Nitric oxide activates cyclooxygenase enzymes

The role of morphine in animal models of human cancer: does morphine promote or inhibit the tumor growth?

Morphine, a highly potent analgesic agent, is widely used to relieve pain and suffering of patients with cancer. Additionally, it has been reported that morphine is important in the regulation of cancerous tissue. Morphine relieves pain by acting directly on the central nervous system, although its activities on peripheral tissues are responsible for many adverse side effects. For these reasons, it is very important also to understand the role of morphine in cancer treatment. The published literature reporting the effect of morphine on tumor growth presents some discrepancies, with reports suggesting that morphine may either promote or inhibit the tumor growth. It has been also demonstrated that morphine modulates angiogenesis which is important for primary tumour growth, invasiveness, and the development of metastasis. This review will focus on the latest findings on the role of morphine in the regulation of cancer cell growth and angiogenesis.

Progesterone reduces the expression of spinal cyclooxygenase-2 and inducible nitric oxide synthase and prevents allodynia in a rat model of central neuropathic pain

BACKGROUND

Spinal cord injury (SCI) results in the development of chronic pain that is refractory to conventional treatment. Progesterone, a neuroprotective steroid, may offer a promising perspective in pain modulation after central injury. Here, we explore the impact of progesterone administration on the post-injury inflammatory cascade involving the enzymes cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) at the spinal cord level. We also analyse pain behaviours, the profile of glial cell activation, and IκB-α mRNA levels, as an index of NF-κB transactivation.

METHODS

We used biochemical, immunohistochemical and molecular techniques, as well as behavioural studies, to investigate the effects of progesterone in a well-characterized model of central neuropathic pain.

RESULTS

Injured animals receiving progesterone presented reduced mRNA levels of the proinflammatory enzymes, as well as decreased COX-2 activity and nitrite levels, as compared to vehicle-treated injured rats. Further, animals receiving the steroid exhibited lower levels of IκB-α mRNA, suggesting decreased NF-κB transactivation. Progesterone administration also attenuated the injury-induced increase in the number of glial fibrillary acidic protein and OX-42 positive cells both at early and late time points after injury, and prevented the development of mechanical and thermal allodynia. Further, when injured rats received early progesterone administration for a critical period of time after injury, they did not display allodynic behaviours even after the treatment had stopped.

CONCLUSIONS

Our results suggest that progesterone, by modulating early neuroinflammatory events triggered after SCI, may represent a useful strategy to prevent the development of central chronic pain.

Amygdalin suppresses lipopolysaccharide-induced expressions of cyclooxygenase-2 and inducible nitric oxide synthase in mouse BV2 microglial cells

BACKGROUND

Amygdalin (D-mandelonitrile-beta-D-gentiobioside) is a cynogenic compound found in sweet and bitter almonds, Persicae semen and Armeniacae semen. Amygdalin has been used for the treatment of cancers and for the relief of the pain. We made an aqueous extraction of amygdalin from Armeniacae semen. In this study, the effect of amygdalin on the lipopolysaccharide (LPS)-induced inflammation was investigated.

METHODS

The effects of amygdalin extracted from Armeniacae semen on the LPS-stimulated mRNA expressions of cyclooxygenase (COX)-1, COX-2 and inducible nitric oxide synthase (iNOS) in the mouse BV2 microglial cells were investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, reverse transcription-polymerase chain reaction (RT-PCR). The effects of amygdalin on the prostaglandins E(2) synthesis and the nitric oxide production were also studied by performing prostaglandins E(2) immunoassay and by detecting nitric oxide.

RESULTS

The present results showed that amygdalin suppressed the prostaglandin E(2) synthesis and the nitric oxide production by inhibiting the LPS-stimulated mRNA expressions of COX-2 and iNOS in the mouse BV2 cells.

CONCLUSION

These results show that amygdalin exerts anti-inflammatory and analgesic effects and it dose so probably by suppressing the mRNA expressions of COX-2 and iNOS.

Piperine inhibits IL-β induced expression of inflammatory mediators in human osteoarthritis chondrocyte

Black pepper (Piper nigrum) is a common remedy in Traditional Chinese Medicine and possesses diverse biological activities including anti-inflammatory properties. Osteoarthritis (OA) is a degenerative joint disease with an inflammatory component that drives the degradation of cartilage extracellular matrix. The present study aimed to assess the effects of piperine, the active phenolic component in black pepper extract, on human OA chondrocytes. In this study, human OA chondrocytes were pretreated with piperine at 10, 50 or 100μg/ml and subsequently stimulated with IL-1β (5ng/ml) for 24h. Production of PGE2 and NO was evaluated by the Griess reaction and an ELISA. Gene expression of MMP-3, MMP-13, iNOS and COX-2 was measured by real-time PCR. MMP-3 and MMP-13 proteins in culture medium were determined using cytokine-specific ELISA. Western immunoblotting was used to analyze the iNOS and COX-2 protein production in the culture medium. The regulation of NF-kB activity and the degradation of IkB were explored using luciferase and Western immunoblotting, respectively. We found that piperine inhibited the production of PGE2 and NO induced by IL-1β. Piperine significantly decreased the IL-1β-stimulated gene expression and production of MMP-3, MMP-13, iNOS and COX-2 in human OA chondrocytes. Piperine inhibited the IL-1β-mediated activation of NF-κB by suppressing the degradation of its inhibitory protein IκBα in the cytoplasm. The present report is first to demonstrate the anti-inflammatory activity of piperine in human OA chondrocytes. Piperine can effectively abrogate the IL-1β-induced over-expression of inflammatory mediators; suggesting that piperine may be a potential agent in the treatment of OA.

Atropa acuminata Royle Ex Lindl. blunts production of pro-inflammatory mediators eicosanoids., leukotrienes, cytokines in vitro and in vivo models of acute inflammatory responses

ETHNOPHARMACOLOGICAL RELEVANCE

Atropa acuminata Royle Ex Lindl. has been widely used in folk medicine for several inflammatory disorders such as arthritis, asthma, conjunctivitis, encephalitis, pancreatitis, peritonitis, acute infections and neuroinflammatory disorders.

AIM OF THE STUDY

Our aim was to evaluate Atropa acuminata for its anti-inflammatory properties and to delineate its possible mechanism of action on the modulation of the inflammatory mediators.

