Regulation of the expression of the inducible isoform of nitric oxide synthase

Revealing the biological mechanism of acupuncture in alleviating excessive inflammatory responses and organ damage in sepsis: a systematic review

Sepsis is a systemic inflammation caused by a maladjusted host response to infection. In severe cases, it can cause multiple organ dysfunction syndrome (MODS) and even endanger life. Acupuncture is widely accepted and applied in the treatment of sepsis, and breakthroughs have been made regarding its mechanism of action in recent years. In this review, we systematically discuss the current clinical applications of acupuncture in the treatment of sepsis and focus on the mechanisms of acupuncture in animal models of systemic inflammation. In clinical research, acupuncture can not only effectively inhibit excessive inflammatory reactions but also improve the immunosuppressive state of patients with sepsis, thus maintaining immune homeostasis. Mechanistically, a change in the acupoint microenvironment is the initial response link for acupuncture to take effect, whereas PROKR2 neurons, high-threshold thin nerve fibres, cannabinoid CB2 receptor (CB2R) activation, and Ca2+ influx are the key material bases. The cholinergic anti-inflammatory pathway of the vagus nervous system, the adrenal dopamine anti-inflammatory pathway, and the sympathetic nervous system are key to the transmission of acupuncture information and the inhibition of systemic inflammation. In MODS, acupuncture protects against septic organ damage by inhibiting excessive inflammatory reactions, resisting oxidative stress, protecting mitochondrial function, and reducing apoptosis and tissue or organ damage.

Comprehensive Characterization of Lignans from Forsythia viridissima by UHPLC-ESI-QTOF-MS, and Their NO Inhibitory Effects on RAW 264.7 Cells

Lignans are known to be an important class of phenylpropanoid secondary metabolites. In the course of our studies on the chemodiversity of lignans, the necessity arose to develop a method for the fast detection and identification of bioactive lignan subclasses. In this study, we detected 10 lignan derivatives of different extracts of F. viridissima by UHPLC-ESI-QTOF-MS. Lignan glycosides (1 and 2), lignans (3 and 4), and lignan dimers (5-10) were identified by analysis of their exact masses and MS^e spectra along with the characteristic mass fragmentation patterns and molecular formulas. We further investigated NO inhibitory effects of F. viridissima fractions and their major lignan derivatives to evaluate those anti-inflammatory effects. The methylene chloride fraction of F. viridissima as well as compounds 8 and 10 showed potent dose-dependent NO inhibitory effects on RAW 264.7 cells. Corresponding to the NO inhibition by compounds 8 and 10, lipopolysaccharide (LPS)-induced inducible nitric oxide synthase (iNOS) expression was notably reduced by both compounds. Our combined data with the bioactive results and the component analysis by UHPLC-ESI-QTOF-MS suggest that the methylene chloride fraction of F. viridissima roots could be potential anti-inflammatory agents and these are related to major lignans including dimeric dibenzylbutyrolactone lignans.

Possible Involvement of Nitric Oxide and Peroxynitrite in Nasal Polyposis

Background

Nitric oxide (NO) is implicated in inflammation. Its role in the pathogenesis of nasal polyposis is not clear.

Methods

The expression of inducible NO synthase (iNOS), and the production of peroxynitrite represented by the formation of 3-nitrotyrosine (3-NT) were examined by immunohisto-chemistry in nasal polyps. The contents of superoxide dismutases (SODs) in nasal polyps and nasal mucosa were assessed by Western blot analyses.

Results

iNOS expression and 3-NT accumulation were noted in mucosal epithelium, vascular endothelium, and interstitial cells of nasal polyps. In comparison with our previous study on the nasal mucosa from patients with rhinitis, the stromal cells of the nasal polyp had higher labeling intensity for both iNOS and 3-NT. The polyp showed similar levels of CuZnSOD and MnSOD as those of nasal mucosa.

Conclusions

The iNOS/NO system may be important in the pathophysiology of nasal polyposis. The increased peroxynitrite may result from increased iNOS expression but is not related to decreased SODs.

c-Jun N-terminal kinase-mediated anti-inflammatory effects of Garcinia subelliptica in macrophages

Garcinia plants have been traditionally used to treat inflammatory diseases, such as skin infections and pain, in many regions including South‑East Asia. Garcinia subelliptica, a plant of the Garcinia species widely distributed from Japan to Thailand, has been reported to contain components similar to other Garcinia plants that exhibit anti‑inflammatory effects. The present study aimed to explore the anti‑inflammatory effects of ethanol extracts of Garcinia subelliptica (EGS) in macrophages, as there are no previous systemic studies that have investigated the effects of Garcinia subelliptica on inflammation. Non‑cytotoxic concentrations of EGS (≤200 µg/ml) were observed to reduce nitric oxide production by modulating iNOS expression in lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages. The expression of cyclooxygenase‑2, the enzyme responsible for the production of prostaglandin E2, was notably reduced by EGS. EGS treatment inhibited the production of pro‑inflammatory cytokines, including IL‑6 and IL‑1β, however, not TNF‑α. Reduced production of inflammatory mediators by EGS was followed by reduced phosphorylation of c‑Jun N‑terminal kinase (JNK) however, not of other mitogen‑activated protein kinases and nuclear factor‑κB. These results indicate that EGS selectively inhibits the excessive production of inflammatory mediators in LPS‑stimulated murine macrophages by reducing the activation of JNK, suggesting that EGS is a candidate for modulating severe inflammation.

Anti-inflammatory effects of Crataeva nurvala Buch. Ham. are mediated via inactivation of ERK but not NF-κB

ETHNOPHARMACOLOGICAL RELEVANCE

Crataeva nurvala Buch. Ham. is an important medicinal plant in India, and its extracts and components were used to treat various inflammatory diseases, such as urinary tract infection, rheumatoid arthritis, and colitis. However, no systemic studies about anti-inflammatory effects of Crataeva nurvala Buch. Ham. and its underlying mechanisms of action have been reported. This study aimed to explore the anti-inflammatory effects of ethanol extracts of Crataeva nurvala Buch. Ham. (ECN).

MATERIALS AND METHODS

The non-cytotoxic and maximal effective concentration of ECN was determined by measuring the formation of formazan from water-soluble tetrazolium salt in living cells. The inhibitory effect of ECN on nitric oxide (NO) synthesis was measured using Griess reagent, and Enzyme-linked immunosorbent assay (ELISA) was used to measure secreted tumor necrosis factor (TNF)-α and interleukin (IL)-6 protein levels. Furthermore, reverse transcription polymerase chain reaction (RT-PCR) and Western blotting analysis were used to assess the mRNA and protein expression of each inflammatory mediator or relating signaling protein, respectively.

RESULTS

A non-cytotoxic concentration of ECN (≤200 μg/ml) significantly reduced the production of NO and IL-6, but not TNF-α, in lipopolysaccharides (LPS)-stimulated RAW 264.7 macrophages. Decreased production of NO by ECN was correlated with reduced expression of iNOS at the mRNA and protein levels. However, cyclooxygenase (COX)-2 expressions at mRNA and protein level were not regulated by ECN. The mRNA expression of IL-6 and IL-1β, but not TNF-α, was also inhibited by ECN treatment in LPS-stimulated RAW 264.7 macrophages. Reduced production of inflammatory mediators by ECN was followed by decreased activity of mitogen-activated protein kinases (MAPKs), especially extracellular signal-regulated kinase (ERK), but not nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB).

CONCLUSIONS

These results indicate that ECN inhibits LPS-induced inflammatory responses via negative regulation of ERK in murine macrophages, suggesting that ECN is a candidate for alleviating severe inflammation.

Methanol extracts of Euphorbia cooperi inhibit the production of inflammatory mediators by inhibiting the activation of c‑Jun N‑terminal kinase and p38 in murine macrophages

Numerous Euphorbiaceae plants have been used for the treatment of diseases, including liver diseases, asthma and rheumatism. The present study evaluated the effect of methanol extracts from Euphorbia cooperi (MEC), a member of the Euphorbiaceae plant family, on the production of inflammatory cytokines interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α, nitric oxide (NO) as well as the activation of mitogen‑activated protein kinase and nuclear factor (NF)‑κB signaling. Non‑cytotoxic concentrations of MEC significantly reduced the production of NO and IL‑6, but not TNF‑α, in lipopolysaccharide (LPS)‑stimulated RAW 264.7 macrophages. The decreased production of NO by MEC was due to alleviated expression of inducible NO synthase. Reporter assays with cells treated with MEC demonstrated reduced activator protein‑1 (AP-1) activity, while NF‑κB activity was not reduced. Furthermore, the phosphorylation levels of c‑Jun N‑terminal kinase (JNK) and p38 were suppressed by MEC while phosphorylation levels of inhibitor of κB were not reduced by MEC, suggesting that MEC‑mediated inactivation of JNK and p38 is the underlying regulatory mechanism for inflammatory mediators in LPS‑stimulated RAW 264.7 macrophages.

