Activity Of Nitric Oxide System Research Articles

PATHOGENETIC ASPECTS OF METABOLIC SYNDROME IN EXPERIMENTAL ANIMALS

The aim: Was to study the state of the nitric oxide system, LPO and antioxidant system in the body of experimental animals in simulated metabolic syndrome. The aim of the study was to study the state of the nitric oxide system, lipid peroxidation and antioxidant system in the body of experimental animals in simulated MS. Materials and methods: The study was performed on 20 white male Wistar rats. Male control rats (n = 10) were fed a normal control diet. Male rats of the main group (n = 10) were fed a diet high in fat (over 60 % energy from fats) for 16 weeks, thus modeling the development of MS. The indicators of the prooxidant and antioxidant system, as well as the nitric oxide system were determined by photospectrographic method. Results: In animals with simulated MS, intensification of lipoperoxidation (statistically significantly higher level of TBA-active products 1.84 times), depletion of antioxidant protection (statistically significantly lower level of superoxide dismutase 2 times), activation of nitric oxide system (statistically significantly higher NO-synthase level 2.15 times) were found compared with intact animals. Conclusions: In animals with simulated MS, activation of lipid peroxidation processes, depletion of antioxidant protection and increased

Protective effects of the fruit extract of raspberry (Rubus fruticosus L.) on pituitary-gonadal axis and testicular histopathology in streptozotocin induced diabetic male rats.

Protective effects of raspberry (Rubus fruticosus L.) fruit extract on pituitary-gonadal axis and testicular tissue in diabetic male rats, were investigated. Sixty male rats were divided into control, sham (saline treated), streptozotocin (STZ)-diabetic, and STZ-diabetic animals treated with 50, 100 and 200 mg/kg/day of raspberry extract. After 4 weeks, blood samples were obtained and left testes were removed and prepared for histopathological studies. Serum levels of Luteinizing hormone (LH), Follicle stimulating hormone (FSH), testosterone, Nitric oxide (NO), and malondialdehyde (MDA), as well as superoxide dismutase (SOD) and catalase (CAT) activity level were assayed. Sperm number and motility in the epididymis samples were measured. Data were analyzed using ANOVA (one-way analysis of variance). Serum levels of LH, FSH and MDA significantly increased in diabetic rats, however, treatment with the extract significantly reversed the alterations. Serum levels of testosterone and NO, activity of SOD and CAT, and sperm number and motility significantly decreased and severe destruction of testicular histology was observed in diabetic animals while treatment with the extract significantly reversed the pathologic alterations observed in diabetic rats. According to the results, 100 and 200 mg/kg of the extract were able to effectively reverse the diabetes complications. Our findings demonstrated that the fruit extract of raspberry has protective effects on male reproductive system in diabetic rats partially due to its improving effects on NO system, and SOD and CAT activity.

Anti-arrhythmic effect of diosgenin in reperfusion-induced myocardial injury in a rat model: activation of nitric oxide system and mitochondrial KATP channel.

This study was designed to investigate the anti-arrhythmic effect of diosgenin preconditioning in myocardial reperfusion injury in rat, focusing on the involvement of the nitric oxide (NO) system and mitochondrial ATP-dependent potassium (mitoKATP) channels in this scenario. After isolation of the hearts of male Wister rats, the study was conducted in an isolated buffer-perfused heart model. Global ischemia (for 30 min) was induced by interruption of the aortic supply, which was followed by 90-min reperfusion. Throughout the experiment, the electrocardiograms of hearts were monitored using three golden surface electrodes connected to a data acquisition system. Arrhythmias were assessed based on the Lambeth convention and were categorized as number, duration and incidence of ventricular tachycardia (VT), ventricular fibrillation (VF), and premature ventricular complexes (PVC), and arrhythmic score. Additionally, lactate dehydrogenase (LDH) levels in coronary effluent were estimated colorimetrically. Diosgenin pre-administration for 20min before ischemia reduced the LDH release into the coronary effluent, as compared with control hearts (P<0.05). In addition, the diosgenin-receiving group showed a lower number of PVC, VT and VF, a reduced duration and incidence of VT and VF, and less severe arrhythmia at reperfusion phase, in comparison with controls. Blocking the mitoKATP channels using 5-hydroxydecanoate as well as inhibiting the NO system through prior administration of L-NAME significantly reduced the positive effects of diosgenin. Our finding showed that pre-administration of diosgenin could provide cardioprotection through anti-arrhythmic effects against ischemia-reperfusion (I/R) injury in isolated rat hearts. In addition, mitoKATP channels and NO system may be the key players in diosgenin-induced cardioprotective mechanisms.