MATERIALS AND METHODS

We investigated the inhibitory action of ethanolic extract of Atropa acuminata (AAEE) on production of NO, TNF-α and IL-1β in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and also assayed it for COX 1/2 and 5-LOX inhibitory activities. Next AAEE was tested in acute inflammatory animal models., carragenean induced rat paw edema, carragenean induce pleurisy in rats and vascular permeability in mice and the effects on NO, PGE2 and LTB4 production in the pleural fluid and paw exudates were evaluated. In addition the effects on leukocyte migration and exudation and vascular permeability were also observed.

RESULTS

Our findings summarized novel anti-inflammatory mechanisms for Atropa acuminata based on dual in vitro cyclooxygenase 1/2/ and 5-Lipoxygenase inhibitory activities and also significant downregulation of nitric oxide (NO) and pro-inflammatory cytokin (TNF-α and Il-1 β) release in LPS-stimulated RAW 246.7 macrophage cell line. In acute inflammatory models in vivo (carragenean induced edema, carragenean induced pleurisy in rats and vascular permeability in mice), AAEE exhibited an extensive diverse mechanism for anti-inflammatory properties. This was indicated on the basis of dose dependent suppression of multi targeted inflammatory mediators., NO, TNF-α and IL-1β, eicosanoids., PGE2 and leukotrienes., LTB4 along with significantly decreased leucocyte migration, exudation and decreased vascular permeability. These effects were more potent and prolonged than traditional NSAIDS, thereby indicating fewer side effects. AAEE was found to be safe for long term administration, as confirmed by the results of acute toxicity studies and MTT assay. The complex mode of action of the herbs was attributed possibly due to the high polyphenolic, flavanol and flavonoid content present in the extracts as observed by means of quantitative screening for phytochemicals.

CONCLUSION

Our study provides scientific evidence to support the traditional anti-inflammatory uses of Atropa acuminata and is probably due to inhibitory effects on multiple inflammatory mediators which indicates a promising potential for the development of a strong anti-inflammatory agent from this plant.

Measurement of exhaled alveolar nitrogen oxide in patients with lung cancer: a friend from the past still precious today

Nitric oxide (NO) is a marker of airway inflammation and indirectly a general indicator of inflammation and oxidative stress. NO is a contributing factor in lung cancer at an early stage and also after chemotherapy treatment of lung cancer. We studied whether exhaled NO levels were altered by three cycles of chemotherapy at diagnosis and after chemotherapy, and whether, directly or indirectly, these changes were related to the course of disease. Also, a correlation of NO levels with other markers of inflammation was performed. We studied 42 patients diagnosed early: 26 men and 16 women with lung cancer. We analyzed blood tests for control of inflammatory markers, functional pulmonary tests, and alveolar exhaled NO. We recorded a decrease in exhaled NO after three cycles of chemotherapy in all patients, regardless of histological type and stage: there were 42 patients with mean 9.8 NO after three cycles (average 7.7). Also, a strong correlation appeared between NO measurements before and after chemotherapy and C-reactive protein (P < 0.05, r = 0.42, before) and (P < 0.045, r = 0.64, after). NO alveolar measurement as an indicator of airway inflammation indicates response to chemotherapy in lung cancer. Also, the inflammatory process in lung cancer was confirmed and indicated response to chemotherapy through an index that is sensitive to inflammatory disease of the airways.

Testosterone-induced effects on lipids and inflammation

Chronic pain has to be considered in all respects a debilitating disease and 10-20% of the world's adult population is affected by this disease. In the most general terms, pain is symptomatic of some form of dysfunction and (often) the resulting inflammatory processes in the body. In the study of pain, great attention has been paid to the possible involvement of gonadal hormones, especially in recent years. In particular, testosterone, the main androgen, is thought to play a beneficial, protective role in the body. Other important elements to be related to pain, inflammation, and hormones are lipids, heterogenic molecules whose altered metabolism is often accompanied by the release of interleukins, and lipid-derived proinflammatory mediators. Here we report data on interactions often not considered in chronic pain mechanisms.

Ulinastatin suppresses lipopolysaccharide-induced prostaglandin E2 synthesis and nitric oxide production through the downregulation of nuclear factor‑κB in BV2 mouse microglial cells

Ulinastatin is an intrinsic serine-protease urinary trypsin inhibitor that can be extracted and purified from human urine. Urinary trypsin inhibitors are widely used to treat patients with acute inflammatory disorders, such as shock and pancreatitis. However, although the anti-inflammatory activities of urinary trypsin inhibitors have been investigated, the mechanisms underlying their actions are not yet fully understood. In the present study, we evaluated the effect of ulinastatin on lipopolysaccharide (LPS)-induced inflammation in relation with nuclear factor-κB (NF-κB) activation using BV2 mouse microglial cells. To accomplish this, we performed a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, reverse transcription-polymerase chain reaction (RT-PCR), western blot analysis, electrophoretic mobility gel shift assay (EMSA), prostaglandin E(2) (PGE(2)) immunoassay and nitric oxide (NO) detection. The results demonstrated that ulinastatin suppressed PGE2 synthesis and NO production by inhibiting the LPS-induced mRNA and protein expression of cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS) in BV2 mouse microglial cells. Ulinastatin suppressed the activation of NF-κB in the nucleus. These findings demonstrate that ulinastatin exerts analgesic and anti-inflammatory effects that possibly occur via the suppression of COX-2 and iNOS expression through the downregulation of NF-κB activity.

Interaction between NO and COX pathways modulating hepatic endothelial cells from control and cirrhotic rats

Reduced intrahepatic nitric oxide (NO) bioavailability and increased cyclooxygenase-1 (COX-1)-derived vasoconstrictor prostanoids modulate the hepatic vascular tone in cirrhosis. We aimed at investigating the reciprocal interactions between NO and COX in the hepatic endothelium of control and cirrhotic rats. NO bioavailability (DAF-FM-DA staining), superoxide (O₂⁻) content (DHE staining), prostanoid production (PGI₂ and TXA₂ by enzyme immunoassays) as well as COX expression (Western Blot), were determined in hepatic endothelial cells (HEC) from control and cirrhotic rats submitted to different experimental conditions: COX activation, COX inhibition, NO activation and NO inhibition. In control and cirrhotic HEC, COX activation with arachidonic acid reduced NO bioavailability and increased O₂⁻ levels. These effects were abolished by pre-treating HEC with the COX inhibitor indomethacin. In control, but not in cirrhotic HEC, scavenging of O₂⁻ by superoxide dismutase (SOD) incubation partially restored the decrease in NO bioavailability promoted by COX activation. NO supplementation produced a significant and parallel reduction in PGI₂ and TXA₂ production in control HEC, whereas it only reduced TXA₂ production in cirrhotic HEC. By contrast, in control and cirrhotic HEC, NO inhibition did not modify COX expression or activity. Our results demonstrate that NO and COX systems are closely interrelated in HEC. This is especially relevant in cirrhotic HEC where COX inhibition increases NO bioavailability and NO supplementation induces a reduction in TXA₂. These strategies may have beneficial effects ameliorating the vasoconstrictor/vasodilator imbalance of the intrahepatic circulation of cirrhotic livers.