Therapeutic applications of PARP inhibitors: anticancer therapy and beyond

The aim of this article is to describe the current and potential clinical translation of pharmacological inhibitors of poly(ADP-ribose) polymerase (PARP) for the therapy of various diseases. The first section of the present review summarizes the available preclinical and clinical data with PARP inhibitors in various forms of cancer. In this context, the role of PARP in single-strand DNA break repair is relevant, leading to replication-associated lesions that cannot be repaired if homologous recombination repair (HRR) is defective, and the synthetic lethality of PARP inhibitors in HRR-defective cancer. HRR defects are classically associated with BRCA1 and 2 mutations associated with familial breast and ovarian cancer, but there may be many other causes of HRR defects. Thus, PARP inhibitors may be the drugs of choice for BRCA mutant breast and ovarian cancers, and extend beyond these tumors if appropriate biomarkers can be developed to identify HRR defects. Multiple lines of preclinical data demonstrate that PARP inhibition increases cytotoxicity and tumor growth delay in combination with temozolomide, topoisomerase inhibitors and ionizing radiation. Both single agent and combination clinical trials are underway. The final part of the first section of the present review summarizes the current status of the various PARP inhibitors that are in various stages of clinical development. The second section of the present review summarizes the role of PARP in selected non-oncologic indications. In a number of severe, acute diseases (such as stroke, neurotrauma, circulatory shock and acute myocardial infarction) the clinical translatability of PARP inhibition is supported by multiple lines of preclinical data, as well as observational data demonstrating PARP activation in human tissue samples. In these disease indications, PARP overactivation due to oxidative and nitrative stress drives cell necrosis and pro-inflammatory gene expression, which contributes to disease pathology. Accordingly, multiple lines of preclinical data indicate the efficacy of PARP inhibitors to preserve viable tissue and to down-regulate inflammatory responses. As the clinical trials with PARP inhibitors in various forms of cancer progress, it is hoped that a second line of clinical investigations, aimed at testing of PARP inhibitors for various non-oncologic indications, will be initiated, as well.

Inflammation and the pathophysiology of Alzheimer's disease

There is increasing evidence that a chronic inflammatory response in the brain in Alzheimer's disease (AD) ultimately leads to neuronal injury and cognitive decline. Microglia, the primary immune effector cells of the brain, are thought to be key to this process. This paper discusses the evidence for inflammation in AD, and describes the mechanism whereby microglia generate neurotoxic cytokines, reactive oxygen species, and nitric oxide. Evidence that the cytokine macrophage colony-stimulating factor (M-CSF) is an important cofactor in microglial activation in AD is presented. Ongoing work using organotypic hippocampal expiant cultures to model the inflammatory process in the AD brain is also discussed. Potential avenues for therapeutic intervention are outlined.

In Vitro and in Vivo Therapeutics of β-Thujaplicin on Lps-Induced Inflammation in Macrophages and Septic Shock in Mice

β-thujaplicin, an active constituent from Chamaecyparis obtusa, has been shown to have acaricidal and antimicrobial effects. Very few studies have focused on the potential of the anti-inflammatory effect of β-thujaplicin. Moreover, its capability of inhibiting inflammatory mediators e.g. TNF-α gene transcription, nitric oxide (NO) and prostaglandin E2, remains unknown. Besides those molecular mechanisms behind the anti-inflammatory effect of β-thujaplicin, solid proof of its effectiveness in vivo has not yet been studied. In our study, in vitro effects of β-thujaplicin were verified on RAW 264.7 macrophages which were stimulated by LPS. Indomethacin was used as a positive control. The inducible NO production after stimulation was measured by Griess reagent. PGE2, IL-6 and TNF-α were measured by ELISA methods. Protein expressions of iNOS, COX2, and NF-κB were evaluated by Western blotting. Septic ICR mice were administered 20 mg/kg of LPS and then the mortality rate was monitored. Within the concentration range which was devoid of cytotoxicty, β-thujaplicin exhibited a clear dose-dependent inhibition on LPS-induced NO production. Furthermore, β-thujaplicin inhibited LPS-induced PGE2, IL-6, and TNF-α production as well as iNOS, COX2, and NF-κB protein expression more substantially potent than indomethacin. In agreement with the in vitro study, β-thujaplicin was shown to be effective in vivo for inhibiting LPS-induced NO and TNF-α production and a significant decrease in mortality rate of mice suffering from septic shock was observed. This study demonstrates the potential of β-thujaplicin in treatment of inflammation and sepsis. These effects occur through an efficient blockage of TNF-α and iNOS production, β-thujaplicin efficacy is comparable to that of indomethacin thus it can be a substitution but bear less depletion of PGE2, making this compound very promising in clinical applications.

A molecular pharmacology study into the anti-inflammatory actions of Euphorbia hirta L. on the LPS-induced RAW 264.7 cells through selective iNOS protein inhibition

Euphorbia hirta L. has been widely used in India and Chinese society. The molecular pharmacology basis of its anti-inflammatory effect is revealed in this work. The ethanol extract of Euphorbia hirta L. (Eh) and its active component were studied in lipopolysaccharide (LPS)-activated macrophage cells (RAW 264.7) as an established inflammation model. After activation, nitric oxide (NO) production and expression of iNOS protein and iNOS mRNA were measured by using a colorimetric assay (Griess reagent), western blotting, and reverse transcription polymerase chain reaction (RT-PCR), respectively. The alteration in the content of PGE(2), TNFalpha, and IL-6 was concurrently monitored by ELISA. In results, we found that in the concentration range without showing cytotoxicity, Eh produced a remarkable anti-inflammatory effect via its active component of beta-amyrin and showed a dose-related inhibition of LPS-induced NO production. This phenomenon is in accordance with a substantial inhibition of iNOS protein. However, the expression of iNOS gene was unaffected by Eh treatments. Compared with indomethacin, Eh has much more potency and a specific action of NO inhibition but Eh works less specifically on PGE(2), IL-6, and TNF-alpha inhibition. The extract of Euphorbia hirta L. and its component beta-amyrin are able to block most of the iNOS protein functions and NO induction, and could therefore be new selective NO inhibitors with great potential in treating arthritis inflammation.

Nitric oxide synthase isoforms play distinct roles during acute peritonitis

Background. Acute peritonitis is the most frequent complication of peritoneal dialysis (PD). Increased nitric oxide (NO) release by NO synthase (NOS) isoforms has been implicated in acute peritonitis, but the role played by the NOS isoforms expressed in the peritoneum is unknown.

Methods. We investigated the structural and functional consequences of acute peritonitis induced by LPS in wild-type (WT) mice versus knockout mice (KO) for the endothelial NOS (eNOS), the inducible NOS (iNOS) or the neuronal NOS (nNOS).

Results. The level of NO metabolites (NOx) in the dialysate was maximal 18 h after LPS injection. LPS induced a significant increase in the transport of small solutes and decreased ultrafiltration in WT mice. These changes, which occurred without vascular proliferation, were paralleled by the upregulation of nNOS and eNOS, and the induction of iNOS. The transport modifications induced by LPS were significantly reversed in eNOS KO mice, but not modified in mice lacking iNOS or nNOS. In contrast, the increase of dialysate NOx was abolished in iNOS KO mice and significantly reduced in eNOS KO mice, but left unchanged in mice lacking nNOS. Mice lacking iNOS also showed more severe inflammatory changes, and a trend towards increased mortality following LPS.

Conclusion. These data demonstrate specific roles for NOS isoforms in the peritoneal membrane and suggest that selective eNOS inhibition may improve peritoneal transport during acute peritonitis.

