Changes In Nitric Oxide Levels Research Articles

Response of the Nitric Oxide System to Hypobaric Hypoxia in the Aged Striatum

Background: Nitric oxide (NO) appears to play a key role in the hypoxic injury to the brain. We have previously reported that hypoxia/reoxygenation downregulated NO synthases (NOS) in the adult striatum. Until now, no data were available concerning the influence of aging in conjunction with hypoxia/reoxygenation on the NO system in the striatum. Objective: The aim of this study was to assess the role of the NO pathway in the hypoxic aged striatum. Methods: Wistar rats 24-25 months old were submitted to hypobaric hypoxia (20 min)/reoxygenation (0 h, 24 h, 5 days). Expression (PCR, immunohistochemistry/image analysis) and activity (NADPH-diaphorase/image analysis) of NOS isoforms (neuronal NOS or nNOS, endothelial NOS or eNOS, inducible NOS or iNOS) were analyzed together with nitrated protein expression (immunohistochemistry/image analysis). NO levels were indirectly quantified as nitrates/nitrites (NOx). Results: The mRNA levels of NOS isoforms were undetectable at 0 h after hypoxia in the striatum compared to the control. At later reoxygenation times, nNOS mRNA decreased, while eNOS mRNA augmented. Protein levels of nNOS and eNOS rose at 24 h after hypoxia, and iNOS protein increased at 5 days. NOx levels remained unchanged, whereas in situ NOS activity and protein nitration diminished during reoxygenation in the aged striatum. Conclusion: The aged striatum may overexpress NOS isoforms as a neuroprotective-adaptive mechanism to hypoxia. However, this mechanism may not work properly in the aged striatum, since no changes in NO levels were detected after hypoxia. This may be related to the low activity of NOS isoforms in the hypoxic striatum.

Humic acid protects barley against salinity

Barley (Hordeum vulgare, cv. Radegast) plants cultured in Hoagland solution were exposed to NaCl and/or humic acid (HA) for 7 days. Plants revealed relatively high sensitivity to NaCl (100 mM), which was manifested by a considerable decline in growth, tissue water depletion, and high sodium accumulation. HA typically increased the content of organic metabolites (syringic acid, alanine, proline, ascorbic acid, glutathione, and phytochelatin 2), NaCl evoked the opposite effect (not for proline), and the combined treatment (NaCl + HA) showed mostly the positive impact of HA. However, these responses differed between shoot and root tissues. Salinity, but not HA, depleted the Krebs cycle acids (except for succinic acid). Salinity induced ROS formation, and HA reversed these symptoms, as evidenced by fluorescence microscopy. Changes of nitric oxide level were also detected. HA suppressed the NaCl-induced increase in Na, while the impact on other nutrients was not extensive. Moreover, foliar and hydroponic HA application revealed similar mitigating effects on NaCl stress. Overall, these data indicate the potential of HA to protect barley against NaCl stress by limiting Na uptake and positively impacting amount of some metabolites.

Changes in Nitric Oxide Level and Thickness Index of Synovial Fluid in Osteoarthritis Patients following Intraarticular Injection of Sodium Hyaluronate

Purpose: To monitor the changes in nitric oxide levels and synovium thickness index in synovial fluid following intra-articular injection of sodium hyaluronate.Methods: One hundred patients diagnosed with osteoarthritis of the knee from April 2014 to January 2015 in The Third Hospital of Jinan, Jinan, Shandong, China were selected and categorized into three phases; namely, mild, moderate and severe. Patients received a 20 mL sodium hyaluronate injection into the articular cavity of the knee once per week for 15 weeks, with continuous observation. The Visual Analogue Scale (VAS) and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) scores were recorded after five weeks. A total of 56 patients (78 knees) remaining in serious condition after 5 weeks were divided into mild, moderate, and severe groups and treated with sodium hyaluronate once a week. Internationally reorganized VAS and WOMAC scores were adopted as clinical observation indices to indicate the curative effect of sodium hyaluronate among the 56 patients after 15 weeks of treatment. The conditions of the patients in the two phases were compared.Results: After 5 weeks of treatment, treatment effective rate in the mild, moderate and severe groups was 72.92, 66.10 and 28.57 %, respectively, with an overall effective rate of 78 %. After 15 weeks of treatment, treatment effective rate in mild, moderate, and severe groups was 96.77, 95.45 and 66.67 %, respectively, with an overall effective rate of 67.95 %.Conclusions: Clinically curative effect of sodium hyaluronate is significant for mild and moderate phase patients after intra-articular injection of sodium hyaluronate, while the effect is insignificant in severe patients. Thus, sodium hyaluronate can effectively improve nitric oxide levels in synovial fluid, reduce synovium thickness, enhances articular cavity lubrication and effectively alleviates disease severity.Keywords: Osteoarthritis, Knee, Intra-articular injection, Sodium hyaluronate, Nitric oxide, Synovium thickness, WOMAC

