Selective pharmacological inhibition of distinct nitric oxide synthase isoforms

2-Aminopyridines with a shortened amino sidechain as potent, selective, and highly permeable human neuronal nitric oxide synthase inhibitors

A series of potent, selective, and highly permeable human neuronal nitric oxide synthase inhibitors (hnNOS) based on the 2-aminopyridine scaffold with a shortened amino sidechain is reported. A rapid and simple protocol was developed to access these inhibitors in excellent yields. Neuronal nitric oxide synthase (nNOS) is a novel therapeutic target for the treatment of various neurological disorders. The major challenges in designing nNOS inhibitors in humans focus on potency, selectivity over other isoforms of nitric oxide synthases (NOSs), and blood-brain barrier permeability. In this context, we discovered a promising inhibitor, 6-(3-(4,4-difluoropiperidin-1-yl)propyl)-4-methylpyridin-2-amine dihydrochloride, that exhibits excellent potency for rat (Ki = 46 nM) and human nNOS (Ki = 48 nM), respectively, with 388-fold human eNOS and 135-fold human iNOS selectivity. It also displayed excellent permeability (Pe = 17.3 × 10-6 cm s-1) through a parallel artificial membrane permeability assay, a model for blood-brain permeability. We found that increasing lipophilicity by incorporation of fluorine atoms on the backbone of the inhibitors significantly increased potential blood-brain barrier permeability. In addition to measuring potency, isoform selectivity, and permeability of NOS inhibitors, we also explored structure-activity relationships via structures of key inhibitors complexed to various isoforms of nitric oxide synthases.

Muscarinic regulation of the neuronal Na+ /K+ -ATPase in rat hippocampus

KEY POINTS

Stimulation of postsynaptic muscarinic receptors was shown to excite principal hippocampal neurons by modulating several membrane ion conductances. We show here that activation of postsynaptic muscarinic receptors also causes neuronal excitation by inhibiting Na⁺ /K⁺ -ATPase activity. Muscarinic Na⁺ /K⁺ -ATPase inhibition is mediated by two separate signalling pathways that lead downstream to enhanced Na⁺ /K⁺ -ATPase phosphorylation by activating protein kinase C and protein kinase G. Muscarinic excitation through Na⁺ /K⁺ -ATPase inhibition is probably involved in cholinergic modulation of hippocampal activity and may turn out to be a widespread mechanism of neuronal excitation in the brain.

ABSTRACT

Stimulation of muscarinic cholinergic receptors on principal hippocampal neurons enhances intrinsic neuronal excitability by modulating several membrane ion conductances. The electrogenic Na⁺ /K⁺ -ATPase (NKA; the 'Na⁺ pump') is a ubiquitous regulator of intrinsic neuronal excitability, generating a hyperpolarizing current to thwart excessive neuronal firing. Using electrophysiological and pharmacological methodologies in rat hippocampal slices, we show that neuronal NKA pumping activity is also subjected to cholinergic regulation. Stimulation of postsynaptic muscarinic, but not nicotinic, cholinergic receptors activates membrane-bound phospholipase C and hydrolysis of membrane-integral phosphatidylinositol 4,5-bisphosphate into diacylglycerol (DAG) and inositol 1,4,5-triphosphate (IP₃ ). Along one signalling pathway, DAG activates protein kinase C (PKC). Along a second signalling pathway, IP₃ causes Ca²⁺ release from the endoplasmic reticulum, facilitating nitric oxide (NO) production. The rise in NO levels stimulates cGMP synthesis by guanylate-cyclase, activating protein kinase G (PKG). The two pathways converge to cause partial NKA inhibition through enzyme phosphorylation by PKC and PKG, leading to a marked increase in intrinsic neuronal excitability. This novel mechanism of neuronal NKA regulation probably contributes to the cholinergic modulation of hippocampal activity in spatial navigation, learning and memory.

Clusterin enhances cell survival by suppressing neuronal nitric-oxide synthase expression in the rhodopsin S334ter-line3 retinitis pigmentosa model

Environmental changes in the retina, including oxidative stress-induced cell death, influence photoreceptor degeneration in Retinitis Pigmentosa (RP). Previously, we tested and discovered that a cytoprotective chaperone protein, clusterin, produced robust preservation of rod photoreceptors of a rat autosomal dominant rhodopsin transgenic model of RP, S334ter-line3. To investigate the biochemical and molecular cytoprotective pathways of clusterin, we examined and compared a known source of cone cell death, nitric oxide (NO), observing nNOS expression using antibody against nNOS in RP retinas with intravitreal injections of saline, clusterin (10 μg/ml), or a non-isoform-selective NOS inhibitor (25 mM), L-NAME, or with an intraperitoneal injection (IP) of L-NAME (100 mg/kg). Rhodopsin-immunoreactive rod photoreceptor cells and nNOS-immunoreactive cells were quantified with immunohistochemistry in the presence or absence of L-NAME or clusterin, and the total nNOS retinal expression was determined by immunoblot analysis. In this study, the level of nNOS expression was significantly up-regulated postnatally (P) at P15 (P < 0.05), P30 (P < 0.001) and P60 (P < 0.0001) in RP retinas compared to normal controls. Clusterin treatment suppressed the up-regulated nNOS expression in RP retinas (P < 0.0001) and was enhanced in Type II amacrine cells. Additionally, IP injection of L-NAME at P15 prolonged rod survival in the later stage of RP retinas (P < 0.001). Conversely, rod survival in L-NAME-treated RP retinas was not equivalent to the rod survival number seen in clusterin-treated retinas, which suggests induction of nNOS expression in RP retinas and its reduction by clusterin is only partly responsible for the rescue observed through the reduction of nNOS expression in S334ter-line3 rat retinas.

Antioxidant-Based Therapy Reduces Early-Stage Intestinal Ischemia-Reperfusion Injury in Rats

Intestinal ischemia-reperfusion injury (i-IRI) is a rare disorder with a high mortality rate, resulting from the loss of blood flow to an intestinal segment. Most of the damage is triggered by the restoration of flow and the arrival of cytokines and reactive oxygen species (ROS), among others. Inactivation of these molecules before tissue reperfusion could reduce intestinal damage. The aim of this work was to analyze the preventive effect of allopurinol and nitroindazole on intestinal mucosal damage after i-IRI. Wag/RijHsd rats were subjected to i-IRI by clamping the superior mesenteric artery (for 1 or 2 h) followed by a 30 min period of reperfusion. Histopathological intestinal damage (HID) was assessed by microscopic examination of histological sections obtained from injured intestine. HID was increased by almost 20% by doubling the ischemia time (from 1 to 2 h). Nitroindazole reduced HID in both the 1 and 2 h period of ischemia by approximately 30% and 60%, respectively (p < 0.001). Our preliminary results demonstrate that nitroindazole has a preventive/protective effect against tissue damage in the early stages of i-IRI. However, to better understand the molecular mechanisms underlying this phenomenon, further studies are needed.

Glossary and tutorial of xenobiotic metabolism terms used during small molecule drug discovery and development (IUPAC Technical Report)

This project originated more than 15 years ago with the intent to produce a glossary of drug metabolism terms having definitions especially applicable for use by practicing medicinal chemists. A first-draft version underwent extensive beta-testing that, fortuitously, engaged international audiences in a wide range of disciplines involved in drug discovery and development. It became clear that the inclusion of information to enhance discussions among this mix of participants would be even more valuable. The present version retains a chemical structure theme while expanding tutorial comments that aim to bridge the various perspectives that may arise during interdisciplinary communications about a given term. This glossary is intended to be educational for early stage researchers, as well as useful for investigators at various levels who participate on today’s highly multidisciplinary, collaborative small molecule drug discovery teams.