Anti-nociceptive and anti-inflammatory effects of Angelicae dahuricae radix through inhibition of the expression of inducible nitric oxide synthase and NO production

The extract of Angelicae dahuricae radix has traditionally been used as an anti-noceptive remedy in China. In this study, the methanol extract of Angelicae dahuricae radix (MEAD) was evaluated to determine if it has anti-noceptive and anti-inflammatory action. The anti-nociceptive activities of MEAD were evaluated by determining the writhing response and sleeping time, as well as by a formalin test. In addition, the anti-inflammatory activities of MEAD were evaluated by a vascular permeability test as well as by measuring the carrageenan-induced paw edema and conducting a myeloperoxidase (MPO) assay. MEAD (600 and 1200 mg/kg) exhibited anti-inflammatory effects on acetic acid-induced vascular permeability, carrageenan-induced paw edema, and MPO activity. Moreover, the results of the formalin test, the acetic acid-induced writhing response and the pentobarbital-induced sleeping time indicated that MEAD had anti-nociceptive effects that occurred in a concentration-dependent manner. To determine the mechanism by which MEAD exerted its effects on the expression of inducible nitric oxide synthase (iNOS) and the production of nitric oxide (NO) by treated murine macrophage RAW 264.7 cells was evaluated. Similar to the in vivo activities, both the iNOS expression and NO production were significantly suppressed by MEAD in a dose-dependent manner. Furthermore, MEAD inhibited the activating phosphorylation of ERK1/2. These results provide a scientific basis that explains the mechanism by which Angelicae dahuricae radix relieves inflammatory pain.

Neuroprotective effect of aminoguanidine on iron-induced neurotoxicity

Iron is a commonly used metal to induce neuronal hyperactivity and oxidative stress. Iron levels rise in the brain in some neurodegenerative disorders such as Parkinson's and Alzheimer's diseases. A body of evidence indicates a link between neuronal death and nitric oxide. The present study was performed to investigate whether nitric oxide produced by inducible nitric oxide synthase is involved in iron-induced neuron death. For this purpose rats were divided into four groups: control, iron, aminoguanidine and iron+aminoguanidine. Animals in iron and iron+aminoguanidine groups received intracerebroventricular FeCl3 injection (200 mM, 2.5 microl). Rats belonging to control and aminoguanidine groups received the same amount of saline into the cerebral ventricles. All animals were kept alive for 10 days following the operation and animals in aminoguanidine and iron+aminoguanidine groups received intraperitoneal aminoguanidine injections once a day (100mg/kg day) during this period. After 10 days, rats were perfused intracardially under deep urethane anesthesia. Removed brains were processed using the standard histological techniques. The total numbers of neurons in hippocampus of all rats were estimated with the unbiased stereological techniques. It was found that aminoguanidine decreased mean neuron loss from 43.4% to 20.3%. Results of the present study suggest that aminoguanidine may attenuate the neurotoxic effects of iron by inhibiting inducible nitric oxide synthase.

Anti-inflammatory activity of c-phycocyanin in lipopolysaccharide-stimulated RAW 264.7 macrophages

C-phycocyanin (C-PC), found in blue green algae, is often used as a dietary nutritional supplement. C-PC has been found to have an anti-inflammatory activity and exert beneficial effect in various diseases. However, little is known about its mechanism of action. Overproduction of nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) plays an important role in the pathogenesis of inflammation. The aim of this study was to determine whether C-PC inhibits production of nitrite, an index of NO, and iNOS expression in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. Our results indicated that C-PC significantly inhibited the LPS-induced nitrite production and iNOS protein expression accompanied by an attenuation of tumor necrosis factor-alpha (TNF-alpha) formation but had no effect on interleukin-10 production in macrophages. Furthermore, C-PC also suppressed the activation of nuclear factor-kappaB (NF-kappaB) through preventing degradation of cytosolic IkappaB-alpha in LPS-stimulated RAW 264.7 macrophages. Thus, the inhibitory activity of C-PC on LPS-induced NO release and iNOS expression is probably associated with suppressing TNF-alpha formation and nuclear NF-kappaB activation, which may provide an additional explanation for its anti-inflammatory activity and therapeutic effect.

Acupuncture stimulation of ST36 (Zusanli) attenuates acute renal but not hepatic injury in lipopolysaccharide-stimulated rats

BACKGROUND

We sought to determine the effects of ST36 acupuncture on sepsis-induced kidney and liver injuries.

METHODS

A total of 120 rats were randomized into 10 groups: 1) lipopolysaccharide (LPS), 2) normal saline (N/S), 3) LPS + ST36, 4) ST36, 5) LPS + P-ST36, 6) P-ST36, 7) LPS + Sham, 8) Sham, 9) LPS + P-Sham, and 10) P-Sham groups. Rats in the LPS + ST36, ST36, LPS +Sham, and Sham groups received ST36 (designated as "ST36") or a nonacupoint (designated as "Sham") acupuncture for 30 min followed by LPS or N/S injection. Rats in the LPS + P-ST36, P-ST36, LPS + P-Sham, and P-Sham groups received LPS or N/S injection for 3 h followed by a 30 min of ST36 or a "nonacupoint" acupuncture. Rats were killed at 6 h after LPS injection.

RESULTS

LPS caused prominent kidney and liver injuries. The renal and hepatic nitric oxide (NO) concentrations and inducible NO synthase (iNOS) expression were also increased by LPS. ST36 acupuncture pretreatment significantly attenuated the LPS-induced kidney injury and the increases in renal NO concentration and iNOS expression. However, ST36 acupuncture pretreatment did not affect the LPS-induced liver injury and increases in hepatic NO concentration or iNOS expression. Furthermore, ST36 acupuncture performed after LPS did not affect the LPS-induced organ injuries or increases in NO concentration and iNOS expression.

CONCLUSIONS

ST36 acupuncture pretreatment significantly attenuated sepsis-induced kidney, but not liver, injury in rats, whereas ST36 acupuncture performed after sepsis induction had no protective effects against sepsis-induced organ injuries.

Effects of acute hypobaric hypoxia on the nitric oxide system of the rat cerebral cortex: Protective role of nitric oxide inhibitors

Exposure to hypobaric hypoxia produces neuropsychological disorders. The brain nitrergic system was investigated following hypobaric hypoxia in the presence or absence of nitric oxide synthase (NOS) inhibitors. Adult rats were exposed to a simulated altitude of 8325 m (27,000 ft) for 7 h and killed after 0, 1, 3, 5, and 10 days of recovery. In addition to normobaric controls, three experimental groups were studied: i) subjected to hypobaric hypoxia without inhibitors; ii) subjected to hypobaric hypoxia and treated with 7-nitroindazole; iii) subjected to hypobaric hypoxia and treated with N(omega)-nitro-l-arginine methyl ester (l-NAME). Cerebral cortex was assayed by immunohistochemistry, Western blotting, and enzymatic assays. In animals subjected to hypobaric hypoxia without inhibitors, there was an increase in neuronal nitric oxide synthase (nNOS) immunoreactivity and Ca(2+)-dependent NOS activity from 0 to 1 days of reoxygenation. In these animals, inducible nitric oxide synthase (iNOS) expression and Ca(2+)-independent activity were undetectable, but nitrotyrosine immunoreactivity was found in some neurons. Administration of either inhibitor prevented the increase in nNOS immunoreactivity and enzymatic activity provoked by hypobaric hypoxia. Concomitantly, nitrotyrosine immunoreactivity decreased progressively. In conclusion, activation of the nitrergic system constitutes a cortical response to hypobaric hypoxia and the administration of NOS inhibitors could provide new therapeutic avenues to prevent and/or treat the symptoms produced by hypobaric hypoxia.

Inhibitory effect of curcumin on nitric oxide production from lipopolysaccharide-activated primary microglia

Curcumin has been shown to exhibit anti-inflammatory, antimutagenic, and anticarcinogenic activities. However, the modulatory effect of curcumin on the functional activation of primary microglial cells, brain mononuclear phagocytes causing the neuronal damage, largely remains unknown. The current study examined whether curcumin influenced NO production in rat primary microglia and investigated its underlying signaling pathways. Curcumin decreased NO production in LPS-stimulated microglial cells in a dose-dependent manner, with an IC(50) value of 3.7 microM. It also suppressed both mRNA and protein levels of inducible nitric oxide synthase (iNOS), indicating that this drug may affect iNOS gene expression process. Indeed, curcumin altered biochemical patterns induced by LPS such as phosphorylation of all mitogen-activated protein kinases (MAPKs), and DNA binding activities of nuclear factor-kappaB (NF-kappaB) and activator protein (AP)-1, assessed by reporter gene assay. By analysis of inhibitory features of specific MAPK inhibitors, a series of signaling cascades including c-Jun N-terminal kinase (JNK), p38 and NF-kappaB was found to play a critical role in curcumin-mediated NO inhibition in microglial cells. The current results suggest that curcumin is a promising agent for the prevention and treatment of both NO and microglial cell-mediated neurodegenerative disorders.

