Nitric Oxide Synthetase Inhibitor Research Articles

Metabolomic Profiling and Biological Investigation of the Marine Sponge-Derived Fungus Aspergillus sp. SYPUF29 in Response to NO Condition.

Marine-derived fungi are assuming an increasingly central role in the search for natural leading compounds with unique chemical structures and diverse pharmacological properties. However, some gene clusters are not expressed under laboratory conditions. In this study, we have found that a marine-derived fungus Aspergillus sp. SYPUF29 would survive well by adding an exogenous nitric oxide donor (sodium nitroprusside, SNP) and nitric oxide synthetase inhibitor (L-NG-nitroarginine methyl ester, L-NAME) in culture conditions. Moreover, using the LC-MS/MS, we initially assessed and characterized the difference in metabolites of Aspergillus sp. SYPUF29 with or without an additional source of nitrogen. We have found that the metabolic pathway of Arginine and proline metabolism pathways was highly enriched, which was conducive to the accumulation of alkaloids and nitrogen-containing compounds after adding an additional source of nitrogen in the cultivated condition. Additionally, the in vitro anti-neuroinflammatory study showed that the extracts after SNP and L-NAME were administrated can potently inhibit LPS-induced NO-releasing of BV2 cells with lower IC50 value than without nitric oxide. Further Western blotting assays have demonstrated that the mechanism of these extracts was associated with the TLR4 signaling pathway. Additionally, the chemical investigation was conducted and led to nine compounds (SF1-SF9) from AS1; and six of them belonged to alkaloids and nitrogen-containing compounds (SF1-SF6), of which SF1, SF2, and SF8 exhibited stronger activities than the positive control, and showed potential to develop the inhibitors of neuroinflammation.

Relaxation Effect of Schisandrol A on Isolated Thoracic Aorta and its Mechanism in Rats

Background Schisandra chinensis (S. chinensis) is a drug commonly used in the clinical treatment of cardiovascular diseases in Traditional Chinese Medicine. However, the specific components and mechanisms of its action are still unclear. We screened six kinds of lignans from S. chinensis with high content and found that schisandrol A and schisantherin A had a strong vasorelaxant effect. The purpose of this study was to investigate the relaxation and underlying mechanism of schisandrol A in the isolated thoracic aorta of rats. Materials and Methods Isolated rat endothelium-intact and endothelium-removed thoracic aorta strips were pre-constricted with phenylephrine (PE), and the relaxation of schisandrol A on the strips was observed. Then, the mechanism was explored by pre-incubating the strips with nitric oxide synthetase inhibitor Nɷ-nitro-l-arginine methyl ester (L-NAME), cyclooxygenase inhibitor (indomethacin), potassium channel blockers 4-aminopyridine (4-AP), barium chloride (BaCl2), tetraethylamine (TEA), and glibenclamide, respectively, and changing the calcium concentration in the bath. In addition, expressions of endothelial nitric oxide synthetase (eNOS) mRNA and protein in rat thoracic aorta were detected. Results Schisandrol A induced both endothelium-dependent and endothelium-independent relaxation of isolated thoracic aorta strips of rats, and the mechanism might be related to promoting the synthesis of NO, inhibiting Ca2+ release from the sarcoplasmic reticulum, and blocking the Ca2+ channels. Conclusion These discoveries may provide a theoretical basis for the traditional application of S. chinensis to treat cardiovascular disease.

Correlation of Asymmetric Dimethyl Arginine Level to Sickle Retinopathy in Children With Sickle Cell Disease.

Asymmetric dimethyl arginine (ADMA) is a competitive inhibitor of nitric oxide synthetase especially in L-arginine deficiency, which is the case in sickle cell disease (SCD). we aimed to assess the level of ADMA in children with sickle retinopathy and to correlate it to the degree of retinopathy. In this cross-sectional study 40 children with SCD were included, 20 of them with sickle cell retinopathy (SCR) (group I), 20 with normal fundus examination (group II), and another 20 healthy children served as controls (group III). We measured ADMA level by ELISA and performed fundus examination. Seventeen of the 20 children included in group I had Grade I retinopathy (85%), 2 children had Grade II retinopathy (10%), and 1 child had Grade III retinopathy (5%). ADMA was significantly higher in SCD than controls ( P -value <0.001), and it was even higher in patients with SCR compared those without retinopathy ( P -value <0.002), and there was positive linear correlation between ADMA and the grade of retinopathy. The type of retinopathy detect in the studied patients was the nonproliferative type. In conclusion, ADMA is elevated in children with SCD, and its level is even higher in those who develop SCR.