Saussureae Radix Attenuates Neuroinflammation in LPS-Stimulated Mouse BV2 Microglia via HO-1/Nrf-2 Induction and Inflammatory Pathway Inhibition

The activation of microglial cells and their subsequent neuroinflammatory reactions are related to various degenerative brain diseases. Therefore, the regulation of microglial cell activation is an important point for the research of therapeutic agents for treating or preventing neurodegenerative disorders. Saussureae Radix (SR) is the root of Saussurea lappa Clarke, and it has been used for a long time as an herbal medicine in East Asia to treat indigestion and inflammation of the digestive system. In previous studies, however, the effect of SR ethanolic extract on microglial cell-mediated neuroinflammation was not fully explained. In this study, we explored the antineuroinflammatory activities and molecular mechanisms of SR in microglial cells stimulated with LPS (lipopolysaccharide). Our results illustrated that SR does not cause cytotoxicity and significantly weakens the production of nitric oxide (NO) and inflammatory cytokines. SR treatment also inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase- (COX-) 2, induced heme oxygenase- (HO-) 1, and activated the nuclear factor erythroid 2-related factor 2 (Nrf-2) pathway. In addition, SR significantly repressed the transcriptional activities of the nuclear factor- (NF-) κB and activator protein- (AP-) 1. Furthermore, SR effectively inhibited the phosphorylation of mitogen-activated protein kinase (MAPK) and Janus kinase (JAK)/signal transducer and activator of transcription (STAT). Isolation and high-performance liquid chromatography (HPLC) analysis indicated two major sesquiterpenoids (costunolide and dehydrocostuslactone). These compounds significantly inhibited the production of neuroinflammatory mediators and induced HO-1 expression. These findings show that SR could be a potential candidate for the treatment of inflammation-related degenerative brain diseases.

Triclosan affects the expression of nitric oxide synthases (NOSs), peroxisome proliferator-activated receptor gamma (PPARγ), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in mouse neocortical neurons in vitro

Triclosan (TCS) is a well-known compound that can be found in disinfectants, personal care products. There is one publication concerning the involvement of PPARγ in the mechanism of action of TCS. It is known that activation of PPARγ regulates the expression of the NF-κB mediated inflammation by acting on nitric oxide synthase (NOS) genes. However, there are no studies demonstrating a relationship between the effects of TCS on the PPARγ signaling pathway, changes in NF-κB expression, and NOS isoform synthesis. Therefore, the aim of this study was to evaluate the effect of TCS on the expression of PPARγ, NF-κB, nNOS, iNOS, and eNOS in mouse neocortical neurons. In addition, the effects of co-administration of synthetic alpha-naphthoflavone (αNF) or beta-naphthoflavone (βNF) flavonoids and triclosan were investigated. Our results show that TCS alters PPARγ, NF-κB, iNOS, and eNOS expression in mouse neurons in vitro. After 48 h of exposure, TCS increased PPARγ expression and decreased NF-κB expression. Moreover, under the influence of TCS, the expression of iNOS was increased and at the same time the expression of nNOS was decreased, which was probably caused by high levels of ROS. The experiments have shown that both αNF and βNF are able to modulate the effects of TCS in primary cultures of mouse cortical neurons.

Some Aspects of Role of Nitric Oxide in the Mechanisms of Hypertension (Experimental Study)

Background

Modulation of endothelial function is a therapeutic option to reduce some of the significant complications of hypertension. However, the relationship between endothelial dysfunction reduced nitric oxide (NO) production, and the development of hypertension is not fully understood. To establish a potential pathogenetic link between impaired NO synthesis and hypertension, we investigated the results of competitive interaction of the substrate of NO synthase, L-arginine, and its analog, an non-selective inhibitor of NO synthase, N-nitro-methyl ether-L-arginine (L-NAME), in experimental rats.

Methods

Arterial hypertension was induced in male Wistar rats by intraperitoneal administration of L-NAME (Sigma-Aldrich) for 4 - 7 weeks. During the last 3 weeks, to a separate group of animals simultaneously with L-NAME, L-arginine (Sigma-Aldrich) was administered. In animals monitored for systolic and diastolic pressure, the level of NO in blood samples was determined spectrophotometrically using a Griess reagent.

Results

Administration of L-NAME for 4 - 7 weeks induced an irreversible decrease of NO content in blood, a reversible increase of systolic pressure (SP) and diastolic pressure (DP), and an irreversible increase in pulse pressure (PP). In rats against the background of 7 weeks of intraperitoneal administration of L-NAME, during the last 3 weeks, they were injected with L-arginine, the SP and DP indices returned to their initial values, PP decreased and the NO content in arterial blood increased.

Conclusions

The results of the study indicate the presence of residual endothelial dysfunction (characterized by insufficient NO) after the correction of hypertension. Therefore, in developing the new therapeutic approaches for the treatment of hypertension, it is necessary to include drugs that, in addition to correcting blood pressure, will support normalization, and potentiation of endothelial function and endogenous NO synthesis.

Physiopathology of nitric oxide in the oral environment and its biotechnological potential for new oral treatments: a literature review

OBJECTIVES

A narrative review on the NO properties and their relationship with the oral environment describing NO's molecular origin, role, and perspectives regarding oral pathological, physiological, and regenerative processes for future applications and possible use as prevention or treatment in dentistry.

MATERIALS AND METHODS

Pubmed was searched using the word "nitric oxide." Reviews, clinical studies, and experimental studies were eligible for the screening process. Similar search procedures were then performed with the additional search words "conservative dentistry," "orthodontics," "endodontics," "implants," "periodontics," "oral cancer," "pulp revascularization," and "oral surgery." Furthermore, references of included articles were examined to identify further relevant articles.

RESULTS

There is a relationship between NO production and oral diseases such as caries, periodontal diseases, pulp inflammation, apical periodontitis, oral cancer, with implants, and orthodontics. Studies on this relationship and uses of NO, in diagnosis, prevention, and treatment, are being developed. Also, some NO and oral cavity patents have already registered.

CONCLUSIONS

The understanding of how NO can interfere in oral health maintenance or disease processes can contribute to elucidate the disease development and optimize treatment approaches.

CLINICAL RELEVANCE

NO has considerable biotechnological potential and can contribute to improving diagnostics and treating the oral environment. As a biomarker, NO has an important role in the early diagnosis of diseases. Regarding treatments, NO can possibly be used as a regulator of inflammation, anti-biofilm action, replacing antibiotics, inducing apoptosis of cancerous cells, and contributing to the angiogenesis. All these studies are initial considerations regarding the relationship between NO and dentistry.

Wavelength- and irradiance-dependent changes in intracellular nitric oxide level

SIGNIFICANCE

Photobiomodulation (PBM) refers to the beneficial effects of low-energy light absorption. Although there is a large body of literature describing downstream physiological benefits of PBM, there is a limited understanding of the molecular mechanisms underlying these effects. At present, the most popular hypothesis is that light absorption induces release of nitric oxide (NO) from the active site of cytochrome c oxidase (COX), allowing it to bind O2 instead. This is believed to increase mitochondrial respiration, and result in greater overall health of the cell due to increased adenosine triphosphate production.

AIM

Although NO itself is a powerful signaling molecule involved in a host of biological responses, less attention has been devoted to NO mechanisms in the context of PBM. The purpose of our work is to investigate wavelength-specific effects on intracellular NO release in living cells.

APPROACH

We have conducted in-depth dosimetry analyses of NO production and function in an in vitro retinal model in response to low-energy exposure to one or more wavelengths of laser light.

RESULTS

We found statistically significant wavelength-dependent elevations (10% to 30%) in intracellular NO levels following laser exposures at 447, 532, 635, or 808 nm. Sequential or simultaneous exposures to light at two different wavelengths enhanced the NO modulation up to 50% of unexposed controls. Additionally, the immediate increases in cellular NO levels were independent of the function of NO synthase, depended greatly on the substrate source of electrons entering the electron transport chain, and did not result in increased levels of cyclic guanosine monophosphate.

CONCLUSIONS

Our study concludes the simple model of light-mediated release of NO from COX is unlikely to explain the wide variety of PBM effects reported in the literature. Our multiwavelength method provides a novel tool for studying immediate and early mechanisms of PBM as well as exploring intracellular NO signaling networks.