Polyamine and aminoguanidine treatments to promote structural and functional recovery in the adult mammalian brain after injury: a brief literature review and preliminary data about their combined administration

The regeneration potential of the adult mammalian central nervous system (CNS) is very modest, due to, among other factors, the presence of either a glial scar, or myelin-associated regeneration inhibitors such as Nogo-A, MAG and OMgp, which all interact with the same receptor (NgR). After a brief review of the key proteins (Rho and PKC) implicated in NgR-mediated signalling cascades, we will tackle the implications of cAMP and Arginase I in overcoming myelin growth-inhibitory influence, and then will focus on the effects of polyamines and aminoguanidine to propose (and to briefly support this proposal by our own preliminary data) that their association might be a potent way to enable functionally-relevant regeneration in the adult mammalian CNS.

Suppression of inducible nitric oxide synthase and cyclooxygenase-2 expression in RAW 264.7 macrophages by sesquiterpene lactones

The molecular mechanism underlying the suppression of lipopolysaccharide (LPS)/interferon-gamma (IFN-gamma)-induced nitric oxide (NO) and prostaglandin (PG) E(2) production was investigated in RAW 264.7 macrophages treated with sesquiterpene lactones, zaluzanin-C and estafiatone, isolated from Ainsliaea. Zaluzanin-C and estafiatone decreased NO production in LPS/IFN-gamma-stimulated RAW 264.7 macrophages with an IC50 of about 6.61 microM and 3.80 microM, respectively. In addition, these compounds inhibited the synthesis of PGE(2) in LPS/IFN-gamma-treated RAW 264.7 macrophages. Furthermore, treatment with zaluzanin-C and estafiatone resulted in a decrease in inducible No Synthase (iNOS) and Cyclooxygenase-2 (COX-2) protein and mRNA expression levels. Zaluzanin-C and estafiatone inhibited nuclear factor-kappaB (NF-kappaB) activation, a transcription factor necessary for iNOS and COX-2 expression in response to LPS/IFN-gamma. This effect was accompanied by parallel reduction of phosphorylation and degradation of inhibitor of kappaB (IkB). In addition, these effects were completely blocked by treatment with cysteine, indicating that the inhibitory effect of zaluzanin-C and estafiatone might be mediated by alkylation of either NF-kappaB itself or an upstream molecule of NF-kappaB. These results demonstrate that the suppression of NF-kappaB activation by zaluzanin-C and estafiatone might be attributed to inhibition of nuclear translocation of NF-kappaB resulting from blockade of the degradation of IkappaB, leading to suppression of the expression of iNOS and COX-2, which play important roles in inflammatory signaling pathways.

New insights on brain stem death: From bedside to bench

As much as brain stem death is currently the clinical definition of death in many countries and is a phenomenon of paramount medical importance, there is a dearth of information on its mechanistic underpinnings. A majority of the clinical studies are concerned only with methods to determine brain stem death. Whereas a vast amount of information is available on the cellular and molecular mechanisms of cell death, rarely are these studies directed specifically towards the understanding of brain stem death. This review presents a framework for translational research on brain stem death that is based on systematically coordinated clinical and laboratory efforts that center on this phenomenon. It begins with the identification of a novel clinical marker from patients that is related specifically to brain stem death. After realizing that this "life-and-death" signal is related to the functional integrity of the brain stem, its origin is traced to the rostral ventrolateral medulla (RVLM). Subsequent laboratory studies on this neural substrate in animal models of brain stem death provide credence to the notion that both "pro-life" and "pro-death" programs are at work during the progression towards death. Those programs (mitochondrial functions, nitric oxide, peroxynitrite, superoxide anion, coenzyme Q10, heat shock proteins and ubiquitin-proteasome system) hitherto identified from the RVLM are presented, along with their cellular and molecular mechanisms. It is proposed that outcome of the interplay between the "pro-life" and "pro-death" programs (dying) in this neural substrate determines the final fate of the individual (being dead). Thus, identification of additional programs in the RVLM and delineation of their regulatory mechanisms should shed new lights on future directions for clinical management of life-and-death.

Inhibitory effects of a fermented ginseng extract, BST204, on the expression of inducible nitric oxide synthase and nitric oxide production in lipopolysaccharide-activated murine macrophages

In this study, the effects of BST204, a fermented ginseng extract, on the expression of inducible nitric oxide synthase (iNOS) and nitric oxide (NO) production are looked into. Crude ginseng extract was incubated with ginsenoside-beta-glucosidase to prepare BST204. BST204, unlike lipopolysaccharide (LPS) and crude ginseng extract, did not affect the level of iNOS protein and NO production in unstimulated RAW 264.7 cells. However, it suppressed the level of iNOS protein and NO production in LPS-stimulated RAW 264.7 cells but did not manifest the same effect on the iNOS mRNA level. An investigation of the activating phosphorylation of p70 S6 kinase and 4E-BP1, which are important for translation, was conducted to investigate the suppressive mechanism of iNOS protein. LPS increased the phosphorylation of p70 S6 kinase, but not 4E-BP1, in a time-dependent manner, and BST204 inhibited it in a dose-dependent manner. The expression of iNOS protein, however, was partially suppressed by rapamycin, an upstream inhibitor of p70 S6 kinase. Therefore, this paper suggests that the suppression of iNOS protein by BST204 was partially correlated with the inhibition of p70 S6 kinase activation.

Modulation of prostaglandin biosynthesis by nitric oxide and nitric oxide donors

The biosynthesis and release of nitric oxide (NO) and prostaglandins (PGs) share a number of similarities. Two major forms of nitric-oxide synthase (NOS) and cyclooxygenase (COX) enzymes have been identified to date. Under normal circumstances, the constitutive isoforms of these enzymes (constitutive NOS and COX-1) are found in virtually all organs. Their presence accounts for the regulation of several important physiological effects (e.g. antiplatelet activity, vasodilation, and cytoprotection). On the other hand, in inflammatory setting, the inducible isoforms of these enzymes (inducible NOS and COX-2) are detected in a variety of cells, resulting in the production of large amounts of proinflammatory and cytotoxic NO and PGs. The release of NO and PGs by the inducible isoforms of NOS and COX has been associated with the pathological roles of these mediators in disease states as evidenced by the use of selective inhibitors. An important link between the NOS and COX pathways was made in 1993 by Salvemini and coworkers when they demonstrated that the enhanced release of PGs, which follows inflammatory mechanisms, was nearly entirely driven by NO. Such studies raised the possibility that COX enzymes represent important endogenous "receptor" targets for modulating the multifaceted roles of NO. Since then, numerous papers have been published extending the observation across various cellular systems and animal models of disease. Furthermore, other studies have highlighted the importance of such interaction in physiology as well as in the mechanism of action of drugs such as organic nitrates. More importantly, mechanistic studies of how NO switches on/off the PG/COX pathway have been undertaken and additional pathways through which NO modulates prostaglandin production unraveled. On the other hand, NO donors conjugated with COX inhibitors have recently found new interest in the understanding of NO/COX reciprocal interaction and potential clinical use. The purpose of this article is to cover the advances which have occurred over the years, and in particular, to summarize experimental data that outline how the discovery that NO modulates prostaglandin production has impacted and extended our understanding of these two systems in physiopathological events.

Neuronal and inducible nitric oxide synthase expression in the rat cerebellum following portacaval anastomosis

In order to determine the role of neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) in the pathogenesis of experimental hepatic encephalopathy (HE), the expression of both was analyzed in the cerebellum of rats 1 month and 6 months after performing portacaval anastomosis (PCA). In control cerebella, nNOS immunoreactivity was mainly observed in the molecular layer (ML), whereas the Purkinje cells did not express nNOS. However, nNOS expression was detected in the Purkinje cells at 1 month after PCA, correlating with a decrease in nNOS expression in the ML--part of an overall reduction in cerebellar nNOS concentrations (as determined by Western blotting). At 6 months post-PCA, a significant increase in nNOS expression was observed in the ML, as well as increased nNOS immunoreactivity in the Purkinje cells. nNOS immunoreactivity was also observed in the Bergmann glial cells of PCA-treated rats. While no immunoreactivity for iNOS was seen in the cerebella of control rats, iNOS immunoreactivity was significantly induced in the cerebellum 1 month after PCA. In addition, the expression of iNOS was greater at 6 months than at 1 month post-PCA. Immunohistochemical analysis revealed this iNOS to be localized in the Purkinje cells and Bergmann glial cells. The induction of iNOS in astroglial cells has been associated with pathological conditions. Therefore, the iNOS expression observed in the Bergmann glial cells might play a role in the pathogenesis of HE, the harmful effects of PCA being caused by them via the production of excess nitric oxide. These results show that nNOS and iNOS are produced in the Purkinje cells and Bergmann glial cells following PCA, implicating nitric oxide in the pathology of HE.

