• The Journal of Internal Korean Medicine
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• v.21 no.4
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• pp.535-542
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• 2000

The water extracts of Samul-tang(SMT) has been used for treatment of ischemic brain damage in Oriental traditional medicine. However, little is known about the mechanism by which the water extracts of SMT rescues brain cells from ischemic damages. To elucidate the protective mechanism on ischemic induced cytotoxicity, I investigate the regulation of LPS and PMA induced iNOS expression in C6 glial cells. LPS and PMA treatment for 72 h in C6 glial cells markedly induce nitric oxide(NO), but treatment of the cells with the water extracts of SMT decrease. dose dependently nitrite formation. In addition, LPS and PMA treatment for 72 h induce severe cell death and LDH release in C6 glial cells. However treatment of the cells with the water extracts of SMT dose not induce significant changes compare to control cells. Furthermore, the protective effects of the water extracts of SMT is mimicked by treatment of $N^{G}MMA$, a specific inhibitor of NOS. LPS and PMA induced iNOS activation in C6 glial cells cause chromosomal condensation and fragmentation of nuclei by caspase activation. The treatment of the cells with the water extracts of SMT may suppress apoptosis via caspase inhibition by regulation of iNOS expression. Taken together, I suggest that the protective effects of the water extracts of SMT against ischemic brain damages may be mediated by regulation of iNOS during ischemic condition.

• BMB Reports
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• v.40 no.5
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• pp.636-643
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• 2007

This study was designed to identify and characterize the mechanism of macrophage activation by AAP, an acidic polysaccharide fraction isolated from the roots of Angelica sinensis (Oliv.) Diels. As a result, AAP significantly enhanced nitric oxide (NO) production and cellular lysosomal enzyme activity in murine peritoneal macrophages in vitro and in vivo. Furthermore, L-NAME, a specific inhibitor of inducible nitric oxide synthase (iNOS), effectively suppressed AAP-induced NO generation in macrophages, indicating that AAP stimulated macrophages to produce NO through the induction of iNOS gene expression and the result was further confirmed by the experiment of the increase of AAP-induced iNOS transcription in a dose-dependent manner. To further investigate, AAP was shown to strongly augment toll-like receptor 4 (TLR4) mRNA expression and the pretreatment of macrophages with anti-TLR4 antibody significantly blocked AAP-induced NO release and the increase of iNOS activity, and tumor necrosis factor-$\alpha$ (TNF-$\alpha$) secretion.

• Biomolecules & Therapeutics
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• v.22 no.4
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• pp.282-287
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• 2014

We show that silymarin, a polyphenolic flavonoid isolated from milk thistle (Silybum marianum), inhibits cytokine mixture (CM: TNF-${\alpha}$, IFN-${\gamma}$, and IL-$1{\beta}$)-induced production of nitric oxide (NO) in the pancreatic beta cell line MIN6N8a. Immunostaining and Western blot analysis showed that silymarin inhibits iNOS gene expression. RT-PCR showed that silymarin inhibits iNOS gene expression in a dose-dependent manner. We also showed that silymarin inhibits extracellular signal-regulated protein kinase-1 and 2 (ERK1/2) phosphorylation. A MEK1 inhibitor abrogated CM-induced nitrite production, similar to silymarin. Treatment of MIN6N8a cells with silymarin also inhibited CM-stimulated activation of NF-${\kappa}B$, which is important for iNOS transcription. Collectively, we demonstrate that silymarin inhibits NO production in pancreatic beta cells, and silymarin may represent a useful anti-diabetic agent.

• Advances in Traditional Medicine
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• v.7 no.3
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• pp.217-228
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• 2007

Agrimonia pilosa Ledeb. has long been used for a useful natural agent ameliorating inflammation related symptoms in the folk medicine recipe. This study was performed to investigate effects of Agrimonia pilosa Ledeb.(AP) on the expression of inflammation related genes such as the inducible nitric oxide synthase (iNOS) in macrophage cell line, RAW 264.7 cells. The AP (whole plants) was extracted with 80% ethanol and sequentially partitioned with solvents in order to increase polarity. Among the various solvent extracts of AP, the n-butanol (BuOH) fraction showed the most powerful inhibitory ability against nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells without affecting cell viability. Reverse transcriptase-polymerase chain reaction and Western blot analysis revealed that the BuOH fraction provided a primary inhibitor of the iNOS protein and mRNA expression in LPS-induced RAW 264.7 cells. The DPPH and OH radical scavenging activities of the several fractions of 80% ethanol extracts of AP significantly increased by EtOAC and BuOH fractions. Thus, the present study suggests that the response of a component of the BuOH fraction to NO generation via iNOS expression provide an important clue to elucidate anti-inflammatory mechanism of AP.