Ameliorating Effect of Piperine on NO-cGMP Pathway in Stress Induced Depression

Depression has become a common illness among individuals of every age group. Among numerous factors held responsible for depression stress is most vital. Behind the specified disorder various hypothesis has been laid out where Nitric Oxide is emerging target to treat stress induced depression. Antidepressant potential of piperine in stressed and unstressed condition was evaluated using tail suspension test and forced swim test whereas locomotor activity was evaluated by actophotometer. Results of the present study indicate the potential of antidepressant effect of piperine in stress. Methylene blue potentiated the effect of sub- effective dose of PP and SB-203580 enhanced effect of Piperine in stressed mice with no array on locomotor activity with direct influence on Nitric oxide. Piperine produced significant changes in Nitric oxide level which is pathophysiologic mediator(s) of depression, which validate the action of piperine on depression symptoms.

Physical Training Regulates Mitochondrial Parameters and Neuroinflammatory Mechanisms in an Experimental Model of Parkinson's Disease.

This study aimed to evaluate the effects of two different protocols for physical exercise (strength and aerobic training) on mitochondrial and inflammatory parameters in the 6-OHDA experimental model of Parkinson's disease. Six experimental groups were used (n = 12 per group): untrained + vehicle (Sham), strength training + vehicle (STR), treadmill training + vehicle (TTR), untrained + 6-OHDA (U + 6-OHDA), strength training + 6-OHDA (STR + 6-OHDA), and treadmill training + 6-OHDA (TTR + 6-OHDA). The mice were subjected to strength or treadmill training for 8 weeks. PD was induced via striatal injection of 6-OHDA 24 h after the last exercise session. Mice were euthanized by cervical dislocation and the striatum and hippocampus were homogenized to determine levels of tyrosine hydroxylase (TH), nuclear factor kappa B (NF-κB) p65, and sirtuin 1 (Sirt1) by western blot; tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-17, interferon-γ (IFN-γ), and transforming growth factor β1 (TGF-β1) levels by ELISA; NO content; and complex I (CI) activity. STR + 6-OHDA mice had higher TH levels and CI activity and lower NF-κB p65 and IFN-γ levels in the striatum compared to U + 6-OHDA mice, while TTR + 6-OHDA mice had higher Sirt1 levels and CI activity in both the striatum and the hippocampus, compared to U + 6-OHDA mice. Strength training increased CI activity and TH and Sirt1 levels and reduced NO, NF-κB p65, TNF-α, IFN-γ, IL-1β, and TGF-β1 levels in 6-OHDA mice, while treadmill exercise increased CI activity and NO, TH, and Sirt1 levels and reduced NF-κB p65, TNF-α, IFN-γ, and IL-1β levels. Our results demonstrated that both treadmill training and strength training promote neuroprotection, possibly by stimulating Sirt1 activity, which may in turn regulate both mitochondrial function and neuroinflammation via deacetylation of NF-κB p65. Changes in nitric oxide levels may also be a mechanism by which 6-OHDA-induced inflammation is controlled.

The impact of human and mouse differences in NOS2 gene expression on the brain's redox and immune environment.