Anti-inflammatory effect from extracts of Red Chinese cabbage and Aronia in LPS-stimulated RAW 264.7 cells

A chronic inflammatory environment facilitates tumor growth and proliferation. Fruits and vegetables are important sources of anthocyanins, polyphenols, and other biologically active substances that can favorably affect the pathogenesis of cancer. The objective of the study was to investigate the anti-inflammatory effects of Red Chinese cabbage (RC) and mixture of commercial Red Chinese cabbage leaves and Aronia fruits (ARC) in LPS-stimulated RAW 264.7 cells. The RAW 264.7 cells were cultured and measured the cytotoxicity by using an MTT assay. The inflammatory markers, such as nitrite, IL-6, and TNF-alpha expression, were evaluated using ELISA, and protein expression of inflammatory markers like iNOS and COX-2 was analyzed using Western blot. MTT assays showed that pretreatment of RAW 264.7 cells with RC and ARC did not change cell growth or cytotoxicity. We also found that ARC extracts reduced inflammation-related biomarker (TNF-a, IL-6, and NO) production and gene expression (iNOS, COX-2). Our results suggested that ARC has good anti-inflammatory properties compared with RC that maybe used as potential nutrients for treating inflammatory diseases.

Association of CYP11B2 gene polymorphism with preeclampsia in north east of Iran (Khorasan province)

PURPOSE

Identification the genetic factors in preeclampsia (PE) are useful to increase the current knowledge of the pathophysiology of the disorder. The genetic factors implicated for all cases of PE remain to be determined. This study was aimed to investigate association between ADD1 1378G > T, AGTR2 1675G > A, AGTR1 1166A > C, NOS3 894 G > T and CYP11B2 -344C > T gene polymorphisms in Iranian women with PE.

MATERIAL AND METHODS

117 pregnant women with PE and 103 healthy women without affected previous pregnancy by PE were selected. Genomic DNA was extracted from peripheral blood and real-time PCR was performed to investigate the polymorphisms using a commercial kit.

RESULTS

There was a significant difference in CYP11B2 -344C > T gene polymorphism between case and control groups (P = 0.025). The odds ratio was 0.71 (CI 95% = 0.28-1.79). There were no statistical significant differences between other genetic polymorphisms.

CONCLUSION

Our results showed a significant association between CYP11B2 -344C > T gene polymorphism with PE. This finding suggests that mentioned polymorphism may be associated with susceptibility to PE at least in IRAN.

Spilanthol Inhibits Inflammatory Transcription Factors and iNOS Expression in Macrophages and Exerts Anti-inflammatory Effects in Dermatitis and Pancreatitis

Activated macrophages upregulate inducible nitric oxide synthase (iNOS) leading to the profuse production of nitric oxide (NO) and, eventually, tissue damage. Using macrophage NO production as a biochemical marker of inflammation, we tested different parts (flower, leaf, and stem) of the medicinal plant, Spilanthes acmella. We found that extracts prepared from all three parts, especially the flowers, suppressed NO production in RAW macrophages in response to interferon-γ and lipopolysaccharide. Follow up experiments with selected bioactive molecules from the plant (α-amyrin, β-caryophylline, scopoletin, vanillic acid, trans-ferulic acid, and spilanthol) indicated that the N-alkamide, spilanthol, is responsible for the NO-suppressive effects and provides protection from NO-dependent cell death. Spilanthol reduced the expression of iNOS mRNA and protein and, as a possible underlying mechanism, inhibited the activation of several transcription factors (NFκB, ATF4, FOXO1, IRF1, ETS, and AP1) and sensitized cells to downregulation of Smad (TF array experiments). The iNOS inhibitory effect translated into an anti-inflammatory effect, as demonstrated in a phorbol 12-myristate 13-acetate-induced dermatitis and, to a smaller extent, in cerulein-induced pancreatitis. In summary, we demonstrate that spilanthol inhibits iNOS expression, NO production and suppresses inflammatory TFs. These events likely contribute to the observed anti-inflammatory actions of spilanthol in dermatitis and pancreatitis.

Atractylodis Rhizoma Alba Attenuates Neuroinflammation in BV2 Microglia upon LPS Stimulation by Inducing HO-1 Activity and Inhibiting NF-κB and MAPK

Microglial activation and the resulting neuroinflammation are associated with a variety of brain diseases, such as Alzheimer’s disease and Parkinson’s disease. Thus, the control of microglial activation is an important factor in the development of drugs that can treat or prevent inflammation-related neurodegenerative disorders. Atractylodis Rhizoma Alba (ARA) has been reported to exhibit antioxidant, gastroprotective, and anti-inflammatory effects. However, the effects of ARA ethanolic extract (ARAE) on microglia-mediated neuroinflammation have not been fully elucidated. In this work, we explored the anti-neuroinflammatory properties and underlying molecular mechanisms of ARAE in lipopolysaccharide (LPS)-stimulated microglial BV2 cells. Our results showed that ARAE significantly attenuates the production of nitric oxide (NO) and inflammatory cytokines induced by LPS. ARAE treatment also inhibited the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 without causing cytotoxicity. ARAE markedly attenuated the transcriptional activities of nuclear factor (NF)-κB and mitogen-activated protein kinases (MAPK) phosphorylation, and induced heme oxygenase (HO)-1 expression. High-performance liquid chromatography (HPLC) analysis showed that ARAE contains three main components—atractylenolide I, atractylenolide III, and atractylodin—all compounds that significantly inhibit the production of inflammatory factors. These findings indicate that ARAE may be a potential therapeutic agent for the treatment of inflammation-related neurodegenerative diseases.

Synthesis and reactivity of an osmium(iii) aminoguanidine complex

The biological activities of aminoguanidine (GNH₂) and its derivatives have been extensively studied due to their properties as radical scavengers and antioxidants. Some of their biological activities may result from their binding to various metals present in biological systems. However, the reactivity of coordinated aminoguanidines has not been investigated. We report herein the synthesis, structure and reactivity of a novel osmium(iii) complex bearing the parent aminoguanidine, mer-[Os{NHC(NH₂)(NHNH₂)}(L)(CN)₃]^- (OsGNH₂, HL = 2-(2-hydroxyphenyl)benzoxazole). The antioxidant properties of OsGNH₂ have been investigated by reactions with various oxidants, including O₂, H₂O₂, m-chloroperbenzoic acid (m-CPBA) and Ce(iv). Various osmium products are produced, which depend on the type of oxidant used. OsGNH₂ is readily oxidized by O₂ or H₂O₂ under ambient conditions to afford an osmium(iii) formamidine complex, [Os^III(NH₂C[double bond, length as m-dash]NH)(L)(CN)₃]^- (OsFA, FA = formamidine). With m-CPBA, the nitrosyl complex, mer-[Os(NO)(L)(CN)₃]^- (OsNO), is formed instead. On the other hand, the nitrido complex mer-[Os(N)(L)(CN)₃]^- (OsN) is produced when the one-electron oxidant (NH₄)₂[Ce^IV(NO₃)₆] (Ce(iv)) is employed. The molecular structures of OsGNH₂ and OsFA have been determined by X-ray crystallography. The oxidation of OsGNH₂ to OsFA by O₂ or H₂O₂ is proposed to go through initial dehydrogenation to give a diazoamidine intermediate. In the oxidation by m-CPBA and Ce(iv), it is proposed that the initially formed OsFA is further oxidized to OsNO and OsN, respectively, via osmium(iii) hydrogen cyanamido and osmium(iv) cyanoimido intermediates.

