• Proceedings of the PSK Conference
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• 2003.10b
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• pp.138.1-138.1
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• 2003

Inflammatory responses from activated microglia are one of major causes of Alzheimer's disease (AD). Particularly, proinflammatory cytokines (PC), such as IL-l$\beta$ and TNF-$\alpha$, and nitric oxide (NO) are correlated with AD by inducing the chronic inflammation in the brain. In the present study, we found that microglia are activated by lipopolisaccharide (LPS) and Abeta42 (A$\beta$42), and those activated microglia produced such repertoires up to 72h with a turning point at 24h. However, no dose dependecy was found during the chasing time courses (6h to 72h). (omitted)

• The Korean Journal of Pain
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• v.34 no.1
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• pp.47-57
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• 2021

Background: Lumbar disc herniation (LDH) is a common cause of radicular pain, but the mechanism is not clear. In this study, we investigated the engagement of toll-like receptor 4 (TLR4) and the nuclear factor-kappa B (NF-κB) in radicular pain and its possible mechanisms. Methods: An LDH model was induced by autologous nucleus pulposus (NP) implantation, which was obtained from coccygeal vertebra, then relocated in the lumbar 4/5 spinal nerve roots of rats. Mechanical and thermal pain behaviors were assessed by using von Frey filaments and hotplate test respectively. The protein level of TLR4 and phosphorylated-p65 (p-p65) was evaluated by western blotting analysis and immunofluorescence staining. Spinal microglia activation was evaluated by immunofluorescence staining of specific relevant markers. The expression of proand anti-inflammatory cytokines in the spinal dorsal horn was measured by enzyme linked immunosorbent assay. Results: Spinal expression of TLR4 and p-NF-κB (p-p65) was significantly increased after NP implantation, lasting up to 14 days. TLR4 was mainly expressed in spinal microglia, but not astrocytes or neurons. TLR4 antagonist TAK242 decreased spinal expression of p-p65. TAK242 or NF-κB inhibitor pyrrolidinedithiocarbamic acid alleviated mechanical and thermal pain behaviors, inhibited spinal microglia activation, moderated spinal inflammatory response manifested by decreasing interleukin (IL)-1β, IL-6, tumor necrosis factor-α expression and increasing IL-10 expression in the spinal dorsal horn. Conclusions: The study revealed that TLR4/NF-κB pathway participated in radicular pain by encouraging spinal microglia activation and inflammatory response.

• The Korea Journal of Herbology
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• v.29 no.2
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• pp.33-38
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• 2014

Objectives : Inflammation is mediated by cellular components, such as leukocytes and microglia, and molecular components, including cytokines, extracellular proteases, and reactive oxygen species. Cnidium Rhizoma effects the anti-inflammatory, antioxidant, suppression of the microglia activation and protection of the nerve cell injury. For this reason, we investigated the anti-inflammatory effects of water extracts of Cnidium Rhizoma on intracerebral hemorrhage (ICH). Method : ICH was induced by the stereotaxic intracerebral injection of bacterial collagenase type IV (0.23 $U/{\mu}{\ell}$, 0.1 ${\mu}{\ell}/min$) in Sprague-Dawley rats. We orally administrated once 3 hours after ICH, then 2 times at 24-hour intervals the water extracts of Cnidium Rhizoma (500 mg/kg), myeloperoxidase (MPO) was observed by using immunofluorescense and expression of inducible nitric oxide synthase (iNOS), tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) and microglia were observed by using immunohistochemistry. Results : Infiltration of MPO expressing neutrophil, expression of iNOS and TNF-${\alpha}$ and activated microglia were significantly reduced in peri-hematoma of the rats fed with water extracts of Cnidium Rhizoma. Conclusion : These results demonstrated that water extracts of Cnidium Rhizoma suppressed an inflammatory reaction through inhibition of MPO, iNOS and TNF-${\alpha}$ positive cell and activated microglia number in peri-hematoma of ICH-induced rats.

