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

• BMB Reports
• /
• v.54 no.10
• /
• pp.516-521
• /
• 2021

Although arginase primarily participates in the last reaction of the urea cycle, we have previously demonstrated that arginase II is an important cytosolic calcium regulator through spermine production in a p32-dependent manner. Here, we demonstrated that rhaponticin (RPT) is a novel medicinal-plant arginase inhibitor and investigated its mechanism of action on Ca²⁺-dependent endothelial nitric oxide synthase (eNOS) activation. RPT was uncompetitively inhibited for both arginases I and II prepared from mouse liver and kidney. It also inhibited arginase activity in both aorta and human umbilical vein endothelial cells (HUVECs). Using both microscope and FACS analyses, RPT treatments induced increases in cytosolic Ca²⁺ levels using Fluo-4 AM as a calcium indicator. Increased cytosolic Ca²⁺ elicited the phosphorylations of both CaMKII and eNOS Ser1177 in a time-dependent manner. RPT incubations also increased intracellular L-arginine (L-Arg) levels and activated the CaMKII/AMPK/Akt/eNOS signaling cascade in HUVECs. Treatment of L-Arg and ABH, arginase inhibitor, increased intracellular Ca²⁺ concentrations and activated CaMKII-dependent eNOS activation in ECs of WT mice, but, the effects were not observed in ECs of inositol triphosphate receptor type 1 knockout (IP3R1^-/-) mice. In the aortic endothelium of WT mice, RPT also augmented nitric oxide (NO) production and attenuated reactive oxygen species (ROS) generation. In a vascular tension assay using RPT-treated aortic tissue, cumulative vasorelaxant responses to acetylcholine (Ach) were enhanced, and phenylephrine (PE)-dependent vasoconstrictive responses were retarded, although sodium nitroprusside and KCl responses were not different. In this study, we present a novel mechanism for RPT, as an arginase inhibitor, to increase cytosolic Ca²⁺ concentration in a L-Arg-dependent manner and enhance endothelial function through eNOS activation.

• Toxicological Research
• /
• v.22 no.3
• /
• pp.293-299
• /
• 2006

We demonstrate that magnolol, a hydroxylated biphenyl compound isolated from Magnolia officinalis, inhibits LPS-induced expression of iNOS gene in RAW 264.7 cells(murine macrophage cell line). Treatment of RAW 264.7 cells with magnolol inhibited LPS-stimulated nitric oxide production in a dose-related manner. RT-PCR analysis showed that the decrease of NO was due to the inhibition of iNOS gene expression. Western immunoblot analysis of phosphorylate p38 kinase showed magnolol significantly inhibited the phosphorylation of p38 kinase which is important in the regulation of iNOS gene expression. The specific p38 inhibiter SB203580 abrogated the LPS-induced NO generation and iNOS expression, whereas the selective MEK-1 inhibitor PD98059 did not affect the NO induction. Immunostaining of p65 and reporter gene assay showed that magnolol inhibited NF-${\kappa}/Rel$ nuclear translocation and transcriptional activation, respectively. Collectively, this series of experiments indicates that magnolol inhibits iNOS gene expression by blocking NF-k/Rel and p38 kinase signaling. Due to the critical role that NO release plays in mediating inflammatory responses, the inhibitory effects of magnolol or iNOS suggest that magnolol may represent a useful anti-inflammatory agent.

• The Korean Journal of Physiology and Pharmacology
• /
• v.8 no.1
• /
• pp.1-5
• /
• 2004

Transient forebrain ischemia results in the delayed neuronal death in the CA1 area of the hippo-campus. The present study was performed to determine effects of aminoguanidine, a selective iNOS inhibitor, on the generation of peroxynitrite and delayed neuronal death occurring in the hippocampus following transient forebrain ischemia. Transient forebrain ischemia was produced in the conscious rats by four-vessel occlusion for 10 min. Treatment with aminoguanidine (100 mg/kg or 200 mg/kg, i.p.) or saline (0.4 ml/100 g, i.p.) was started 30 min following ischemia-reperfusion and the animals were then injected twice daily until 12 h before sacrifice. Immunohistochemical method was used to detect 3-nitrotyrosine, a marker of peroxynitrite production. Posttreatment of aminoguanidine (200 mg/kg) significantly attenuated the neuronal death in the hippocampal CA1 area 3 days, but not 7 days, after ischemia-reperfusion. 3-Nitrotyrosine immunoreactivity was enhanced in the hippocampal CA1 area 3 days after reperfusion, which was prevented by the treatment of aminoguanidine (100 mg/kg and 200 mg/kg). Our findings showed that (1) the generation of peroxynitrite in the hippocampal CA1 area 3 days after ischemia-reperfusion was dependent on the iNOS activity; (2) the postischemic delayed neuronal death was attenuated in the early phase through the prevention of peroxynitrite generation by an iNOS inhibitor.