Pharmacophore modeling, 3D-QSAR and molecular docking studies of quinazolines and aminopyridines as selective inhibitors of inducible nitric oxide synthase

Pharmacophore modeling and 3D-Quantitative Structure Activity Relationship (3D-QSAR) studies have been performed on a dataset of thirty-two quinazoline and aminopyridine derivatives to get an insight into the important structural features required for binding to inducible nitric oxide synthase (iNOS). A four-point CPH (Common Pharmacophore Hypothesis), AHPR.29, with a hydrogen bond acceptor, hydrophobic group, positively charged ionizable group and an aromatic ring, has been obtained as the best pharmacophore model. Satisfactory statistical parameters of correlation ([Formula: see text]) and cross-validated ([Formula: see text]) correlation coefficients, 0.9288 and 0.6353, respectively, show high robustness and good predictive ability of our selected model. The contour maps have been developed from this model and the analysis has provided an interpretable explanation of the effect that various features and substituents have on the potency and selectivity of inhibitors towards iNOS. Docking studies have also been performed in order to analyze the interactions between the enzyme and the inhibitors. Our proposed model can thus be further used for screening a large database of compounds and design new iNOS inhibitors.

Effect of TRPV1 on Activity of Isoforms of Constitutive Nitric Oxide Synthase during Regulation of Bicarbonate Secretion in the Stomach

Application of mild irritants (1 M NaCl; pH 2.0) on the gastric mucosa potentiates the protective secretion of bicarbonates by epithelial cells. This response is mainly mediated by capsaicin-sensitive afferent nerve endings located in the submucosa. It was shown that activation of vanilloid type 1 receptors (TRPV1) induced by exogenous acidification of GM is not sufficient to potentiate the production of HCO₃, including production depending on neuronal NO synthase. However, the effect of exogenous acid on TRPV1 leads to activation of endothelial NO synthase that restrict the gastric secretion of [Formula: see text].

Involvement of inducible nitric oxide synthase (iNOS) in immune-functioning of Paphia malabarica (Chemnitz, 1782)

In recent years, the role of inducible nitric oxide synthase (iNOS) isoform has been widely studied because of its immunological relevance in higher organisms as well as invertebrates including bivalves. However, little is known about the immunological role of iNOS in Paphia malabarica defense mechanism. In this study, we immunodetected the presence of iNOS in P. malabarica hemocytes using antibody N9657 monoclonal anti-nitric oxide synthase. In addition, increased iNOS activity was evident in response to a higher bacterial dosage (Vibrio parahaemolyticus and V. cholerae), highlighting the dose-dependent iNOS activity induction. Also, higher bacterial survivability was observed in the presence of iNOS inhibitor, i.e., S-methylisothiourea hemisulphate (SMIS) thus, validating the bactericidal role of iNOS. These findings implicate the involvement of iNOS in immune-functioning of P. malabarica. Future work should focus on elucidating the expression and regulation of pathogenesis in P. malabarica, involving iNOS.

Glucocorticoids decrease the numbers and activation of mast cells by inducing the transactivation receptors of AGEs

Glucocorticoids (GCs) are potent anti-allergic compounds that function, at least in part, by inhibiting signaling pathways in mast cells. We hypothesized that the GC-induced mastocytopenia and suppression of mast cell activation are mediated by the advanced glycation end products (AGEs)/receptors of AGEs (RAGEs) signaling axis. We evaluated the role of AGEs in GC-mediated mastocytopenia and impaired mast cell degranulation in male Wistar rats and Swiss-Webster mice subcutaneously injected with dexamethasone or prednisolone (0.1 mg/kg) once a day for 21 consecutive days. The animals were treated with either the AGE inhibitor aminoguanidine (250 mg/kg), the RAGE antagonist FPS-ZM1 (1 mg/kg) or the galectin-3 antagonist GSC-100 (1 mg/kg) daily for 18 days, starting 3 days following GC treatment. Aminoguanidine inhibited GC-induced mast cell apoptosis and restored mast cell numbers in the pleural cavity of GC-treated rats. Aminoguanidine also reversed the GC-induced reduction in histamine release triggered by allergens or compound 48/80 in vitro. GC treatment induced RAGE and galectin expression in mast cells, and blocking these agents by FPS-ZM1 or GSC-100 significantly reversed mast cell numbers in the peritoneal cavity and mesenteric tissue of GC-treated mice. In addition, the combination of GC and AGE-induced mast cell apoptosis in vitro was inhibited by both FPS-ZM1 and GSC-100. We concluded that the GC-induced mastocytopenia and suppression of mast cell stimulation are associated with the gene transactivation of RAGE and galectin-3.

Amelioration of inflammatory responses by Socheongryong-Tang, a traditional herbal medicine, in RAW 264.7 cells and rats

Socheongryong-Tang (SCRT) is a natural medicine prescription that has been mainly used in East Asia for the treatment of inflammatory disorders, including asthma and allergic rhinitis. The present study evaluated the anti-inflammatory effects of SCRT on lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and in a rat model of carrageenan (CA)-induced paw edema. Levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6 and prostaglandin E2 (PGE2) in the culture supernatant were quantified and nitric oxide (NO) production was monitored. In addition, the effect of SCRT on the protein expression of nuclear factor-κB (NF-κB), mitogen-activated protein kinases (MAPKs), inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) was assessed by western blot analysis. Furthermore, the effects of SCRT on acute inflammation in vivo and changes in the histomorphometry and histopathology of paw skin were observed using CA-treated rats. SCRT (1 mg/ml) inhibited the LPS-induced changes in the protein expression of NF-κB, JNK, ERK1/2, iNOS and COX-2, as well as the production of NO, PGE2 and cytokines. In the rat paw edema assay, administration of 1 g/kg of lyophilized powder obtained from the aqueous extracts of SCRT for 3 consecutive days inhibited the CA-induced increases in skin thickness, mast cell degranulation, and infiltration of inflammatory cells in the ventral and dorsal pedis skin within 4 h. These results demonstrated that SCRT exerts its anti-inflammatory activities in LPS-stimulated RAW 264.7 cells through decreasing the production of inflammatory mediators, including PGE2, NO and cytokines, via suppression of the NF-κB and JNK and ERK1/2 signaling pathways. In addition, the data of the CA-induced paw edema indicated an anti-edema effect of SCRT. SCRT (1 g/kg) reduced acute edematous inflammation through inhibition of mast cell degranulation and infiltration of inflammatory cells. Therefore, the present study provided scientific evidence for the anti-inflammatory activities of SCRT as well as the underlying mechanisms.

Cardioprotection by intermittent hypoxia conditioning: evidence, mechanisms, and therapeutic potential

The calibrated application of limited-duration, cyclic, moderately intense hypoxia-reoxygenation increases cardiac resistance to ischemia-reperfusion stress. These intermittent hypoxic conditioning (IHC) programs consistently produce striking reductions in myocardial infarction and ventricular tachyarrhythmias after coronary artery occlusion and reperfusion and, in many cases, improve contractile function and coronary blood flow. These IHC protocols are fundamentally different from those used to simulate sleep apnea, a recognized cardiovascular risk factor. In clinical studies, IHC improved exercise capacity and decreased arrhythmias in patients with coronary artery or pulmonary disease and produced robust, persistent, antihypertensive effects in patients with essential hypertension. The protection afforded by IHC develops gradually and depends on β-adrenergic, δ-opioidergic, and reactive oxygen-nitrogen signaling pathways that use protein kinases and adaptive transcription factors. In summary, adaptation to intermittent hypoxia offers a practical, largely unrecognized means of protecting myocardium from impending ischemia. The myocardial and perhaps broader systemic protection provided by IHC clearly merits further evaluation as a discrete intervention and as a potential complement to conventional pharmaceutical and surgical interventions.