&lt;i&gt;Paramecium caudatum&lt;/i&gt; Avoids from Naloxone

Protozoa aggregate to or avoid from chemical substances. We aimed to show the significance of nitric oxide (NO) in the performance of the eukaryotes to misuse drug exposure. The micro-organism Paramecium caudatum was collected from natural sources and properly isolated by repeatedly sub-cultivation in hay infusion. Number of cells per 1ml of pure medium culture was counted using Sedgwick-Rafter cell chamber. Doses of naloxone (0.05-0.4µg/µl) solely or jointly with the NO agents were infused into the chamber. Cell response was recorded after drug infusion with intervals (0-180 sec). Negative control received distilled water (1µl) instead of naloxone (legend 0). Along with, the Ca channels or cGMP pathway was banded to discuss the mechanism. According to the results, the Paramecia showed negative chemo-taxis to the naloxone, the response which is comparable with signs of withdrawal from abused drugs. This response was potentiated by activation of NO system, but, reversed after usage of the system blocker. The inhibition of Ca channels or cGMP signaling pathway markedly enhanced the avoidance. In conclusion, this study may clearly contribute the signal molecule NO in the dependence of the eukaryotes on sedative misuse drugs.

Effect of Acute Alloxan Diabetes on Ischemic and Reperfusion Arrhythmias in Rats with Different Activity of Nitric Oxide System

Similar degree of glycemia (28-31 mmol/liter) and similar mortality (37-42%) were revealed in August rats exhibiting enhanced activity of NO system and in Wistar rats 3 weeks after alloxan treatment. Under conditions of myocardial ischemia caused by 10-min coronary artery ligation, the intensity of arrhythmias did not differ from the control in Wistar rats with diabetes mellitus and increased in August rats. Under conditions of reperfusion, diabetes produced an antiarrhythmic effect in Wistar rats and did not affect arrhythmia in August rats. Plasma concentrations of nitrates and nitrites in Wistar and August rats increased by 82 and 143%, respectively, compared to the control. The level of hemoxygenase-1 (hsp32) in the myocardium remained unchanged in Wistar rats and decreased by 26% in August rats. Thus, the absence of antiarrhythmic effect of acute diabetes in August rats is probably related to elevated NO content and reduced antioxidant activity.

INHIBITION OF MORPHINE TOLERANCE WITHIN THE RAT NUCLEUS ACCUMBENS BY NITRIC OXIDE

The role of glutamate receptors within the nucleus accumbens in morphine tolerance has been postulated. Previous studies have reported that glutamate receptors exert their effects in part through the release of nitric oxide (NO). In the present study, the effect of intra-accumbal injections of L-arginine, the NO precursor and L-NAME, the NOS inhibitor on the morphine tolerance in Wistar rats (250-300 g) were investigated. For this purpose, male rats (n = 8/group) were anesthetized and bilateral cannulation (23-gauge, AP=1.7mm, L=±0.8, V= 7.1 mm) was performed into nucleus accumbens. Five days after cannulation, animals were trained in an Un-Biased conditioned place preference apparatus for five consecutive days. The NOergic drugs were injected in two ways: first; the animals were trained with morphine and were received L-arginine or L-NAME at 5th day of experiments just before the test. Second group received L-arginine or L-NAME before morphine injection. At the 5th day of the experiments, each animal was placed in the apparatus and its behavior was recorded for 10 min. The results showed that pretreatment of the animals with L-arginine did not produce any effect on morphine tolerance. Pretreatment of the animals with L-NAME potentiated both development and expression of morphine tolerance. In conclusion, present experiments showed that morphine tolerance is in part dependent on activation of NO system within the nucleus accumbens and the role of this neuromodulator in morphine dependence must be considered in further treatments of morphine addicts.

Nitric oxide mediation of morphine sensitization in the rat nucleus accumbens

Previous studies have reported that morphine exerts its effects in part through the release of nitric oxide (NO). It has been pustulated that drug sensitization is a major cause of relapse to drug use in addicts. In the present study the effects of intra-accumbal injections of L-arginine, the NO precursor and L-NAME, the NOS inhibitor on the morphine sensitization in Wistar rats (250-300 g) were investigated. Male rats (n = 8/group) were anesthetized and bilateral cannulation in nucleus accumbens (23-gauge, AP = 1.7mm, L = ±0.8, V = 7.1 mm) was performed. Five days after cannulation, animals were trained in an Un-Biased conditioned place preference apparatus for five consecutive days. The NOergic drugs were injected to the animals in two ways: first; the animals were trained with morphine and were received L-arginine or L-NAME at 5th day of experiments just before the test. Second group received L-arginine or L-NAME before morphine injection. At the 5th day of the experiments, each animal was placed in the apparatus and its behavior was recorded for 10 min. The results showed that pretreatment of the animals with L-arginine augments the development, but reduced the expression of morphine sensitization. Pretreatment of the animals with L-NAME reduced both development and expression of morphine sensitization. In conclusion, present experiments showed that morphine sensitization is in part dependent on the activation of NO system within the nucleus accumbens and the role of this neuromodulator in morphine dependence must be considered in further treatments of morphine addicts.