Immunosuppressive properties of flavonoids isolated from Boerhaavia diffusa Linn

Plant extracts have been widely evaluated for possible immunomodulatory properties. We have earlier reported that ethanolic extract of Boerhaavia diffusa root, a plant used in Indian traditional medicine, has significant immunomodulatory potential. B. diffusa hexane, chloroform and ethanol extracts, and two pure compounds Bd-I (eupalitin-3-O-beta-D-galactopyranoside) and Bd-II (eupalitin) were evaluated in vitro for their effect on T cell mitogen (phytohemagglutinin; PHA) stimulated proliferation of human peripheral blood mononuclear cell (PBMC), mixed lymphocyte culture, lipopolysaccharide (LPS) stimulated nitric oxide production by RAW 264.7, PHA and LPS induced IL-2 and TNF-alpha production, in human PBMCs, superoxide production in neutrophils, human natural killer (NK) cell cytotoxicity and nuclear translocation of nuclear factor-(kappa)B and AP-1 in PHA stimulated PBMCs. The chloroform and ethanol extracts inhibited PHA stimulated proliferation of peripheral blood mononuclear cells, two-way MLR, NK cell cytotoxicity as well as LPS induced NO production by RAW 264.7; the hexane extract showed no activity. Bd-I purified from the ethanolic extract at equivalent dose, inhibited PHA-stimulated proliferation of peripheral blood mononuclear cells, two-way MLR and NK cell cytotoxicity as well as LPS induced NO production by RAW 264.7 equally or more effectively than the parent ethanolic extract. Bd-I inhibited production of PHA stimulated IL-2 at the protein and mRNA transcript levels and LPS stimulated TNF-alpha production in human PBMCs; it also blocked the activation of DNA binding of nuclear factor-(kappa)B and AP-1, two major transcription factors centrally involved in expression of the IL-2 and IL-2R gene, which are necessary for T cell activation and proliferation. Our results report selective immunosuppressive activity of B. diffusa leaf extracts and that this activity lies in eupalitin-3-O-beta-D-galactopyranoside (Bd-I) isolated and purified from the ethnaolic extract. Thus, Bd-I could be a candidate for development as an immunosuppressive agent.

Roles of nitric oxide and prostaglandins in pathogenesis of delayed colonic transit after burn injury in rats

Burn injury has been shown to impair gut transit, but the exact mechanism remains unknown. The present study investigated whether nitric oxide synthase (NOS) and cyclooxygenase (COX) mediated changes in burn-induced colonic transit. After rats underwent 30% total body surface area burn injury, they were injected with S-methylisothiourea (SMT, selective inducible NOS inhibitor), 7-nitronidazole (7-NI, selective neuronal NOS inhibitor), and nimesulide (NIM, selective COX-2 inhibitor), respectively. The protein and mRNA of NOS and COX-2 were measured by Western blot analysis and real-time RT-RCR, and localization of NOS and COX-2 protein was determined by immunohistochemistry. Our results showed that colonic transit assessed by the geometric center was delayed from 3.47+/-0.28 in controls to 2.21+/-0.18 after burn (P<0.009). SMT and NIM significantly improved colonic transit in burned rats but had no effect in sham-operated rats. 7-NI failed to modify delayed transit in burned rats but significantly delayed colonic transit in sham-operated rats. Both protein and mRNA of inducible NOS and COX-2 increased significantly but not neuronal NOS in burned rats. Inducible NOS protein expression was noted not only in epithelial cells but also in neurons of the myenteric ganglia in burned rats. These findings suggest that nitric oxide (NO) produced by neuronal NOS plays an important role in mediating colonic transit under the physiological condition. NO produced by inducible NOS and prostaglandins synthesized by COX-2 are both involved in the pathogenesis of delayed colonic transit after burn injury. Inducible NOS expression in neurons of the myenteric ganglia may contribute to dysmotility with burn injury.

Possible involvement of nitric oxide and peroxynitrite in the pathogenesis of human vocal polyps and nodules

Nitric oxide (NO) is a molecule involved in multiple functions including vasodilatation, neural transmission, immune response and inflammation. However, the role of NO in the pathophysiology of vocal cord diseases is not clear. The present study investigated the possible involvement of NO and its toxic metabolite, peroxynitrite, in the pathogenesis of vocal polyps and nodules. Vocal polyps and nodules were obtained from patients receiving surgery for their conditions. Immunohistochemistry was applied to evaluate the expression of the inducible form of nitric oxide synthase (iNOS) as well as the production of peroxynitrite represented by the formation of its biological footprint, 3-nitrotyrosine (3-NT). Each section was given a score of 0 to 4 according to the labeling intensity seen, with the highest number representing the highest labeling intensity. The results showed that vocal polyp had an average iNOS labeling score of 3.2, which was significantly higher than the value of 1.9 in vocal nodules. The average labeling score of 3-NT was 2.8 in vocal polyps, which was also significantly higher than the value of 1.8 in vocal nodules. There was also a positive correlation between the level of iNOS expression and the extent of 3-NT formation. These results suggest that increased peroxynitrite production, resulting from increased iNOS expression and NO formation, may have an important pathogenic role in these vocal diseases.

The role of inflammatory processes in the pathophysiology and treatment of brain and spinal cord trauma

Traumatic injury to the brain and spinal cord results in an early inflammatory response that is initiated by the release of proinflammatory cytokines followed by the infiltration and accumulation of polymorphonuclear leukocytes (PMNLs). The role of the inflammatory cascade on traumatic outcome remains controversial. Pleiotropic cytokines appear to function both protectively and destructively. The induction of cytokines can lead to the expression of the inducible form of nitric oxide synthase (iNOS), which in turn provokes the release of excessive amounts of nitric oxide (NO) that may participate in the pathogenesis of tissue injury. Hypothermia has been reported by various groups to be neuroprotective in brain and spinal cord trauma. We studied the effect of therapeutic hypothermia on cerebral IL-1beta concentrations, PMNL accumulation and iNOS activity after traumatic brain injury (TBI) and spinal cord injury (SCI). Based on current data therapeutic hypothermia may protect in models of traumatic injury by modulating deleterious inflammatory processes.

Nitric Oxide System and Protein Nitration are Modified by an Acute Hypobaric Hypoxia in the Adult Rat Hippocampus

Changes in the nitric oxide system of the hippocampus from rats submitted to hypobaric hypoxia were investigated. Adult rats were exposed to a simulated altitude of 8,325 m (27,000 ft) for 7 h and killed after 0 h, 1, 3, 5, 10 and 20 days of reoxygenation. The number of neuronal nitric oxide synthase immunoreactive neurons and their dendritic plexus, as well as neuronal nitric oxide synthase immunoblotting densitometry and calcium-dependent activity increased from 0 h to 3 days of reoxygenation. In addition, endothelial nitric oxide synthase immunoreactivity peaked after 7 h of hypobaric hypoxia. Nitrotyrosine immunoreactivity showed an increase in the pyramidal cells of CA2-CA3 and in glial cells surrounding the blood vessels after 0 h, 1 and 3 days of reoxygenation. Immunoblotting densitometry of 1 of the 2 nitrotyrosine-immunoreactive bands detected also increased after 0 h and 1 day of reoxygenation. Inducible nitric oxide synthase immunoreactivity was found only in some blood vessels after 0 h, 1 and 3 days of reoxygenation, but no changes in inducible nitric oxide synthase activity or immunoblotting were detected. We conclude that transient activation of the nitric oxide system constitutes a hippocampal response to hypobaric hypoxia.