In Vitro and In Vivo Anti-Osteoarthritis Effects of 2,3,5,4'-Tetrahydroxystilbene-2-O-β-d-Glucoside from Polygonum Multiflorum

Polygonum multiflorum Thunb. is a traditional herbal medicine that is rich in polyphenols. The major compound, 2,3,5,4'-tetrahydroxystilbene-2-O-β-d-glucoside (THSG) has many pharmacological activities, such as antioxidative and free radical-scavenging properties, and the abilities to reduce hyperlipidemia, prevent lipid peroxidation, and protect the cardiovascular system. In this study, the anti-osteoarthritis (OA) effects of THSG were explored using in vitro and in vivo models. THSG inhibited nitric oxide (NO) and prostaglandin E₂ (PGE₂) production and inducible NO synthase (iNOS) and cyclooxygenase-2 expressions by lipopolysaccharide-stimulated RAW 264.7 cells. On the other hand, THSG inhibited PGE₂ production and iNOS and matrix metalloproteinase-13 expressions by interleukin-1β-stimulated primary rat chondrocytes. Through a mono-iodoacetate-induced rat OA model assay, THSG reduced paw edema and improved the weight-bearing distribution. Therefore, THSG has anti-inflammatory activity and could be applied as a lead compound for the development as an OA drug.

Role of endogenous and exogenous nitric oxide, carbon monoxide and hydrogen sulfide in HCT116 colon cancer cell proliferation

The role of the three gasotransmitter systems - nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S) - in cancer cells has not yet been studied simultaneously in the same experimental system. We measured the expression of NO and CO and H2S generating enzymes in primary colon cancer tissues and HCT116 colon cancer cells, and evaluated the effect of their pharmacological inhibition or pharmacological donation on cell proliferation. Increased expression of iNOS, nNOS, HO-1, CBS and 3-MST was detected in colon cancer. Inhibitors of NOS, HO-1/2, CBS/CSE and 3-MST, at lower concentrations, slightly stimulated HCT116 cell proliferation, but inhibited proliferation at higher concentrations. Donors of NO, CO or H2S inhibited HCT116 proliferation in a concentration-dependent manner. Inhibition of the cGMP/VASP pathway, Akt and p44/42 MAPK (Erk1/2) inhibited HCT116 cell proliferation. Endogenous NO and H2S biosynthesis were found to play a role in the maintenance of the activity of the cGMP/VASP pathway in HCT116 cells. We conclude that each of the three gasotransmitters play similar, bell-shaped roles in the control of HCT116 cell proliferation: endogenously produced NO, CO and H2S, at an optimal concentration, support HCT116 proliferation; inhibition of their production (which decreases gasotransmitter levels below optimal concentrations) as well as exogenous delivery of these gasotransmitters (which increases gasotransmitter levels above optimal concentrations) suppresses colon cancer cell proliferation. The current data give a mechanistic explanation for the paradoxical finding that both inhibitors and donors of NO, CO and H2S exert anticancer actions in cancer cells.

Function of neuronal nitric oxide synthase enzyme in temozolomide-induced damage of astrocytic tumor cells

Astrocytic tumors, including astrocytomas and glioblastomas, are the most common type of primary brain tumors. Treatment for glioblastomas includes radiotherapy, chemotherapy with temozolomide (TMZ) and surgical ablation. Despite certain therapeutic advances, the survival time of patients is no longer than 12-14 months. Cancer cells overexpress the neuronal isoform of nitric oxide synthase (nNOS). In the present study, it was examined whether the nNOS enzyme serves a role in the damage of astrocytoma (U251MG and U138MG) and glioblastoma (U87MG) cells caused by TMZ. First, TMZ (250 µM) triggered an increase in oxidative stress at 2, 48 and 72 h in the U87MG, U251MG and U138MG cell lines, as revealed by 2',7'-dichlorofluorescin-diacetate assay. The drug also reduced cell viability, as measured by MTT assay. U87MG cells presented a more linear decline in cell viability at time-points 2, 48 and 72 h, compared with the U251MG and U138MG cell lines. The peak of oxidative stress occurred at 48 h. To examine the role of NOS enzymes in the cell damage caused by TMZ, N(ω)-nitro-L-arginine methyl ester (L-NAME) and 7-nitroindazole (7-NI) were used. L-NAME increased the cell damage caused by TMZ while reducing the oxidative stress at 48 h. The preferential nNOS inhibitor 7-NI also improved the TMZ effects. It caused a 12.8% decrease in the viability of TMZ-injured cells. Indeed, 7-NI was more effective than L-NAME in restraining the increase in oxidative stress triggered by TMZ. Silencing nNOS with a synthetic small interfering (si)RNA (siRNAnNOShum_4400) increased by 20% the effects of 250 µM of TMZ on cell viability (P<0.05). Hoechst 33342 nuclear staining confirmed that nNOS knock-down enhanced TMZ injury. In conclusion, our data reveal that nNOS enzymes serve a role in the damage produced by TMZ on astrocytoma and glioblastoma cells. RNA interference with nNOS merits further studies in animal models to disclose its potential use in brain tumor anticancer therapy.

Combination of Pelargonium sidoides and Coptis chinensis root inhibits nuclear factor kappa B-mediated inflammatory response in vitro and in vivo

Background

Pelargonium sidoides (PS) and Coptis chinensis root (CR) have traditionally been used to treat various diseases, including respiratory and gastrointestinal infections, dysmenorrhea, and hepatic disorders. The present study was conducted to evaluate the anti-inflammatory effects of a combination of PS and CR in vitro and in vivo.

Methods

The in vitro effects of PS + CR on the induction of inflammation-related proteins were evaluated in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. The levels of nitric oxide (NO) and of inflammatory cytokines and prostaglandin E₂ (PGE₂) were measured using the Griess reagent and enzyme-linked immunosorbent assay (ELISA) methods, respectively. The expression of inflammation-related proteins was confirmed by Western blot. Additionally, the effects of PS + CR on paw edema volume, skin thickness, and numbers of infiltrated inflammatory cells, mast cells, COX-2-, iNOS-, and TNF-α-immunoreactive cells in dorsum and ventrum pedis skin were evaluated in a rat model of carrageenan (CA)-induced paw edema.

Results

PS + CR significantly reduced production of NO, PGE₂ and three pro-inflammatory cytokines (tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6) and also decreased levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Treatment with PS + CR significantly reduced the protein expression levels of LPS-stimulated nuclear factor kappa B (NF-κB) and phosphorylated inhibitor of NF-κB (p-I-κBα). Additionally, PS + CR significantly inhibited the increases in paw swelling, skin thickness, infiltrated inflammatory cells, mast cell degranulation, COX-2-, iNOS-, and TNF-α-immunoreactive cells in the rat model of CA-induced acute edematous paw.

Conclusions

These results demonstrate that PS + CR exhibits anti-inflammatory properties through decreasing the production of pro-inflammatory mediators (NO, PGE₂, TNF-α, IL-1β, and IL-6), suppressing NF-κB signaling in LPS-induced RAW 264.7 cells. Additionally, the results of the CA-induced rat paw edema assay revealed an anti-edema effect of PS + CR. Furthermore, it is suggested that PS + CR also inhibits acute edematous inflammation by suppressing mast cell degranulation and inflammatory mediators (COX-2, iNOS, and TNF-α). Thus, PS + CR may be a potential candidate for the treatment of various inflammatory diseases, and it may also contribute to a better understanding of the molecular mechanisms underlying inflammatory response regulation.

Aqueous Extract of Carica Papaya Linn Roots Halts Sodium Arsenite-Induced Renal Inflammation through Inhibiting Adenosine Deaminase, 8-Hydroxy-2′-Deoxyguanosine, C-Reactive Protein and Inducible Nitric Oxide Synthase Activity

Objectives: Inflammation plays a crucial role in many of the metabolic abnormalities. The prototypic marker of inflammation is C-reactive protein (CRP), Nitric Oxide (NO), inducible nitric oxide synthase (iNOS) and their inhibition is considered a promising strategy to combat inflammation. Here, we report the anti-inflammatory mechanism of Carica papaya root aqueous extract in sodium arsenic-induced renal dysfunction.

