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European Journal of Pharmacology Dec 2023Myopia is one of the most prevalent eye diseases that seriously threaten the eyesight of children and adolescents worldwide. However, the pathogenesis is still unclear,...
Suppressive effect of nitric oxide synthase (NOS) inhibitor L-NMMA acetate on choroidal fibrosis in experimental myopic guinea pigs through the nitric oxide signaling pathway.
Myopia is one of the most prevalent eye diseases that seriously threaten the eyesight of children and adolescents worldwide. However, the pathogenesis is still unclear, and effective drugs are still scarce. In the present study, the guinea pigs were randomly divided into a normal control (NC) group, a lens-induced myopia (LIM) group, a NOS inhibitor (L-NMMA) injection group, and a NOS inhibitor solvent phosphate-buffered saline (PBS) group and the animals received relevant treatments. After 2- and 4-week different treatments, we noted that the refraction and choroidal thickness in the LIM group decreased compared with the NC group, whereas the ocular axial length increased significantly, and the choroid showed a fibrotic trend. The expression of NOS1, NOS3, TGF-β1, COLI, and α-SMA at gene and protein levels was increased significantly in the choroid (all P < 0.05). After intravitreal injection of NOS inhibitor L-NMMA, we found that compared with the LIM group, the refraction and the choroidal thickness significantly increased, whereas the axial length reduced significantly, accompanied by an increase of choroidal thickness and an improvement of choroidal fibrosis. The expression levels of choroidal NOS1, NOS3, TGF-β, COLI, and α-SMA were significantly reduced (all P < 0.05). In conclusion, the trend of choroidal fibrosis in LIM guinea pigs is positively correlated with the increase in axial length. The NOS inhibitor L-NMMA can alleviate the process of choroidal fibrosis in myopic guinea pigs by inhibiting NO signaling pathway.
Topics: Child; Guinea Pigs; Animals; Humans; Adolescent; omega-N-Methylarginine; Nitric Oxide; Myopia; Choroid; Enzyme Inhibitors; Signal Transduction; Nitric Oxide Synthase
PubMed: 37863413
DOI: 10.1016/j.ejphar.2023.176111 -
World Journal of Gastroenterology Aug 2022The mechanisms underlying gastrointestinal (GI) dysmotility with ulcerative colitis (UC) have not been fully elucidated. The enteric nervous system (ENS) plays an...
BACKGROUND
The mechanisms underlying gastrointestinal (GI) dysmotility with ulcerative colitis (UC) have not been fully elucidated. The enteric nervous system (ENS) plays an essential role in the GI motility. As a vital neurotransmitter in the ENS, the gas neurotransmitter nitric oxide (NO) may impact the colonic motility. In this study, dextran sulfate sodium (DSS)-induced UC rat model was used for investigating the effects of NO by examining the effects of rate-limiting enzyme nitric oxide synthase (NOS) changes on the colonic motility as well as the role of the ENS in the colonic motility during UC.
AIM
To reveal the relationship between the effects of NOS expression changes in NOS-containing nitrergic neurons and the colonic motility in a rat UC model.
METHODS
Male rats ( = 8/each group) were randomly divided into a control (CG), a UC group (EG1), a UC + thrombin derived polypeptide 508 trifluoroacetic acid (TP508TFA; an NOS agonist) group (EG2), and a UC + NG-monomethyl-L-arginine monoacetate (L-NMMA; an NOS inhibitor) group (EG3). UC was induced by administering 5.5% DSS in drinking water without any other treatment (EG1), while the EG2 and EG3 were gavaged with TP508 TFA and L-NMMA, respectively. The disease activity index (DAI) and histological assessment were recorded for each group, whereas the changes in the proportion of colonic nitrergic neurons were counted using immunofluorescence histochemical staining, Western blot, and enzyme linked immunosorbent assay, respectively. In addition, the contractile tension changes in the circular and longitudinal muscles of the rat colon were investigated using an organ bath system.