BackgroundMouse models are used in the study of human disease. Despite well-known homologies, the difference in immune response between mice and humans impacts the application of data derived from mice to human disease outcomes. Nitric oxide synthase-2 (NOS2) is a key gene that displays species-specific outcomes via altered regulation of the gene promoter and via post-transcriptional mechanisms in humans that are not found in mice. The resulting levels of NO produced by activation of human NOS2 are different from the levels of NO produced by mouse Nos2. Since both tissue redox environment and immune responsiveness are regulated by the level of NO and its interactions, we investigated the significance of mouse and human differences on brain oxidative stress and on immune activation in HuNOS2tg/mNos2-/- mice that express the entire human NOS2 gene and that lack a functional mNos2 compared to wild type (WT) mice that express normal mNos2.Methods/resultsSimilarly to human, brain tissue from HuNOS2tg/mNos2-/- mice showed the presence of a NOS2 gene 3′UTR binding site. We also identified miRNA-939, the binding partner for this site, in mouse brain lysates and further demonstrated reduced levels of nitric oxide (NO) typical of the human immune response on injection with lipopolysaccharide (LPS). HuNOS2tg/mNos2-/- brain samples were probed for characteristic differences in redox and immune gene profiles compared to WT mice using gene arrays. Selected genes were also compared against mNos2-/- brain lysates. Reconstitution of the human NOS2 gene significantly altered genes that encode multiple anti-oxidant proteins, oxidases, DNA repair, mitochondrial proteins and redox regulated immune proteins. Expression levels of typical pro-inflammatory, anti-inflammatory and chemokine genes were not significantly different with the exception of increased TNFα and Ccr1 mRNA expression in the HuNOS2tg/mNos2-/- mice compared to WT or mNos2-/- mice.ConclusionsNO is a principle factor in establishing the tissue redox environment and changes in NO levels impact oxidative stress and immunity, both of which are primary characteristics of neurodegenerative diseases. The HuNOS2tg/mNos2-/- mice provide a potentially useful mechanism to address critical species- specific immune differences that can impact the study of human diseases.

An experimental study on the endothelium protective effect of adenosine-lidocaine cardioplegia on canine coronary artery

Objective By observing the changes in levels of nitric oxide (NO),endothelin (ET) and circulating endothelial cells (CEC),and that in functions of coronary vasomotor,the author discusses the protective effects of adenosine-Lidocaine cardioplegia on endothelial cells of canine coronary artery and its possible mechanism.Methods 12 mongrel dogs were randomly divided into two groups:experimental group with Adenosine-lidocaine cardioplegia (AL group,n =6) and the control group with ST.Thomas Ⅱ cardioplegia (K group,n =6).Measured the changes in levels of NO,ET and CEC on three time points:before operation (T1),1 h after heart re-beat (T2) and 2 h after heart re-beat (T3),observed the changes in functions of coronary vasodilation,and analyzed the coronary ultrastructure by using electron microscope.Results There were no statistical differences between the two groups in T1.On the time point of T3,NO in plasma of group K has been significantly decreased than that of group AL (P ＜ 0.05).ET has been increased significantly (P ＜ 0.05),so as CEC (P ＜ 0.05).The maximum percentage of coronary vasodilation in group K is (29.13 ± 8.24)％ which is lower than that of AL group (68.52 ± 11.32)％ (P ＜ 0.01).Electron microscopy results show that the damage of coronary vascular endothelial cell ultrastructure of group K is more serious than that of group AL.Conclusion The protective effect of Adenosine-Lidocaine cardioplegia on canine coronary vascular endothelial cell is superior to that of ST.Thomas Ⅱ cardioplegia. Key words: Adenosine ; Lidocaine; Cardiopulmonary bypass; Coronary artery ; Circulating endothelial cell

Effects of prostaglandin E1 on nitric oxide and oxygen dynamics during rat myocardial ischemia–reperfusion utilizing sol–gel derived microsensors