Methodology: Thirty-five rats were used for the experiments. Griess assay was used to evaluate the inhibitory effect of Carica papaya roots aqueous extract on the overproduction of nitric oxide (NO). ELISA was used to determine the level of pro-inflammatory markers including c-reactive protein (CRP). ELISA was used to analyze 8-OHdG. The inhibitory effect on the enzymatic activity of inducible nitric oxide synthase (iNOS), adenosine deaminase (ADA), malondialdehyde (MDA) was tested by enzyme activity assay kits.

Results: Carica papaya roots aqueous extract suppressed sodium arsenite-stimulated NO production and proinflammatory secretion, such as CRP. Carica papaya roots aqueous extract significantly (p < 0.05) decrease the activities of iNOS, 8-OHdG, ADA and MDA.

Conclusion: These results indicated that potent inhibition on CRP, NO, iNOS, ADA, 8-OHdG might constitute the anti-inflammatory mechanism of Carica papaya roots aqueous extract.

Obesity-induced vascular inflammation involves elevated arginase activity

Obesity-induced vascular dysfunction involves pathological remodeling of the visceral adipose tissue (VAT) and increased inflammation. Our previous studies showed that arginase 1 (A1) in endothelial cells (ECs) is critically involved in obesity-induced vascular dysfunction. We tested the hypothesis that EC-A1 activity also drives obesity-related VAT remodeling and inflammation. Our studies utilized wild-type and EC-A1 knockout (KO) mice made obese by high-fat/high-sucrose (HFHS) diet. HFHS diet induced increases in body weight, fasting blood glucose, and VAT expansion. This was accompanied by increased arginase activity and A1 expression in vascular ECs and increased expression of tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), interleukin-10 (IL-10), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) mRNA and protein in both VAT and ECs. HFHS also markedly increased circulating inflammatory monocytes and VAT infiltration by inflammatory macrophages, while reducing reparative macrophages. Additionally, adipocyte size and fibrosis increased and capillary density decreased in VAT. These effects of HFHS, except for weight gain and hyperglycemia, were prevented or reduced in mice lacking EC-A1 or treated with the arginase inhibitor 2-(S)-amino-6-boronohexanoic acid (ABH). In mouse aortic ECs, exposure to high glucose (25 mM) and Na palmitate (200 μM) reduced nitric oxide production and increased A1, TNF-α, VCAM-1, ICAM-1, and MCP-1 mRNA, and monocyte adhesion. Knockout of EC-A1 or ABH prevented these effects. HFHS diet-induced VAT inflammation is mediated by EC-A1 expression/activity. Limiting arginase activity is a possible therapeutic means of controlling obesity-induced vascular and VAT inflammation.

The mechanism of cone cell death in Retinitis Pigmentosa

Retinitis Pigmentosa (RP) is a group of diseases in which one of a large number of mutations causes death of rod photoreceptors. After rods die, cone photoreceptors slowly degenerate in a characteristic pattern. The mechanism of rod cell death varies depending upon the gene that is mutated and the rate that rods degenerate is an important prognostic feature, because cones do not begin to degenerate until almost all rods have been eliminated. Rod cell death causes night blindness, but visual disability and blindness result from cone degeneration and therefore it is critical to determine the mechanisms by which it occurs. The death of rods reduces oxygen consumption resulting in high tissue levels of oxygen in the outer retina. The excess oxygen stimulates superoxide radical production by mismatches in the electron transport chain in mitochondria and by stimulation of NADPH oxidase activity in cytoplasm. The high levels of superoxide radicals overwhelm the antioxidant defense system and generate more reactive species including peroxynitrite which is extremely damaging and difficult to detoxify. This results in progressive oxidative damage in cones which contributes to cone cell death and loss of function because drugs or gene transfer that reduce oxidative stress promote cone survival and maintenance of function. Compared with aqueous humor samples from control patients, those from patients with RP show significant elevation of carbonyl content on proteins indicating oxidative damage and a reduction in the ratio of reduced to oxidized glutathione indicating depletion of a major component of the antioxidant defense system from ongoing oxidative stress. The first step in clinical trials will be to identify doses of therapeutic agents that reverse these biomarkers of disease to assist in design of much longer trials with functional and anatomic endpoints.

Inhibitory effect of Gardenblue blueberry (Vaccinium ashei Reade) anthocyanin extracts on lipopolysaccharide-stimulated inflammatory response in RAW 264.7 cells

Blueberries are a rich source of anthocyanins, which are associated with health benefits contributing to a reduced risk for many diseases. The present study identified the functional Gardenblue blueberry (Vaccinium ashei Reade) anthocyanin extracts (GBBAEs) and evaluated their capacity and underlying mechanisms in protecting murine RAW 264.7 cells from lipopolysaccharide (LPS)-stimulated inflammation in vitro. Enzyme-linked immunosorbent assay (ELISA) kit results showed that GBBAEs significantly inhibited the production of nitric oxide (NO), prostaglandin E2 (PGE2), interleukin-6 (IL-6), IL-1β, and interferon-γ (INF-γ). Real-time polymerase chain reaction (PCR) analysis indicated that the mRNA expression levels of IL-6, IL-1β, tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), and cyclooxygenase 2 (COX-2) were suppressed in LPS-stimulated RAW 264.7 cells. Additionally, Western blot analysis was used to evaluate the relative protein expression levels of COX-2 and nuclear factor-κB p65 (NF-κBp65). All these results suggested the potential use of GBBAEs as a functional food for the treatment of inflammatory diseases.

Inhibition of neuronal nitric oxide synthase activity does not alter vasopressin secretion in septic rats

BACKGROUND/PURPOSE

During the early phase of sepsis, hypotension is accompanied by increase of plasma vasopressin hormone (AVP) levels, which decline during the late phase. This hypotension is due in part to increase of nitric oxide (NO) synthesis by nitric oxide synthase (NOS) enzyme. Neuronal isoform of this enzyme (nNOS) is present in vasopressinergics neurons of hypothalamus, but its role in vasopressin secretion during sepsis is unknown.

METHODS

We evaluated the role of nNOS in NO production and vasopressin secretion during sepsis. Wistar rats received 7-nitroindazole (50 mg/kg, i.p.), an inhibitor of nNOS activity, or vehicle and were submitted to septic stimulus by cecal ligation and puncture (CLP). At the time points 0, 4, 6, 18 and 24 h after sepsis induction the animals were decapitated and neurohypophysis and hypothalamus were removed for analysis of vasopressin content and NOS activity, respectively. Hematocrit, serum sodium, osmolality, proteins and plasmatic AVP were quantified.

RESULTS

Mortality was not affected by 7-nitroindazole (7-NI). Sodium and plasma proteins levels decreased after CLP and the treatment anticipated the protein loss, and delayed serum sodium decrease. Septic animals treated with 7-NI showed decrease of osmolality 4 h after CLP. Nitric oxide synthase activity in hypothalamus increased at 4 and 24 h after CLP and was reduced with 7-NI. Neurohypophysis content of AVP diminished after CLP and 7-NI did not alter this parameter. Plasma AVP levels increased at 6 h and decreased 18 and 24 h after CLP. Treatment with 7-NI did not alter plasma vasopressin levels.

CONCLUSION

We concluded that nNOS does not have a substantial role in vasopressin secretion during experimental sepsis.

Cheongsangbangpung-tang ameliorated the acute inflammatory response via the inhibition of NF-κB activation and MAPK phosphorylation

Background

Cheongsangbangpung-tang (CBT) is a traditional herbal formula used in Eastern Asia to treat heat-related diseases and swellings in the skin. The present study was conducted to evaluate the anti-inflammatory effects of cheongsangbangpung-tang extract (CBTE) both in vitro and in vivo.

Methods

The in vitro effects of CBTE on the lipopolysaccharide (LPS)-induced production of inflammation-related proteins were examined in RAW 264.7 cells. The levels of nitric oxide (NO) were measured with the Griess reagent. Inflammatory cytokines and prostaglandin E₂ (PGE₂) were detected using the enzyme-linked immunosorbent assay (ELISA) method. Inflammation-related proteins were detected by Western blot. The effect of CBTE on acute inflammation in vivo was evaluated using carrageenan (CA)-induced paw oedema. To evaluate the anti-inflammatory effect, paw oedema volume, thickness of the dorsum and ventrum pedis skin, number of infiltrated inflammatory cells, and number of COX-2-, iNOS-immunoreactive cells were measured.