Reciprocal regulation of the nitric oxide and cyclooxygenase pathway in pathophysiology: relevance and clinical implications

The nitric oxide (NO) and cyclooxygenase (COX) pathways share a number of similarities. Nitric oxide is the mediator generated from the NO synthase (NOS) pathway, and COX converts arachidonic acid to prostaglandins, prostacyclin, and thromboxane A(2). Two major forms of NOS and COX have been identified to date. The constitutive isoforms critically regulate several physiological states. The inducible isoforms are overexpressed during inflammation in a variety of cells, producing large amounts of NO and prostaglandins, which may underlie pathological processes. The cross-talk between the COX and NOS pathways was initially reported by Salvemini and colleagues in 1993, when they demonstrated in a series of in vitro and in vivo studies that NO activates the COX enzymes to produce increased amounts of prostaglandins. Those studies led to the concept that COX enzymes represent important endogenous "receptor" targets for amplifying or modulating the multifaceted roles of NO in physiology and pathology. Since then, numerous studies have furthered our mechanistic understanding of these interactions in pathophysiological settings and delineated potential clinical outcomes. In addition, emerging evidence suggests that the canonical nitroxidative species (NO, superoxide, and/or peroxynitrite) modulate biosynthesis of prostaglandins through non-COX-related pathways. This article provides a comprehensive state-of-the art overview in this area.

Nitrosothiols in the immune system: signaling and protection

SIGNIFICANCE

In the immune system, nitric oxide (NO) has been mainly associated with antibacterial defenses exerted through oxidative, nitrosative, and nitrative stress and signal transduction through cyclic GMP-dependent mechanisms. However, S-nitrosylation is emerging as a post-translational modification (PTM) involved in NO-mediated cell signaling.

RECENT ADVANCES

Precise roles for S-nitrosylation in signaling pathways have been described both for innate and adaptive immunity. Denitrosylation may protect macrophages from their own S-nitrosylation, while maintaining nitrosative stress compartmentalized in the phagosomes. Nitrosothiols have also been shown to be beneficial in experimental models of autoimmune diseases, mainly through their role in modulating T-cell differentiation and function.

CRITICAL ISSUES

Relationship between S-nitrosylation, other thiol redox PTMs, and other NO-signaling pathways has not been always taken into account, particularly in the context of immune responses. Methods for assaying S-nitrosylation in individual proteins and proteomic approaches to study the S-nitrosoproteome are constantly being improved, which helps to move this field forward.

FUTURE DIRECTIONS

Integrated studies of signaling pathways in the immune system should consider whether S-nitrosylation/denitrosylation processes are among the PTMs influencing the activity of key signaling and adaptor proteins. Studies in pathophysiological scenarios will also be of interest to put these mechanisms into broader contexts. Interventions modulating nitrosothiol levels in autoimmune disease could be investigated with a view to developing new therapies.

Impaired acetylcholine-induced cutaneous vasodilation in young smokers: roles of nitric oxide and prostanoids

Cigarette smoking attenuates acetylcholine (ACh)-induced cutaneous vasodilation in humans, but the underlying mechanisms are unknown. We tested the hypothesis that smokers have impaired nitric oxide (NO)- and cyclooxygenase (COX)-dependent cutaneous vasodilation to ACh infusion. Twelve young smokers, who have smoked more than 5.2 ± 0.7 yr with an average daily consumption of 11.4 ± 1.2 cigarettes, and 12 nonsmokers were tested. Age, body mass index, and resting mean arterial pressure were similar between the groups. Cutaneous vascular conductance (CVC) was evaluated as laser-Doppler flux divided by mean arterial pressure, normalized to maximal CVC (local heating to 43.0°C plus sodium nitroprusside administration). We evaluated the increase in CVC from baseline to peak (CVCΔpeak) and area under the curve of CVC (CVCAUC) during a bolus infusion (1 min) of 137.5 μM ACh at four intradermal microdialysis sites: 1) Ringer (control), 2) 10 mM N(G)-nitro-l-arginine methyl ester (l-NAME; NO synthase inhibitor), 3) 10 mM ketorolac (COX inhibitor), and 4) combination of l-NAME + ketorolac. CVCΔpeak and CVCAUC at the Ringer site in nonsmokers were greater than in smokers (CVCΔpeak, 42.9 ± 5.1 vs. 22.3 ± 3.5%max, P < 0.05; and CVCAUC, 8,085 ± 1,055 vs. 3,145 ± 539%max·s, P < 0.05). In nonsmokers, CVCΔpeak and CVCAUC at the l-NAME site were lower than the Ringer site (CVCΔpeak, 29.5 ± 6.2%max, P < 0.05; and CVCAUC, 5,377 ± 1,109%max·s, P < 0.05), but in smokers, there were no differences between the Ringer and l-NAME sites (CVCΔpeak, 16.8 ± 4.3%max, P = 0.11; and CVCAUC, 2,679 ± 785%max·s, P = 0.30). CVCΔpeak and CVCAUC were reduced with ketorolac in nonsmokers (CVCΔpeak, 13.3 ± 3.6%max, P < 0.05; and CVCAUC, 1,967 ± 527%max·s, P < 0.05) and smokers (CVCΔpeak, 7.8 ± 1.8%max, P < 0.05; and CVCAUC, 1,246 ± 305%max·s, P < 0.05) and at the combination site in nonsmokers (CVCΔpeak, 15.9 ± 3.1%max, P < 0.05; and CVCAUC, 2,660 ± 512%max·s, P < 0.05) and smokers (CVCΔpeak, 11.5 ± 2.6%max, P < 0.05; and CVCAUC, 1,693 ± 409%max·s, P < 0.05), but the magnitudes were greater in nonsmokers (P < 0.05). These results suggest that impaired ACh-induced skin vasodilation in young smokers is related to diminished NO- and COX-dependent vasodilation.

