• The Korean Journal of Physiology and Pharmacology
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• 제14권1호
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• pp.37-43
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• 2010

The serine/threonine kinase Akt has been shown to play a role of multiple cellular signaling pathways and act as a transducer of many functions initiated by growth factor receptors that activate phosphatidylinositol 3-kinase (PI3K). It has been reported that phosphorylated Akt activates eNDS resulting in the production of NO and that NO stimulates soluble guanylate cyclase (sGC), which results in accumulation of cGMP and subsequent activation of the protein kinase G (PKG). It has been also reported that PKG activates PI3K/Akt signaling. Therefore, it is possible that PI3K, Akt, eNOS, sGC, and PKG form a loop to exert enhanced and sustained activation of Akt. However, the existence of this loop in eNOS-expressing cells, such as endothelial cells or astrocytes, has not been reported. Thus, we examined a possibility that Akt phosphorylation might be enhanced via eNOS/sGC/PKG/PI3K pathway in astrocytes in vivo and in vitro. Phosphorylation of Akt was detected in astrocytes after KA treatment and was maintained up to 72 h in mouse hippocampus. 2 weeks after KA treatment, astrocytic Akt phosphorylation was normalized to control. The inhibition of eNOS, sGC, and PKG significantly decreased Akt and eNDS phosphorylation induced by KA in astrocytes. In contrast, the decreased phosphorylation of Akt and eNDS by eNDS inhibition was significantly reversed with PKG activation. The above findings in mouse hippocampus were also observed in primary astrocytes. These data suggest that Akt/eNOS/sGC/PKG/PI3K pathway may constitute a loop, resulting in enhanced and sustained Akt activation in astrocytes.

• 대한화학회지
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• 제51권3호
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• pp.251-257
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• 2007

니코틴은 사람 대식세포에서 interleukin 2 (IL-2)와 종양괴사인자 (tumor necrosis factor-alpha; TNF-α) 가 생성되는 것을 억제하는데, 이러한 억제작용은 cytokine 유전자 발현 중 전사단계에서 전사인자의 활성을 억제함으로써 일어난다. 이러한 니코틴의 면역반응 억제작용은 아프타성궤양 및 궤양성대장염, 알레르기성폐 포염, 건초열 등에서도 보고되고 있다. 만일 중추신경계에서도 위와 같은 니코틴의 면역억제 작용이 일어난 다면 다발성경화증과 같은 면역반응 매개질환의 치료에 새로운 전기가 마련될 수 있을 것이다. 본 연구에서 는 중추신경계의 여러 면역반응 매개질환의 병태생리에 대한 이해를 넓히고자, 이미 알려진 니코틴의 cytokine 생성억제가 사람 중추신경계의 성상세포에서도 일어남을 확인하고 그 억제기전을 밝히고자 하였다. 이를 위 하여 사람 태아 성상세포에 다양한 농도의 니코틴과 IL-1β를 처리한 다음 TNF-α mRNA의 발현 정도와 NF- κB의 활성을 비교, 분석하여 다음과 같은 결과를 얻었다. 1. 사람 태아 성상세포를 0.1-20 μg/ml의 니코틴으로 처리해 본 결과 10 μg/ml 이상의 농도에서 세포독성능이 나타나기 시작하였다. 2. 사람 태아 성상세포에 IL- 1β를 처리하면 2시간만에 TNF-α mRNA가 최대로 발현되었으며 그 이후로는 점진적으로 감소하였다. 3. 사 람 태아 성상세포를 1 및 0.1 μg/ml의 니코틴으로 전처리한 후 IL-1β로 자극한 군에서는 IL-1β 단독 처리군에 비해 TNF-α mRNA의 발현이 감소하는 양상을 보였다. 1 μg/ml의 니코틴을 처리한 경우에는 8시간 이후부터 TNF-α mRNA의 발현이 현저하게 감소하여 12시간에 최대로 감소하였다. 또한 0.1 μg/ml의 니코틴을 처리한 군에서는 24시간에 가장 현저하게 감소하였다. 4. 성상세포에 IL-1β로 처리한 군에서는 강력한 NF-κB의 활성 을 확인할 수 있었으며, 니코틴을 전처리하고 IL-1β 자극한 군에서는 NF-B의 활성이 감소하였다. 결론적으로 일정농도 이상의 니코틴은 세포독성효과를 나타내나 적정한 농도와 시간 경과후 니코틴은 사람 태아 성상세포에서 IL-1β에 의해 유도되는 TNF-α의 발현 감소를 유도하며, 이는 NF-κB의 활성을 감소시킴으로써 나타난다고 생각된다.

