• Asian Pacific Journal of Cancer Prevention
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• v.15 no.4
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• pp.1807-1810
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• 2014

Background: It is known that inducible nitric oxide synthase (iNOS)/nitric oxide (NO) plays an integral role during intestinal inflammation, an important factor for colon cancer development. Natural compounds from Curcuma longa L. (Zingiberaceae) have long been a potential source of bioactive materials with various beneficial biological functions. Among them, a major active curcuminoid, demethoxycurcumin (DMC) has been shown to possess anti-inflammatory properties in lipopolysaccharide (LPS)-activated macrophages or microglia cells. However, the role of DMC on iNOS expression and NO production in an in vitro inflamed human intestinal mucosa model has not yet been elucidated. This study concerned inhibitory effects on iNOS expression and NO production of DMC in inflamed human intestinal Caco-2 cells. An in vitro model was generated and inhibitory effects on NO production of DMC at 65 ${\mu}M$ for 24-96 h were assessed by monitoring nitrite levels. Expression of iNOS mRNA and protein was also investigated. DMC significantly decreased NO secretion by 35-41% in our inflamed cell model. Decrease in NO production by DMC was concomitant with down-regulation of iNOS at mRNA and protein levels compared to proinflammatory cytokine cocktail and LPS-treated controls. Mechanism of action of DMC may be partly due to its potent inhibition of the iNOS pathway. Our findings suggest that DMC may have potential as a therapeutic agent against inflammation-related diseases, especially in the gut.

• The Korean Journal of Physiology and Pharmacology
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• v.5 no.4
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• pp.343-351
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• 2001

This study was undertaken to investigate the mechanism of lipopolysaccharide (LPS) and nitric oxide (NO) as a regulator of vascular smooth muscle cell (VSMC) proliferation. VSMC was primarily cultured from rat aorta and confirmed by the immunocytochemistry with anti-smooth muscle myosin antibody. The number of viable VSMCs were counted, and lactate dehydrogenase (LDH) activity was measured to assess the degree of cell death. Concentrations of nitrite in the culture medium were measured as an indicator of NO production. LPS was introduced into the medium to induce the inducible nitric oxide synthase (iNOS) in VSMC, and Western blot for iNOS protein and RT-PCR for iNOS mRNA were performed to confirm the presence of iNOS. Inhibitors of iNOS and soluble guanylate cyclase (sGC), sodium nitroprusside (SNP) and L-arginine were employed to observe the action of LPS on the iNOS-NO-cGMP signalling pathway. LPS and SNP decreased number of VSMCs and increased the nitrite concentration in the culture medium, but there was no significant change in LDH activity. A cell permeable cGMP derivative, 8-Bromo-cGMP, decreased the number of VSMCs with no significant change in LDH activity. L-arginine, an NO substrate, alone tended to reduce cell count without affecting nitrite concentration or LDH level. Aminoguanidine, an iNOS specific inhibitor, inhibited LPS-induced reduction of cell numbers and reduced the nitrite concentration in the culture medium. LY 83583, a guanylate cyclase inhibitor, suppressed the inhibitory actions of LPS and SNP on VSMC proliferation. LPS increased amounts of iNOS protein and iNOS mRNA in a concentration-dependent manner. These results suggest that LPS inhibits the VSMC proliferation via production of NO by inducing iNOS gene expression. The cGMP which is produced by subsequent activation of guanylate cyclase would be a major mediator in the inhibitory action of iNOS-NO signalling on VSMC proliferation.