• Genomics & Informatics
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• v.21 no.1
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• pp.2.1-2.14
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• 2023

Microglia, similar to peripheral macrophages, are the primary immune cells of the central nervous system (CNS). Microglia exist in the resting state in the healthy CNS, but can be activated and polarized into either M1 or M2 subtypes for immune defense and the maintenance of CNS homeostasis by multiple stimuli. Several long noncoding RNAs (lncRNAs) mediate human inflammatory diseases and neuropathologies by regulating their target genes. However, the function of common lncRNAs that contribute to microglial activation remains unclear. Thus, we used bioinformatic approaches to identify common lncRNAs involved in microglial activation in vitro. Our study identified several lncRNAs as common regulators of microglial activation. We identified 283 common mRNAs and 53 common lncRNAs during mouse M1 microglial activation processes, whereas 26 common mRNAs and five common lncRNAs were identified during mouse M2 microglial activation processes. A total of 648 common mRNAs and 274 common lncRNAs were identified during the activation of human M1 microglia. In addition, we identified 1,920 common co-expressed pairs in mouse M1 activation processes and 25 common co-expressed pairs in mouse M2 activation processes. Our study provides a comprehensive understanding of common lncRNA expression profiles in microglial activation processes in vitro. The list of common lncRNAs identified in this study provides novel evidence and clues regarding the molecular mechanisms underlying microglial activation.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.3
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• pp.219-228
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• 2015

Excessive microglial activation and subsequent neuroinflammation lead to synaptic loss and dysfunction as well as neuronal cell death, which are involved in the pathogenesis and progression of several neurodegenerative diseases. Thus, the regulation of microglial activation has been evaluated as effective therapeutic strategies. Although dieckol (DEK), one of the phlorotannins isolated from marine brown alga Ecklonia cava, has been previously reported to inhibit microglial activation, the molecular mechanism is still unclear. Therefore, we investigated here molecular mechanism of DEK via extracellular signal-regulated kinase (ERK), Akt and nicotinamide adenine dinuclelotide phosphate (NADPH) oxidase-mediated pathways. In addition, the neuroprotective mechanism of DEK was investigated in microglia-mediated neurotoxicity models such as neuron-microglia co-culture and microglial conditioned media system. Our results demonstrated that treatment of anti-oxidant DEK potently suppressed phosphorylation of ERK in lipopolysaccharide (LPS, $1{\mu}g/ml$)-stimulated BV-2 microglia. In addition, DEK markedly attenuated Akt phosphorylation and increased expression of $gp91^{phox}$, which is the catalytic component of NADPH oxidase complex responsible for microglial reactive oxygen species (ROS) generation. Finally, DEK significantly attenuated neuronal cell death that is induced by treatment of microglial conditioned media containing neurotoxic secretary molecules. These neuroprotective effects of DEK were also confirmed in a neuron-microglia co-culture system using enhanced green fluorescent protein (EGFP)-transfected B35 neuroblastoma cell line. Taken together, these results suggest that DEK suppresses excessive microglial activation and microglia-mediated neuronal cell death via downregulation of ERK, Akt and NADPH oxidase-mediated pathways.

• Journal of fish pathology
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• v.7 no.1
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• pp.63-70
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• 1994

Nitric oxide(NO) has recently been shown to play an important role on central nervous system(CNS) function in mammals. It is synthesized from L-arginine by the enzyme NO synthase. In this study, we examined this enzyme's existence in CNS of rainbow trout(Oncorhynchus mykiss) and described the forms of microglia. astrocytes. and oligodendrocytes. Two forms of microglia are distributed in CNS. one resembling their mammalian counterpart(large microglia : LM). and the other comprising small microglia(SM) with very little cytoplasm. CNS contained astrocytes of a distinct type which form reticular network, but lack connections to capillaries. The oligodendrocyte was generally a much denser cell than the astrocyte. We have detected NOS($1.04{\pm}0.12\;pg/min/mg$) from rainbow trout CNS. It could be inhibited reversibly or irreversibly by $N^{G}MMA$ and EGTA. These result suggest that the formation of NO from L-arginine in CNS is calcium-dependent and a pathway of early evolutionary orgin.

• Biomolecules & Therapeutics
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• v.19 no.4
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• pp.431-437
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• 2011