RESULTS
The proportion of NOS-positive neurons within the colonic myenteric plexus (MP), the relative expression of NOS, and the NOS concentration in serum and colonic tissues were significantly elevated in EG1, EG2, and EG3 compared with CG rats. In UC rats, stimulation with agonists and inhibitors led to variable degrees of increase or decrease for each indicator in the EG2 and EG3. When the rats in EGs developed UC, the mean contraction tension of the colonic smooth muscle detected was higher in the EG1, EG2, and EG3 than in the CG group. Compared with the EG1, the contraction amplitude and mean contraction tension of the circular and longitudinal muscles of the colon in the EG2 and EG3 were enhanced and attenuated, respectively. Thus, during UC, regulation of the expression of NOS within the MP improved the intestinal motility, thereby favoring the recovery of intestinal functions.
CONCLUSION
In UC rats, an increased number of nitrergic neurons in the colonic MP leads to the attenuation of colonic motor function. To intervene NOS activity might modulate the function of nitrergic neurons in the colonic MP and prevent colonic motor dysfunction. These results might provide clues for a novel approach to alleviate diarrhea symptoms of UC patients.
Topics: Animals; Male; Rats; Colitis, Ulcerative; Colon; Dextran Sulfate; Drinking Water; Gastrointestinal Motility; Nitrergic Neurons; Nitric Oxide; Nitric Oxide Synthase; omega-N-Methylarginine; Thrombin; Trifluoroacetic Acid
PubMed: 36157548
DOI: 10.3748/wjg.v28.i29.3854 -
Clinical Laboratory Jan 2022In this study, we aimed to show that methylated arginines are the predictors of non-clinical atherosclerotic cardiovascular complications in metal workers exposed to Cd.
BACKGROUND
In this study, we aimed to show that methylated arginines are the predictors of non-clinical atherosclerotic cardiovascular complications in metal workers exposed to Cd.
METHODS
The 80 Cd-exposed metal workers and 80 non-exposed workers (control) included in the study were available for measuring arginine, ADMA, SDMA, and L-NMMA levels.
RESULTS
The average urine Cd levels (CdU) found were 1.03 ± 0.8 µg/g creatinine (0.84 ± 0.65 µg/L) ranging from 0.01 to 3.00 µg/g creatinine in the control group and 5.41 ± 5.2 µg/g creatinine (4.29 ± 3.81 µg/L) ranged from 0.11 to 27.2 µg/g creatinine in metal workers. On the other hand, the median ratios of the different groups (exposed and control) were found to be 449.35 and 483.88 for arginine/ADMA and 1.28 and 1.33 SDMA/ADMA, respectively.
CONCLUSIONS
The present study was undertaken to investigate the relationship between cadmium exposure and methylated arginines such as ADMA/SDMA/L-NMMA parameters which is important for the early detection atherosclerotic cardiovascular diseases.
Topics: Arginine; Atherosclerosis; Cadmium; Creatinine; Humans; omega-N-Methylarginine
PubMed: 35023667
DOI: 10.7754/Clin.Lab.2021.210504 -
The Journal of Physiology Nov 2020Preclinical models have demonstrated that nitric oxide is a key component of neurovascular coupling; this has yet to be translated to humans. We conducted two separate...
KEY POINTS
Preclinical models have demonstrated that nitric oxide is a key component of neurovascular coupling; this has yet to be translated to humans. We conducted two separate protocols utilizing intravenous infusion of a nitric oxide synthase inhibitor and isovolumic haemodilution to assess the influence of nitric oxide on neurovascular coupling in humans. Isovolumic haemodilution did not alter neurovascular coupling. Intravenous infusion of a nitric oxide synthase inhibitor reduced the neurovascular coupling response by ∼30%, indicating that nitric oxide is integral to neurovascular coupling in humans.
ABSTRACT
Nitric oxide is a vital neurovascular signalling molecule in preclinical models, yet the mechanisms underlying neurovascular coupling (NVC) in humans have yet to be elucidated. To investigate the contribution of nitric oxide to NVC in humans, we utilized a visual stimulus paradigm to elicit an NVC response in the posterior cerebral circulation. Two distinct mechanistic interventions were conducted on young healthy males: (1) NVC was assessed during intravenous infusion of saline (placebo) and the non-selective competitive nitric oxide synthase inhibitor N -monomethyl-l-arginine (l-NMMA, 5 mg kg bolus & subsequent 50 μg kg min maintenance dose; n = 10). The order of infusion was randomized, counterbalanced and single blinded. A subset of participants in this study (n = 4) underwent a separate intervention with phenylephrine infusion to independently consider the influence of blood pressure changes on NVC (0.1-0.6 μg kg min constant infusion). (2) NVC was assessed prior to and following isovolumic haemodilution, whereby 20% of whole blood was removed and replaced with 5% human serum albumin to reduce haemoglobin concentration (n = 8). For both protocols, arterial and internal jugular venous blood samples were collected at rest and coupled with volumetric measures of cerebral blood flow (duplex ultrasound) to quantify resting cerebral metabolic parameters. l-NMMA elicited a 30% reduction in the peak (P = 0.01), but not average (P = 0.11), NVC response. Neither phenylephrine nor haemodilution influenced NVC. Nitric oxide signalling is integral to NVC in humans, providing a new direction for research into pharmacological treatment of humans with dementia.