TCT-482: Circulating Levels of Vascular Endothelial Growth Factor, Endotelin-1 and the Activity of Nitric Oxide System after Coronary Stent Implantation

TCT-482: Circulating Levels of Vascular Endothelial Growth Factor, Endotelin-1 and the Activity of Nitric Oxide System after Coronary Stent Implantation

Normotensive menopausal rats: Effects of Enalapril on Sexual Hormones and on Nitric Oxide System Activity in the Kidney, Heart and Aorta

Studies in animal models suggest that sexual hormones, oxidative stress, and impaired nitric oxide (NO) system and renin‐angiotesin system activation play a role in hypertension during menopause. However, the involved mechanisms are still unknown.Objective: To evaluate the effects of enalapril, an inhibitor of the angiotesin‐converting enzyme (ACE), on systolic blood pressure (SBP), sexual hormones and NO syntase (NOS) activity in normotensive menopausal rats.Wistar rats were ovariectomized, and ten weeks later were divided into two groups: Experimental (E) treated with enalapril for 30 days (15 mg/Kg/day) and Control (C) with tap water. We measured: indirect SBP, androgen, estradiol and FSH plasma levels, and NOS activity (14C‐arginine) in the kidney, aorta and heart at the end of treatment.Results: treatment with enalapril did not induce any changes in SBP, estradiol, androgen and FSH plasma levels.NOS activity (pmol/min 100g tissue), * p&lt;0.01 vs ControlConclusions: The ACE inhibition did not modify SBP or sexual hormones in normotensive menopause rats, but treatment with enalapril improved NOS activity significantly in all the studied tissues. This fact could improve renal and cardiovascular function during menopause.

Action of nitric oxide on healthy and inflamed human dental pulp tissue

Irreversible pulpitis has been associated with pain and an increase in the number of pulp inflammatory cells. Based on the action of nitric oxide (NO) elsewhere, NO may possibly participate in the sensory and autonomic innervation of the dental pulp, and may influence local inflammatory responses. The purpose of this study was to analyze normal and inflamed human dental pulp for the presence of NADPH-diaphorase (NADPH-d), as an index of NO system activity. Six non-carious second premolar pulp tissue samples were obtained from young patients who required extractions for orthodontic reasons and six inflamed samples were obtained from symptomatic carious second premolars clinically diagnosed with irreversible pulpitis. Pulp tissue was carefully removed, fixed by immersion in a cold 4% PFA buffered solution for 120 min, rinsed in cold phosphate buffer, and quickly-frozen for cryostat sectioning. Pulp tissue was sectioned perpendicularly to the vertical axis of the tooth at 20 μm and processed for histochemistry. Sections of each specimen were stained with hematoxylin-eosin and other sections were subjected to histochemical NADPH-d detection. Results indicated the presence of NADPH reactivity within the pulps of both normal and carious teeth. In the normal teeth NADPH-d activity was detected in a small number of vascular endothelial cells and fibroblasts. The inflammatory response of the pulp from carious premolars was detected in connective tissue by the presence of an increased number of fibroblasts, angioblasts and collagen fibers. It was possible to determine the extent of odontoblast reactivity since the odontoblast layer was usually absent in these split-peel preparations. There were no obvious signs of stained pulpal nerve fibers. Overall NADPH-d staining was significantly more intense within inflamed pulp tissues compared to normal healthy samples (Mann–Whitney test, p < 0.002). These results suggest that NADPH-d may be used as a marker of inflammatory activity in pulpitis and provide the basis for further studies aiming to clarify the possible functions of NO in human dental pulp in pathophysiological situations.

Detrimental role of endogenous nitric oxide in host defence against Sporothrix schenckii

We earlier demonstrated that nitric oxide (NO) is a fungicidal molecule against Sporothrix schenckii in vitro. In the present study we used mice deficient in inducible nitric oxide synthase (iNOS-/-) and C57BL/6 wild-type (WT) mice treated with Nomega-nitro-arginine (Nitro-Arg-treated mice), an NOS inhibitor, both defective in the production of reactive nitrogen intermediates, to investigate the role of endogenous NO during systemic sporotrichosis. When inoculated with yeast cells of S. schenckii, WT mice presented T-cell suppression and high tissue fungal dissemination, succumbing to infection. Furthermore, susceptibility of mice seems to be related to apoptosis and high interleukin-10 and tumour necrosis factor-alpha production by spleen cells. In addition, fungicidal activity and NO production by interferon-gamma (IFN-gamma) and lipopolysaccharide-activated macrophages from WT mice were abolished after fungal infection. Strikingly, iNOS-/- and Nitro-Arg-treated mice presented fungal resistance, controlling fungal load in tissues and restoring T-cell activity, as well as producing high amounts of IFN-gamma Interestingly, macrophages from these groups of mice presented fungicidal activity after in vitro stimulation with higher doses of IFN-gamma. Herein, these results suggest that although NO was an essential mediator to the in vitro killing of S. schenckii by macrophages, the activation of NO system in vivo contributes to the immunosuppression and cytokine balance during early phases of infection with S. schenckii.