Results

In an in vitro study, CBTE inhibited the production of NO and PGE₂ and also decreased the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) activity, interleukin (IL)-1β, IL-6 and tumuor necrosis factor-α. In LPS-activated macrophages, nuclear factor-kappaB (NF-κB) and mitogen-activated protein kinase (MAPK) signalling is a pivotal pathway in the inflammatory process. These plausible molecular mechanisms increased the phosphorylation of I-κBα, while the activation of NF-κB and the phosphorylation of MAPK by LPS were blocked by CBTE treatment. In our in vivo study, a CA-induced acute oedematous paw inflammation rat model was used to evaluate the anti-inflammatory effect of CBTE. CBTE significantly reduced the increases in paw swelling, skin thicknesses, infiltrated inflammatory cells and iNOS-, COX-2 positive cells induced by CA injection.

Conclusions

Based on these results, CBTE should favourably inhibit the acute inflammatory response through modulation of NF-κB activation and MAPK phosphorylation. Furthermore, the inhibition of CBTE in rat paw oedema induced by CA is considered to be clear evidence that CBTE may be a useful source to treat inflammation.

Protective vascular effects of quercitrin in acute TNBS-colitis in rats: the role of nitric oxide

Quercitrin (quercetin 3-rhamnoside) is a bioflavonoid with anti-inflammatory activity in experimental colitis.

Effect of Aminoguanidine in Ligature-induced Periodontitis in Rats

The role of nitric oxide and reactive oxygen species is well-demonstrated in inflammation. In this study, we evaluated the effect of aminoguanidine, a nitric oxide synthase inhibitor, in a rat model of periodontitis. We induced periodontitis in rats by placing a piece of 2/0 braided silk around the lower left 1st molar. At day 8, the gingivomucosal tissue encircling the mandibular 1st molar was removed for biochemical and histological analysis. Ligation significantly increased inducible nitric oxide synthase activity and expression, and damaged tissue revealed increased neutrophil infiltration, lipid peroxidation, and positive staining for nitrotyrosine formation and poly (ADP-ribose) polymerase activation. Ligation significantly increased Evans blue extravasation in gingivomucosal tissue and alveolar bone destruction. Aminoguanidine (100 mg/kg i.p., daily for 8 days) treatment significantly reduced all these inflammatory parameters, indicating that it protects against the tissue damage associated with periodontitis by reducing nitric oxide production and oxidative stress.

The Role of Inducible-Nitric Oxide in Cocaine-Induced Kindling

Experimentally naive male Sprague Dawley rats (weighing 85–110 g) were used to examine the role of inducible nitric oxide synthase (iNOS) in cocaine-induced kindling. Repeated administration of cocaine (45 mg/kg, ip) to Sprague Dawley male rats for 7 consecutive days produced a progressive increase in the Convulsive responsiveness and death. Pretreatment with iNOS inhibitors, L-N6-(1-iminoethyl)lysine (NIL; 10 mg/kg, ip) and (–)-ePigalloocatechin gallate (EGCG; 10 mg/kg, ip) 30 min before cocaine (45 mg/kg, ip) administration for 7 days attenuated the development of cocaine kindling and blocked cocaine-induced death. Results of NMDA receptor binding assay in the hippocampus showed a significant increase in the affinity without changes in the density in animals treated with cocaine, but there were no changes in these parameters in the cortex. Pretreatment with NIL or EGCG prior to cocaine administration abolished the cocaine-induced effect in the NMDA receptor affinity in the hippocampus. These results suggest that iNOS induction followed by an increase of NMDA receptor affinity in the hippocampus after repeated exposure to cocaine may participate in the process of the development of cocaine kindling.

Effects of radiodetoxified endotoxin on nitric oxide production in J774 macrophages and in endotoxin shock

Radiodetoxified lipopolysaccharide (RD-LPS) is a 60Co-gamma-irradiated LPS with a modified structure, which decreases its toxic effects. To obtain a better understanding of the mechanism of the reduced toxicity of RD-LPS, here we studied the effect of RD-LPS on the regulation of nitric oxide (NO) production in vitro and in vivo. In control cells, stimulation by native LPS (10 μg/ml) induced the expression of the inducible NO synthase (iNOS) and production of NO, as measured by increase in the concentration of nitrite, breakdown product of NO. Pre-exposure of the cells for 24 h to a subthreshold concentration of RD-LPS (10 ng/ml) induced a complete desensitization to the LPS-induced NO production in comparison to control cells (P < 0.01). On the contrary, pre-exposure of the cells with native LPS (10 ng/ml) did not reduce LPS-induced NO synthesis. RD-LPS induced a smaller production of tumor necrosis factor (TNF) than native LPS, but did not induce a desensitization against subsequent LPS-induced TNF synthesis. ln in vivo studies, pretreatment of rats with repeated doses of sublethal RD-LPS (1 mg/kg/day i.p. for 4 days) inhibited increase of plasma nitrate/nitrite levels, NO production in peritoneal macrophages ex vivo and induction of lung iNOS activity, in response to a high-dose LPS challenge (15 mg/kg i.p.) given at the fifth day. Pretreatment with repeated sublethal doses of the native LPS (1 mg/kg/day i.p.) did not affect NO production in rats subjected to endotoxic shock. The results demonstrate that RD-LPS induces tolerance to the stimulatory effect of LPS on NO synthesis. Suppression of iNOS induction was only observed with RD-LPS, but not with native LPS in the models used herein. It remains to be further investigated whether suppression of iNOS induction by RD-LPS contributes to the protective effects of this compound in shock and inflammation.

Vitamin K3 inhibits mouse uterine contraction in vitro via interference with the calcium transfer and the potassium channels

Previous studies have demonstrated vitamin K3 had a great relief to smooth muscle spastic disorders, but no researches have yet pinpointed its possible anti-contractile activity in the uterus. Here, we evaluated the effect of vitamin K3 on myometrial contractility and explored the possible mechanisms of vitamin K3 action. Myograph apparatus were used to record the changes in contractility of isolated mouse uterine strips in a tissue bath. Uterine strips were exposed to vitamin K3 or vehicle. Vitamin K3 suppressed spontaneous contractions in a concentration dependent manner. It significantly decreased the contractile frequency induced by PGF2ɑ but not their amplitude (expect 58.0 μM). Prior incubation with vitamin K3 reduced the effectiveness of PGF2ɑ-induced contraction. The antispasmodic effect of vitamin K3 was also sensitive to potassium channel blockers, such as tetraethylammonium, 4-aminopyridine, iberiotoxin) but not to the nitric oxide related pathway blockers. High concentrations (29.0, 58.0 μM) of vitamin K3 weakened the Ca(2+) dose response and inhibited phase 1 contraction (intracellular stored calcium release). These dates suggest that vitamin K3 specifically suppresses myometrial contractility by affecting calcium and potassium channels; thus, this approach has potential therapy for uterine contractile activity related disorders.

Interactions between apelin and angiotensin II on rat portal vein

Apelin (AP), an endogenous ligand of the APJ receptor, is involved in the regulation of cardiovascular homeostasis. Regardless the multiple similarities between AP and angiotensin II (Ang II), their roles seem to be different. We studied both the interactions between Apelin 13 (AP13) and Ang II and to what extent, if any, nitric oxide (NO) is involved.The experiments were performed in endothelium-denuded or endothelium-intact rat portal vein in the presence of 10 µM N(G)-nitro L-arginine methyl ester or 10 µM aminoguanidine. AP13 did not modify the isolated rat portal vein tone by itself, but inhibited the Ang II-induced contractions acting mainly by a NO-dependent mechanism. Our results sustain the hypothesis that AP13 could increase the activity of both constitutive and inducible NO synthase on either endothelium intact or endothelium denuded rat portal vein rings.