Topics: Cerebrovascular Circulation; Enzyme Inhibitors; Humans; Male; Neurovascular Coupling; Nitric Oxide; omega-N-Methylarginine
PubMed: 32785972
DOI: 10.1113/JP280162 -
American Journal of Physiology. Heart... Jan 2022Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and...
Central adiposity is associated with greater sympathetic support of blood pressure. β-adrenergic receptors (β-AR) buffer sympathetically mediated vasoconstriction and β-AR-mediated vasodilation is attenuated in preclinical models of obesity. With this information, we hypothesized β-AR vasodilation would be lower in obese compared with normal weight adults. Because β-AR vasodilation in normal weight adults is limited by cyclooxygenase (COX) restraint of nitric oxide synthase (NOS), we further explored the contributions of COX and NOS to β-AR vasodilation in this cohort. Forearm blood flow (FBF, Doppler ultrasound) and mean arterial blood pressure (MAP, brachial arterial catheter) were measured and forearm vascular conductance (FVC) was calculated (FVC = FBF/MAP). The rise in FVC from baseline (ΔFVC) was quantified during graded brachial artery infusion of isoproterenol (Iso, 1-12 ng/100 g/min) in normal weight ( = 36) and adults with obesity ( = 22) (18-40 yr old). In a subset of participants, Iso-mediated vasodilation was examined before and during inhibition of NOS [-monomethyl-l-arginine (l-NMMA)], COX (ketorolac), and NOS + COX (l-NMMA + ketorolac). Iso-mediated increases in FVC did not differ between groups ( = 0.57). l-NMMA attenuated Iso-mediated ΔFVC in normal weight ( = 0.03) but not adults with obesity ( = 0.27). In normal weight adults, ketorolac increased Iso-mediated ΔFVC ( < 0.01) and this response was lost with concurrent l-NMMA ( = 0.67). In contrast, neither ketorolac ( = 0.81) nor ketorolac + l-NMMA ( = 0.40) altered Iso-mediated ΔFVC in adults with obesity. Despite shifts in COX and NOS, β-AR vasodilation is preserved in young adults with obesity. These data highlight the presence of a compensatory shift in microvascular control mechanisms in younger humans with obesity. We examined β-adrenergic receptor-mediated vasodilation in skeletal muscle of humans with obesity and normal weight. Results show that despite shifts in the contribution of cyclooxygenase and nitric oxide synthase, β-adrenergic-mediated vasodilation is relatively preserved in young, otherwise healthy adults with obesity. These data highlight the presence of subclinical changes in microvascular control mechanisms early in the obesity process and suggest duration of obesity and/or the addition of primary aging may be necessary for overt dysfunction.
Topics: Adrenergic beta-Agonists; Adult; Blood Vessels; Cyclooxygenase Inhibitors; Female; Humans; Isoproterenol; Ketorolac; Male; Muscle, Skeletal; Nitric Oxide Synthase Type III; Obesity; Prostaglandin-Endoperoxide Synthases; Receptors, Adrenergic, beta; Vasodilation; omega-N-Methylarginine
PubMed: 34738833
DOI: 10.1152/ajpheart.00449.2021 -
Clinical and Experimental Hypertension... 2020Asymmetric dimethylarginine, symmetric dimethylarginine, and L-monomethylarginine are originated from the subsequent proteolytic catalysis of methylated arginine...