• IMMUNE NETWORK
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• v.3 no.1
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• pp.69-77
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• 2003

Background: Celecoxib, a COX-2 specific inhibitor, has recently been used for the treatment of rheumatoid arthritis. However, the molecular and cellular mechanisms of celecoxib against RA inflammation remain to be defined. To elucidate the action mechanism of celecoxib on inflammatory cells, we investigated the effect of celecoxib on the production of two important mediators of inflammation, nitric oxide and PGE2 Methods: RAW 264.7 cells stimulated with LPS were preincubated with various concentrations of celecoxib (from $10^{-8}$ to $10^{-5}$ M) and $10{\mu}M$ hydrocortisone, respectively. The production of NO and PGE2, the end products of iNOS and COX-2 genes, were estimated in culture supernatants by Greiss method and EIA, respectively. The expression of iNOS gene, COX-2 gene, $NF-{\kappa}B$, and $I-{\kappa}B$ were determined by RT-PCR and western blot analysis. Results: Celecoxib and hydrocortisone inhibited the production of NO and PGE2 in dose dependent manner, when RAW 264.7 cells were stimulated with LPS. The expression of iNOS was also down-regulated by celecoxib and hydrocortisone. Interestingly, COX-2 gene differentially expressed according to the dose of celecoxib, a decrease with lower dose ($10^{-8}$ M) but an increase with higher dose ($10^{-5}$ M). $NF-{\kappa}B$ binding activity was decreased by lower dose of celecoxib, whereas was not affected by higher dose of it. The expression of $I-{\kappa}B$ was suppressed by higher dose of celecoxib. Conclusion: The celecoxib strongly suppressed the production of NO and PGE2 in LPS-stimulated RAW264.7 cells. The decrease of NO seems to be linked to the inhibition of iNOS by celecoxib. The lower and higher dose of celecoxib differentially regulated the COX-2 expression and $NF-{\kappa}B$ activity.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.133-140
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• 2019

Triglycerides (TG) are one of the triggers of chronic inflammatory lesions in the blood vessels. In the key factors in the development of inflammatory diseases, Pro-inflammatory cytokines such as tumor necrosis factor-alpha $(TNF-){\alpha}$ and interleukin-1 beta ($IL-1{\beta}$) contribute to the development of inflammatory lesions by recruiting other immune cells in the inflamed area or causing cell necrotic death. In this study, I investigated the effect of Jurkat T lymphocytes and U937 monocytes involved in vascular inflammation development on the expression of $TNF-{\alpha}$ and $IL-1{\beta}$ on exposure to TGs. In Jurkat cells, mRNA expression of $TNF-{\alpha}$ is increased by exposure to TGs. However, the expression levels of $TNF-{\alpha}$ and $IL-1{\beta}$ were increased by TGs in U937 cells. To investigate whether inducible nitric oxide synthase (iNOS) is involved in the increase of expression of $TNF-{\alpha}$ and $IL-1{\beta}$ by TGs, treatment of W1400 (an iNOS inhibitor) resulted in recovery of expression level both $TNF-{\alpha}$ and $IL-1{\beta}$. Based on the present study, it was confirmed that the expression of $TNF-{\alpha}$ and $IL-1{\beta}$ in monocytes and T lymphocytes. This increased cytokines contribute to development of vascular inflammatory lesions. In addition, iNOS is involved in the increase of $TNF-{\alpha}$ and $IL-1{\beta}$ expression by TGs.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.2
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• pp.233-239
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• 1998

Stimulated alveolar macrophages and neutrophils produce nitric oxide, a free radical by an inducible nitric oxide synthase(iNOS), which reacts with superoxide anion to form peroxynitrite, a more highly reactive toxic species. The objectives of the present study were to evaluate acute inflammatory lung injury and to determine iNOS mRNA induction and nitric oxide production by rat broncho-alveolar lavage cells following intratracheal treatment of silica. After 4 h exposure to silica, differential counts of broncho-alveolar lavage cells and lactate dehydrogenase(LDH) activity as well as total protein in the broncho-alveolar lavage fluid were determined. Broncho-alveolar lavage cells were also assayed for iNOS mRNA and the productions of nitrite and nitrate measured in the cells cultured. Differential analysis of broncho-alveolar lavage cells showed that the number of alveolar macrophages slightly decreased following silica treatment; however, red blood cells, lymphocytes, and neutrophils significantly were increased by 9-, 14-, and 119-fold following silica treatment, respectively, compared with the saline control. It was also found significant increases in the LDH activity and total protein in the lavage fluid obtained from silica-treated rats, indicating silica-induced acute lung injury. Northern blot analysis demonstrated that the steady state levels of iNOS mRNA in broncho-alveolar lavage cells were increased following silica treatment. The productions of nitrite and nitrate in the cultured cells were significantly increased by 2-fold following silica treatment, respectively, which were attenuated by the NOS inhibitor $N{\omega}-nitro-L-arginine-methyl$ ester(L-NAME) and partially reversed by L-arginine. These findings suggest that nitric oxide production in alveolar macrophages and recruited neutrophils is increased in response to silica. Nitric oxide may contribute in part to acute inflammatory lung injury.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.5
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• pp.1233-1240
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• 2006