Inhibitory effects of Persicariae Rhizoma aqueous extracts on experimental periodontitis and alveolar bone loss in Sprague-Dawley rats

Persicariae Rhizoma (PR) is the dried stem parts of Persicaria tinctoria H. Gross (Polygonaceae), and has been traditionally used as anti-inflammatory and detoxifying agent. In the present study, the effects of PR aqueous extracts on ligation-induced experimental periodontitis (EPD) and associated alveolar bone loss in rats were examined. Following the induction of EPD in rats, PR extracts were orally administered once a day for 10 days, and the changes and gains in body weight, alveolar bone loss and total aerobic bacterial counts of buccal gingiva were observed with histopathological analysis. In addition, anti-inflammatory effects were evaluated by monitoring myeloperoxidase (MPO) activities, and interleukin (IL)-1β and tumor necrosis factor (TNF)-α contents, and anti-oxidant effects were investigated by measuring inducible nitric oxide synthase (iNOS) activities and malondialdehyde (MDA) levels. Bacterial proliferation, periodontitis and associated alveolar bone loss induced by ligature placement were significantly and dose-dependently inhibited by the treatment with PR extracts. The inhibitory effects of 200 mg/kg PR were similar to those of 5 mg/kg indomethacin on ligation-induced periodontitis and associated alveolar bone losses in this study. The results suggest that PR effectively inhibits ligature placement-induced periodontitis and alveolar bone loss in rats via antibacterial, antioxidative and anti-inflammatory activities.

Macrophages and inflammatory mediators in pulmonary injury induced by mustard vesicants

Sulfur mustard (SM) and nitrogen mustard (NM) are cytotoxic alkylating agents that cause severe and progressive injury to the respiratory tract, resulting in significant morbidity and mortality. Evidence suggests that macrophages and the inflammatory mediators they release play roles in both acute and long-term pulmonary injuries caused by mustards. In this article, we review the pathogenic effects of SM and NM on the respiratory tract and potential inflammatory mechanisms contributing to this activity.

Anti-inflammatory effects of Viola yedoensis and the application of cell extraction methods for investigating bioactive constituents in macrophages

BACKGROUND

Viola yedoensis (VY, Violaceae) is a popular medicinal herb used in traditional eastern medicine for treating lots of diseases, including inflammation and its related symptoms. However, the anti-inflammatory properties of VY have not been demonstrated. In the present study, we investigated the anti-inflammatory effects of VY ethanol extract (VYE) on macrophages and attempted to identify the bioactive components of VYE.

METHODS

We assessed the effects of VYE on secretion of nitric oxide (NO) and inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β. In addition, we explored the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, and changes in heme oxygenase (HO)-1, nuclear factor (NF)-kB, and mitogen-activated protein kinase (MAPK) signaling pathways in RAW 264.7 macrophages stimulated by lipopolysaccharide (LPS). In addition, a rapid and useful approach to identify potential bioactive components in VYE with anti-inflammatory effects was developed using murine macrophage cell extraction coupled with high-performance liquid chromatography tandem mass spectrometry (LC-MS).

RESULTS

We found that VYE exerted anti-inflammatory activity by inhibiting the production of key inflammation mediators and related products, as well as suppression of HO-1, NF-kB, and MAPK signaling pathway activation in RAW 264.7 cells. In addition, we identified two compounds in VYE via the cell extraction method.

CONCLUSIONS

Our results revealed that VYE exerts anti-inflammatory activities and its detailed inhibitory mechanism in macrophages. Furthermore, we identified bioactive components of VYE.

The Effects of Topical Application of Polycal (a 2:98 (g/g) Mixture of Polycan and Calcium Gluconate) on Experimental Periodontitis and Alveolar Bone Loss in Rats

The aim of this study was to observe whether Polycal has inhibitory activity on ligation-induced experimental periodontitis and related alveolar bone loss in rats following topical application to the gingival regions. One day after the ligation placements, Polycal (50, 25, and 12.5 mg/mL solutions at 200 μL/rat) was topically applied to the ligated gingival regions daily for 10 days. Changes in bodyweight, alveolar bone loss index, and total number of buccal gingival aerobic bacterial cells were monitored, and the anti-inflammatory effects were investigated via myeloperoxidase activity and levels of the pro-inflammatory cytokines IL-1β and TNF-α. The activities of inducible nitric oxide synthase (iNOS) and lipid peroxidation (MDA) were also evaluated. Bacterial proliferation, periodontitis, and alveolar bone loss induced by ligature placements were significantly inhibited after 10 days of continuous topical application of Polycal. These results indicate that topical application of Polycal has a significant inhibitory effect on periodontitis and related alveolar bone loss in rats mediated by antibacterial, anti-inflammatory, and anti-oxidative activities.

Anti‑inflammatory and antioxidant activity of the traditional herbal formula Gwakhyangjeonggi‑san via enhancement of heme oxygenase‑1 expression in RAW264.7 macrophages

Gwakhyangjeonggi‑san (GHJGS) is a mixture of herbal plants, including Agastache rugosa, Perilla frutescens, Angelica dahurica, Areca catechu, Poria cocos, Magnolia officinalis, Atractylodes macrocephala, Citrus reticulata, Pinellia ternata, Platycodon grandiflorum, Glycyrrhiza uralensis, Ziziphus jujuba and Zingiber officinale. GHJGS has been used for treating diarrhea‑predominant irritable bowel syndrome in traditional Korean medicine. In the present study, the anti‑inflammatory and antioxidant effects of GHJGS were investigated using the RAW 264.7 murine macrophage cell line. GHJGS significantly reduced production of the proinflammatory cytokines, tumor necrosis factor‑α, interleukin‑6 and prostaglandin E2 in lipopolysaccharide (LPS)‑stimulated macrophages. GHJGS markedly suppressed LPS‑induced phosphorylation of mitogen‑activated protein kinases, whereas it had no effect on nuclear factor‑κB activation. Furthermore, GHJGS enhanced expression of heme oxygenase‑1 and prevented the generation of reactive oxygen species in RAW 264.7 cells. These results indicate that GHJGS is a viable therapeutic agent against inflammation and oxidative stress‑associated disorders.

Inhibition of Nitric Oxide Synthase 1 Induces Salt-Sensitive Hypertension in Nitric Oxide Synthase 1α Knockout and Wild-Type Mice

We recently showed that α, β, and γ splice variants of neuronal nitric oxide synthase (NOS1) expressed in the macula densa and NOS1β accounts for most of the NO generation. We have also demonstrated that the mice with deletion of NOS1 specifically from the macula densa developed salt-sensitive hypertension. However, the global NOS1 knockout (NOS1KO) strain is neither hypertensive nor salt sensitive. This global NOS1KO strain is actually an NOS1αKO model. Consequently, we hypothesized that inhibition of NOS1β in NOS1αKO mice induces salt-sensitive hypertension. NOS1αKO and C57BL/6 wild-type (WT) mice were implanted with telemetry transmitters and divided into 7-nitroindazole (10 mg/kg/d)-treated and nontreated groups. All of the mice were fed a normal salt (0.4% NaCl) diet for 5 days, followed by a high-salt diet (4% NaCl). NO generation by the macula densa was inhibited by >90% in WT and NOS1αKO mice treated with 7-nitroindazole. Glomerular filtration rate in conscious mice was increased by ≈ 40% after a high-salt diet in both NOS1αKO and WT mice. In response to acute volume expansion, glomerular filtration rate, diuretic and natriuretic response were significantly blunted in the WT and knockout mice treated with 7-nitroindazole. Mean arterial pressure had no significant changes in mice fed a high-salt diet, but increased ≈ 15 mm Hg similarly in NOS1αKO and WT mice treated with 7-nitroindazole. We conclude that NOS1β, but not NOS1α, plays an important role in control of sodium excretion and hemodynamics in response to either an acute or a chronic salt loading.