• Biomedical Science Letters
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• v.19 no.3
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• pp.180-187
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• 2013

Hypoxia is an integral part of the environment during luteolysis. In this study we examined whether hypoxia could directly stimulate endothelial cells to produce nitric oxide (NO). Endothelial cells were cultured in hypoxic (5% $O_2$) or normoxic (20% $O_2$) conditions and the levels of total NO, inducible NO and endothelial NO was measured. We found that hypoxia but not normoxia upregulated NO production. The increased NO levels correlated with increased inducible NO synthase (iNOS) expression whereas expression of endothelial NOS (eNOS) expression remained constant. Addition of the iNOS specific inhibitor 1400W to hypoxic cultures prevented NO production suggesting that hypoxia-induced NO production in endothelial cells was due mainly to upregulation of iNOS. We also found that prostaglandin $F_{2{\alpha}}$ (PGF) production was unaffected by hypoxia suggesting that upregulation of NO was not due to increased synthesis of PGF. In summary, we report that endothelial cells cultured under hypoxic conditions produce NO via the iNOS pathway. This study provides the importance of the relation between the hypoxic environment and the induction of NO by endothelial cells during regression of the corpus luteum in the ovary.

• The Journal of Korean Medicine
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• v.24 no.2
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• pp.166-178
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• 2003

Objectives : Nitric oxide (NO) plays an important role in normal and pathophysiological cells as a messenger molecule, neurotransmitter, microbiological agent, or dilator of blood vessels and arteriosclerosis, respectively. This study was undertaken to understand the mechanism of NO production and effect of Hyeolbuchukeo-tang (Xiefuzhuyu-tang) on NO production in cultured vascular smooth muscle cell (VSMC). Methods and Results : VSMC was isolated from aorta and cultured. Cultured primary cells were identified as VSMC with anti--smooth muscle actin antibody. A large amount of NO was produced in cultured VSMC treated with $IFN-{\gamma}$ plus TNF in a time- and dose-dependent manner. $TNF-{\alpha}$ was a more efficient stimulator than $IFN-{\gamma}$ in NO production of cultured VSMC. iNOS protein wasdetected within 3 hrs and it increased up to 12 hrs in a time-dependent manner. However, accumulated NO in cytokine-treated VSMC was not detected within 3 hrs. NO production in cytokine-treated VSMC showed the dose- and time-dependent manner, and increased up to 48 hrs. The activated VSMC produced a large amount of NO (about 60 uM). Hyeolbuchukeo-tang (Xiefuzhuyu-tang) alone did not induceNO production, but it potentiated the effect of $TNF-{\alpha}$ on NO production and increased NO production by about 20%. Hyeolbuchukeo-tang (Xiefuzhuyu-tang) did not affect the transcriptional activity of iNOS gene, but increased the accumulation of iNOS. These results indicate that Hyeolbuchukeo-tang (Xiefuzhuyu-tang) could modulate the translational level of iNOS. PKC did not modulate NO production, but calcium ionophore A23187 decreased NO production. However, Hyeolbuchukeo-tang (Xiefuzhuyu-tang) elevated the decreased NO production in A23187-treated VSMC by modulating the stability of iNOS transcripts. Half-life of the synthesized transcripts appeared to have about 6 hrs. PDTC, an $NF-{\kappa}B$ inhibitor, blocked the accumulation of iNOS mRNA, indicating that $NF-{\kappa}B$ served as an important modulator in the transcriptional regulation of iNOS. As Hyeolbuchukeo-tang (Xiefuzhuyu-tang) potentiated the effect of the $TNF-{\alpha}$ on NO production but had no additional effect on PDTC-modulated NO production, it is suggested that Hyeolbuchukeo-tang (Xiefuzhuyu-tang) enhances the $TNF-{\alpha}-mediated$ NO production of VSMC by modulating the iNOS activity and the stability of iNOS transcripts in activated VSMC having the elevated intracellular calcium ion. Conclusions : This study suggests that Hyeolbuchukeo-tang (Xiefuzhuyu-tang) has a potential capacity for preventing and treating diseases of the circulation system, including arteriosclerosis.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.5
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• pp.515-521
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• 1997