Involvement of inflammatory cells in the dorsal root ganglion in oxaliplatin-induced neuropathic pain

Oxaliplatin is a platinum-based chemotherapeutic agent treating colorectal and gastric cancer. The most common dose-limiting adverse event of oxaliplatin treatment is chronic neuropathic pain, while the detailed mechanisms remain unknown. The present study investigated the molecular mechanisms of microglial regulation of the oxaliplatin-induced neuropathic pain. Intrathecal (I.t.) treatment with inducible nitric oxide synthetase (iNOS) inhibitor 1400W attenuated the oxaliplatin-induced cold and mechanical hypersensitivity. In addition, pharmacological and chemogenetical inhibition of macrophage/microglia also attenuated the oxaliplatin-induced cold and mechanical hyperalgesia. I.t. treatment with STAT3 inhibitor stattic attenuated the oxaliplatin-indued cold and mechanical hypersensitivity. Oxaliplatin induced the increased phosphorylation of neural STAT3 in the dorsal root ganglion (DRG), which was attenuated by i.t. pretreatment with 1400W. Since STAT3 phosphorylation was regulated by PTEN, effects of oxaliplatin on the PTEN activity in the DRG were examined. PTEN expression was decreased by oxaliplatin treatment. Our present study suggested that oxaliplatin induces neural STAT3 activation through the iNOS induction by macrophage/microglial activation in the DRG, which resulted in the oxaliplatin-induced neuropathic pain.

Vascular interactions of Croton schiedeanus major flavonoids in isolated aortic rings from Wistar rats

Background: Ayanin (3,7,4’-Tri-O-methylquercetin) and 3,7-Di-O-methylquercetin (DMQ) are the main active metabolites isolated by bioguided fractionation from Croton schiedeanus, species known popularly in Colombia as “almizclillo”, which has been studied in experimental models in rats, exerting vasodilator and antihypertensive effects. Also, when the effect of these flavonoids was studied separately, important vasodilation was observed. Objective: To evaluate whether flavonoids from Croton schiedeanus have synergistic vasodilator properties when different combinations are used in isolated aorta rings. Methods: Cumulative concentrations of ayanin (10-8 M - 6x10-5 M or 0.01 μM - 60 μM) were assayed in the absence and presence of an increasing concentration of 3,7-Di-O-methylquercetin (DMQ) (10-8 – 3x10-5 M or 0.01–30 μM) in isolated rings from Wistar rats, pre-contracted with phenylephrine. The concentration-response curve with the maximal effect was compared with that obtained by Croton schiedeanus whole ethanolic extract (10-6 – 3x10-4 g/mL). Also, this combination was assayed in the presence of the nitric oxide synthetase inhibitor L-NAME (10-4 M) and the guanylate cyclase inhibitor methylene blue (10-4 M) to assess the role of the NO/cGMP pathway in this interaction. Results: Ayanin and DMQ display a dual interaction in vascular relaxant response: agonism at higher concentration ranges (10-6 – 3x10-5 M or 1–30 μM) and antagonism at lower concentration ranges (10-8 – 3x10-7 M or 0.01–0.3 μM). The efficacy at the highest concentration was greater than that obtained by the whole extract (Emax: 98.4% vs. 33.9%). This response was decreased but not reverted in the presence of L-NAME and methylene blue. Thus, the vasodilator effect of this combination does not depend entirely on the NO/cGMP cyclic pathway. Conclusion: The combined use of appropriate concentrations of these flavonoids could represent an advantage over Croton schiedeanus whole extract for vasodilator purposes.

Glabridin Relaxes Vascular Smooth Muscles by Activating BKCa Channels and Inhibiting Phosphodiesterase in Human Saphenous Vein.

