toxicity in DA phenotype (RA/BDNF) cells. Lipopolysaccharide (LPS) plus K(+)-stimulated DA release enhanced toxicity by 500-fold. DA induced microglial chemotaxis in Boyden chambers. Spiperone inhibited this effect. Cultured human elderly microglia expressed mRNAs for D1-D4 but not D5 DA receptors. The microglia, as well as PD microglia in situ, were also immunoreactive for D1-D4 but not D5 DA receptors. These findings demonstrate that activated microglia express DA receptors, and suggest that this mechanism may play a role in the selective vulnerability of DA neurons in PD.     

Effects of noradrenaline on neuronal NOS2 expression and viability

The authors previously showed that conditioned media (CM) from activated microglia increased inducible nitric oxide synthase (NOS2) in cortical neurons. Here they examined the ability of noradrenaline (NA) to reduce neuronal NOS2 or cell death. Primary mouse cortical neurons were activated using CM from microglia incubated with lipopolysaccharide (LPS). Neuronal NOS2 was assessed by increases in nitrite accumulation, and increases in NOS2 mRNA levels and fluorescence of the NO-sensitive probe DAF-2 DA. NOS2 induction was associated with an increase in neuronal LDH release. When NA was added during microglial activation, neuronal NOS2 was significantly reduced (by approximately 70%); in contrast if NA was added to the neurons along with CM, there was less reduction (about 35% decrease) in NOS2 expression. NA added to either microglia or to neurons reduced neuronal LDH release comparably. Pretreatment of CM with blocking antibody to TNFalpha, alone or with IL1-receptor antagonist, partially reduced neuronal cell death and NOS2. Incubation of neurons with NA increased IkBalpha, which could reduce NOS2. These results demonstrate that NA modulates neuronal NOS2 expression and damage, and that these effects are primarily due to inhibition of microglia released factors. Perturbations of NA could exacerbate neuronal damage by allowing for increased inflammatory responses.     

Estrogen enhances the number of nigral dopaminergic neurons of adult male mice without affecting nigral neuroglial number and morphology

Emerging evidence indicate the modulating effects of estrogen on dopaminergic neurons in the substantia nigra pars compacta (SNpc). One of the mechanisms underlying the effect of estrogen is through neuroglia. To determine whether estrogen affects the number of dopaminergic neurons and reactive astrocytes and microglia in the SNpc of male mice, 14-week-old C57Bl/6 male mice were injected with 17beta-estradiol (E2) or vehicle for 10.5 days. On day 11 all mice were killed and the SNpc were collected and processed for lectin (GSI-B4) histochemistry, tyrosine hydroxylase (TH) immunohistochemistry or glial fibrillary acidic protein (GFAP) immunohistochemistry. Quantitative studies demonstrated that E2 significantly increases the number of TH-immunoreactive (IR) neurons in the SNpc but the hormone induces no change either in cell number or cell morphology of GFAP-IR astroglia and GSI-B4(+ve) microglia. These observations suggest that E2 can influence the number of nigral dopaminergic neurons of male mice and possibly protects dopaminergic neuronal loss during normal aging and in Parkinson's disease.     

Inflammatory priming of the substantia nigra influences the impact of later paraquat exposure: Neuroimmune sensitization of neurodegeneration

Activation of microglia along with the release of inflammatory cytokines and oxidative factors often accompanies toxin-induced degeneration of substantia nigra pars compacta (SNc) dopamine (DA) neurons. Multiple toxin exposure may synergistically influence microglial-dependent DA neuronal loss and, in fact, pre-treatment with one toxin may sensitize DA neurons to the impact of subsequent insults. Thus, we assessed whether priming SNc neurons with the inflammatory agent, lipopolysaccharide (LPS), influenced the impact of later exposure to the pesticide, paraquat, which has been reported to provoke DA loss. Indeed, LPS infusion into the SNc sensitized DA neurons to the neurodegenerative effects of a series of paraquat injections commencing 2 days later. In contrast, LPS pre-treatment actually protected against some of neurodegenerative effects of paraquat when the pesticide was administered 7 days after the endotoxin. These sensitization and de-sensitization effects were associated with altered expression of reactive microglia expressing inducible immunoproteasome subunits, as well as variations of fibroblast growth factor and a time-dependent infiltration of peripheral immune cells. Circulating levels of the inflammatory cytokines, interleukin (IL)-6, IL-2, tumor necrosis factor-α and interferon-γ were also time-dependently elevated following intra-SNc LPS infusion. These data suggest that inflammatory priming may influence DA neuronal sensitivity to subsequent environmental toxins by modulating the state of glial and immune factors, and these findings may be important for neurodegenerative conditions, such as Parkinson's disease (PD).     