Endothelial cells play a central role in the inflammatory processes, and activation of nuclear factor kappa B ($NF-_{\kappa}B$) is a key component in that inflammatory processes. Previously, we reported that tumor necrosis factor alpha($TNF{\alpha}$) had protective effect of cell death induced by serum deprivation and this protection was related to $NF-_{\kappa}B$ activation. Inducible nitric oxide synthase (iNOS) is a member of the molecules which transcription is regulated mainly by $NF-_{\kappa}B$. And the role of nitric oxide (NO) generated by iNOS on cell viability is still controversial. To elucidate the mechanism of $TNF{\alpha}$ and $NF-_{\kappa}B$ activation on cell death protection, we investigate the effect of NO on the cell death induced by serum- deprivation in bovine cerebral endothelial cells in this study. Addition of $TNF{\alpha}$, which are inducer of iNOS, prevented serum-deprivation induced cell death. Increased expression of iNOS was confirmed indirectly by nitrite measurement. When selective iNOS inhibitors were treated, the protective effect of $TNF{\alpha}$ on cell death was partially blocked, suggesting that iNOS expression was involved in controlling cell death. Exogenously added NO substrate (L-arginine) and NO donors (sodium nitroprusside and S-nitroso-N-acetylpenicillamine) also inhibited the cell death induced by serum deprivation. These results suggest that NO has protective effect on bovine cerebral endothelial cell death induced by serum-deprivation and that iNOS is one of the possible target molecules by which $NF-_{\kappa}B$ exerts its cytoprotective effect.

• Journal of Veterinary Clinics
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• v.32 no.4
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• pp.289-294
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• 2015

Fucoidan which is sulfated polysaccharide extracted from brown seaweed has a wide variety of internal biological activities. The objectives of this study were to examine the effect of fucoidan on nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated porcine peripheral blood mononuclear cells (PBMCs) and to investigate whether this effect is involved in the expression of inducible nitric oxide synthase (iNOS) and the activation of activator portein-1 (AP-1). The levels of NO production and AP-1 activity in the culture supernatants from porcine PBMCs were measured by the enzyme-linked immunosorbent assay and the levels of iNOS and AP-1 mRNA were determined by real time polymerase chain reaction. Fucoidan in LPS-naïve PBMCs has no effects on the production of NO and activity of AP-1. Expressions of iNOS and AP-1 mRNA in LPS-naïve PBMCs were also not affected by treatment of fucoidan. However, NO production, AP-1 activity and expressions of iNOS and AP-1 mRNA were dramatically increased in PBMCs stimulated with LPS. Enhancing effects of NO production and AP-1 activity in PBMCs induced by LPS were reduced by addition of fucoidan. Fucoidan also inhibited an increase in expressions of iNOS and AP-1 mRNA in LPS-stimulated PBMCs. These results suggested that fucoidan exerts anti-inflammatory effect by down-regulating production of NO via suppressing expression of iNOS and activity of AP-1 in LPS-stimulated porcine PBMCs.

• BMB Reports
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• v.43 no.9
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• pp.629-634
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• 2010

Endotoxin including lipopolysaccharide (LPS) confers organ tolerance against subsequent challenge by ischemia and reperfusion (I/R) insult. The mechanisms underlying this powerful adaptive defense remain to be defined. Therefore, in this study we attempted to determine whether nitric oxide (NO) and its associated enzymes, inducible NOS (iNOS) and endothelial NOS (eNOS, a constitutive NOS), are associated with LPS-induced renal tolerance against I/R injury, using iNOS (iNOS knock-out) or eNOS (eNOS knock-out) gene-deleted mice. A systemic low dose of LPS pretreatment protected kidney against I/R injury. LPS treatment increased the activity and expression of iNOS, but not eNOS, in kidney tissue. LPS pretreatment in iNOS, but not eNOS, knock-out mice did not protect kidney against I/R injury. In conclusion, the kidney tolerance to I/R injury conferred by pretreatment with LPS is mediated by increased expression and activation of iNOS.