Hypobaric hypoxia modifies constitutive nitric oxide synthase activity and protein nitration in the rat cerebellum

Ischemic hypoxia provokes alterations in the production system of nitric oxide in the cerebellum. We hypothesize that the nitric oxide system may undergo modifications due to hypobaric hypoxia and that may play a role in high altitude pathophysiology. Therefore, changes in the nitric oxide system of the cerebellum of rats submitted to acute hypobaric hypoxia were investigated. Adult rats were exposed for 7 h to a simulated altitude of 8235 m (27000 ft.) and then killed after 0 h or 1, 3, 5 and 10 days of reoxygenation. Nitric oxide synthase calcium-dependent and -independent activity, immunoblotting and immunohistochemistry of neuronal, endothelial, and inducible nitric oxide synthase, and nitrotyrosine were evaluated. Immunoreactivity for neuronal nitric oxide synthase slightly increased in the baskets of the Purkinje cell layer and in the granule cells, after 0 h of reoxygenation, although no changes in neuronal nitric oxide synthase immunoblotting densitometry were detected. Calcium-dependent activity significantly rose after 0 h of reoxygenation, reaching control levels in the following points, and being coincident with a peak of eNOS expression. Nitrotyrosine formation showed significant increments after 0 h and 1 day of reoxygenation. Nitrotyrosine immunoreactivity showed an intracellular location change in the neurons of the cerebellar nuclei and in addition, an appearance of nitration in the soma of the Purkinje cells was detected. No changes in inducible nitric oxide synthase activity, immunoblotting or immunohistochemistry were detected. We conclude that at least part of the nitric oxide system is involved in cerebellum responses to hypobaric hypoxia.

Differential distribution of nitric oxide synthase isoforms in the rostral ventrolateral medulla of the rat

We evaluated the distribution of nitric oxide synthase (NOS) isoforms in the rostral ventrolateral medulla (RVLM), the medullary origin of sympathetic neurogenic vasomotor tone, and the contribution of NOS III to the cardiovascular actions of endogenous NO in the RVLM. Adult Sprague-Dawley rats were used. Reverse transcription-polymerase chain reaction or Western blot analysis revealed that NOS I, II or III was expressed in the ventrolateral medulla at the mRNA or protein level under basal conditions. However, laser scanning confocal microscopic analysis of double-immunofluorescence images showed that whereas NOS I or II immunoreactivity colocalized with cells within the confines of the RVLM that stained positively with the neuronal marker, NeuN, NOS III immunoreactivity was associated primarily with blood vessels. Furthermore, bilateral microinjection into the RVLM of the selective NOS III inhibitor, N(5)-(1-iminoethyl)-L-ornithine, elicited minimal alterations in baseline systemic arterial pressure, heart rate or sympathetic vasomotor outflow in rats anesthetized with propofol. We conclude that whereas NOS I and II are present in neurons within the confines of the RVLM, NOS III is associated primarily with blood vessels. Our results further indicate that NOS III does not appear to contribute to the maintenance of basal sympathetic vasomotor outflows and arterial pressure by the endogenous NO at the RVLM.

Treatment of experimental autoimmune encephalomyelitis in rat by 1,25-dihydroxyvitamin D3 leads to early effects within the central nervous system

We report here that curative treatment of the multiple sclerosis paradigm, chronic relapsing experimental autoimmune encephalomyelitis (EAE) of the Lewis rat, by 1,25-dihydroxyvitamin D(3 )(1,25-D3) leads to a rapid clinical improvement accompanied by an inhibition of CD4, MHC class II and type II nitric oxide synthase (NOS II) expression in the posterior areas of the central nervous system (CNS). In contrast, the hormone has no effect on transforming growth factor-beta1 transcripts. Computer analysis of the NOS II promoter, expressed by microglia and astrocytes, reveals consensus sequence for vitamin D receptor binding, emphasizing the idea that 1,25-D3 may regulate some aspects of EAE by acting directly on CNS constituent cells. We also demonstrate that vitamin D deprivation leads to minimal effects on the kinetic profile of EAE accompanied by a moderate exacerbation of the clinical symptoms. Interestingly, curative treatment of vitamin D-deprived rats with a non-toxic-1,25-D3 analogue (MC1288) strongly inhibited EAE symptoms, thus promulgating the potential interest of such compounds in the management of multiple sclerosis.

Nitric oxide, platelet function, myocardial infarction and reperfusion therapies

Platelets play an important role in physiologic hemostasis and pathologic thrombosis that complicate the course of vascular disorders. A number of platelet functions including adhesion, aggregation and recruitment are controlled by nitric oxide (NO) generated by platelets and the endothelial cells. Derangements in this generation may contribute to the pathogenesis of thrombotic complications of vascular disorders. The pharmacologic supplementation of the diseased vasculature with drugs releasing NO may help to restore the hemostatic balance.

The nitric oxide-endothelin-1 connection

Nitric oxide (NO) and endothelin-1 (ET-1) are endothelium-derived mediators that play important roles in vascular homeostasis. This review is focused on the role and reciprocal interactions between NO and ET-1 in health and diseases associated with endothelium dysfunction. We will also discuss the clinical significance of NO donors and drugs that antagonize ET receptors.

Effect of chirality at C-20 of methyl 11beta,17alpha,20-trihydroxy-3-oxo-1,4-pregnadien-21-oate derivatives on antiinflammatory activity

In an effort to determine the C-20 chirality effect on the antiinflammatory activity of 17beta-glycolate esters, methyl 11beta,17alpha,20-trihydroxy-3-oxo-1,4-pregnadien-21-oate and its 9alpha-fluoro analog, their acetonide and their carbonate derivatives were synthesized and evaluated. The agents were tested for their binding potency to the macrophage glucocorticoid receptor, and their effect on LPS-induced nitric oxide generation in RAW 264.7 cells. The acetonide derivatives showed the highest binding affinity while the triols and carbonates bound rather poorly to the receptors. With the exception of the triols, the alpha-isomer in each pair of the agents exhibited higher binding affinity to the receptor than its corresponding beta-isomer, clearly indicating that C-20 chirality has a significant effect on antiinflammatory activity. In addition, the alpha-isomers of the acetonides showed substantially higher binding affinity than the parent compound, prednisolone. In contrast to the high binding activity exhibited by some of the acetonides, all of the agents showed weak inhibitory effect on NO generation. Metabolic inactivation during assessment of NO inhibition may play a role in the divergence noted between receptor affinity and the measured biologic activity resulting from the binding.

Effects of oxygen and glucose deprivation on the expression and distribution of neuronal and inducible nitric oxide synthases and on protein nitration in rat cerebral cortex

Changes in the nitric oxide (NO) system of the rat cerebral cortex were investigated by immunohistochemistry, immunoblotting, NO synthase (NOS) activity assay, and magnetic resonance imaging (MRI) in an experimental model of global cerebral ischemia and reperfusion. Brains were perfused transcardially with an oxygenated plasma substitute and subjected to 30 minutes of oxygen and glucose deprivation, followed by reperfusion for up to 12 hours with oxygenated medium containing glucose. A sham group was perfused without oxygen or glucose deprivation, and a further group was treated with the NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) before and during perfusion. Global ischemia led to cerebrocortical injury as shown by diffusion MRI. This was accompanied by increasing morphologic changes in the large type I interneurons expressing neuronal NOS (nNOS) and the appearance of nNOS immunoreactivity in small type II neurons. The nNOS-immunoreactive band and calcium-dependent NOS activity showed an initial increase, followed by a fall after 6 hours of reperfusion. Inducible NOS immunoreactivity appeared in neurons, especially pyramidal cells of layers IV-V, after 4 hours of reperfusion, with corresponding changes on immunoblotting and in calcium-independent NOS activity. Immunoreactive protein nitrotyrosine, present in the nuclear area of neurons in nonperfused controls and sham-perfused animals, showed changes in intensity and distribution, appearing in the neuronal processes during the reperfusion period. Prior and concurrent L-NAME administration blocked the changes on diffusion MRI and attenuated the morphologic changes, suggesting that NO and consequent peroxynitrite formation during ischemia-reperfusion contributes to cerebral injury.

"Mangifera indica L. extract (QF808) reduces ischaemia-induced neuronal loss and oxidative damage in the gerbil brain"

The effect of oral administration of Mangifera indica L. extract (QF808) on ischemia-reperfusion-induced neuronal death in the gerbil hippocampal CA1 sector was examined. Oral administration of QF808 for 7 days dose-dependently protected against neuronal cell death following transient ischaemia and reperfusion as assessed by histopathology. In addition, locomotor activity assessment prior to ischaemia and 7 days after correlated well with the histological results. To evaluate redox alterations by reactive oxygen species, total sulfhydryl, non-protein sulfhydryl groups (NPSH), malondialdehyde + 4-hydroxyalkenals and total nitrogen oxide levels were assayed in hippocampus and cortex homogenates. QF808 treatment attenuated NPSH loss, nitrogen oxide levels and lipid peroxidation in the hippocampus. These results suggest that orally administered QF808 is absorbed across the blood-brain barrier and attenuates neuronal death of the hippocampal CA1 area after ischaemia-reperfusion. These protective effects are most likely due to the antioxidant activity of QF808.