We have recently demonstrated that Siegesbeckia glabrescens(SG), a herbal medicine, induces apoptosis via nitric oxide(NO) production in human aortic smooth muscle cells(HASMCS). However, the molecular pathways involved in SG-mediated apoptosis are not fully understand. In the present study, we investigated the cellular mechanisms of SG-induced apoptosis in HASMCS. SG induced NO production through inducible nitric oxide synthase(iNOS) induction. The apoptotic effect of SG was attenuated by L-NNA, a NOS inhibitor. In the presence of L-NNA, the degradation of procaspase-3 by SG was inhibited. SG treatment induced a decrease in Bcl-2 expression but did not affect the expression of Bax. In addition, SG treatment evoked both down-regulation of PKC ${\alpha}$ and inhibition of PKC ${\alpha}$ phosphorylation. These downregulations were reversed by addition of L-NNA. It seems likely to De a downregulation of PKC${\alpha}$ due to long term treatment with PMA. Taken together, these results suggest that apoptotic effects of SG may be due to NO production via iNOS mRNA expression. Furthermore, Bcl-2 and PKC${\alpha}$ downregulation, and caspase-3 activation may be involved in the mechanisms for apoptotic effects by SG.

• Natural Product Sciences
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• v.5 no.3
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• pp.113-120
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• 1999

Nitric oxide (NO) is a free radical synthesized from L-arginine by nitric oxide synthase (NOS). It is believed that NO is an important mediator in numerous physiological and inflammatory responses. Particularly, a large amount of NO released from the inducible nitric oxide synthase (iNOS) is mostly associated with inflammatory processes. Overproduction of NO in these processes including sepsis and autoimmune diseases can have deleterious consequences and pathophysiologic relevance. Therefore, for the discovery of new inhibitory agents against iNOS activity, we have evaluated about 100 kinds of natural products after partition into three layers (n-hexane, ethyl acetate and aqueous) from 100% methanol extracts to study inhibitory effects on iNOS activity induced by lipopolysaccharide (LPS) in RAW264.7 cells culture system. As a positive control, curcumin, which is known as an anti-tumor promoter, anti-inflammatory agent as an iNOS inhibitor, was used and showed the dose-dependent inhibitory effect $(IC_{50},\;2.5\;{\mu}g/ml)$. Among tested fractions, the n-hexane fraction of Cimicifuga heracleifolia $(IC_{50}:\;9.65\;{\mu}g/ml)$, Forsythiae fructus $(IC_{50}:\;6.36\;{\mu}g/ml)$, Saposhnikovia divaricata $(IC_{50}:\;5.92\;{\mu}g/ml)$, and the ethyl acetate fraction of Chrysanthemum sibiricum $(IC_{50}:\;2.56\;{\mu}g/ml)$, Gastrodia elata $(IC_{50}:\;3.46\;{\mu}g/ml)$, and the aqueous fraction of Dianthus chinensis $(IC_{50}:\;6.73\;{\mu}g/ml)$, Euonymus alatus $(IC_{50}:\;6.78\;{\mu}g/ml)$, Mechania urticifoloria $(IC_{50}:\;8.01\;{\mu}g/ml)$ showed strong inhibitory activity against LPS-stimulated iNOS. Especially, the ethyl acetate fraction of Chrysanthemum sibiricum $(IC_{50}:\;2.56\;{\mu}g/ml)$, which exhibited the strongest inhibition against iNOS, was fractionated with silica-gel column chromatography. These subfractions exhibited dose-dependent inhibition against iNOS activity in the range of $2.59-5.6\;{\mu}g/ml$ except for fraction No. 3, 4, 5, 6, 8, 9, and 16. Our study shows that Chrysanthemum sibiricum has the strongest inhibitory effect against iNOS activity and has similar effect to curcumin. Therefore, further studies for the identification of active principles from Chrysanthemum sibiricum and investigation for the mechanism of the inhibition of iNOS by active principles will be performed.

• Journal of Life Science
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• v.21 no.1
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• pp.44-55
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• 2011

This study aimed to investigate the effects of water extract of Rubus coreanus (RCE) on the expression and activity of endothelial nitric oxide synthase (eNOS), as well as its signal transduction pathways in human umbilical vein endothelial cells (HUVECs). The specific inhibitors of NOS show RCE treatment increases NO production in HUVECs due to the up-regulation of eNOS rather than iNOS. The real-time expression level of eNOS mRNA was also increased upon RCE treatment in HUVECs. While a PKC-specific inhibitor, RO-317549, did not alter RCE-induced NO production in HUVECs, tamoxifen (estrogen receptor-specific inhibitor), PD98059 (ERK-specific inhibitor) and LY-294002 (PI3K/Akt-specific inhibitor) did have suppressive effects. Increased NO production by RCE seems to result from a higher level of active eNOS (pSer1177). Specifically, inhibition of ERK not only decreased the level of active eNOS, but also increased the inactive form of the enzyme (pThr495) in HUVECs. This study suggests that RCE treatment increases NO production in HUVECs due to the increased expression and activity of eNOS. It is also shown that RCE-induced eNOS activation occurs partly through the binding of RCE to the estrogen receptor, along with ERK and PI3K/Akt-dependent signal transduction pathways. In addition, the regulatory binding proteins of eNOS including Hsp90 and caveolin-1 were related to these effects of RCE on eNOS activity in HUVECs.