Interleukin-10 protects against inflammation-mediated degeneration of dopaminergic neurons in substantia nigra

Inflammation has been increasingly recognized to play an important role in the pathogenesis of Parkinson's disease (PD). Using immunocytochemistry and electron microscopy, we found that intranigral injection of lipopolysaccharide (LPS) caused marked microglial activation and a dose-dependent selective loss of dopaminergic neurons, which was mediated by apoptosis as evidenced by prominent TUNEL labeling. RNase protection assays revealed that mRNA for Bax, Fas and the pro-inflammatory cytokines interleukin (IL)-1α, IL-1β, IL-6 and tumor necrosis factor (TNF)-α were significant increased ipsilaterally in LPS-injected side of SN, while expression of the anti-apoptotic gene Bcl-2 was decreased. Osmotic pump infusion of IL-10, a global inhibitor of cytokine synthesis, protected against LPS-induced cell death of dopaminergic neurons, with a corresponding decrease in the number of activated microglia, suggesting that the reduction in microglia-mediated release of inflammatory mediators may contribute to the anti-inflammatory effect of IL-10. Our results provide evidence that LPS induces apoptotic cell death in SNpc, which is likely through the expression of Fas, Bax, caspase-3, and the pro-inflammatory cytokines.     

Primary phagocytosis of viable neurons by microglia activated with LPS or Abeta is dependent on calreticulin/LRP phagocytic signalling

ABSTRACT: BACKGROUND: Microglia are resident brain macrophages that can phagocytose dead, dying or viable neurons, which may be beneficial or detrimental in inflammatory, ischaemic and neurodegenerative brain pathologies. Cell death caused by phagocytosis of an otherwise viable cell is called 'primary phagocytosis' or 'phagoptosis'. Calreticulin (CRT) exposure on the surface of cancer cells can promote their phagocytosis via LRP (low-density lipoprotein receptor-related protein) on macrophages, but it is not known whether this occurs with neurons and microglia. METHODS: We used primary cultures of cerebellar neurons, astrocytes and microglia to investigate the potential role of CRT/LRP phagocytic signalling in the phagocytosis of viable neurons by microglia stimulated with LPS (lipopolysaccharide) or nanomolar concentrations of amyloid-beta peptide1-42 (Abeta). Exposure of CRT on the neuronal surface was investigated using surface biotinylation and western blotting. A phagocytosis assay was also developed using BV2 and PC12 cell lines to investigate CRT/LRP signalling in microglial phagocytosis of apoptotic cells. RESULTS: We found that BV2 microglia readily phagocytosed apoptotic PC12 cells, but this was inhibited by a CRT blocking antibody or LRP-blocking protein (Receptor-Associated Protein: RAP). Activation of primary rat microglia with LPS or Abeta resulted in loss of co-cultured cerebellar granule neurons, and this was blocked by RAP or antibodies against CRT or against LRP, preventing all neuronal loss and death. CRT was present on the surface of viable neurons, and this exposure did not change in inflammatory conditions. CRT antibodies prevented microglia-induced neuronal loss when added to neurons, while LRP antibodies prevented neuronal loss when added to the microglia. Pre-binding of CRT to neurons promoted neuronal loss if activated microglia were added, but pre-binding of CRT to microglia or both cell types prevented microglia-induced neuronal loss. CONCLUSIONS: CRT exposure on the surface of viable or apoptotic neurons appears to be required for their phagocytosis via LRP receptors on activated microglia, but free CRT can block microglial phagocytosis of neurons by acting on microglia. Phagocytosis of CRT-exposing neurons by microglia can be a direct cause of neuronal death during inflammation, and might therefore contribute to neurodegeneration and be prevented by blocking the CRT/LRP pathway.     