Arginine vasopressin increases iNOS–NO system activity in cardiac fibroblasts through NF-κB activation and its relation with myocardial fibrosis

Previous studies have shown that arginine vasopressin (AVP) promotes myocardial fibrosis (MF), whereas nitric oxide (NO) inhibits MF. Cardiac fibroblasts (CFs) are the main target cells of MF. However, the modulatory effect of AVP on NO production in CFs and the role of this effect in MF are still unknown. In the present study, CFs obtained from Sprague–Dawley rats were stimulated with or without AVP and pyrrolidine dithiocarbamate (PDTC), a specific inhibitor of nuclear factor kappa-B (NF-κB). NO production and NOS activity were detected with absorption spectrometry, inducible nitric oxide synthase (iNOS) protein with Western blot analysis, iNOS mRNA with real-time PCR, CF collagen synthesis with [ 3H]proline incorporation, and NF-κB activation with immunofluorescence staining and Western blot analysis. The results showed that AVP increased NO production in a dose- and time-dependent manner, with maximal effects at 10 − 7 mol/l after 24-h stimulation. AVP also increased NOS activity, protein and mRNA levels of iNOS in a coincident manner. Furthermore, AVP also increased CF collagen synthesis in a dose- and time-dependent manner. In addition, it was found that NF-κB was activated by AVP, and that PDTC could inhibit NO production, NOS activity, protein and mRNA levels of iNOS stimulated by AVP in a dose-dependent manner. The inhibitory effects of PDTC on NF-κB translocation were coincident with the effects of PDTC on iNOS–NO system activity. It is suggested that AVP increases NO production via the regulation of iNOS gene expression, and the upregulation of iNOS gene expression stimulated by AVP is mediated through NF-κB activation. NO production induced by AVP may counteract the profibrotic effects of AVP, thus the development of MF perhaps depends on the balance between profibrotic AVP and antifibrotic NO effects on MF.

Tu-P10:511 Diminished activity of nitric oxide system in patients with restenosis after coronary stent implantation

Tu-P10:511 Diminished activity of nitric oxide system in patients with restenosis after coronary stent implantation

Nitric Oxide–Dependent Renal Vasodilatation Is Not Altered in Rat with rHuEpo–Induced Hypertension

Background: Recombinant human erythropoietin (rHuEpo) is the treatment of choice in anemia associated with end–stage renal disease. Its major side effect is hypertension, which occurs in 8–30% of uremic patients. The exact mechanism of rHuEpo–induced hypertension has not been fully elucidated, and several possibilities have been proposed, such as a direct vascular effect of the drug with a shift in the balance of constrictor and relaxing endothelial factors (endothelins and nitric oxide (NO)). Recent papers suggested an enhanced rather than reduced activity of endogenous NO system in rats with normal renal function and rHuEpo–induced hypertension. Our study was designed to verify whether, in spite of enhanced activity of the renal NO system, rHuEpo may affect endothelium–dependent (acetylcholine–induced) and/or endothelium–independent (sodium nitroprusside–induced) vasorelaxation and to evaluate basal NO release by the infusion of N^G–nitro–L–arginine methyl ester (L–NAME) in an isolated and perfused rat kidney model. Methods: To investigate this hypothesis, we have determined systemic and renal NO activity in Wistar rats treated with a hypertensive dose of rHuEpo (150 IU/kg b.w. every other day for 2 weeks) by measuring stable NO metabolites (NO₂+NO₃) in the urine and have also evaluated variations in renal vascular resistance after the injection of Ach, SNP and the infusion of L–NAME. Results: Hematocrit, hemoglobin concentration and arterial blood pressure were significantly increased in the treated group as compared with the controls. Urinary excretion of NO₂+NO₃ was significantly higher in treated than in the controls (438±66 vs. 294±36 nM/ml/min, p<0.01, respectively). There were no significant differences in the dose–response curves to Ach and SNP between the two groups. The renal vasoconstriction following the infusion of L–NAME was also similar in the two groups. Conclusions: The analysis of our results seems to indicate that the endogenous NO system activity was enhanced in rHuEpo–induced hypertension in rats with normal renal function and a resistance to NO was not developed in renal circulation. Further studies seem to be necessary to better clarify the exact mechanisms underlying the development of rHuEpo–induced hypertension.