Role of glia in the regulation of gonadotropin-releasing hormone neuronal activity and secretion

Gonadotropin-releasing hormone (GnRH) neurons are the final common pathway for the central control of reproduction. The coordinated and timely activation of these hypothalamic neurons, which determines sexual development and adult reproductive function, lies under the tight control of a complex array of excitatory and inhibitory transsynaptic inputs. In addition, research conducted over the past 20 years has unveiled the major contribution of glial cells to the control of GnRH neurons. Glia use a variety of molecular and cellular strategies to modulate GnRH neuronal function both at the level of their cell bodies and at their nerve terminals. These mechanisms include the secretion of bioactive molecules that exert paracrine effects on GnRH neurons, juxtacrine interactions between glial cells and GnRH neurons via adhesive molecules and the morphological plasticity of the glial coverage of GnRH neurons. It now appears that glial cells are integral components, along with upstream neuronal networks, of the central control of GnRH neuronal function. This review attempts to summarize our current knowledge of the mechanisms used by glial cells to control GnRH neuronal activity and secretion.

Houttuynia cordata Thunb. volatile oil exhibited anti-inflammatory effects in vivo and inhibited nitric oxide and tumor necrosis factor-α production in LPS-stimulated mouse peritoneal macrophages in vitro

Houttuynia cordata Thunb. (HC) is a medicinal herb that generally used in traditional Chinese medicine for treating allergic inflammation. The present study investigated the inhibitory effect of the volatile oil from HC Thunb. on animal models of inflammation and the production of inflammatory mediators in vivo and in vitro. In vivo, xylene-induced mouse ear edema, formaldehyde-induced paw edema and carrageenan-induced mice paw edema were significantly decreased by HC volatile oil. HC volatile oil showed pronounced inhibition of prostaglandin (PG) E2 and malondialdehyde production in the edematous exudates. In vitro exposure of mouse resident peritoneal macrophages to 1, 10, 100 and 1000 µg/mL of HC volatile oil significantly suppressed lipopolysaccharide (LPS)-stimulated production of NO and tumor necrosis factor-α (TNF-α) in a dose-dependent manner. Exposure to HC volatile oil had no effect on cell viability and systemic toxicity. Furthermore, HC volatile oil inhibited the production of NO and TNF-α by down-regulating LPS-stimulated iNOS and TNF-α mRNA expression. Western blot analysis showed that HC volatile oil attenuated LPS-stimulated synthesis of iNOS and TNF-α protein in the macrophages, in parallel. These findings add a novel aspect to the biological profile of HC and clarify its anti-inflammatory mechanism.

Modulation of nitric oxide synthase activity in macrophages

L-Arginine is converted to the highly reactive and unstable nitric oxide (NO) and L-citrulline by an enzyme named nitric oxide synthase (NOS). NO decomposes into other nitrogen oxides such as nitrite (NO₂^-) and nitrate (NO₂^-), and in the presence of superoxide anion to the potent oxidizing agent peroxynitrite (ONOO⁻). Activated rodent macrophages are capable of expressing an inducible form of this enzyme (iNOS) in response to appropriate stimuli, i.e., lipopolysaccharide (LPS) and interferon-γ (IFNγ). Other cytokines can modulate the induction of NO biosynthesis in macrophages. NO is a major effector molecule of the anti-microbial and cytotoxic activity of rodent macrophages against certain micro-organisms and tumour cells, respectively. The NO synthesizing pathway has been demonstrated in human monocytes and other cells, but its role in host defence seems to be accessory. A delicate functional balance between microbial stimuli, host-derived cytokines and hormones in the microenvironment regulates iNOS expression. This review will focus mainly on the known and proposed mechanisms of the regulation of iNOS induction, and on agents that can modulate NO release once the active enzyme has been expressed in the macrophage.

Nitric oxide production in murine spleen cells: role of interferons and prostaglandin E(2) in the generation of cytotoxic activity

The production of nitric oxide (NO) was measured in cultures of spleen cells stimulated by lipopolysaccharide (LPS), IL-2 or LPS + IL-2. We observed that NO synthesis is increased by IFN-γ but inhibited by IFN-α/β. This is not the case when IL-2 is present in the cultures, since interferons play a minor role in the regulation of the NO production. When IL-2 and LPS were associated in the cultures, the IFN-α/β role seems more important than that of IFN-γ. PGE₂ inhibits NO production in LPS supplemented cultures but has a slight effect in the presence of IL-2 and no effect with IL-2 + LPS. 3-isoButyl-1-methylxanthine (IBMX), an inhibitor of phosphodiesterases, induces a decrease of IFN production. In the presence of H-7, an inhibitor of protein kinase C (PKC), NO production is reduced when the cultures are supplemented by LPS or IL-2 but not when IL-2 and LPS are both added. H-7 also reduced IFN production. In the presence of N^G-monomethyl-L-arginine (N-MMA), an inhibitor of NO synthesis, IFN production was increased, with no change in the cytotoxic activity. Hence, interferons regulate NO production by mouse spleen cells and, in return, NO modulates the generation of IFN.

Rat intestinal mast cell amines are released during nitric oxide synthase inhibition in vitro

Inhibition of nitric oxide synthase increases microvascular permeability in rat small intestinal villi. To determine the mechanism(s) whereby this occurs we have perfused the vasculature of rat isolated small intestines with a gelatin-containing physiological salt solution. Inclusion of N-nitro-L-argintne methyl ester (L-NAME, 100 μM) or indomethacin (1 μM) in the perfusate increased leakage of injected colloidal carbon into microvessel walls. Pre-treatment with sodium nitroprusside (10 μM) significantly reduced the effects of both L-NAME and indomethacin, whereas carbacyclin (1 μM) only reduced the effects of indomethacin. PD151242 (1 μM) showed some antagonism towards the effects of L-NAME, but nordihydroguaiaretic acid (3 μM) was inactive. Pre-tment with cyproheptadine (10 μM) reduced the effects of both L-NAME and indomethacin, and also significantly reduced background (control) colloidal carbon leakage. Small intestines from polymixin B-treated rats showed significantly reduced colloidal carbon leakage in response to L-NAME. This suggests that the leakage-enhancing effects of both L-NAME and indomethacin in this preparation may be mediated by mast cell-derived amines.