miR-29c-3p regulates TET2 expression and inhibits autophagy process in Parkinson's disease models

Autophagy in dopamine (DA) neurons is concerned to be associated with Parkinson's disease (PD), but the detailed mechanism remains unknown. Herein, we aimed to investigate the function of microRNA (miR)-29c-3p in autophagy in PD models. Intraperitoneal injection of MPTP (20 mg/kg) was given to C57BL/6 mice to establish PD mouse model. SH-SY5Y cells were treated with MPP⁺ (1 mmol/L) to establish in vitro PD model. The results indicated that in the substantia nigra pars compacta (SNpc) DA neurons of PD mice, autophagy was activated accompanied by down-regulated miR-29c-3p and up-regulated ten-eleven translocation 2 (TET2) expression. Up-regulation of miR-29c-3p inhibited TET2 expression and SNpc (including DA neurons) autophagy in PD mice. In vitro PD model confirmed that MPP⁺ treatment markedly down-regulated miR-29c-3p expression and up-regulated TET2 expression in SH-SY5Y cells in a dose/time-dependent manner. Moreover, miR-29c-3p up-regulation also inhibited autophagy and TET2 expression in vitro. Additionally, TET2 was proved to be targeted and down-regulated by miR-29c-3p. TET2 knockdown inhibited MPP⁺-induced autophagy, whereas TET2 over-expression reversed the effects of miR-29c-3p over-expression on SH-SY5Y cell autophagy. Overall, miR-29c-3p over-expression inhibits autophagy in PD models, which may be mediated by TET2. Our finding may provide new insights for regulating autophagy to improve PD progression.     

Parkin protects human dopaminergic neuroblastoma cells against dopamine-induced apoptosis

Parkinson's disease (PD) is characterized by the selective degeneration of dopaminergic (DA) neurons in substantia nigra pars compacta (SNpc). A combination of genetic and environmental factors contributes to such a specific loss. Among the five PD-linked genes identified so far, parkin, a protein-ubiquitin E3 ligase, appears to be the most prevalent genetic factor in PD. Although a variety of substrates have been identified for parkin, none of them is selectively expressed in nigral DA neurons. It remains unclear how accumulation of these substrates in the absence of functional parkin may cause the selective death of DA neurons in SNpc. Here, we show that overexpression of parkin protected human DA neuroblastoma cell line (SH-SY5Y) against apoptosis induced by DA or 6-OHDA, but not by H(2)O(2) or rotenone. Parkin significantly attenuated dopamine-induced activation of c-Jun N-terminal kinase (JNK) and caspase-3. It also decreased the level of reactive oxygen species (ROS) and protein carbonyls in the cell. Inhibiting DA uptake through dopamine transporter or treating the cell with antioxidants significantly reduced oxidative stress and dopamine toxicity. Furthermore, PD-linked mutations of parkin significantly abrogated the protective effect of wild-type parkin, as well as its ability to suppress ROS and protein carbonylation. These results suggest that parkin protects against dopamine toxicity by decreasing oxidative stress and ensuing activation of apoptotic programs such as the JNK/caspase pathway. This protective function of parkin, which is greatly attenuated by its PD-linked mutations, may be uniquely important for the survival of DA neurons, as they are constantly threatened by oxyradicals produced during dopamine oxidation.     

Minocycline Alleviates Cluster Formation of Activated Microglia and Age-dependent Dopaminergic Cell Death in the Substantia Nigra of Zitter Mutant Rat

Microglial activation is a component of neurodegenerative pathology. Here, we examine whether activated microglia participate in age-related dopaminergic (DA) cell death in the substantia nigra pars compacta (SNc) of the zitter (zi/zi) rat, a mutant characterized by deletion of the attractin gene. Confocal microscopy with double-immunohistochemical staining revealed activated microglia-formed cell-clusters surrounding DA neurons in the SNc from 2 weeks after birth. An immunoelectron microscopic study showed that the cytoplasm of activated microglia usually contains phagosome-like vacuoles and lamellar inclusions. Expression levels of the pro-inflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) were increased in the midbrain of 2-month-old zi/zi rats. Chronic treatment with the anti-inflammatory agent minocycline altered the morphology of the microglia, reduced cluster formation by the microglia, and attenuated DA cell death in the SNc, and reduced the expression of IL-1β in the midbrain. These results indicate that activated microglia, at least in part and especially at the initial phase, contribute to DA cell death in the SNc of the zi/zi rat.     