• Archives of Pharmacal Research
• /
• v.21 no.4
• /
• pp.481-484
• /
• 1998

In activated macrophages the inducible form of nitric oxide synthase (i-NOS) generates high amounts of toxic mediator, nitric oxide (NO) which contributes to the circulatory failure associated with septic shock. A sesquiterpene lactone compound (yomogin) isolated from medicinal plant Artemisia princeps Pampan inhibited the production of NO in LPS-activated RAW 264.7 cells by suppressing i-NOS enzyme expression. Thus, yomogin may be a useful candidate for the development of new drugs to treat endotoxemia and inflammation accompanied by the overproduction of NO.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2003.11a
• /
• pp.101-101
• /
• 2003

Prostaglandins (PGs) and nitric oxide (NO) produced by inducible cyclooygenase (COX-2) and nitric oxide synthase (iNOS), respectively, have been implicated as important mediators in the process of inflammation and carcinogenesis. On this line, the potential COX-2 or iNOS inhibitors have been considered as anti-inflammatory and cancer chemopreventive agents. In our continuing efforts of searching for novel cancer chemopreventive agents from natural products, we isolated natural sesquiterpenoids as potential COX-2 and iNOS inhibitors in cultured lipopolysaccharide (LPS)-activated mouse macrophage RAW 264.7 cells. Alantolactone, a natural eudesmane-type sesquiterpenoid, exhibited a potent inhibition of COX-2 (IC50 = 0.4 $\mu\textrm{g}$/$m\ell$) and iNOS activity (IC50 = 0.08 $\mu\textrm{g}$/$m\ell$) in the assay system determined by PGE2 and NO accumulation, respectively. The inhibitory potential of alantolactone on the PGE2 and NO production was well coincided with the suppression of COX-2 and iNOS protein and mRNA expression in LPS-induced macrophages. Furthermore, alantolactone inhibited NF-kB but not AP-l binding activity on nuclear extracts evoked by LPS-stimulated macrophage cells, suggesting the possible involvement of NF-kB in the regulation of COX-2 and iNOS expression. In further study with COX-2-expressing human colon HT-29 cells, alantolactone inhibited the cell proliferation, down-regulated COX-2, and inhibited the ERK phosphorylation in the early time. These results suggest that a natural sesquiterpenoid alantolactone might be a potential lead candidate for further developing COX-2 or iNOS inhibitor possessing cancer chemopreventive or anti-inflammatory activity

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

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.18 no.3
• /
• pp.908-913
• /
• 2004

Farfrae Flos has been clinically used for the treatment of asthma in traditional oriental medicine. There is lack of studies regarding the effects of Farfrae Flos on the immunological activities. The present study was conducted to evaluate the effect of Farfrae Flos on the regulatory mechanism of cytokines and nitric oxide (NO) for the immunological activities in Raw 264.7 cells. In Raw 264.7 cells stimulated with lipopolysaccharide (LPS) to mimic inflammation, Farfrae Flos water extract inhibited nitric oxide production in a dose-dependent manner and abrogated inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX-2). Farfrae Flos water extract did not affect on cell viability. To investigate the mechanism by which Farfrae Flos water extract inhibits iNOS and COX-2 gene expression, we examined the on the phospholylation of inhibitor κBα and production of TNF-α, IL-1β and IL-6. Results provided evidence that Farfrae Flos inhibited the production of interleukin-1β (IL-1β) and the activation of phospholylation of inhibitor κBα in Raw 264.7 cells activated with LPS. These findings suggest that Farfrae Flos can produce anti-inflammatory effect, which may play a role in adjunctive therapy in Gram-negative bacterial infections.

• Biomolecules & Therapeutics
• /
• v.19 no.4
• /
• pp.438-444
• /
• 2011

The mushroom Coriolus versicolor contains biologically active polysaccharides, most of which belong to the ${\beta}$-glucan group. Diverse physicochemical properties, due to different sources and isolated types of ${\beta}$-glucans, can induce distinct biological activities. We investigated the effects of ${\beta}$-glucans from C. versicolor on phagocytic activity, nitric oxide (NO), TNF-${\alpha}$ production, and signaling of dectin-1, a well-known ${\beta}$-glucan receptor, in macrophages. ${\beta}$-Glucans increased phagocytic activity and TNF-${\alpha}$ and NO-iNOS/eNOS production. Laminarin, a specific inhibitor of dectin-1, showed strong inhibitory effects on phagocytosis and subsequent TNF-${\alpha}$, iNOS, and eNOS production increased by ${\beta}$-glucans, indicating that ${\beta}$-glucans reacts with dectin-1 receptors. We examined whether the aforementioned cytokines were involved in the signaling pathway from the dectin-1 receptor to phagocytosis, and found that the inhibition of iNOS, eNOS, and TNF-${\alpha}$ receptors significantly decreased ${\beta}$-glucan-induced phagocytosis. In conclusion, our study showed that dectin-1 signaling, triggered by ${\beta}$-glucans, subsequently elicited TNF-${\alpha}$ and NO-iNOS/eNOS production, and that these molecules seem to act as secondary molecules that cause eventual phagocytosis by macrophages. These findings suggest that C. versicolor could be used as a nutritional medicine that may be useful in the treatment of infectious disease.

• The Korean Journal of Physiology and Pharmacology
• /
• v.1 no.6
• /
• pp.665-672
• /
• 1997

This study aimed to investigate the mechanism of cerebroprotection of platelet-activating factor(PAF) antagonists in transient cerebral ischemia of rat. Right middle cerebral artery(MCA) of Sprague-Dawley rat was occluded for 2 hours using an intraluminal filament technique. After 22 hours of reperfusion, morphometrically detectable infarct was developed in the cortex and striatum identical to the territory of MCA. The infarct size was significantly reduced by PAF antagonists, BN 52021 and CV-6209, as well as an inducible nitric oxide synthase(iNOS) inhibitor aminoguanidine(1 mg/kg, i.p., respectively) administered 5 min after MCA occlusion. PAF antagonists significantly inhibited the enzymatic activities of both myeloperoxidase and iNOS in the cerebral hemisphere ipsilateral to ischemia, whereas aminoguanidine did not inhibit myeloperoxidase activity but significantly inhibited the iNOS activity. These results suggest that PAF antagonists exert a cerebroprotective effect against ischemic brain damage through inhibition of leukocyte infiltration and iNOS activity in the postischemic brain.