Exposure to nerve agents: from status epilepticus to neuroinflammation, brain damage, neurogenesis and epilepsy

Epilepsy is a common neurological disorder characterized by an initial injury due to stroke, traumatic brain injury, brain infection, or febrile seizures causing status epilepticus (SE). This phenomenon precedes recurrent (secondary) seizures, the latent period (period without seizures) and downstream appearance of spontaneous recurrent seizures (SRS). Epilepsy inducers include the organophosphorous (OP) compounds modified as chemical warfare nerve agents, such as soman. SE induced by soman is a result of cholinergic system hyperactivity caused by the irreversible inhibition of acetylcholinesterase, and the subsequent increase in the amount of the neurotransmitter acetylcholine at central and peripheral sites. SE leads to profound, permanent, complex and widespread brain damage and associated cognitive and behavioral deficits, accompanied by impaired neurogenesis. Several anticonvulsant and neuroprotective strategies have been studied in order to avoid the epileptogenesis which occurs after SE caused by soman exposure. In recent studies, we showed that SRS occur post-soman exposure and neuropathology can be reduced with diazepam (DZP) and valproic acid (VPA) when administered in combination treatment. These effects are accompanied by neurogenesis seen 15 days post-exposure in the hippocampal dentate gyrus (DG). This review discusses several findings about epilepsy induced by soman exposure such as behavioral changes, EEG anomalies, neuropathology, neuroinflammation, neurogenesis, possible circuitry changes and current strategies for treatment. The soman seizure model is an important model of temporal lobe epilepsy (TLE) and comparable in certain respects with well studied models in the literature such as pilocarpine and kainic acid. All these models together allow for a greater understanding of the different mechanisms of seizure induction, propagation and options for treatment. These studies are very necessary for current military and civilian treatment regimens, against OP nerve agent exposure, which fail to prevent SE resulting in severe neuropathology and epilepsy.

Expression of endothelial nitric oxide synthase in the uterus of patients with leiomyoma or adenomyosis

AIM

To confirm the difference in the expression of endothelial nitric oxide synthase in the normal endometrium and myometrium of women who have leiomyoma or adenomyosis compared with controls, and its correlation with the pathogenesis of menorrhagia or dysmenorrhea in patients with uterine leiomyoma.

METHODS

Fifty-one hysterectomized patients were divided into three groups: (i) patients with leiomyoma (n=24); (ii) those with adenomyosis (n = 19); and (iii) the control group (n=8). The expression of endothelial nitric oxide synthase was confirmed on immunohistochemistry and analyzed using an evaluation nomogram.

RESULTS

The expression of endothelial nitric oxide synthase was significantly higher in the leiomyoma group and the adenomyosis group as compared with the control group. In the subgroup analysis of leiomyoma depending on symptoms (menorrhagia or dysmenorrhea or both), the expression of endothelial nitric oxide synthase was significantly higher in the symptomatic subgroup than the asymptomatic subgroup (endometrium P=0.0029, myometrium P=0.0276).

CONCLUSIONS

Based on the findings that the expression of endothelial nitric oxide synthase was significantly higher in the uterus with leiomyoma or adenomyosis, it can therefore be inferred that nitric oxide might have a pathological effect on the uterus with the above diseases. In particular, it is also presumed that endothelial nitric oxide synthase is closely associated with menorrhagia and dysmenorrhea.

Saikosaponin a and its epimer saikosaponin d exhibit anti-inflammatory activity by suppressing activation of NF-κB signaling pathway

Saikosaponin a (SSa) and its epimer saikosaponin d (SSd) are major triterpenoid saponin derivatives from Radix bupleuri (RB), which has been long used in Chinese traditional medicine for treatment of various inflammation-related diseases. In the present study, the anti-inflammatory activity, as well as the underlying mechanism, of SSa and SSd was investigated in lipopolysaccharide (LPS)-induced RAW264.7 cells. Our results demonstrated that both SSa and SSd significantly inhibited the expression of inducible nitric-oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-induced RAW264.7 cells, and finally resulted in the reduction of nitric oxide (NO) and prostaglandin E(2) (PGE(2)). In addition, LPS-induced production of major pro-inflammatory cytokines: the tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), was suppressed in a dose-dependent manner by the treatment of SSa or SSd in RAW264.7 cells. Further analysis revealed that both SSa and SSd could inhibit translocation of nuclear factor-κB (NF-κB) from the cytoplasm to the nucleus in the LPS-induced RAW264.7 cells. Furthermore, SSa and SSd exhibited significant anti-inflammatory activity in two different murine models of acute inflammation, carrageenan-induced paw edema in rats and acetic acid-induced vascular permeability in mice. In conclusion, SSa and SSd showed potent anti-inflammatory activity through inhibitory effects on NF-κB activation and thereby on iNOS, COX-2 and pro-inflammatory cytokines.

Procyanidin B3 prevents articular cartilage degeneration and heterotopic cartilage formation in a mouse surgical osteoarthritis model

Osteoarthritis (OA) is a common disease in the elderly due to an imbalance in cartilage degradation and synthesis. Heterotopic ossification (HO) occurs when ectopic masses of endochondral bone form within the soft tissues around the joints and is triggered by inflammation of the soft tissues. Procyanidin B3 (B3) is a procyanidin dimer that is widely studied due to its high abundance in the human diet and antioxidant activity. Here, we evaluated the role of B3 isolated from grape seeds in the maintenance of chondrocytes in vitro and in vivo. We observed that B3 inhibited H(2)O(2)-induced apoptosis in primary chondrocytes, suppressed H(2)O(2)- or IL-1ß-induced nitric oxide synthase (iNOS) production, and prevented IL-1ß-induced suppression of chondrocyte differentiation marker gene expression in primary chondrocytes. Moreover, B3 treatment enhanced the early differentiation of ATDC5 cells. To examine whether B3 prevents cartilage destruction in vivo, OA was surgically induced in C57BL/6J mice followed by oral administration of B3 or vehicle control. Daily oral B3 administration protected articular cartilage from OA and prevented chondrocyte apoptosis in surgically-induced OA joints. Furthermore, B3 administration prevented heterotopic cartilage formation near the surgical region. iNOS protein expression was enhanced in the synovial tissues and the pseudocapsule around the surgical region in OA mice fed a control diet, but was reduced in mice that received B3. Together, these data indicated that in the OA model, B3 prevented OA progression and heterotopic cartilage formation, at least in a part through the suppression of iNOS. These results support the potential therapeutic benefits of B3 for treatment of human OA and heterotopic ossification.

Berberine suppresses amyloid-beta-induced inflammatory response in microglia by inhibiting nuclear factor-kappaB and mitogen-activated protein kinase signalling pathways

Objectives

The neuroinflammation induced by amyloid-beta peptide (Aβ) is one of the key events in Alzheimer's disease (AD) progress in which microglia are the main cells involved. Berberine, one of the major constituents of Chinese herb Rhizoma coptidis, is known for its anti-inflammatory, anti-oxidative and anti-microbial activity. In this study, we examined the effects and possible underlying mechanisms of berberine in Aβ-induced neuroinflammation using murine primary microglia cells and cultured BV2 microglia cells.