The aim of the current study was to investigate the pharmacological activity of glabridin on the isolated human saphenous vein (SV) and explore the underlying mechanisms. Samples of patients' SVs were removed during bypass surgery, and 4-mm lengths of the vessels were placed in Krebs solution at +4°C and hung in an isolated organ bath to assess their contraction/relaxation responses. The contraction/relaxation responses were recorded to observe if the cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) pathway mediates the relaxant effect of glabridin after treatment with blockers like ODQ (a guanylate cyclase inhibitor), KT5823 (a PKG inhibitor), isobutylmethylxanthine [IBMX, a phosphodiesterase (PDE) inhibitor], and cantharidin [Cant, a myosin light-chain phosphatase (MLCP) inhibitor]. Moreover, nitric oxide (NO), cGMP, and PKG levels in SV tissues were determined by ELISA after incubation with glabridin, N(ω)-nitro-L-arginine methyl ester (L-Name, a NO synthetase inhibitor), phenylephrine (PE), ODQ, IBMX, and KT5823. The results showed that glabridin relaxed the vascular smooth muscle of human SV pretreated with PE in a dose-dependent manner, which was independent of the endothelium. The vasorelaxant effect of glabridin was only inhibited by iberiotoxin (IbTX), Cant, and KT5823. Glabridin increased cGMP and PKG levels in SV homogenates, whereas it did not alter the NO level. The enhancing effects of cGMP and PKG levels by glabridin were abolished by ODQ and KT5823. In conclusion, glabridin has a vasorelaxant effect, which is associated with the activation of BKCa channels and inhibition of PDE.

Role of Rho in Salt-Sensitive Hypertension.

A high amount of salt in the diet increases blood pressure (BP) and leads to salt-sensitive hypertension in individuals with impaired renal sodium excretion. Small guanosine triphosphatase (GTP)ase Rho and Rac, activated by salt intake, play important roles in the pathogenesis of salt-sensitive hypertension as key switches of intracellular signaling. Focusing on Rho, high salt intake in the central nervous system increases sodium concentrations of cerebrospinal fluid in salt-sensitive subjects via Rho/Rho kinase and renin-angiotensin system activation and causes increased brain salt sensitivity and sympathetic nerve outflow in BP control centers. In vascular smooth muscle cells, Rho-guanine nucleotide exchange factors and Rho determine sensitivity to vasoconstrictors such as angiotensin II (Ang II), and facilitate vasoconstriction via G-protein and Wnt pathways, leading to increased vascular resistance, including in the renal arteries, in salt-sensitive subjects with high salt intake. In the vascular endothelium, Rho/Rho kinase inhibits nitric oxide (NO) production and function, and high salt amounts further augment Rho activity via asymmetric dimethylarginine, an endogenous inhibitor of NO synthetase, causing aberrant relaxation and increased vascular tone. Rho-associated mechanisms are deeply involved in the development of salt-sensitive hypertension, and their further elucidation can help in developing effective protection and new therapies.

Proteolytic activity of Triatoma infestans saliva associated with PAR-2 activation and vasodilation.

ABSTRACTBackground Triatoma infestans (Hemiptera: Reduviidae) is a hematophagous insect and the main vector of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae). In the present study, the authors investigated whether a serine protease activity from the saliva of T. infestans has a role in vasomotor modulation, and in the insect-blood feeding by cleaving and activating protease-activated receptors (PARs).Methods T. infestans saliva was chromatographed as previously reported for purification of triapsin, a serine protease. The cleavage activity of triapsin on PAR peptides was investigated based on FRET technology. Mass spectrometry was used to analyze the sites of PAR-2 peptide cleaved by triapsin. NO measurements were performed using the DAN assay (2,3-diaminonapthalene). The vasorelaxant activity of triapsin was measured in vessels with or without functional endothelium pre-contracted with phenylephrine (3 µM). Intravital microscopy was used to assess the effect of triapsin on mouse skin microcirculation.Results Triapsin was able to induce hydrolysis of PAR peptides and showed a higher preference for cleavage of the PAR-2 peptide. Analysis by mass spectrometry confirmed a single cleavage site, which corresponds to the activation site of the PAR-2 receptor. Triapsin induced dose-dependent NO release in cultured human umbilical vein endothelial cells (HUVECs), reaching a maximum effect at 17.58 nM. Triapsin purified by gel-filtration chromatography (10-16 to 10-9 M) was applied cumulatively to mouse mesenteric artery rings and showed a potent endothelium-dependent vasodilator effect (EC30 = 10-12 M). Nitric oxide seems to be partially responsible for this vasodilator effect because L-NAME (L-NG-nitroarginine methyl ester 300 µM), a nitric oxide synthetase inhibitor, did not abrogate the vasodilation activated by triapsin. Anti-PAR-2 antibody completely inhibited vasodilation observed in the presence of triapsin activity. Triapsin activity also induced an increase in the mouse ear venular diameter.Conclusion Data from this study suggest a plausible association between triapsin activity mediated PAR-2 activation and vasodilation caused by T. infestans saliva.

