Cell Line ; Cyclin-Dependent Kinase 5 ; metabolism ; Humans ; Lipopolysaccharides ; Microglia ; cytology ; drug effects ; metabolism ; Stilbenes ; pharmacology

The possible role of minocycline in microglial activation and neuronal death after cardiac arrest (CA) and cardiopulmonary resuscitation (CPR) in mice was investigated in this study. The mice were given potassium chloride to stop the heart beating for 8 min to achieve CA, and they were subsequently resuscitated with epinephrine and chest compressions. Forty adult C57BL/6 male mice were divided into 4 groups (n=10 each): sham-operated group, CA/CPR group, CA/CPR+minocycline group, and CA/CPR+vehicle group. Animals in the latter two groups were intraperitoneally injected with minocycline (50 mg/kg) or vehicle (normal saline) 30 min after recovery of spontaneous circulation (ROSC). Twenty-four h after CA/CPR, the brains were removed for histological evaluation of the hippocampus. Microglial activation was evaluated by detecting the expression of ionized calcium-binding adapter molecule-1 (Iba1) by immunohistochemistry. Neuronal death was analyzed by hematoxylin and eosin (H&E) staining and the levels of tumor necrosis factor-alpha (TNF-α) in the hippocampus were measured by enzyme-linked immunosorbent assay (ELISA). The results showed that the neuronal death was aggravated, most microglia were activated and TNF-α levels were enhanced in the hippocampus CA1 region of mice subjected to CA/CPR as compared with those in the sham-operated group (P<0.05). Administration with minocycline 30 min after ROSC could significantly decrease the microglial response, TNF-α levels and neuronal death (P<0.05). It was concluded that early administration with minocycline has a strong therapeutic potential for CA/CPR-induced brain injury.
Animals ; Cardiopulmonary Resuscitation ; Cell Death ; drug effects ; Enzyme-Linked Immunosorbent Assay ; Heart Arrest ; pathology ; Hippocampus ; cytology ; drug effects ; metabolism ; Male ; Mice ; Mice, Inbred C57BL ; Microglia ; cytology ; drug effects ; Minocycline ; pharmacology ; Neurons ; drug effects ; Tumor Necrosis Factor-alpha ; metabolism

Abundant evidence has suggested that neuroinflammation participates in the pathogenesis of Parkinson's disease (PD). The emerging evidence has supported that microglia may play key roles in the progressive neurodegeneration in PD and might be a promising therapeutic target. Ganoderma lucidum (GL), a traditional Chinese medicinal herb, has been shown potential neuroprotective effect in our clinical trials that lead us to speculate that it might possess potent anti-inflammatory and immunomodulating properties. To test this hypothesis, the present study investigated the potential neuroprotective effect of GL and underlying mechanism through inhibiting microglial activation using co-cultures of dopaminergic neurons and microglia. The cultures of microglia or MES23.5 cells alone or together were treated for 24 h with lipopolysaccharide (LPS, 0.25 μg/mL) as a positive control, GL extracts (50-400 μg/mL) or MES23.5 cell membrane fragments (150 μg/mL) were used in treatment groups. Microglia activation, microglia-derived harmful factors and [(3)H]dopamine ([(3)H]DA) uptake of MES23.5 cells were analyzed. The results showed that microglia were activated by LPS and MPP(+)-treated MES23.5 cell membrane fragments, respectively. Meanwhile, GL extracts significantly prevented the production of microglia-derived proinflammatory and cytotoxic factors, including nitric oxide, tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β), in a dose-dependent manner and down-regulated the TNF-α and IL-1β expressions on mRNA level. In addition, GL extracts antagonized the reduction of [(3)H]DA uptake induced by MPP(+) and microglial activation. In conclusion, these results suggest that GL may be a promising agent for the treatment of PD through anti-inflammation.
Cell Line ; Dopaminergic Neurons ; cytology ; drug effects ; Down-Regulation ; drug effects ; Humans ; Interleukin-1beta ; metabolism ; Materia Medica ; pharmacology ; Microglia ; cytology ; metabolism ; Neuroprotective Agents ; pharmacology ; Nitric Oxide ; metabolism ; Parkinson Disease ; physiopathology ; Reishi ; chemistry ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo observe the effect of normobaric hyperoxia exposure on the functions of N9 microglia and explore the underlying mechanism of hyperoxia-induced immature brain injury.