• The Korean Journal of Physiology and Pharmacology
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• 제12권2호
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• pp.37-41
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• 2008

Melatonin has been reported to protect neurons from a variety of neurotoxicity. However, the underlying mechanism by which melatonin exerts its neuroprotective property has not yet been clearly understood. We previously demonstrated that melatonin protected kainic acid-induced neuronal cell death in mouse hippocampus, accompanied by sustained activation of Akt, a critical mediator of neuronal survival. To further elucidate the neuroprotective action of melatonin, we examined in the present study the causal mechanism how Akt signaling pathway is regulated by melatonin in a rat primary astrocyte culture model. Melatonin resulted in increased astrocytic Akt phosphorylation, which was significantly decreased with wortmannin, a specific inhibitor of PI3K, suggesting that activation of Akt by melatonin is mediated through the PI3K-Akt signaling pathway. Furthermore, increased Akt activation was also significantly decreased with luzindole, a non-selective melatonin receptor antagonist. As downstream signaling pathway of Akt activation, increased levels of CREB phoshorylation and GDNF expression were observed, which were also attenuated with wortmannin and luzindole. These results strongly suggest that melatonin exerts its neuroprotective property in astrocytes through the activation of plasma membrane receptors and then PI3K-Akt signaling pathway.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2002년도 창립10주년기념 및 국립독성연구원 의약품동등성평가부서 신설기념 국재학술대회:생물학적 동등성과 의약품 개발 전략을 위한 국제심포지움
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• pp.225-225
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• 2002

• Toxicological Research
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• 제12권1호
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• pp.69-79
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• 1996

Primary culture of cerebellar neuronal cells derived from 8-day old Long-Evans rats was used. Pure granule cells, astrocytes or mixed cells culture systems were prepared. These cells were differentiated and developed synaptic connections. And the astrocytes were identified by immunostaining with glial fibrillary acidic protein (GFAP). Methamphetamine (MAP), which acts on dopaminergic system and cadmium (Cd), a toxic heavy metal, were applied and biochemical assays and electrophysiological studies were performed. $LC_50$ values estimated by MTT assay of MAP and Cd were 3 mM and 2$\mu M$ respectively. Cells were treated with 1 mM or 2 mM MAP and 1$\mu M$ $CdCl_2$ for 48 hour, and the incubation media were analyzed for the content of released LDH. MAP (2 mM) and Cd significantly increased the LDH release. Cell viability was decreased in both groups and some cytopathological changes like cell swelling or vacuolization were seen. The cerebellar granule cells were used for measuring membrane currents using whole-cell clamp technique. Sodium and potassium currents were not affected by MAP neither Cd, but calcium current was significantly reduced by Cd but not affected by MAP. Therefore, in vitro neurotoxicity test system using neuronaI cells and astrocytes cultures were established and can be used in screening of potential neurotoxic chemicals.

• Asian Pacific Journal of Cancer Prevention
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• 제16권5호
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• pp.1839-1843
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• 2015

Background: MicroRNAs are a class of noncoding RNAs which regulate multiple cellular processes during tumor development. The purpose of this report is to investigate the clinicopathological and prognostic significance of miR-218 in human gliomas. Materials and Methods: Quantitative RT-PCR (qRT-PCR) was conducted to detect the expression of miR-218 in primary normal human astrocytes, three glioma cell lines and 98 paired glioma and adjacent normal brain tissues.Associations of miR-218 with clinicopathological variables of glioma patients were statistically analyzed. Finally, a survival analysis was performed using the Kaplan-Meier method and Cox's proportional hazards model. Results: The expression level of miR-218 in primary normal human astrocytes was significantly higher than that in glioma cell lines (p<0.01). Also, the expression level of miR-218 in glioma tissues was significantly downregulated in comparison with that in the adjacent normal brain tissues (p<0.001). Statistical analyses demonstrated that low miR-218 expression was closely associated with advanced WHO grade (p=0.002) and low Karnofsky performance score (p=0.010) of glioma patients. Kaplan-Meier analysis with the log-rank test showed that patients with low-miR-218 expression had poorer disease-free survival and overall survival (p=0.0045 and 0.0124, respectively). Multivariate analysis revealed that miR-218 expression was independently associated with the disease-free survival (p=0.009) and overall survival (p=0.004) of glioma patients. Conclusions: Our results indicate that miR-218 is downregulated in gliomas and that its status might be a potential valuable biomarker for glioma patients.

• Molecules and Cells
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• 제25권3호
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• pp.376-384
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• 2008

The glial fibrillary acidic protein (GFAP) is traditionally used as a marker for astrocytes of the brain, and more recently for the hepatic stellate cells (HSCs) of the liver. Several GFAP splice variants have been previously reported in the astrocytes of the CNS and in the non-myelinating Schwann cells of the PNS. In this study, we investigate whether GFAP splice variants are present in the HSCs and their expression as a function of HSCs activation. Furthermore, the regulation of these transcripts upon treatment with interferon gamma ($IFN-{\gamma}$) will be explored. Using semi-quan-titative RT-PCR and real-time PCR, we examine the expression and regulation of GFAP splice variants in HSCs as well as their respective half-life. We discover that most of the GFAP splice variants ($GFAP{\alpha}$, ${\beta}$, ${\delta}$, ${\varepsilon}$ and $\kappa$) found in the neural system are also expressed in quiescent and culture-activated primary HSCs. Interestingly, $GFAP{\alpha}$ is the predominant form in quiescent and culture-activated primary HSCs, while $GFAP{\beta}$, predominates in the SV40-immortalized activated HSC-T6. $GFAP{\delta}$, ${\varepsilon}$ and ${\kappa}$ have similar half-lives of 10 hours, while $GFAP{\beta}$ has a half-life of 17 hours. Treatment of HSC-T6 with $IFN-{\gamma}$ results in a significant 1.29-fold up-regulation of $GFAP{\alpha}$ whereas the level of the other transcripts remains unchanged. In summary, $GFAP{\alpha}$, ${\beta}$, ${\delta}$, ${\varepsilon}$ and $\kappa$ are present in HSCs. They are differentially regulated on the transcription level, implying a role of the 5' and 3' untranslated regions.