Morphine Induces Apoptosis, Inflammation, and Mitochondrial Oxidative Stress via Activation of TRPM2 Channel and Nitric Oxide Signaling Pathways in the Hippocampus.

Morphine as an opioid is an important drug in the treatment of moderate to severe pain. Several stress factors via generation of nitric oxide (NO) and oxidative stress (OS) are responsible for the adverse effects of morphine-induced analgesia, addiction, and antinociceptive tolerance, including altered Ca2+ concentration, inflammation, OS, and release of apoptotic factors. TRPM2 is a Ca2+-permeable cation channel and it is activated by OS and NO. Hence, adverse effect of morphine addiction may occur via the OS and NO-induced TRPM2 activation. Because of the unclear etiology of morphine-induced adverse effects in the hippocampus, investigating the involvement of TRPM2 and NO synthetase (NOS) activations in the treatment of morphine-induced OS, apoptosis, and neuroinflammation is a major challenge. The hippocampal neuron of TRPM2 wild-type (TRPM2-WT) and knockout (TRPM2-KO) mice were divided into control, morphine, NOS inhibitor (L-NAME) + morphine, and TRPM2 channel blockers (ACA and 2-APB) + morphine. The morphine-induced increases of apoptosis, neurondeath, OS, lipid peroxidation, caspase-3 and caspase-9, neuroinflammatory cytokines (IL-1β, TNF-α, IL-6), and Ca2+ levels in the hippocampal neuron of TRPM2-WT mouse were decreased by the L-NAME, ACA, and 2-APB treatments, although cell viability, neuron count, and reduced glutathione and glutathioneperoxidase levels were increased by the treatments. However, the effects of morphine were not observed in the hippocampus of TRPM2-KO mice. Taken together, our data show that neurodegeneration adverse effects of morphine were induced by activation of TRPM2, and excessive generations of NO and OS. Thus, inhibition of TRPM2 may modulate morphine-induced neurodegeneration in the hippocampus.

The Involvement of DDAH1 in the Activation of Spinal NOS Signaling in Early Stage of Mechanical Allodynia Induced by Exposure to Ischemic Stress in Mice.

The pathophysiological mechanism of central post-stroke pain (CPSP) is complicated and not well understood. Recently, it has been reported that an increase in the levels of spinal nitric oxide synthetase (NOS) occurs in cerebral ischemia, and spinal NOS is involved in the development of neuropathic pain. The aim of this study was to elucidate the mechanism of spinal NOS signaling in the development of CPSP. Male ddY mice were subjected to 30-min long bilateral carotid artery occlusion (BCAO). The withdrawal responses to mechanical stimuli were significantly increased as determined with von Frey test on days 1 and 3 after BCAO. Protein expression of spinal N(G),N(G)-dimethylarginine dimethylaminohydralase 1 (DDAH1), a key enzyme involved in the metabolism of the endogenous NOS, increased on day 1 after BCAO, but not on day 3. Intrathecal (i.t.) injection of PD404182, a DDAH1 inhibitor, significantly suppressed mechanical allodynia on day 1, but not on day 3 after BCAO. In addition, i.t. administration of NG-nitro-L-arginine methyl ester (L-NAME), a non-selective NOS inhibitor, significantly blocked mechanical allodynia on days 1 and 3 after BCAO. Furthermore, BCAO-induced increment of spinal NOS activity was inhibited by the pretreatment with PD404182. These results suggest that mechanical allodynia in the early stage of CPSP is caused by increment of NOS activity through upregulated DDAH1 in the spinal cord.

Dl-3n-butylphthalide reduces oxygen-glucose deprivation-induced endothelial cell damage by increasing PGC-1α.