Aberrant activation of microglia has been reported to cause neuronal damages by releasing a variety of pro-inflammatory cytokines. Besides where microglia become active, damages have been also observed in remote places, which is considered due to the migration of activated microglia. Therefore, an agent that could suppress abnormal activation of microglia and their subsequent migration might be valuable in activated microglia-related brain pathologies. The objective of the present study was to evaluate anti-inflammatory effects of betulinic acid on lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Pretreatment of betulinic acid significantly attenuated LPS-induced NO production and protein expression of iNOS. Betulinic acid also significantly suppressed LPS-induced release and expression of cytokines such as TNF-${\alpha}$ and IL-$1{\beta}$. Furthermore, betulinic acid significantly uppressed LPS-induced MMP-9 expression, which has been suggested to play an important role in the migration of activated microglia. In order to understand the possible mechanism by which betulinic acid suppresses LPS-induced cytokine production and migration of microglia, the role of NF-kB, a major pro-inflammatory transcription factor, was examined. Betulinic acid significantly suppressed LPS-induced degradation of IKB, which retains NF-kB in the cytoplasm. Therefore, nuclear translocation of NF-kB upon LPS stimulation was significantly suppressed with betulinic acid. Taken together, the present study for the first time demonstrates that betulinic acid possesses anti-inflammatory activity through the suppression of nuclear translocation of NF-kB in BV2 microglial cells.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.1
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• pp.204-211
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• 2005

We hypothesize that bear's gall may have a certain role in anti-inflammation through a preventive effect of pro-inflammatory potentials. Secondly, we tried to connect the experimental results to Alzheimer's disease (AD), which chronic inflammation is a main cause of the disease. For this theme, we designed to elucidate the efficacy of bear's gall in suppressing the pro-inflammatory mediators, such as nitric oxide (NO) and $interleukin-1{\beta}\;(IL-1{\beta})$ in rat microglia. From the study, we concluded that bear's gall plays a positive role in suppressing such pro-inflammatory repertoire from rat microglia comparing to normal and positive control, such as culture media and cyclosporine. Interestingly, bear's gall showed a prolonged effect of anti-inflammation comparing with cyclosporine when time goes by up to 48h with a significant suppression at $1.2\;mg/m{\ell}$. Therefore, we can consider that bear's gall in part can be applied to AD therapy in that it suppresses the expression of pro-inflammatory mediators as well as its continued effect.

• Molecular & Cellular Toxicology
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• v.1 no.1
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• pp.40-45
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• 2005

Ursodeoxycholic acid (UDCA) has long been used as an adjuvant or first choice of therapy for liver disease. Commonly, UDCA has been reported to play a role in improving hyperbilirubinemia and disorder of bromsulphalein. More commonly, UDCA has been used in reducing the rate of cholesterol level in bile juice that can cause cholesterol stone. The effects on the promotion of bile acid release that leads an excretion of toxic materials and wastes produced in liver cells as well as various arrays of liver disease such as hepatitis. Other than already reported in clinical use, immunosuppressive effect has been studied, especially in transplantation. In the study, we hypothesized that UDCA might have a certain role in anti-inflammation through a preventive effect of pro-inflammatory potentials in the brain macrophages, microglia. We found that the treatment of $200\;{\mu}g/ml$ UDCA effectively suppressed the pro-inflammatory mediators (i.e. nitric oxide and interleukin-$1{\beta}$) in rat microglia compared to comparators. Interestingly, RT-PCR analysis suggested that UDCA strongly attenuated the expression of $IL-1{\beta}$ that was comparable with cyclosporine A at 48 h incubation. Conclusively, we found that UDCA may playa cytoprotective role in microglial cells through direct or indirect pathways by scavenging a toxic compound or an anti-inflammatory effect, which are known as major causes of neurodegenerative diseases.

• The Korea Journal of Herbology
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• v.21 no.4
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• pp.93-101
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• 2006

Objectives : Increasing evidence has linked chronic inflammation to a number of neurodegenerative disorders including Alzheimer's disease(AD), Parkinson's disease(PD) and Huntington's disease(HD) in the inflammatory process. Uncontrolled activation of microglia may directly toxic to neurons by releasing various substances such as inflammatory cytokines ($TNF-{\alpha}$, $IL-1{\beta}$ and IL-6), NO, PEG2 and superoxide. In this study, the immunomodulatory effects of the herbal extract Panax notoginseng on cultured BV2 microglial cells and primary microglia were investigated to address potential therapeutic or toxic effects. Notoginseng radix extracts extracted from the root of the plant using Methanol. Methods : Cells were stimulated with LPS and treated with notoginseng at different concentrations. Results : Notoginseng significantly decreased LPS-induced production of $TNF-{\alpha}$ and IL-6 by the cultured microglial cells in a dose-dependent manner. The activation of iNOS mRNA and secretion of nitric oxide(NO) in microglial cells were inhibited in microglial cells in a dose-dependent manner by notoginseng. Conclusion : These results indicate that notoginseng inhibits LPS-induced activation of microglial cells and demonstrates notoginseng possess anti-inflammatory and immunosuppressive properties in vitro.