Prostaglandin E1 (Alprostadil®, PGE1) is often used for patients with critical limb ischemia due to its vasodilator and anti-platelet effects. Although PGE1 is considered to have a cardioprotective effect against myocardial ischemia–reperfusion (IR) injury, its mechanism and correlation with nitric oxide (NO) for cardioprotection are not clear. In this study, we used sol–gel-modified electrochemical NO and O2 microsensors to simultaneously measure the changes in NO level and oxygen tension (pO2) in the myocardium during myocardial IR that were induced by PGE1 pretreatment. Rat hearts were randomly divided into two groups: a control group (n=5) and a PGE1 group (n=5, with PGE1 pretreatment). Myocardium that underwent PGE1 pretreatment (26.0±13.1%, p<0.001) demonstrated more highly reduced endogenous NO production during the ischemic period than that of the control group (86.7±18.5%). After the onset of reperfusion, %NO level in the PGE1 group increased to a maximum of 82.0±6.4 but did not exceed the pre-ischemic basal NO level. However, in the control group, the maximum %NO response (164.9±41.0) on reperfusion was approximately double that of the PGE1 group (p<0.01, n=5). The restoration value of pO2 in the PGE1 group significantly increased and was restored to pre-ischemic level (82.2±21.3%); however, the pO2 of the control group did not increase throughout the reperfusion period (12.3±7.9%, p<0.001). As a result, we suggest that the cardioprotective effect of PGE1 might be attributed to a reduction in excessive NO production during reperfusion. Therefore, simultaneous and real-time monitoring of NO and pO2 dynamics in the myocardium would be effective in evaluating the effects of therapeutic treatments such as drug administration. Also, the reduction in excessive NO release during the early reperfusion period might be helpful as a therapeutic strategy to protect the myocardium from IR injury.

Fabrication of a nitric oxide gas sensor using microwires and basic research for its application

Purpose: Although nitric oxide (NO) is considered one of the initial signals that promote postsurgery liver regeneration, NO’s exact role in the liver regeneration mechanism is still not clear. Therefore, developing a practical gas sensor and testing it in a clinical setting through basic research will lay the groundwork for advanced clinical research on the action mechanism of NO. Methods: A thin nano wire NO sensor was made by wrapping a pair of parlyene-coated gold wires around a needle. The NO blood concentration determined by measuring the potential difference across the oscilloscope using electrical conductivity. In order to measure changes in NO level before and after the surgery, the NO sensor was inserted in the hepatic portal vein and a 75 percent partial hepatectomy was performed. The NO blood concentration was measured regularly with both the NO kit and the sensor. Results: One significant challenge was separation of the wire upon insertion into the hepatic portal vein. Despite separation, the constant measurements of the wire-type sensor were similar to those measured by the NO measurement kit. Conclusion: The development of a needle-type sensor allowed for easier insertion. In the future, using difference in electric potential, as used in the NO sensor, may be a more effective method of measuring blood ion concentration.

Far red/near infrared light treatment promotes femoral artery collateralization in the ischemic hindlimb

Nitric oxide (NO) is a crucial mediator of hindlimb collateralization and angiogenesis. Within tissues there are nitrosyl-heme proteins which have the potential to generate NO under conditions of hypoxia or low pH. Low level irradiation of blood and muscle with light in the far red/near infrared spectrum (670nm, R/NIR) facilitates NO release. Therefore, we assessed the impact of red light exposure on the stimulation of femoral artery collateralization. Rabbits and mice underwent unilateral resection of the femoral artery and chronic R/NIR treatment. The direct NO scavenger carboxy-PTIO and the nitric oxide synthase (NOS) inhibitor L-NAME were also administered in the presence of R/NIR. DAF fluorescence assessed R/NIR changes in NO levels within endothelial cells. In vitro measures of R/NIR induced angiogenesis were assessed by endothelial cell proliferation and migration. R/NIR significantly increased collateral vessel number which could not be attenuated with L-NAME. R/NIR induced collateralization was abolished with c-PTIO. In vitro, NO production increased in endothelial cells with R/NIR exposure, and this finding was independent of NOS inhibition. Similarly R/NIR induced proliferation and tube formation in a NO dependent manner. Finally, nitrite supplementation accelerated R/NIR collateralization in wild type C57Bl/6 mice. In an eNOS deficient transgenic mouse model, R/NIR restores collateral development. In conclusion, R/NIR increases NO levels independent of NOS activity, and leads to the observed enhancement of hindlimb collateralization.