Methods

The effects of berberine on Aβ-stimulated inflammatory factor expression and secretion were examined using RT-PCR and ELISA analysis. The signal pathways involved in berberine's effects were also investigated using Western blot and immunofluorescence analysis.

Results

In primary microglial and BV2 cells, berberine treatment significantly inhibited Aβ-stimulated production of interleukin-6 and monocyte chemotactic protein-1. Berberine treatment down-regulated the expression of cyclo-oxygenase-2 and induced nitric oxide synthase in these cells. Moreover, berberine strongly inhibited the nuclear factor-kappaB (NF-κB) activation, presumably through blocking the phosphoinositide 3-kinase/protein kinase B and mitogen-activated protein kinase signalling pathways.

Conclusions

Our data indicated berberine is a potent suppressor of neuroflammation, presumably through inhibition of NF-κB activation, and suggested berberine has therapeutic potential for the treatment of neuroinflammation that is involved in neurological diseases such as AD.

Endothelial cells influence the sodium nitroprusside mediated inhibition of platelet aggregation by an as yet unkown pathway

The clinical use of Sodium nitroprusside (SNP) may be associated with an alteration of platelet function. The main focus of this study was the effect of SNP on platelet aggregation in the absence or presence of endothelial cells.

Methods: Platelets were incubated with different concentrations of SNP with and without endothelial cells. Platelet aggregation was induced by ADP.

Results: Platelet aggregation was significantly inhibited by all concentrations of SNP. Endothelial cells significantly increased this inhibitory effect of SNP. Time course studies showed an inverse correlation of incubation time to platelet aggregation inhibition in the absence of endothelial cells, and a direct correlation in the presence of endothelial cells. Blocking platelet and endothelial cell guanylate cyclase with 1 H-(1,2,4)-oxadiazolo(4,3-a) quinoxalin-1-one (ODQ), or pretreatment of the endothelial cells with cyclooxygenase – inhibitors, had no influence on the increased inhibitory effect of the endothelial cells. Cyanide reversed the inhibitory effect of SNP completely.

Conclusion: Endothelial cells play an important role in the SNP mediated inhibition of platelet aggregation. The effect is reversible only by cyanide, not by blocking classical NO signal transduction.

Nitric oxide induces cell death in canine cruciate ligament cells by activation of tyrosine kinase and reactive oxygen species

Background

There is increasing evidence suggesting that development of progressive canine cranial cruciate ligament (CCL) rupture involves a gradual degeneration of the CCL itself, initiated by a combination of factors, ranging from mechanical to biochemical. To date, knowledge is lacking to what extent cruciate disease results from abnormal biomechanics on a normal ligament or contrary how far preliminary alterations of the ligament due to biochemical factors provoke abnormal biomechanics. This study is focused on nitric oxide (NO), one of the potential biochemical factors. The NO-donor sodium nitroprusside (SNP) has been used to study NO-dependent cell death in canine cranial and caudal cruciate ligament cells and to characterize signaling mechanisms during NO-stimulation.

Results

Sodium nitroprusside increased apoptotic cell death dose- and time-dependently in cruciate ligamentocytes. Cells from the CCL were more susceptible to apoptosis than CaCL cells. Caspase-3 processing in response to SNP was not detected. Testing major upstream and signal transducing pathways, NO-induced cruciate ligament cell death seemed to be mediated on different levels. Specific inhibition of tyrosine kinase significantly decreased SNP-induced cell death. Mitogen activated protein kinase ERK1 and 2 are activated upon NO and provide anti-apoptotic signals whereas p38 kinase and protein kinase C are not involved. Moreover, data showed that the inhibition reactive oxygen species (ROS) significantly reduced the level of cruciate ligament cell death.

Conclusions

Our data support the hypothesis that canine cruciate ligamentocytes, independently from their origin (CCL or CaCL) follow crucial signaling pathways involved in NO-induced cell death. However, the difference on susceptibility upon NO-mediated apoptosis seems to be dependent on other pathways than on these tested in the present study. In both, CCL and CaCL, the activation of the tyrosine kinase and the generation of ROS reveal important signaling pathways. In perspective, new efforts to prevent the development and progression of cruciate disease may include strategies aimed at reducing ROS.

Possible involvement of S-nitrosylation of brain cyclooxygenase-1 in bombesin-induced central activation of adrenomedullary outflow in rats

We previously reported that both nitric oxide (NO) generated from NO synthase by bombesin and NO generated from SIN-1 (NO donor) activate the brain cyclooxygenase (COX) (COX-1 for bombesin), thereby eliciting the secretion of both catecholamines (CA) from the adrenal medulla by brain thromboxane A(2)-mediated mechanisms in rats. NO exerts its effects via not only soluble guanylate cyclase, but also protein S-nitrosylation, covalent modification of a protein cysteine thiol. In this study, we clarified the central mechanisms involved in the bombesin-induced elevation of plasma CA with regard to the relationship between NO and COX-1 using anesthetized rats. Bombesin (1 nmol/animal, i.c.v.)-induced elevation of plasma CA was attenuated by carboxy-PTIO (NO scavenger) (0.5 and 2.5 μmol/animal, i.c.v.), but was not influenced by ODQ (soluble guanylate cyclase inhibitor) (100 and 300 nmol/animal, i.c.v.). The bombesin-induced response was effectively reduced by dithiothreitol (thiol-reducing reagent) (0.4 and 1.9 μmol/kg/animal, i.c.v.) and by N-ethylmaleimide (thiol-alkylating reagent) (0.5 and 2.4 μmol/kg/animal, i.c.v.). The doses of dithiothreitol also reduced the SIN-1 (1.2 μmol/animal, i.c.v.)-induced elevation of plasma CA, but had no effect on the U-46619 (thromboxane A(2) analog) (100 nmol/animal, i.c.v.)-induced elevation of plasma CA even at higher doses (1.9 and 9.7 μmol/kg/animal, i.c.v.). Immunohistochemical studies demonstrated that the bombesin increased S-nitroso-cysteine-positive cells co-localized with COX-1 in the spinally projecting neurons of the hypothalamic paraventricular nucleus (PVN). Taken together, endogenous NO seems to mediate centrally administered bombesin-induced activation of adrenomedullary outflow at least in part by S-nitrosylation of COX-1 in the spinally projecting PVN neurons in rats.