METHODSN9 microglial cells were exposed to 900 ml/L O(2) for 2, 6, 12, 24 or 48 h, and the cell apoptotic rate was assessed using flow cytometry. The intracellular oxidative stress was measured using a fluorescent DCFH-DA probe, and the expression of Toll-like receptor 4 (TLR4) mRNA was detected using RT-PCR. Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) concentrations in the supernatant of the cell cultures were tested with ELISA following the exposures. TLR4 protein expression was observed using immunofluorescence staining.

RESULTSSignificant cell apoptosis was detected after oxygen exposures for 12-24 h. Accumulation of reactive oxygen species (ROS) were detected after a 2-h exposure. After prolonged hyperoxia exposure, TLR4 expression and IL-1β and TNF-α levels significantly increased in the cells.

CONCLUSIONHyperoxia exposure activates TLR4 signaling pathway in N9 microglial cells in vitro, leading to massive production of ROS, IL-1β, and TNF-α and thus triggering cell apoptosis.

Animals ; Apoptosis ; drug effects ; Cell Hypoxia ; Cells, Cultured ; Interleukin-1beta ; metabolism ; Mice ; Mice, Inbred ICR ; Microglia ; cytology ; drug effects ; physiology ; Oxygen ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Reactive Oxygen Species ; metabolism ; Toll-Like Receptor 4 ; genetics ; metabolism

This study examined the neuroprotective effect of cluster of differentiation molecule 200 (CD200) against methamphetamine (METH)-induced neurotoxicity. In the in vitro experiment, neuron-microglia cultures were treated with METH (20 μmol/L), METH (20 μmol/L)+CD200-Fc (10 μg/mL) or CD200-Fc (10 μg/mL). Those untreated served as control. Microglia activation expressed as the ratio of MHC-II/CD11b was assessed by flow cytometry. The cytokines (IL-1β, TNF-α) secreted by activated microglia were detected by enzyme-linked immunosorbent assay (ELISA). In the in vivo experiment, 40 SD rats were divided into control, METH, METH+CD200-Fc and CD200-Fc groups at random. Rats were intraperitoneally injected with METH (15 mg/kg 8 times at 12 h interval) in METH group, with METH (administered as the same dose and time as the METH group) and CD200-Fc (1 mg/kg at day 0, 2, 4 after METH injection) in METH+CD200-Fc group, with CD200-Fc (1 mg/kg injected as the same time as the METH+CD200-Fc group) or with physiological saline solution in the control group. The level of striatal dopamine (DA) in rats was measured by high-performance liquid chromatography (HPLC). The microglial cells were immunohistochemically detected for the expression of Iba-1, a marker for microglial activation. The results showed that METH could increase the microglia activation in the neuron-microglia cultures and elevate the secretion of IL-1β and TNF-α, which could be attenuated by CD200-Fc. Moreover, CD200-Fc could partially reverse the striatal DA depletion induced by METH and reduce the number of activated microglia, i.e. Iba-1-positive cells. It was concluded that CD200 may have neuroprotective effects against METH-induced neurotoxicity by inhibiting microglial activation and reversing DA depletion in striatum.
Animals ; Animals, Newborn ; Antigens, CD ; administration & dosage ; Cells, Cultured ; Coculture Techniques ; Corpus Striatum ; cytology ; drug effects ; immunology ; Cytokines ; immunology ; Dopamine ; immunology ; Drug Interactions ; Male ; Methamphetamine ; toxicity ; Microglia ; drug effects ; immunology ; Neurons ; metabolism ; Rats ; Rats, Sprague-Dawley