Reduced functional expression and molecular synthesis of inducible nitric oxide synthase in rostral ventrolateral medulla of spontaneously hypertensive rats

BACKGROUND

We demonstrated recently that the prevalence of neuronal (nNOS) over inducible (iNOS) nitric oxide synthase activity at the rostral ventrolateral medulla (RVLM), the medullary origin of sympathetic neurogenic vasomotor tone, and the associated dominance of sympathoexcitation over sympathoinhibition underlie the maintenance of sympathetic vasomotor outflow by the endogenous NO. Here, we evaluated the hypothesis that a significant downregulation of iNOS at the RVLM may play a crucial role in the genesis of augmented sympathetic vasomotor tone during hypertension.

METHODS AND RESULTS

Spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats anesthetized with propofol were used. Compared with SHR, the hypotension, bradycardia, or depression in sympathetic vasomotor tone induced by bilateral microinjection of lipopolysaccharide (5 or 10 ng) into the RVLM of WKY rats exhibited significantly shorter-onset latency, appreciably steeper slope, and a greater incidence of mortality. All these effects of lipopolysaccharide (10 ng) were significantly blunted by coadministration of the selective iNOS inhibitor S-methylisothiourea (250 pmol). Reverse transcription-polymerase chain reaction and Western blot analyses further revealed significantly lower iNOS mRNA and protein levels at the ventrolateral medulla in SHR under basal conditions or on activation by lipopolysaccharide (10 ng). Conversely, nNOS mRNA and protein levels remained constant in the RVLM and were comparable in both strains of rats.

CONCLUSIONS

We conclude that a significant downregulation in both functional expression and molecular synthesis of iNOS at the RVLM may underlie the augmented sympathetic vasomotor tone during hypertension.

Overexpression of macrophage colony-stimulating factor receptor on microglial cells induces an inflammatory response

Microglia are important in the inflammatory response in Alzheimer's disease (AD). We showed previously that macrophage colony-stimulating factor receptor (M-CSFR), encoded by the c-fms protooncogene, is overexpressed on microglia surrounding amyloid beta (Abeta) deposits in the APP(V717F) mouse model for AD. The M-CSFR is also increased on microglia after experimental brain injury and in AD. To determine the relevance of these findings, we transiently expressed M-CSFR on murine BV-2 and human SV-A3 microglial cell lines using an SV40-promoted c-fms construct. M-CSFR overexpression resulted in microglial proliferation and increased expression of inducible nitric-oxide synthase, the proinflammatory cytokines interleukin-1alpha, macrophage inflammatory protein 1-alpha, and interleukin-6 and of macrophage colony-stimulating factor (M-CSF) itself. Antibody neutralization of M-CSF showed that the M-CSFR-induced proinflammatory response was dependent on M-CSF in the culture media. By using a co-culture of c-fms-transfected murine microglia and rat organotypic hippocampal slices and a species-specific real time reverse transcriptase-polymerase chain reaction assay and enzyme-linked immunosorbent assay, we showed that M-CSFR overexpression on exogenous microglia induced expression of interleukin-1alpha by the organotypic culture. These results show that increased M-CSFR expression induces microglial proliferation, cytokine expression, and a paracrine inflammatory response, suggesting that in APP(V717F) mice increased M-CSFR on microglia could be an important factor in Abeta-induced inflammatory response.

Differential cardiovascular responses to blockade of nNOS or iNOS in rostral ventrolateral medulla of the rat

We investigated the contribution of neuronal or inducible nitric oxide synthase (nNOS or iNOS) at the rostral ventrolateral medulla (RVLM) to central cardiovascular regulation by endogenous nitric oxide (NO), using Sprague-Dawley rats anaesthetized and maintained with propofol. Microinjection bilaterally into the RVLM of a NO trapping agent, carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-l-oxy-l-3-oxide (10, 50 or 100 nmoles) resulted in significant hypotension and bradycardia. Similar application of a selective antagonist of nNOS, 7-nitroindazole (1, 2.5 or 5 pmoles), or selective antagonists of iNOS, aminoguanidine (125, 250 or 500 pmoles), N(6)-(l-iminoethyl)-L-lysine (250 pmoles) or S-methylisothiourea (250 pmoles), induced respectively a reduction or an enhancement in systemic arterial pressure, heart rate and power density of the vasomotor components in the spectrum of arterial blood pressure signals, the experimental index for sympathetic neurogenic vasomotor tone. Both hypotension and bradycardia induced by the NO precursor, L-arginine (100 nmoles), were significantly blunted when aminoguanidine (250 pmoles) was co-microinjected bilaterally into the RVLM. On the other hand, co-administered 7-nitroindazole (2.5 pmoles) was ineffective. Whereas low doses of S-nitro-N-acetylpenicillamine (0.25 or 0.5 nmoles) elicited hypertension and tachycardia, high doses of this non-nitrate NO donor (5 nmoles) induced hypotension and bradycardia. Reverse transcription - polymerase chain reaction analysis revealed that both iNOS and nNOS mRNA were expressed in the ventrolateral medulla. We conclude that the prevalence of nNOS over iNOS activity at the RVLM and the associated dominance of sympathoexcitation over sympathoinhibition may underlie the maintenance of sympathetic vasomotor outflow and stable systemic arterial pressure by the endogenous NO.

Nitric oxide synthase 2 through an autocrine loop via respiratory epithelial cell-derived mediator

Respiratory epithelium expresses nitric oxide synthase 2 (NOS2) continuously in vivo; however, mechanisms responsible for its expression are only partially understood. We definitively identify an autocrine mechanism of induction and maintenance of NOS2 in human airway epithelial cells through the synthesis and secretion of a soluble mediator. Short exposure of human airway cells to interferon (IFN)-γ leads to prolonged NOS2 expression. Transfer of the overlying culture medium (conditioned medium) induces NOS2 expression in other airway epithelial cells, suggesting the presence of an intermediary substance regulating NOS2 expression in an autocrine loop. Characterization of the soluble mediator reveals that it is stable and transferable in conditioned medium for up to 7 days. However, soluble mediator does not induce NOS2 mRNA in human alveolar macrophages, indicating that the response to soluble mediator is unique to human respiratory epithelium. Soluble mediator is heat labile but is not inactivated by acid treatment, unlike IFN-γ itself. Importantly, IFN regulatory factor-1, which is critical for murine NOS2 expression, is expressed and activated by soluble mediator through the signal transducer and activator of transcription-1-dependent pathway. Based on these findings, we propose novel regulatory mechanisms for NOS2 expression in human airway epithelium.

Rapid expression of neuronal and inducible nitric oxide synthases during post-ischemic reperfusion in rat brain

OBJECTIVE

To determine whether neuronal and inducible nitric oxide synthase (nNOS and iNOS) isoforms are expressed within cortical neurons during early reperfusion after focal cerebral ischemia.

METHODS

Male spontaneously hypertensive rats underwent occlusion of the left middle cerebral artery for 2 h. Coronal brain sections with normal and ischemic cortex were obtained after 15 min or 1, 6 or 24 h of reperfusion. Immunohistochemical and double-label immunofluorescent techniques were used to confirm cellular identity and localize nNOS and iNOS.

RESULTS

Immunoreactive nNOS was identified within isolated neurons in layer V of normal cortex. However, the number of nNOS-immunoreactive neurons in ischemic cortex rose markedly at 15 min and persisted for 24 h (P< or =0.001 at each time point when compared to normal cortex). Cells that were immunoreactive for nNOS appeared in perivascular clusters within ischemic brain at all sampling times. Immunoreactive iNOS was also expressed within neurons in ischemic cortex, peaking after 15 min of reperfusion (P< or =0.01). Although nNOS-immunoreactive neurons were observed in random numbers within normal tissue throughout reperfusion, iNOS-immunoreactive neurons increased steadily in the same region (P< or =0.05).

CONCLUSIONS

Ischemic neurons become immunoreactive for both nNOS and iNOS during early reperfusion. Expression of iNOS immunoreactivity in unaffected neurons may reflect transcription of immediate early genes in response to stimulatory neurotransmission from ischemic cortex.