Ameliorative effect of combined administration of inducible nitric oxide synthase inhibitor with cyclooxygenase-2 inhibitors in neuropathic pain in rats

OBJECTIVES

The objective of this study was to examine the effects of rofecoxib, meloxicam, both cyclooxygenase-2 (COX-2) inhibitors and aminoguanidine hydrochloride, an inducible nitric oxide synthase (iNOS) inhibitor and their combinations in neuropathic pain in rats.

METHODS

Neuropathy was induced by chronic constriction injury (CCI) of right sciatic nerve under ketamine anesthesia in rats. Effect of ED(50) of aminoguanidine hydrochloride, rofecoxib and meloxicam administered orally was investigated using behavioral tests. Effect of combinations of aminoguanidine hydrochloride with rofecoxib and meloxicam was also investigated in neuropathic pain employing behavioral tests.

RESULTS

Behavioral tests, mechanical, thermal and cold stimuli confirmed the development of neuropathic pain after CCI. Aminoguanidine hydrochloride, rofecoxib and meloxicam when administered alone, produced significant increase in paw withdrawal threshold to mechanical stimuli at 6 h in ipsilateral hind paw after CCI. Co-administration of aminoguanidine hydrochloride (30 mg/kg) with rofecoxib (1.31 mg/kg) and meloxicam (1.34 mg/kg) was also found to produce significant increase in paw withdrawal latencies to mechanical stimuli at 6 h. Combined administration of aminoguanidine hydrochloride with meloxicam and rofecoxib produced significant rise in pain threshold for mechanical hyperalgesia in ipsilateral hind paw when compared with the groups treated with aminoguanidine hydrochloride, meloxicam and rofecoxib alone.

CONCLUSION

Co-administration of meloxicam and rofecoxib with aminoguanidine hydrochloride may be an alternative approach for the treatment of neuropathic pain.

Chemoprevention of Colon Cancer by iNOS-Selective Inhibitors

Nitric oxide (NO) is a short-lived pleiotropic regulator and is required for numerous pathophysiological functions, including macrophage-mediated immunity and cancer. It is a highly reactive free radical produced from l-arginine by different isoforms of NO synthases (NOSs). Sustained induction of inducible NOS (iNOS) during chronic inflammatory conditions leads to the formation of reactive intermediates of NO, which are mutagenic and cause DNA damage or impairment of DNA repair, alter cell signaling, and promote proinflammatory and angiogenic properties of the cell, thus contributing to carcinogenesis. Besides its well-established role in inflammation, increased expression of iNOS has been observed in colorectal tumors and other cancers. NO-related signaling pathways involved in colon tumorigenesis seem to progress through stimulation of proinflammatory cytokines and via posttranslational protein modifications of important antiapoptotic molecules in the tumors. NO can stimulate and enhance tumor cell proliferation by promoting invasive, angiogenic, and migratory activities. In contrast, studies also suggest that high levels of NO may be protective against tumor growth by inducing tumor cell death. However, a number of in vitro studies and particularly experimental animal data support the notion that NO and its reactive metabolite peroxynitrite stimulate cyclooxygenase-2 activity, leading to generation of prostaglandins that enhance tumor growth. These prostaglandins further augment tumor promotion and invasive properties of tumor cells. Hence, selective inhibitors of iNOS and combination strategies to inhibit both iNOS and cyclooxygenase-2 may have a preventive role in colon cancer.

Anti-superoxide and anti-peroxynitrite strategies in pain suppression

Superoxide (SO, O(2)·(-)) and its reaction product peroxynitrite (PN, ONOO(-)) have been shown to be important in the development of pain of several etiologies. While significant progress has been made in teasing out the relative contribution of SO and PN peripherally, spinally, and supraspinally during the development and maintenance of central sensitization and pain, there is still a considerable void in our understanding. Further research is required in order to develop improved therapeutic strategies for selectively eliminating SO and/or PN. Furthermore, it may be that PN is a more attractive target, in that unlike SO it has no currently known beneficial role. Our group has been at the forefront of research concerning the role of SO and PN in pain, and our current findings have led to the development of two new classes of orally active catalysts which are selective for PN decomposition while sparing SO. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Redox characterization of usnic acid and its cytotoxic effect on human neuron-like cells (SH-SY5Y)

Usnic acid (UA) is the most common and abundant lichenic secondary metabolite with potential therapeutic application. Anti-inflammatory and antitumour properties have already been reported and UA-enriched extracts are widely used to treat several diseases in the folk medicine. First, we performed in silico evaluation of UA interactions with genes/proteins and important compounds for cellular redox balance and NO pathway. Then, we assessed UA redox properties against different reactive species (RS) generated in vitro, and evaluated its action on SH-SY5Y neuronal like cells upon hydrogen peroxide (H(2)O(2)), since no in vitro neurotoxicological data has been reported so far. Total reactive antioxidant potential index (TRAP) showed a significant antioxidant capacity of UA at the highest tested concentration; UA was also effective against hydroxyl radicals and reduced the formation of nitric oxide. In vitro, lipoperoxidation was enhanced by UA and changed the cellular viability at highest concentration of 20μg/mL for 1 and 4h, as well as 2 and 20μg/mL for 24h of treatment, according to MTT reduction assay. Moreover, UA did not display protective effects against H(2)O(2)-induced cell death in any case. Evaluation of intracellular RS production by the DCFH-based assay indicated that UA was able to induce changes in basal RS production at concentration of 20μg/mL for 1h and from 2ng/mL to 20μg/mL for 4 and 24h. In conclusion, UA could display variable redox-active properties, according to different system conditions and/or cellular environment. Moreover, our results suggest that potential neurotoxicological effects of UA should be further studied by additional approaches; for instance, in vivo and clinical studies.

Anti-inflammatory activities and mechanisms of action of the petroleum ether fraction of Rosa multiflora Thunb. hips

ETHNOPHARMACOLOGICAL RELEVANCE

The hip of Rosa multiflora Thunb. has been traditionally used as a dietary supplement and a herbal remedy for the treatment of various diseases including cold, flu, inflammation, osteoarthritis, rheumatoid arthritis and chronic pain in China.

AIMS OF THE STUDY

To explore the anti-inflammatory ingredient of the hip of R. multiflora Thunb. and its mechanism of action.