• Journal of Life Science
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• v.33 no.1
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• pp.50-55
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• 2023

This study was designed to determine the activities of Rosa davurica Pall. leaf extract and their regulatory mechanisms in macrophage inflammation. Anti-inflammatory potential of Rosa davurica Pall. leaf extract was evaluated by measuring the nitric oxide (NO) release and inducible nitric oxide synthase (iNOS) synthesis in lipopolysaccharide (LPS)-treated macrophage Raw 264.7 cells. Rosa davurica Pall. leaf extract potently inhibited LPS-induced NO release in a dose dependent manner. However, cell viability decreased to about 50% at high dose of 500 ㎍/ml, resulting in cytotoxicity. LPS-induced iNOS protein expression was also reduced significantly after treatment with Rosa davurica Pall. leaf extract. Furthermore, extract of Rosa davurica Pall. attenuated LPS-mediated phosphorylation of IκB and nuclear factor (NF-κB). Suppression of NF-κB signaling by treatment with PDTC, an NF-κB specific inhibitor, accelerated the inhibition of NO production and iNOS protein expression. These results suggest that Rosa davurica Pall. exhibits the anti-inflammatory potential in LPS-induced macrophage inflammation, partly through inhibition of NO production by down-regulation of NF-κB signaling.

• Tuberculosis and Respiratory Diseases
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• v.42 no.4
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• pp.447-454
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• 1995

Cytokine release from alveolar macrophages and subsequent interaction of these cytokines with the bronchial epithelium can induce epithelial cells to release inflammatory mediators. Nitric oxide(NO), a highly reactive gas formed from arginine by nitric oxide synthase(NOS), is known to be involved in inflammation and edema formation, and the inducible form of NOS(iNOS) can be increased by cytokines. In this context, we hypothesized that lung epithelial cells could be stimulated by cytokines released by alveolar macrophages to express iNOS. To test this hypothesis, the murine lung epithelial cell line, LA-4, or the human lung epithelial cell line, A549, were stimulated with culture supernatant fluids from alveolar macrophages. NO production was assessed by evaluating the culture supernatant fluids for nitrite and nitrate, the stable end products of NO. Both murine and human cell culture supernatant fluids demonstrated an increase in nitrite and nitrate which were time- and dose-dependent and attenuated by $TNF{\alpha}$ and IL-$1{\beta}$ antibodies(p<0.05, all comparisons). Consistent with these observations, cytomix a combination of $TNF{\alpha}$, IL-$1{\beta}$, and $\gamma$-interferon, stimulated the lung epithelial cell lines as well as primary cultures of human bronchial epithelial cells to increase their NO production as evidenced by an increase in nitrite and nitrate in their culture supernatant fluids, an increase in the iNOS staining by immunocytochemistry, and an increase in iNOS mRNA by Northern blottin(p<0.05, all comparisons). The cytokine effects on iNOS were all attenuated by dexamethasone. To determine if these in vitro observations are reflected in vivo, exhaled NO was measured and found to be increased in asthmatics not receiving corticosteroids. These data demonstrate that alveolar macrophage derived cytokines increase iNOS expression in lung epithelial cells and that these in vitro observations are mirrored by increased exhaled NO levels in asthmatics. Increased NO in the lung may contribute to edema formation and airway narrowing.

• Toxicological Research
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• v.22 no.2
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• pp.103-107
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• 2006

We demonstrate that paclitaxel, an antitumor agent derived from yew tree, inhibits LPS-induced expression of iNOS gene in RAW 264.7 cells. Previously, paclitaxel has been known to induce iNOS gene expression in macrophages. However, in this report we described that the pre-treatment of macrophages with paclitaxel ($0.1{\mu}M$) for 8 h inhibited LPS-induced iNOS gene expression. Pretreatment of RAW 264.7 cells with paclitaxel significantly inhibited LPS-stimulated nitric oxide (NO) production. Western immunoblot of iNOS and RT-PCR analysis showed that the decrease of NO was due to the inhibition of iNOS gene expression in RAW 264.7 cells. Immunocytochemical staining of iNOS further confirmed that pretreatment of macrophages with paclitaxel inhibited macrophage activation. Electrophoretic mobility shift assay showed that paclitaxel inhibited $NF-_{\kappa}/Rel$ DNA binding. Collectively, these series of experiments indicate that paclitaxel inhibits iNOS gene expression by blocking $NF-_{\kappa}B/Rel$ activation.