Urinary nitric oxide in newborns with sepsis: a useful follow-up marker

Neonatal Sepsis is a major problem in newborn nurseries because of the difficulty of early diagnosis and because of high morbidity and mortality. The objective of this study was to investigate whether urinary nitric oxide (NO) level could be useful for the diagnosis and follow-up of infected newborns. Urinary NO was measured for 30 newborns with sepsis on the first and on the fourth day (group I) and compared with 10 age-matched healthy control (group II). Ninety percent of the septic group showed increase in the urinary NO level during sepsis, while there was decrease in the NO level in the control group. The levels of NO did not differ significantly between cases and control on the first day (p = 0.24), but the difference was significant between the two groups on day 4 (p = 0.02). On comparing the change in NO level from first to fourth day between the two groups, a statistically significant difference was found (p = 0.000). Although urinary NO levels were higher in the infected newborns as compared to the controls on the fourth day, its failure to rise to statistically significant levels on day 1 makes it a nonsuitable marker for early diagnosis of neonatal sepsis, it can however be used for monitoring infection due to its rising level and ease of sample collection.

Oxidative Modification of Rat Blood Proteins after Lesioning of Capsaicin-Sensitive Nerves and Changes in Nitric Oxide Levels

Oxidative modification of blood proteins in rats after lesioning of afferent nerves with capsaicin (150 mg/kg, s.c.) and changes in nitric oxide (NO) contents were studied in terms of levels of protein carbonyl derivatives. Deafferentation of capsaicin-sensitive nerves induced increases in the level of protein carbonyl derivatives. Increases in NO levels using L-arginine did not alter measures of the oxidative modification of proteins after lesioning of capsaicin-sensitive innervation. A similar lack of effect was seen after blockade of neuronal NO synthase (n-NOS) by the selective inhibitor 7-nitroindazole (7-NI). Increases in markers of oxidative destruction of proteins in capsaicin-treated animals were seen after blockade of NO synthesis by the nonselective inhibitor L-NAME. These results show that deafferentation of capsaicin-sensitive nerves induces oxidative modification of proteins and that this process involves NO.

Age-related alterations in mitochondrial physiological parameters and nitric oxide production in synaptic and non-synaptic brain cortex mitochondria

Brain aging has been associated with mitochondrial dysfunction and changes in nitric oxide levels. The aim of this study was to evaluate the susceptibility of synaptic and non-synaptic mitochondria to aging-dependent dysfunction. State 3 respiratory rate and respiratory control were 43% and 33% decreased, respectively in brain cortex synaptosomes from 14-month-old animals, as compared with synaptosomes from 3-month-old mice. Respiratory rates were not significantly affected by aging in non-synaptic mitochondrial fractions. Mitochondrial dysfunction was associated with increases of 84% and 38% in H₂O₂ production rates in brain cortex synaptosomes and non-synaptic mitochondria, respectively, from 14-month-old mice, as compared with young animals. Synaptic mitochondria seem to be more susceptible to calcium insult in 14-month-old mice, as compared with non-synaptic mitochondria, as measured by response of both types of fractions to calcium-induced depolarization. With aging, nitric oxide (NO) production was 44% and 27% decreased both in synaptosomal and non-synaptic mitochondrial fractions, respectively. The results of this study suggest that with aging, mitochondrial function at the nerve terminals would be more susceptible to suffer alterations by the constant calcium changes occurring as a consequence of synaptic activity. Non-synaptic mitochondria would be more resistant to age-related dysfunction and oxidative damage.