Animal experiments verified that dl-3-n-butylphthalide (NBP) can protect vascular endothelial cells from ischemic damage and promote vascular proliferation in ischemic stroke treatment, but the underlying mechanism has not been fully clarified. This study aimed to investigate the effects of NBP on peroxisome proliferators-activated receptor-γ coactivator-1α (PGC-1α) expression in endothelial cells exposed to oxygen-glucose deprivation (OGD) and to clarify the related molecular mechanism. SV40-transformed aortic rat endothelial cell line was cultured and subjected to OGD in the presence or absence of NBP. The cell viability was evaluated by using thiazolyl blue tetrazolium bromide (MTT) method. The cellular endothelial nitric oxide synthase (eNOS) activity was measured by using eNOS activity assay. The nuclear changes were assessed with Hoechst 33342 fluorescent dye. The immunofluorescence analysis and Western blotting assay were conducted to evaluate the protein expression. We found that NBP could significantly prevent endothelial cells from OGD-induced injuries, in terms of cell morphology and cell viability. Both immunofluorescence analysis and Western blot findings confirmed that the NBP treatment further enhanced PGC-1α expression during OGD, which was prevented in the presence of selective endothelial nitric oxide synthetase (eNOS) inhibitor N5-(1-Iminoethyl)-L-ornithine-HCL (L-NIO). Furthermore, we found that NBP could protect the eNOS activity about by 40% during OGD and did not influence the eNOS protein level in the spectrophotometric-based analysis. NBP maintained the endothelial PGC-1α expression via regulating eNOS activity during the exposure to OGD; therefore, it presented its protective function to cell viability and vascular proliferation.

Endothelial-Dependent and Independent Vascular Relaxation Effect of Tetrahydropalmatine on Rat Aorta.

Tetrahydropalmatine (THP) is an active natural alkaloid isolated from Corydalis yanhusuo W.T. Wang which has been widely used for treating pain and cardiovascular disease in traditional Chinese medicine. Previous studies suggested THP have various pharmacological effects in neural and cardio tissue while the vascular reactivity of THP was not fully established. The present study found that THP relaxed rat aorta which contracted by phenylephrine (Phe), KCl, and U46619. The vascular relaxation effect of THP was partially attenuated by PI3K inhibitor wortmannin, Akt inhibitor IV, endothelial nitric oxide synthetase (eNOS) inhibitor L-NAME, guanylate cyclase inhibitors and the mechanical removal of endothelium. Also, the eNOS substrate L-arginine reversed the inhibition effect of L-NAME on THP-induced vascular relaxation. THP also induced intracellular NO production in human umbilical vein endothelial cells. However, Pre-incubation with β-adrenergic receptor blocker propranolol, angiotensin II receptor 1 (AT1) inhibitor losartan, angiotensin II receptor 2 (AT1) inhibitor PD123319 or angiotensin converting enzyme inhibitor enalapril enhanced the vascular relaxation effect of THP. THP did not affect the angiotensin II induced vascular contraction. Cyclooxygenase-2 (COX2) inhibitor indomethacin did not affect the vascular relaxation effect of THP. Furthermore, pre-treatment THP attenuated KCl and Phe induced rat aorta contraction in standard Krebs solution. In Ca2+ free Krebs solution, THP inhibited the Ca2+ induced vascular contraction under KCl or Phe stress and reduced KCl stressed Ca2+ influx in rat vascular smooth muscle cells. THP also inhibited intracellular Ca2+ release induced vascular contraction by blocking Ryr or IP3 receptors. In addition, the voltage-dependent K+ channel (Kv) blocker 4-aminopyridine, ATP-sensitive K+ channel (KATP) blocker glibenclamide and inward rectifying K+ channel blocker BaCl2 attenuated THP induced vascular relaxation regardless of the Ca2+-activated K+ channel (KCa) blocker tetraethylammonium. Thus, we could conclude that THP relaxed rat aorta in an endothelium-dependent and independent manner. The underlying mechanism of THP relaxing rat aorta involved PI3K/Akt/eNOS/NO/cGMP signaling path-way, Ca2+ channels and K+ channels rather than COX2, β-adrenergic receptor and renin-angiotensin system (RAS). These findings indicated that THP might be a potent treatment of diseases with vascular dysfunction like hypertension.