Selective COX-2 inhibition prevents progressive dopamine neuron degeneration in a rat model of Parkinson's disease

Several lines of evidence point to a significant role of neuroinflammation in Parkinson's disease (PD) and other neurodegenerative disorders. In the present study we examined the protective effect of celecoxib, a selective inhibitor of the inducible form of cyclooxygenase (COX-2), on dopamine (DA) cell loss in a rat model of PD. We used the intrastriatal administration of 6-hydroxydopamine (6-OHDA) that induces a retrograde neuronal damage and death, which progresses over weeks. Animals were randomized to receive celecoxib (20 mg/kg/day) or vehicle starting 1 hour before the intrastriatal administration of 6-OHDA. Evaluation was performed in vivo using micro PET and selective radiotracers for DA terminals and microglia. Post mortem analysis included stereological quantification of tyrosine hydroxylase, astrocytes and microglia. 12 days after the 6-OHDA lesion there were no differences in DA cell or fiber loss between groups, although the microglial cell density and activation was markedly reduced in animals receiving celecoxib (p < 0.01). COX-2 inhibition did not reduce the typical astroglial response in the striatum at any stage. Between 12 and 21 days, there was a significant progression of DA cell loss in the vehicle group (from 40 to 65%) that was prevented by celecoxib. Therefore, inhibition of COX-2 by celecoxib appears to be able, either directly or through inhibition of microglia activation to prevent or slow down DA cell degeneration.     

胚胎期脂多糖暴露可通过钟样受体4引起出生后多巴胺能神经元减少

目的 观察钟样受体4(TLR-4)在胚胎期脂多糖 (LPS) 暴露引起的出生后个体脑内多巴胺 (DA) 能神经元减少中的作用.方法 TLR-4 突变型C57BL/10ScNCr小鼠和野生型C57BL/10ScSn小鼠各15只,在妊娠期第10.5天给小鼠腹腔注射LPS或肽聚糖(PDG),出生后4月龄时收集大脑组织标本(n=5),通过免疫组织化学染色和体视学技术定量DA能神经元和小胶质细胞数量,高效液相色谱法测定DA及其代谢物水平,免疫荧光法结合流式细胞术测定TNF-α和IL-1β蛋白水平.结果 出生前接触过LPS的4月龄C57BL/10ScSn小鼠,与注射生理盐水的对照小鼠比较,黑质DA能神经元减少(25.3±2.1)%,纹状体DA含量降低(33.5±5.0)%,黑质小胶质细胞数量增加(294±24)%,黑质和纹状体TNF-α和IL-1β蛋白水平也明显增高;但是出生前接触过LPS的TLR-4突变型C57BL/10ScNCr小鼠脑内无相应变化.出生前接触过TLR-2配体PDG的4月龄C57BL/10ScNCr 和C57BL/10ScSn小鼠均出现脑内DA能神经元减少和免疫炎症改变.结论 胚胎期接触LPS可通过TLR-4引起出生后个体脑内DA能神经元减少.     

Releasing factors from mature neurons modulate microglial survival via purinergic receptor activation

Activated microglia release many types of substances to neurons. However, little is known concerning how information from neurons is received by microglia prior to the induction of these substances. Here, we examined whether neurons modulate microglial function. Treatment with conditioned medium of mature cerebellar granule neurons (CGCs) and cortical neurons significantly induced the death of lipopolysaccharide (LPS)-stimulated microglia. On the other hand, treatment with conditioned medium of mature superior ganglion neurons induced microglial cell death in neither the presence nor absence of LPS. Conditioned medium of mature CGCs induced nuclear condensation. In contrast, treatment with heat-treated conditioned medium or low-calcium ion medium prevented the death of LPS-stimulated microglia. Pretreatment with P2X7 agonist enhanced microglial cell death in neither the presence nor absence of LPS. These findings suggest that unknown pyrolytic releasing factors of brain-derived mature neurons influence microglial survival.     