Attenuation of host NO production by MAMPs potentiates development of the host in the squid-vibrio symbiosis

Bacterial pathogens typically upregulate the host's production of nitric oxide synthase (NOS) and nitric oxide (NO) as antimicrobial agents, a response that is often mediated by microbe-associated molecular patterns (MAMPs) of the pathogen. In contrast, previous studies of the beneficial Euprymna scolopes/Vibrio fischeri symbiosis demonstrated that symbiont colonization results in attenuation of host NOS/NO, which occurs in high levels in hatchling light organs. Here, we sought to determine whether V. fischeri MAMPs, specifically lipopolysaccharide (LPS) and the peptidoglycan derivative tracheal cytotoxin (TCT), attenuate NOS/NO, and whether this activity mediates the MAMPs-induced light organ morphogenesis. Using confocal microscopy, we characterized levels of NOS with immunocytochemistry and NO with a NO-specific fluorochrome. When added exogenously to seawater containing hatchling animals, V. fischeri LPS and TCT together, but not individually, induced normal NOS/NO attenuation. Further, V. fischeri mutants defective in TCT release did not. Experiments with NOS inhibitors and NO donors provided evidence that NO mediates apoptosis and morphogenesis associated with symbiont colonization. Attenuation of NOS/NO by LPS and TCT in the squid-vibrio symbiosis provides another example of how the host's response to MAMPs depends on the context. These data also provide a mechanism by which symbiont MAMPs regulate host development.

Mechanisms of the effects of experimental diabetes on the development of tolerance to morphine antinociception in rat

Opiates, chiefly morphine, are commonly known as the best drugs for relief of pain, but due to development of tolerance and the physical or mental dependency the use of these drugs are restricted. Several neuroendocrine complications including diabetes change the antinociception of morphine and the development of tolerance and dependency to this drug. The withdrawal signs in diabetic rats significantly reduce in comparing to non-diabetic animals. The exact mechanism of these effects has not been known yet. Due to known role of nitric oxide in development of morphine tolerance this study was designed to evaluate the role of nitric oxide in the effects of diabetes on morphine tolerance. In this study the alloxan-induced diabetic male rats are used, and the changes in nitric oxide level is measured by spectrophotometric method. These changes are also measured in tolerant animals after the injection of repeated doses of morphine sulfate and by the use of inhibitors or producers of NO syntheses we are trying to clarify the role of this neurotransmitter in diabetic state.

Neonatal ventral hippocampus lesion induces increase in no levels which is attenuated by subchronic haloperidol treatment

Haloperidol is a potent dopamine receptor antagonist and used to treat psychotic disorders, such as schizophrenia. Recent clinical and preclinical studies demonstrated the overactivity of the nitric oxide (NO) system in schizophrenia. Neonatal ventral hippocampal (nVH) lesions in rats have been widely used as a neurodevelopmental model that mimics schizophrenia-like behaviors. Here, we investigate first whether the nVH lesion causes changes in NO levels in different limbic brain regions in young adults, postnatal day (PD) 81, and second, whether haloperidol treatment from PD60 to PD81 reverses these changes, by determining the accumulation of nitrites. The results show that NO levels at the level of the prefrontal cortex, occipital cortex, and cerebellum are higher in the nVH lesion animals, and that the haloperidol, in part, attenuates these altered NO levels. The NO levels observed in the nVH lesion animals with and without haloperidol treatment may be relevant to behaviors observed in schizophrenia.

Hormonal modulation of endothelial NO production

Since the discovery of endothelium-derived relaxing factor and the subsequent identification of nitric oxide (NO) as the primary mediator of endothelium-dependent relaxations, research has focused on chemical and physical stimuli that modulate NO levels. Hormones represent a class of soluble, widely circulating chemical factors that impact production of NO both by rapid effects on the activity of endothelial nitric oxide synthase (eNOS) through phosphorylation of the enzyme and longer term modulation through changes in amount of eNOS protein. Hormones that increase NO production including estrogen, progesterone, insulin, and growth hormone do so through both of these common mechanisms. In contrast, some hormones, including glucocorticoids, progesterone, and prolactin, decrease NO bioavailability. Mechanisms involved include binding to repressor response elements on the eNOS gene, competing for co-regulators common to hormones with positive genomic actions, regulating eNOS co-factors, decreasing substrate for eNOS, and increasing production of oxygen-derived free radicals. Feedback regulation by the hormones themselves as well as the ability of NO to regulate hormonal release provides a second level of complexity that can also contribute to changes in NO levels. These effects on eNOS and changes in NO production may contribute to variability in risk factors, presentation of and treatment for cardiovascular disease associated with aging, pregnancy, stress, and metabolic disorders in men and women.