Luteolin-induced coronary arterial relaxation involves activation of the myocyte voltage-gated K+ channels and inward rectifier K+ channels

AimsLuteolin has been shown to be beneficial to cardiovascular tissues and organs. We aimed to study its vasospasmolytic effects against various vasoconstrictors in the isolated rat coronary arteries (RCAs) and its electrophysiological effects on K+ currents via voltage-gated potassium (Kv) channels and inward rectifier potassium (Kir) channels in freshly isolated rat coronary arterial smooth muscle cells (RCASMCs). Main methodsThe vascular tone of the endothelium-denuded RCAs was recorded by a wire myograph. Kv currents and Kir currents in RCASMCs were assessed using whole-cell patch clamp. Key findingsPreincubation with luteolin depressed the contractions elicited by KCl, thromboxane A2 analog U46619, vasopressin, Kir blocker BaCl2, Kv blocker 4-aminopyridine and elevation of extracellular calcium ([Ca2+]o) in high K+ depolarizing solution. Instant application of luteolin produced concentration-dependent relaxations in the endothelium-denuded RCAs precontracted with KCl or U46619. Both 4-aminopyridine and BaCl2 attenuated luteolin-induced relaxation in U46619-precontracted RCAs, while neither nitric oxide synthetase inhibitor NG-nitro-L-arginine methyl ester nor cyclooxygenase inhibitor indomethacin affected the relaxation. Luteolin augmented both Kv currents and Kir currents in RCASMCs and the augmentations were antagonized by 4-aminopyridine and BaCl2, respectively. SignificanceThe present results demonstrated that luteolin antagonizes various vasoconstrictors in RCAs and augments both Kv currents and Kir currents in RCASMCs, suggesting that the direct action of luteolin on Kv channels and Kir channels is contributory to its vasospasmolytic effect. These findings indicate that luteolin may be a promising food additive with the aim of preventing coronary arterial spasm.

Evidence of a role for spinal HMGB1 in ischemic stress-induced mechanical allodynia in mice

We have previously showed that spinal high-mobility group box-1 (HMGB1) plays an important role in the induction of central post-stroke pain (CPSP). It has been reported that HMGB1 exacerbates inflammation and pain via TLR4 or RAGE. Furthermore, the relationship between glial cells, such as microglia and astrocytes, involved in pain exacerbation and HMGB1 has also attracted attention. In this study, we investigated whether the interaction between spinal glial cells and HMGB1 signaling, including its receptors TLR4 or RAGE, is directly involved in the induction of CPSP.Spinal HMGB1 expression increased on day 3 after bilateral carotid artery occlusion (BCAO), and spinal microglia and astrocytes were clearly activated. HMGB1 colocalized with neurons, but not with microglia and astrocytes after BCAO. Intrathecal (i.t.) injection of lipopolysaccharides from Rhodobacter sphaeroides (LPS-RS, a TLR4 antagonist) and low-molecular-weight heparin (LMWH, a RAGE antagonist) significantly blocked mechanical allodynia on day 3 after BCAO. BCAO-induced activation of spinal microglia and astrocyte were suppressed by i.t. anti-HMGB1 monoclonal antibody (mAb) and LPS-RS administration. In addition, i.t. injection of NG-nitro-l-arginine methyl ester [a nonselective nitric oxide synthetase (NOS) inhibitor] significantly blocked mechanical allodynia on day 3 after BCAO and i.t. administration of anti-HMGB1 mAb, LPS-RS, and LMWH significantly inhibited the increase of NOS activity in the spinal cord on day 3 after BCAO.These results showed that the interaction between spinal glial cells and HMGB1/TLR4/NOS or HMGB1/RAGE/NOS is directly involved in the induction of CPSP.

Cytoprotective Role of Nrf2 in Electrical Pulse Stimulated C2C12 Myotube.

Regular physical exercise is central to a healthy lifestyle. However, exercise-related muscle contraction can induce reactive oxygen species and reactive nitrogen species (ROS/RNS) production in skeletal muscle. The nuclear factor-E2-related factor-2 (Nrf2) transcription factor is a cellular sensor for oxidative stress. Regulation of nuclear Nrf2 signaling regulates antioxidant responses and protects organ structure and function. However, the role of Nrf2 in exercise- or contraction-induced ROS/RNS production in skeletal muscle is not clear. In this study, using differentiated C2C12 cells and electrical pulse stimulation (EPS) of muscle contraction, we explored whether Nrf2 plays a role in the skeletal muscle response to muscle contraction-induced ROS/RNS. We found that EPS (40 V, 1 Hz, 2 ms) stimulated ROS/RNS accumulation and Nrf2 activation. We also showed that expression of NQO1, HO-1 and GCLM increased after EPS-induced muscle contraction and was remarkably suppressed in cells with Nrf2 knockdown. We also found that the antioxidant N-acetylcysteine (NAC) significantly attenuated Nrf2 activation after EPS, whereas the nitric oxide synthetase inhibitor Nω-nitro-L-arginine methyl ester (L-NAME) did not. Furthermore, Nrf2 knockdown after EPS markedly decreased ROS/RNS redox potential and cell viability and increased expression of the apoptosis marker Annexin V in C2C12 myotubes. These results indicate that Nrf2 activation and expression of Nrf2 regulated-genes protected muscle against the increased ROS caused by EPS-induced muscle contraction. Thus, our findings suggest that Nrf2 may be a key factor for preservation of muscle function during muscle contraction.