Suppression by a sesquiterpene lactone from Carpesium divaricatum of inducible nitric oxide synthase by inhibiting nuclear factor-kappaB activation

Excessive nitric oxide (NO) produced by inducible NO synthase (iNOS) acts as a causative regulator in various inflammatory disease states. Carpesium divaricatum has been used in Korean traditional herbal medicine for its antipyretic, analgesic, vermifugic, and anti-inflammatory properties. We investigated the molecular mechanism for the suppression of lipopolysaccharide/interferon-gamma (LPS/IFN-gamma)-induced NO production in RAW 264.7 macrophages by the sesquiterpene lactone 2beta,5-epoxy-5,10-dihydroxy-6alpha-angeloyloxy-9beta-isobutyloxy-germacran-8alpha,12-olide (C-1), which has been identified recently as a new compound from C. divaricatum. C-1 decreased NO production in LPS/IFN-gamma-stimulated RAW 264.7 cells in a concentration-dependent manner, with an IC50 of approximately 2.16 microM; however, it had no direct effect on the iNOS activity of fully LPS/IFN-gamma-stimulated RAW 264.7 cells. Furthermore, treatment with C-1 led to a decrease in iNOS protein and mRNA. These effects appear to be due to inhibition of nuclear factor-kappaB (NF-kappaB) activation through a mechanism involving stabilization of the NF-kappaB/inhibitor of the kappaB (I-kappaB) complex, since inhibition of NF-kappaB DNA binding activity by C-1 was accompanied by a parallel reduction of nuclear translocation of subunit p65 of NF-kappaB and I-kappaBalpha degradation. Taken together, the results suggest that the ability of C-1 to inhibit iNOS gene expression may be responsible, in part, for its anti-inflammatory effects.

Adenovirus infection increases iNOS and peroxynitrite production in the lung

Host inflammatory and immune responses limit viral gene expression after administration of replication-deficient adenoviruses to the lung. The current study asks whether inducible nitric oxide synthase (iNOS) expression and peroxynitrite generation accompanied the inflammatory response following intratracheal administration of adenovirus. Pulmonary iNOS mRNA and protein were increased 2, 7, and 14 days following administration of 2 x 10(9) plaque-forming units of recombinant adenovirus (Av1Luc1) to BALB/c mice. Adenovirus infection was associated with a marked increase in nitrotyrosine staining. Intense nitrotyrosine staining was observed in alveolar macrophages, respiratory epithelial cells, conducting airways, and alveolar spaces 2 days postinfection. Two weeks after exposure to adenovirus, nitrotyrosine staining was detected within alveolar macrophages, suggesting adenovirus enhanced the nitration of proteins that were subsequently taken up by alveolar macrophages. Western blot analysis using anti-nitrotyrosine antibody did not demonstrate accumulation of nitrated surfactant protein A (SP-A), although a small fraction of aggregated SP-A comigrated with a nitrotyrosine-positive protein. iNOS expression, peroxynitrite, and nitrotyrosine generation accompany and may contribute to inflammatory responses to adenovirus in the lung.

Suppression of inducible nitric oxide synthase expression in RAW 264. 7 macrophages by two beta-carboline alkaloids extracted from Melia azedarach

We investigated the mechanism of suppression of inducible nitric oxide synthase (iNOS) by two beta-carboline alkaloids isolated from Melia azedarach, 4,8-dimethoxy-1-vinyl-beta-carboline (compound 1, C-1) and 4-methoxy-1-vinyl-beta-carboline (compound 2, C-2). iNOS activity in a cell-free extract of lipopolysaccharide/interferon-gamma-stimulated RAW 264.7 cells was found to be markedly increased, and this increase was prevented by C-1 and C-2, accompanied by the parallel reduction in nitrite accumulation in culture medium. However, C-1 and C-2 had no further effect on the iNOS activity prepared from fully lipopolysaccharide/interferon-gamma-stimulated RAW 264.7 cells. Treatment with C-1 or C-2 decreased the levels of iNOS protein and mRNA in a concentration-dependent manner. In addition, prostaglandin E(2) production, cyclooxygenase-2 protein and DNA binding of nuclear factor-kappaB (NF-kappaB) in lipopolysaccharide-stimulated RAW 264.7 cells were reduced by these compounds. These results indicate that C-1 and C-2 primarily inhibit iNOS and cyclooxygenase-2 activities via the suppression of de novo synthesis of these two enzymes, and that the inhibition of iNOS expression may be associated with the inhibition of NF-kappaB activation. Taken together, the results suggest that suppression of iNOS and cyclooxygenase-2 induction by lipopolysaccharide is responsible for the anti-inflammatory activity of these alkaloids through selective inhibition of the expression of genes, which play important roles in inflammatory signaling pathways.

The involvement of tyrosine kinases, cyclic AMP/protein kinase A, and p38 mitogen-activated protein kinase in IL-13-mediated arginase I induction in macrophages: its implications in IL-13-inhibited nitric oxide production

In macrophages, L-arginine can be used by NO synthase and arginase to form NO and urea, respectively. Therefore, activation of arginase may be an effective mechanism for regulating NO production in macrophages through substrate competition. Here, we examined whether IL-13 up-regulates arginase and thus reduces NO production from LPS-activated macrophages. The signaling molecules involved in IL-13-induced arginase activation were also determined. Results showed that IL-13 increased arginase activity through de novo synthesis of the arginase I mRNA and protein. The activation of arginase was preceded by a transient increase in intracellular cAMP, tyrosine kinase phosphorylation, and p38 mitogen-activated protein kinase (MAPK) activation. Exogenous cAMP also increased arginase activity and enhanced the effect of IL-13 on arginase induction. The induction of arginase was abolished by a protein kinase A (PKA) inhibitor, KT5720, and was down-regulated by tyrosine kinase inhibitors and a p38 MAPK inhibitor, SB203580. However, inhibition of p38 MAPK had no effect on either the IL-13-increased intracellular cAMP or the exogenous cAMP-induced arginase activation, suggesting that p38 MAPK signaling is parallel to the cAMP/PKA pathway. Furthermore, the induction of arginase was insensitive to the protein kinase C and p44/p42 MAPK kinase inhibitors. Finally, IL-13 significantly inhibited NO production from LPS-activated macrophages, and this effect was reversed by an arginase inhibitor, L-norvaline. Together, these data demonstrate for the first time that IL-13 down-regulates NO production through arginase induction via cAMP/PKA, tyrosine kinase, and p38 MAPK signalings and underline the importance of arginase in the immunosuppressive activity of IL-13 in activated macrophages.

Inotropic response to endothelin-1, isoprenaline and calcium in cardiomyocytes isolated from endotoxin treated rats: effects of ethyl-isothiourea and dexamethasone

1. The contractile effects of endothelin-1, isoprenaline and extracellular calcium were assessed on ventricular cardiomyocytes isolated from lipopolysaccharide-treated rats. The involvement of nitric oxide was investigated using dexamethasone (in vivo) and ethyl isothiourea (in vitro). 2. Male Wistar rats (n=70) were injected with either saline (1 ml kg(-1)) or lipopolysaccharide (LPS; 5 mg kg(-1)) alone, or following pre-treatment with dexamethasone (DEX+LPS; 5 mg kg(-1)). Ventricular cell shortening was recorded using a video edge detection system, and concentration-response relationships were established for endothelin-1, isoprenaline and calcium, in the absence or presence of ethyl isothiourea (ETU; 10 microM). iNOS expression was assessed using reverse transcription-polymerase chain reaction. 3. iNOS mRNA expression was greater (P<0.001) in the LPS (iNOS/GAPDH ratio: 0.90+/-0.09) treated group compared to saline (iNOS/GAPDH ratio: 0.36+/-0.02). Baseline contractile amplitude was reduced (P<0.05) in the LPS (7.3+/-0.2 microm) and DEX+LPS groups (6.7+/-0.3 microm) compared to saline (8. 0+/-0.2 microm). 4. The concentration-dependent contractile response to endothelin-1 was attenuated (P<0.05) in the LPS group compared to saline (maximum change: 0.45+/-0.2 vs 1.8+/-0.2 microm). Neither ETU nor dexamethasone improved contractile function in the LPS-treated animals. 5. The concentration-dependent increase in the contractile response to isoprenaline was attenuated in the LPS-treated group compared to saline (P<0.05; maximum change: 1.7+/-0.4 vs 3.1+/-0.4 microm). This effect was reversed by ETU (maximum change: 3.7+/-0.6 microm). Pre-treatment with dexamethasone prevented a significant fall in contraction amplitude (maximum change: 2.4+/-0.4 microm). 6. The contractile response to calcium was reduced (P<0.05) in the LPS group compared to saline (maximum change: 8.7+/-0.6 vs 10.7+/-0.8 microm). Neither ETU nor dexamethasone restored contractile function in the LPS-treated group. 7. In conclusion, a nitric oxide-mediated inhibitory pathway is not responsible for the diminished contractile response to either endothelin-1 or extracellular calcium, but contributes to the hyporesponsiveness to isoprenaline in lipopolysaccharide treated rats.