Animals ; Animals, Newborn ; Cells, Cultured ; Corticotropin-Releasing Hormone ; pharmacology ; Interleukin-6 ; metabolism ; Microglia ; cytology ; drug effects ; metabolism ; Nitric Oxide ; metabolism ; Rats ; Rats, Sprague-Dawley ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVE: : To determine the effects of cysteinyl leukotriene receptors (CysLTR and CysLTR) on phagocytosis of mouse BV2 microglial cells. METHODS: : BV2 cells were stimulated with microglial activators lipopolysaccharide (LPS) or CysLT receptor agonists LTD. The phagocytosis of BV2 cells was observed by immunofluorescence analysis and flow cytometry. The intracellular distributions of CysLTR and CysLTR in BV2 cells were examined with immunofluorescence staining. RESULTS: : Both LPS and LTD could significantly enhance the phagocytosis of BV2 cells, and such effect could be inhibited by CysLTR selective antagonist Montelukast and CysLTR selective antagonist HAMI 3379. The activation of BV2 cells induced by LTD or LPS resulted in changes in intracellular distributions of CysLTR and CysLTR. CysLTR and CysLTR was co-localization with a similar distribution. CONCLUSIONS : CysLTR and CysLTR regulate the phagocytosis of mouse BV2 microglial cells with a synergistic effect.
Acetates ; pharmacology ; Animals ; Cell Line ; Cyclohexanecarboxylic Acids ; pharmacology ; Lipopolysaccharides ; pharmacology ; Mice ; Microglia ; cytology ; Phagocytosis ; drug effects ; Phthalic Acids ; pharmacology ; Protein Binding ; drug effects ; Quinolines ; pharmacology ; Receptors, Leukotriene ; agonists ; metabolism

Myristoylated alanine-rich C kinase substrate (MARCKS) is a widely distributed protein kinase C (PKC) substrate and has been implicated in actin cytoskeletal rearrangement in response to extracellular stimuli. Although MARCKS was extensively examined in various cell culture systems, the physiological function of MARCKS in the central nervous system has not been clearly understood. We investigated alterations of cellular distribution and phosphorylation of MARCKS in the hippocampus following kainic acid (KA)-induced seizures. KA (25 mg/kg, i.p.) was administered to eight to nine week-old C57BL/6 mice. Behavioral seizure activity was observed for 2 h after the onset of seizures and was terminated with diazepam (8 mg/kg, i.p.). The animals were sacrificed and analyzed at various points in time after the initiation of seizure activity. Using double-labeling immunofluorescence analysis, we demonstrated that the expression and phosphorylation of MARCKS was dramatically upregulated specifically in microglial cells after KA-induced seizures, but not in other types of glial cells. PKC alpha, beta I, beta II and delta, from various PKC isoforms examined, also were markedly upregulated, specifically in microglial cells. Moreover, immunoreactivities of phosphorylated MARCKS were co-localized in the activated microglia with those of the above isoforms of PKC. Taken together, our in vivo data suggest that MARCKS is closely linked to microglial activation processes, which are important in pathological conditions, such as neuroinflammation and neurodegeneration.
Up-Regulation/drug effects ; Time Factors ; Seizures/chemically induced/*metabolism ; Protein Kinase C-delta/analysis ; Protein Kinase C-alpha/analysis ; Protein Kinase C/*analysis ; Protein Biosynthesis/drug effects ; Phosphorylation/drug effects ; Microscopy, Confocal ; Microglia/cytology/drug effects/*metabolism ; Mice, Inbred C57BL ; Mice ; Membrane Proteins/*analysis/metabolism ; Kainic Acid/*toxicity ; Isoenzymes/analysis ; Intracellular Signaling Peptides and Proteins/*analysis/metabolism ; Immunohistochemistry ; Animals