Effects of a Manual Medicine Treatment Procedures on Nitric Oxide Release in 23 Healthy Adults

Objective The objective of this study was to measure if a manual treatment would alter the levels of exhaled nitric oxide levels in healthy adults. Methods A study was performed using 23 healthy adults (age, 18-30 years). Nitric oxide (NO) was measured amperometrically before and after a manual treatment. The treatment used was a cranial-thoracic trapezius stretch. Results In healthy adults, manual manipulation was associated with changes in NO levels in exhaled breath. The level of NO increased from 13.3 ± 2.09 (SD) to 15.0 ± 2.95 (SD) ppb ( P = .001, based upon the paired t tests of the subjects). The median level of NO before manual manipulation was 13.0 ppb (ranging from 8 to 17ppb); after manual manipulation, it was 16.0 ppb (ranging from 6 to 18 ppb). Conclusion The cranial-thoracic trapezius stretch was associated with an increase in exhaled NO, compared to baseline levels for the subjects in this study.

Nitric Oxide is Negatively Correlated to Pain during Acute Inflammation

BackgroundThe role that nitric oxide (NO) plays in modulating pain in the periphery is unclear. We show here, the results of two independent clinical studies (microdialysis and gene expression studies) and a pilot dose finding study (glyceryl trinitrate study), to study the role of NO in the early phase of acute inflammatory pain following oral surgery. The effect of ketorolac on NO production and nitric oxide synthase (NOS) gene expression was also studied.ResultsMicrodialysis samples showed significantly higher levels of NO at the first 100 min compared to the last 80 minutes in the placebo treated group. In the ketorolac group, on the other hand, NO levels gradually decreased over the first 60 min but were similar to placebo over the later 100-180 min, with no significant change in NO level over time. The levels of NO were negatively correlated to pain intensity scores. Local infusion of the NO donor glyceryl trinitrate at the site of surgery, showed a small analgesic effect that did not reach statistical significance in the sample size used. While the gene expression of iNOS and eNOS were not up-regulated, 3 hours after surgery, nNOS was downregulated in both treatment groups and eNOS gene expression was significantly lower in the ketorolac group compared to the placebo group. Further, there was a positive correlation between the change in gene expression of nNOS and eNOS in the placebo goup but not in the ketorolac group.ConclusionWe suggest that at this early stage of inflammatory pain in man, NO is analgesic in the periphery. Further, ketorolac down-regulates eNOS gene expression.

Nitric oxide mitigates apoptosis in human endothelial cells induced by 9,10-phenanthrenequinone: Role of proteasomal function

It has been widely recognized that nitric oxide (NO) suppresses oxidative damage of endothelial cell, but little is known about its pathophysiological role in apoptotic induction by 9,10-phenanthrenequinone (9,10-PQ), a major quinone component in diesel exhaust particles. Here, we have investigated the change in NO level in human aortic endothelial cells and the effect of NO in each step of apoptotic signaling initiated by 9,10-PQ. Treatment with 9,10-PQ evoked a bell-shaped production of NO, which was presumably due to increase in an active form of endothelial NO synthase. Pretreatment with exogenous NO decreased the susceptibility of the cells to 9,10-PQ, and retrieved from apoptotic signaling (reactive oxygen species generation, glutathione depletion and caspase activation) induced during exposure to high concentrations of 9,10-PQ. In addition, inhibition of endogenous NO production augmented the toxicity of 9,10-PQ. Interestingly, the 9,10-PQ treatment resulted in marked decreases in the proteasomal activities, which were partially abrogated by NO and a cell-permeable cGMP analog. These results indicate that proteasomal dysfunction by oxidative stress participates in the 9,10-PQ-induced apoptotic signaling and is ameliorated by NO via a cGMP-dependent pathway, thereby suggesting the protective role of NO in vascular damage caused by 9,10-PQ.