Neurochemical phenotype and function of endomorphin 2-immunopositive neurons in the myenteric plexus of the rat colon.

The distribution and activity of endomorphins (EMs), which are endogenous μ-opioid receptor (MOR) ligands in the gastrointestinal tract (GI), are yet to be elucidated. The current study aimed to shed light on this topic. EM2 was expressed in the enteric neurons in the myenteric plexus of the mid-colon. Of the EM2-immunoreactive (EM2-IR) neurons, 53 ± 4.6%, 26 ± 4.5%, 26 ± 2.8% and 49 ± 4.2% displayed immunopositive staining for choline acetyl transferase (ChAT), substance P (SP), vasoactive intestinal peptide (VIP) and nitric oxide synthetase (NOS), respectively. A bath application of EM2 (2 μM) enhanced spontaneous contractile amplitude and tension, which were reversed by β-FNA (an antagonist of MOR) but not NG-nitro-L-arginine methyl ether (L-NAME, a non-selective inhibitor of NOS) or VIP6-28 (an antagonist of the VIP receptor) in the colonic strips. EM2 significantly suppressed inhibitory junction potentials (IJPs) in 14 of the 17 examined circular muscle cells, and this effect was not antagonized by preincubation in L-NAME. EM2 was widely expressed in interneurons and motor neurons in the myenteric plexus and presynaptically inhibited fast IJPs, thereby enhancing spontaneous contraction and tension in the colonic smooth muscle.

A potential link between endothelial function, cardiovascular risk, and metabolic syndrome in patients with Non-alcoholic fatty liver disease

BackgroundAsymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide (NO) synthetase. Elevated ADMA reduces NO formation and is associated with endothelial dysfunction. The aims of this study were to evaluate endothelial function and the cardiovascular risk (CVR) profile in patients with non-alcoholic fatty liver disease (NAFLD), and to determine whether or not an association with metabolic syndrome (MS) increases these parameters.MethodsA total of 100 consecutive patients with NAFLD, who were seen in Liver Disease Outpatient clinic and 45 age- and sex-matched controls were included. Endothelial function was evaluated based on the serum ADMA level measured using a validated ELISA kit (DLD Diagnostika GMBH, Hamburg, Germany) and flow-mediated vasodilatation (FMV) measured via high-resolution external ultrasonography. The CVR profile was calculated according to the Framingham equation.ResultsAt baseline there weren’t any significant differences in brachial artery diameter between the NAFLD and control groups (3.7 ± 0.6 mm vs. 3.6 ± 0.6 mm, respectively). FMV and flow-independent vasodilatation in response to sublingual nitroglycerin did not differ between the NAFLD and control groups (mean: 16% ± 9.4% vs. 17.9% ± 12.4%, and 21.4% ± 14% vs. 17.8% ± 11.3%, respectively, p > 0.05). No significant difference in the serum ADMA concentration between the NAFLD and control groups was observed (mean: 0.8 ± 0.07 μmol L-1 vs. 0.74 ± 0.2 μmol L-1, respectively). The CVR profile was significantly higher in the NAFLD group than in the control group (mean: 9% ± 6.9% vs. 4.6% ± 3.8%, P = 0.000). MS associated with NAFLD significantly increased the CVR profile (mean: 11.2% ± 7.4%, P = 0.000). An abnormal serum alanine aminotransferase level (>37 IU L-1) and the presence of fibrosis did not increase the CVR profile (p > 0.05).ConclusionsThe risk of cardiovascular events is increased in patients with NAFLD. The association with MS is further increased such risk.