尼古丁对PD大鼠黑质多巴胺能神经元变性的影响

目的 探讨尼古丁对帕金森病(PD)大鼠黑质多巴胺能神经元变性的影响及其机制. 方法 45只大鼠随机分为PBS对照组(CON)、生理盐水+ 脂多糖(NS)组、尼古丁+脂多糖(NIC)组,每组15只.黑质内立体定向注射脂多糖(LPS)或PBS后24h,免疫印迹法检测黑质诱导性一氧化氮合酶(iNOS)蛋白表达变化;黑质注射药物后14d,采用免疫组织化学法观察大鼠黑质酪氨酸羟化酶(TH)阳性神经元数量及OX-42阳性细胞形态学变化,RT-PCR及免疫印迹检测黑质TH mRNA及TH蛋白的表达水平. 结果 与CON组相比,NS组大鼠黑质iNOS表达明显增多,TH阳性神经元、TH mRNA及TH蛋白明显减少,小胶质细胞大多呈胞体大突起短粗的形态;NIC组黑质iNOS表达明显少于NS组,黑质TH阳性神经元、TH mRNA及TH蛋白表达较NS组明显增多,大部分小胶质细胞呈胞体小,突起细长的形态. 结论 尼古丁可以减轻LPS介导的多巴胺能神经元变性,对多巴胺能神经元有保护作用,其保护机制与抑制小胶质细胞激活、减少iNOS的表达有关.     

尼古丁对脂多糖诱导的小胶质细胞激活及活化后细胞死亡的影响

目的 观察尼古丁对脂多糖(LPS)诱导的小胶质细胞激活及活化后细胞死亡的影响. 方法 建立慢性尼古丁暴露的小鼠动物模型,腹腔注射LPS诱导小胶质细胞激活,应用免疫组织化学方法 观察皮质、海马、黑质CD-11b阳性小胶质细胞表达的变化;BV2细胞(小鼠小胶质瘤细胞系)传代培养,运用CCK-8试剂盒检测细胞活性,一氧化氮检测试剂盒检测一氧化氮(NO)释放情况,RT-PCR分析诱导型一氧化氮合酶(iNOS)、肿瘤坏死因子(TNF-α)、白细胞介素1(IL-1β)、白细胞介素6(IL-6)、环氧化酶-2(COX-2)、干扰素调节因子1(IRF-1)、Caspase-11 mRNA的表达,免疫印迹法分析P-I-κB、Caspase-3的表达变化. 结果 尼古丁抑制LPS诱导的皮质、海马、黑质CD-11b阳性小胶质细胞的表达;尼古丁抑制LPS刺激引起的BV2细胞的死亡,NO的释放,iNOS、TNF-α、IL-1β、IL-6、COX-2、IRF-1、Caspase-11 mRNA的表达,P-I-κB、Caspase-3蛋白的表达. 结论 尼古丁可以抑制LPS诱导的小胶质细胞活化及激活诱导的细胞死亡(AICD),对脑内炎症反应具有神经保护作用.     

姜黄素对LPS激活小胶质细胞条件培养基诱导损伤的海马神经元保护作用及机制

目的:通过脂多糖(LPS)激活小胶质细胞条件培养基(MCM)引起原代培养SD大鼠海马神经元损伤,体外模拟炎症相关性神经退行性疾病,探讨姜黄素的保护作用及机制。方法:5μg/LLPS作用于原代培养的SD大鼠小胶质细胞12h,取激活后培养基作用于原代培养的SD大鼠海马神经元。实验分为5组:空白对照组,LPS组,姜黄素组,MCM组,姜黄素+MCM组。相差显微镜下观察海马神经元各组处理前后形态学改变,MTT法检测各组海马神经元的存活率,并通过全自动生化仪检测各组海马神经元内乳酸盐与丙酮酸盐比值来评价神经元内氧利用情况,RT-PCR法观察各组海马神经元1,4,5-三磷酸肌醇受体3个亚型(IP3R1,IP3R2,IP3R3)的表达情况。结果:LPS激活的小胶质细胞条件培养基引起海马神经元形态发生明显改变,乳酸盐与丙酮酸盐比值较空白对照组亦有明显增加;姜黄素组海马神经元形态未发生明显改变,乳酸盐与丙酮酸盐比值较MCM组降低,MCM组IP3R1及IP3R3表达明显升高,IP2R2无显著变化;姜黄素组IP3R1的表达较MCM组明显下降,但IP3R3表达无明显变化。结论:LPS激活小胶质细胞条件培养基可引起海马神经元损伤,姜黄素对该损伤海马神经元的保护性作用可能是通过增加细胞内氧利用率,降低IP3R1的表达及敏感性,从而减低神经元内钙离子浓度及细胞内钙离子超载机率而发挥作用的。     