MATERIALS AND METHODS

The ethanol extract of the hip of R. multiflora Thunb. was fractioned with petroleum ether, ethyl acetate and water, and each fraction was screened for anti-inflammatory activity in xylene-induced mouse ear edema model. Three more models, acetic acid-induced mouse vascular permeation, cotton pellet-induced rat granuloma, and carrageenan-induced rat hind paw edema were also employed to verify the anti-inflammatory effect of the identified fraction. To explore the mechanism of action, the activity of inducible nitric oxide synthase (iNOS) and the level of nitric oxide (NO) in sera, as well as mRNA expression level of cyclo-oxygenase-2 (COX-2) in inflammatory tissues of rats with carrageenan-induced hind paw edema were measured. GC-MS technology was applied to identify the active components in the active fraction.

RESULTS AND CONCLUSIONS

The petroleum ether fraction (PEF) was identified to be the active fraction in inflammation animal models (i.e., oral administration of PEF (168.48, 42.12 and 10.53 mg/kg) evoked a significantly (P<0.001) dose-dependent inhibition of the xylene-induced mice ear edema). Down-regulating COX-2 expression (P<0.001) and reducing NO production (P<0.05) through inhibiting iNOS activity (P<0.001) may be the partial mechanism of action of PEF. GC-MS analysis indicated that unsaturated fatty acids are enriched in PEF and may be responsible for the anti-inflammatory activity of PEF and this herb. The results of this study provide pharmacological and chemical basis for the application of the hip of R. multiflora Thunb. in inflammatory disorders.

Hericium erinaceus suppresses LPS-induced pro-inflammation gene activation in RAW264.7 macrophages

The aim of this study was to investigate the anti-inflammatory properties of each fraction of Hericium erinaceus (HE). The ethanol extract from HE was partitioned with different solvents in the order of increasing polarity. The treatment with 10-100 μg/mL of each fraction did not reduce RAW 264.7 cell viability except ethyl acetate fraction. Among the various extracts, the chloroform fraction showed the most potent activity against nitric oxide (NO), prostaglandin E(2) (PGE(2)) and reactive oxygen species (ROS). The western blotting and reverse transcriptase polymerase chain reaction (RT-PCR) analyses revealed that chloroform fraction from HE (CHE) significantly reduced the protein level of iNOS and cyclooxygenase-2 (COX-2) or mRNA levels of iNOS in lipopolysaccharide-induced macrophages. Furthermore, CHE inhibited the translocation of nuclear factor (NF)-κB p65 subunit, phsophorylation of I-κB, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) in a dose-dependent manner. Furthermore, the activation of both activator protein-1 (AP-1) and NF κB in the nucleus were abrogated by CHE with luciferase assay. In conclusion, these results indicate that CHE may provide an anti-inflammatory effect by attenuating the generation of excessive NO, PGE(2), and ROS and by suppressing the expression of pro-inflammatory genes through the inhibition of NF-κB and JNK activity.

Effects of instillation of eyedrops containing disulfiram and hydroxypropyl-β-cyclodextrin inclusion complex on endotoxin-induced uveitis in rats

OBJECTIVE

To investigate the anti-inflammatory effects of the instillation of disulfirum (DSF) eyedrops that enhance solubility using 2-hydroxypropyl-β-cyclodextrin (HPβCD) and hydroxypropylmethylcellulose (HPMC) on endotoxin-induced uveitis (EIU) in rats and mechanisms related to ocular inflammation.

METHODS

EIU was induced in male Lewis rats by subcutaneous injection of 200 μg lipopolysaccharide (LPS). DSF (0.125%, 0.25% and 0.5%) or commercially available 0.05% dexamethasone (Dexa) was topically applied to both eyes of rats 1 hour before, immediately after, and 1 and 2 hours after injection of LPS. The aqueous humor (AqH) was collected 24 hours after LPS injection, and the number of infiltrating cells, protein concentration, and levels of tumor necrosis factor-α (TNF-α), nitric oxide (NO) and prostaglandin E2 (PGE2) were determined. Immunohistochemical analysis of the iris ciliary body (ICB) cells was performed to determine the expression of activated nuclear factor κB (NF-κB), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2).

RESULTS

The topical administration with DSF suppressed, in a dose-dependent manner, the number of inflammatory cells, the protein concentration, and the levels of NO, TNF-α and PGE2 in the AqH and improved the histologic status of the ocular tissue. The anti-inflammatory potency of 0.5% DSF treatment was as strong as that of 0.05% Dexa. Topical DSF treatment also suppressed the activated NF-κB 3 hours after LPS injection, and iNOS and COX-2 expression in the ICB 24 hours after LPS injection.

CONCLUSIONS

The present results demonstrate that the topical instillation of DSF eyedrops suppresses the inflammation in EIU, suggesting a possible novel approach for the treatment of ocular inflammation.

The role of manganese superoxide dismutase in inflammation defense

Antioxidant enzymes maintain cellular redox homeostasis. Manganese superoxide dismutase (MnSOD), an enzyme located in mitochondria, is the key enzyme that protects the energy-generating mitochondria from oxidative damage. Levels of MnSOD are reduced in many diseases, including cancer, neurodegenerative diseases, and psoriasis. Overexpression of MnSOD in tumor cells can significantly attenuate the malignant phenotype. Past studies have reported that this enzyme has the potential to be used as an anti-inflammatory agent because of its superoxide anion scavenging ability. Superoxide anions have a proinflammatory role in many diseases. Treatment of a rat model of lung pleurisy with the MnSOD mimetic MnTBAP suppressed the inflammatory response in a dose-dependent manner. In this paper, the mechanisms underlying the suppressive effects of MnSOD in inflammatory diseases are studied, and the potential applications of this enzyme and its mimetics as anti-inflammatory agents are discussed.

Roles of reactive oxygen and nitrogen species in pain

Peroxynitrite (PN; ONOO⁻) and its reactive oxygen precursor superoxide (SO; O₂•⁻) are critically important in the development of pain of several etiologies including pain associated with chronic use of opiates such as morphine (also known as opiate-induced hyperalgesia and antinociceptive tolerance). This is now an emerging field in which considerable progress has been made in terms of understanding the relative contributions of SO, PN, and nitroxidative stress in pain signaling at the molecular and biochemical levels. Aggressive research in this area is poised to provide the pharmacological basis for development of novel nonnarcotic analgesics that are based upon the unique ability to selectively eliminate SO and/or PN. As we have a better understanding of the roles of SO and PN in pathophysiological settings, targeting PN may be a better therapeutic strategy than targeting SO. This is because, unlike PN, which has no currently known beneficial role, SO may play a significant role in learning and memory. Thus, the best approach may be to spare SO while directly targeting its downstream product, PN. Over the past 15 years, our team has spearheaded research concerning the roles of SO and PN in pain and these results are currently leading to the development of solid therapeutic strategies in this important area.