Inhibition of Nitric Oxide Mediated Protein Nitration

Experimental animal study. This study investigated whether nitric oxide (NO) mediated protein nitration is involved in the pathogenesis of radiculopathy and whether the symptoms can be relieved by its suppression. It has been reported that nitration of protein mediated by NO is involved in the degenerative neurological disorders, but its involvement is not clear in the radiculopathy. Two kinds of rat models of radiculopathy were used. Radiculopathy was induced either by ligation of spinal nerve roots or transplantation of autologous nucleus pulposus. In separate groups of rats, aminoguanidine, a potent nitric oxide synthetase inhibitor, was administered just before induction of radiculopathy, to suppress NO production and resultant nitration of protein. Sensation of the hind limb was evaluated by plantar stimulation test, and motor weakness was assessed by observation of gait pattern. Nitrotyrosine, product of protein nitration, was assayed quantitatively by Western immunoblotting. Mechanical allodynia was observed in both compression and nucleus pulposus groups, but motor weakness was observed only in the compression group. Preoperative administration of aminoguanidine attenuated mechanical allodynia and motor weakness. Optical densities of nitrotyrosine bands increased significantly in radiculopathy groups, but they were lowered by administration of aminoguanidine. NO mediated protein nitration contributes to the development of both types of radiculopathies. Suppression of NO production can decrease protein nitration and relieve neural dysfunctions of radiculopathy. N/A.

NO/NOS system in prostate cancer

Via activating G-protein receptor transduction pathways,nitric oxide (NO),an important signal molecule,has a complex and diverse role which is closely related with activity and gene expression of nitric oxide synthetase (NOS).NO is involved in tumor related events such as cellular proliferation,migration,especially the angiogenic process,and it is closely related with the occurrence and progression of prostate cancer.NO donors and NOS inhibitors have anti-cancer and radio-chemotherapy enhancement roles. Key words: Nitric oxide; Nitric oxide synthase; Prostatic neoplasmas; Angiogenesis modulating agents

Prevention and treatment of nitric oxide synthetase inhibitor on galactose cataract in rat

Background Researches showed that the content of nitric oxide (NO) and nitric oxide synthetase (NOS) increases in blood,aqueous humor and tear of cataract patient.But the function of NO and NOS in cataract formation is still elusive.Objective The aim of this study was to explore the prevention and treatment effect of NOS inhibitor,1-nitro-arginine methyl ester (L-NAME),on galactose cataract.Methods Sixty clean three-week-old Wistar rats were equally and randomly divided into 3 groups.0.9％ Normal saline solution (30 ml/kg) was subcutaneously injected every day for 30 days in the rats of the control group,and 50％ of D-galactose solution (30 ml/kg) was used in the rats of the model and L-NAME group at the same way.L-NAME eye drops was simultaneously administered in the L-NAME group 3 times per day for 30 days.The eyes of the rats were examined under the slit lamp in 10,20 and 30 days,and the degree of lens opacification was scored.Lenses of the rats were obtained at the end of this experiment for the detect of NO,NOS contents.Flow cytometry was used to assay the caspase-3 level of rat lens.Repeated measurement two factor analysis of variance was used to analyze the difference of lens opacification scores in different groups and different time points,and one-way ANOVA was used to analyze the differences of NO,NOS and caspase-3 contents in lens among the groups.Results Lens opacification appeared in 10 days after injection of 50％ D-galactose solution in the rats of the model group and L-NAME group.Lens opacification score was higher among the different groups and different time points (Ftime =435.251,P =0.000 ;Fgroup =395.120,P=0.000).NO content in the lens was (0.45±0.15) μmol/g,(2.67 ± 0.47) μmol/g and (1.68±0.34) μmol/g in the control group,model group and L-NAME group,showing a significant difference (F=58.872,P=0.000).The NOS contents in the lens was (0.0160±0.0020) U/ml,(0.0370±0.0040) U/ml and (0.0270±0.0010) U/ml in the control group,model group and L-NAME group,showing a significant difference (F =66.174,P=0.000).Caspase-3 contents in the lens was (339.4 ± 37.9),(697.7 ± 46.5) and (650.7 ± 53.1),Showing a significant difference among them (F =100.005,P =0.000).Conclusions The increase of NO,NOS and caspase3 levels are associated with lens opacification.Topical administration of L-NAME eye drops can down-regulate NOS content in lens,reduce the NO formation and inhibit the apoptosis of lens epithelial cells. Key words: Nitric oxide synthetase; Cataract; Caspase-3; Apoptosis