To elucidate the roles of 8-hydroxydeoxyguanosine (oh8dG), the nucleoside of 8-hydroxyguanine (oh8Gua), we examined the effects of oh8dG upon LPS-induced intercellular adhesion molecule-1 (ICAM-1) expression and the underlying mechanisms in brain microglial cells. We found that oh8dG reduces LPS-induced reactive oxygen species (ROS) production, STAT3 activation, and ICAM-1 expression. oh8dG also suppresses pro-inflammatory cytokines, such as TNF-alpha, IL-6 and IFN-gamma. Overexpression of dominant negative STAT3 completely diminshed STAT3-mediated ICAM-1 transcriptional activity. Chromatin immunoprecipitation studies revealed that oh8dG inhibited recruitment of STAT3 to the ICAM-1 promoter, followed by a decrease in ICAM-1 expression. Using mice lacking a functional Toll-like receptor 4 (TLR4), we demonstrated that, while TLR4+/+ microglia were activated by LPS, TLR4-/-microglia exhibited inactivated STAT3 in response to LPS. Evidently, LPS modulates STAT3-dependent ICAM-1 induction through TLR4-mdiated cellular responses. Oh8dG apparently plays a role in anti-inflammatory actions via suppression of ICAM-1 gene expression by blockade of the TLR4-STAT3 signal cascade in inflammation-enhanced brain microglia. Therefore, oh8dG in the cytosol probably functions as an anti-inflammatory molecule and should be considered as a candidate for development of anti-inflammatory agents.
Toll-Like Receptor 4/genetics ; STAT3 Transcription Factor/physiology ; Reactive Oxygen Species/metabolism ; Microglia/*drug effects/metabolism ; Mice, Knockout ; Mice, Inbred C57BL ; Mice ; Male ; Lipopolysaccharides/*pharmacology ; Intercellular Adhesion Molecule-1/*metabolism ; Inflammation Mediators/metabolism ; Encephalitis/drug therapy ; Deoxyguanosine/*analogs & derivatives/pharmacology/therapeutic use ; Cytokines/biosynthesis ; Cell Survival/drug effects ; Brain/cytology/drug effects ; Anti-Inflammatory Agents, Non-Steroidal/*pharmacology ; Animals

Recent studies have reported that the "cholinergic anti-inflammatory pathway" regulates peripheral inflammatory responses via alpha7 nicotinic acetylcholine receptors (alpha7 nAChRs) and that acetylcholine and nicotine regulate the expression of proinflammatory mediators such as TNF-alpha and prostaglandin E2 in microglial cultures. In a previous study we showed that ATP released by beta-amyloid-stimulated microglia induced reactive oxygen species (ROS) production, in a process involving the P2X7 receptor (P2X7R), in an autocrine fashion. These observations led us to investigate whether stimulation by nicotine could regulate fibrillar beta amyloid peptide (1-42) (fA beta(1-42))-induced ROS production by modulating ATP efflux-mediated Ca2+ influx through P2X7R. Nicotine inhibited ROS generation in fA beta(1-42)-stimulated microglial cells, and this inhibition was blocked by mecamylamine, a non-selective nAChR antagonist, and a-bungarotoxin, a selective alpha7 nAChR antagonist. Nicotine inhibited NADPH oxidase activation and completely blocked Ca2+ influx in fA beta(1-42)-stimulated microglia. Moreover, ATP release from fA beta(1-42)-stimulated microglia was significantly suppressed by nicotine treatment. In contrast, nicotine did not inhibit 2',3'-O-(4-benzoyl)-benzoyl ATP (BzATP)-induced Ca2+ influx, but inhibited ROS generation in BzATP-stimulated microglia, indicating an inhibitory effect of nicotine on a signaling process downstream of P2X7R. Taken together, these results suggest that the inhibitory effect of nicotine on ROS production in fA beta(1-42)-stimulated microglia is mediated by indirect blockage of ATP release and by directly altering the signaling process downstream from P2X7R.
Adenosine Triphosphate/analogs & derivatives/metabolism/pharmacology ; Amyloid/*metabolism ; Amyloid beta-Protein/*pharmacology ; Animals ; Calcium/metabolism ; Enzyme Activation/drug effects ; Microglia/cytology/*drug effects/enzymology/*metabolism ; NADPH Oxidase/metabolism ; Nicotine/pharmacology ; Nicotinic Antagonists/pharmacology ; Peptide Fragments/*pharmacology ; Rats ; Rats, Sprague-Dawley ; Reactive Oxygen Species/*metabolism ; Receptors, Nicotinic/*metabolism ; Receptors, Purinergic P2/metabolism