脑内炎症对黑质多巴胺能神经元的选择性损伤作用

目的 探讨脑内炎症反应对中脑黑质多巴胺能神经元的选择性变性作用.方法 健康SD雄性大鼠10只,随机分为实验组和对照组,实验组行脂多糖(LPS)右侧脑室定位注射,对照组注射生理盐水.注射后48周用免疫组织化学或组织化学法观察黑质多巴胺能、中缝核5-羟色胺能及基底核胆碱能3种不同类型神经元的变性及上述不同脑区小胶质细胞的激活情况.结果 免疫组织化学染色显示,LPS组在黑质、海马、纹状体、中缝核部位均可见到OX6阳性小胶质细胞,说明不同脑区均出现炎症反应.不同类型神经元染色结果显示,LPS组黑质多巴胺能神经元胞体变小、染色变浅、突起减少甚至消失,神经元数量比对照组减少40.1%(P<0.01);5-羟色胺能神经元及胆碱能神经元形态及数量均无明显改变.结论脑室注射LPS导致的脑内炎症反应可选择性引起黑质多巴胺能神经元变性损伤.     

Posttreatment with propofol attenuates lipopolysaccharide-induced up-regulation of inflammatory molecules in primary microglia

Background

Activation of microglia is involved in a broad range of neuroinflammatory diseases. Suppression of microglial activation may, therefore, contribute to alleviate the progression of neuroinflammatory diseases. It has been reported that propofol has a potent anti-inflammatory property. In the present study, we investigated the effects of posttreatment with propofol on the production of inflammatory molecules in lipopolysaccharide (LPS)-stimulated microglia.

Materials and methods

Microglia were exposed to various concentrations (25, 50, 100, 250 μM) of propofol for 1 h after LPS stimulation for 24 h. The levels of proinflammatory mediators inducible nitric oxide synthase (iNOS)/nitric oxide (NO), cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured.

Results

Propofol at a concentration of 25 μM did not affect the production of proinflammatory mediators, which was enhanced by LPS. At the concentrations of 50, 100, and 250 μM, propofol significantly inhibited LPS-mediated production of NO, PGE2, TNF-α, and IL-1β and the expression of iNOSmRNA, COX-2mRNA, TNF-α mRNA, and IL-1β mRNA.

Conclusions

These results suggest that propofol, at clinically relevant concentrations, can reduce inflammatory responses in LPS-induced inflammation in activated microglia and might be an intravenous anesthetic of choice when patients with neuroinflammatory diseases require sedation and/or general anesthesia.     

The influence of microglia on the pathogenesis of Parkinson's disease

Parkinson's disease (PD) is characterised by degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Inflammation may be associated with the neuropathology of PD due to the following accumulating evidence: excessive microglial activation and increased levels of the pro-inflammatory cytokines tumour necrosis factor-α and interleukin-1β in the SNpc of patients with PD; the emergence of PD-like symptoms following influenza infection; the increased susceptibility to PD associated with bacterial vaginosis; the presence of inflammatory mediators and activators in animal models of PD; the ability of anti-inflammatory drugs to decrease susceptibility to PD; and the emerging possibility of the use of microglial activation inhibitors as a therapy in PD. In this review, we will discuss the role of inflammation in PD. We will focus on the influence of microglia in the pathogenesis of PD and discuss potential therapeutic interventions for PD, that target microglia.