• Journal of Ginseng Research
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• 제28권2호
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• pp.120-126
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• 2004

수천 년 동안 전통적 약제로 사용되어온 고려인삼은 중추신경계의 항상성을 유지하고 면역기능을 강화하는 효능을 나타내는 것으로 알려져 있다. 신경계질환의 진행이 대부분 염증 또는 면역반응을 수반하며, 이로 인하여 손상된 신경세포의 수복과정에 교세포 기원의 매개물질들이 기여하므로, 교세포에서의 cytokine 및 NO생성에 대한 연구는 신경기능과 신경면역기능의 조절 뿐 아니라 신경계 질환에 대한 연구의 초석이라고 할 수 있다. 따라서 본 연구에서는 고려인삼의 신경면역 및 염증반응 조절효과에 대하여 연구하고자 하였으며, 이를 위하여 흰쥐 대뇌피질의 교세포를 일차배양하며 고려인삼사포닌 분획을 처치하여 TNF-$\alpha$, IL-1$\beta$, 및 NO의 생성변동을 연구하였다. 백삼 사포닌은 50-500$\mu\textrm{g}$/ml 용량에서 TNF-$\alpha$와 IL-1$\beta$ 생성을 증가시켰으며, 미세교세포에서 iNOS 발현 및 NO생성을 유도하였고 성상세포의 stellation을 초래하였다. 특히 백삼사포닌 50-100 $\mu\textrm{g}$/ml는 세포독성을 거의 나타내지 않았으므로 이들 용량에 의한 교세포의 적절한 활성화가 중추신경계 면역기능 증가 및 염증반응 조절에 기여할 것으로 생각된다.

• Biomolecules & Therapeutics
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• 제18권1호
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• pp.48-55
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• 2010

Neural progenitor cells (NPCs) differentiate into astrocytes, neurons and oligodendrocytes, which is controlled by various factors in brain. Recent evidences suggest that small molecules modulating the proliferation and differentiation of NPCs may have therapeutic value as well as the potential use as chemical probes. Phylligenin is a lignan with anti-inflammatory activity that is isolated from the fruits of Forsythia koreana. We investigated effects of phylligenin on proliferation and differentiation of NPCs. Treatment of phylligenin decreased the number of proliferating NPCs in culture without effects on the differentiation and survival of neural cells such as neurons and astrocytes. To examine the mechanism of the decreased NPCs number, we performed cell cycle analysis. Proliferation of NPCs was decreased via G1-S transition block by phylligenin treatment, and it was mediated by the increase of p21 level. However, phylligenin did not induce apoptosis of NPCs as determined by TUNEL assay and PARP cleavage. We also found that viability of glioma cell lines such as C6 and U87MG glioma cells, but not that of primary neuron and astrocyte, was inhibited by phylligenin. These results suggest that phylligenin selectively inhibits proliferation of rapidly growing cells such as neural stem cells and glioma cells. Given that the possible role of brain tumor stem cells in the pathology of brain cancers, the inhibitory effects of phylligenin might be useful in the development of new therapeutic agents against brain cancers.

• The Korean Journal of Pain
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• 제37권2호
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• pp.91-106
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• 2024

The mechanisms of the chronic pain and depression comorbidity have gained significant attention in recent years. The complement system, widely involved in central nervous system diseases and mediating non-specific immune mechanisms in the body, remains incompletely understood in its involvement in the comorbidity mechanisms of chronic pain and depression. This review aims to consolidate the findings from recent studies on the complement system in chronic pain and depression, proposing that it may serve as a promising shared therapeutic target for both conditions. Complement proteins C1q, C3, C5, as well as their cleavage products C3a and C5a, along with the associated receptors C3aR, CR3, and C5aR, are believed to have significant implications in the comorbid mechanism. The primary potential mechanisms encompass the involvement of the complement cascade C1q/C3-CR3 in the activation of microglia and synaptic pruning in the amygdala and hippocampus, the role of complement cascade C3/C3a-C3aR in the interaction between astrocytes and microglia, leading to synaptic pruning, and the C3a-C3aR axis and C5a-C5aR axis to trigger inflammation within the central nervous system. We focus on studies on the role of the complement system in the comorbid mechanisms of chronic pain and depression.