Asymmetric dimethylarginine, symmetric dimethylarginine, and L-monomethylarginine are originated from the subsequent proteolytic catalysis of methylated arginine residues on different proteins and inhibit the endogenous nitric oxide generation. The changes in total methylarginine load (Asymmetric dimethylarginine plus symmetric dimethylarginine plus L-monomethylarginine) may contribute to hypertension. The aim of this study was to determine serum methylarginine concentrations in patients with masked hypertension and determine the association between these biomarkers and blood pressure measurements. Control group, masked hypertension and hypertension groups consisted of 40 subjects (11 males, 28 females, mean age 48.6 ± 13.1), 28 subjects (14 males, 14 females, mean age 50.9 ± 11.0) and 36 subjects (15 males, 21 females, mean age 54.4 ± 12.3 years), respectively (= 0.149). Serum total methylarginine load was significantly higher in hypertension group (0.63 ± 0.23) compared to masked hypertension (0.49 ± 0.16) and control groups (0.38 ± 0.13) (= 0.008 and < 0.001). While there was no statistically significant difference between healthy control groups [0.147 (0.03-0.29)] and masked hypertension patients [0.144 (0.05-0.42)] for serum symmetric dimethylarginine levels (= 0.970), it was markedly elevated in hypertension group [0.25 (0.07-0.54)] compared to masked hypertension group [0.14 (0.05-0.42)] (= 0.001). Serum total methylarginine load was positively correlated with night-time SBP (r = 0.214, = 0.029). Serum methylarginine levels might be a useful marker for determining the courses of clinical hypertension.
Topics: Arginine; Biomarkers; Blood Pressure Determination; Female; Humans; Hypertension; Male; Masked Hypertension; Middle Aged; Nitric Oxide; Risk Factors; omega-N-Methylarginine
PubMed: 30795691
DOI: 10.1080/10641963.2019.1583246 -
The Journal of Physiology Mar 2022Cerebrovascular CO reactivity (CVR) is often considered a bioassay of cerebrovascular endothelial function. We recently introduced a test of cerebral shear-mediated...
Cerebrovascular CO reactivity (CVR) is often considered a bioassay of cerebrovascular endothelial function. We recently introduced a test of cerebral shear-mediated dilatation (cSMD) that may better reflect endothelial function. We aimed to determine the nitric oxide (NO)-dependency of CVR and cSMD. Eleven volunteers underwent a steady-state CVR test and transient CO test of cSMD during intravenous infusion of the NO synthase inhibitor N -monomethyl-l-arginine (l-NMMA) or volume-matched saline (placebo; single-blinded and counter-balanced). We measured cerebral blood flow (CBF; duplex ultrasound), intra-arterial blood pressure and . Paired arterial and jugular venous blood sampling allowed for the determination of trans-cerebral NO exchange (ozone-based chemiluminescence). l-NMMA reduced arterial NO by ∼25% versus saline (74.3 ± 39.9 vs. 98.1 ± 34.2 nM; P = 0.03). The steady-state CVR (20.1 ± 11.6 nM/min at baseline vs. 3.2 ± 16.7 nM/min at +9 mmHg ; P = 0.017) and transient cSMD tests (3.4 ± 5.9 nM/min at baseline vs. -1.8 ± 8.2 nM/min at 120 s post-CO ; P = 0.044) shifted trans-cerebral NO exchange towards a greater net release (a negative value indicates release). Although this trans-cerebral NO release was abolished by l-NMMA, CVR did not differ between the saline and l-NMMA trials (57.2 ± 14.6 vs. 54.1 ± 12.1 ml/min/mmHg; P = 0.49), nor did l-NMMA impact peak internal carotid artery dilatation during the steady-state CVR test (6.2 ± 4.5 vs. 6.2 ± 5.0% dilatation; P = 0.960). However, l-NMMA reduced cSMD by ∼37% compared to saline (2.91 ± 1.38 vs. 4.65 ± 2.50%; P = 0.009). Our findings indicate that NO is not an obligatory regulator of steady-state CVR. Further, our novel transient CO test of cSMD is largely NO-dependent and provides an in vivo bioassay of NO-mediated cerebrovascular function in humans. KEY POINTS: Emerging evidence indicates that a transient CO stimulus elicits shear-mediated dilatation of the internal carotid artery, termed cerebral shear-mediated dilatation. Whether or not cerebrovascular reactivity to a steady-state CO stimulus is NO-dependent remains unclear in humans. During both a steady-state cerebrovascular reactivity test and a transient CO test of cerebral shear-mediated dilatation, trans-cerebral nitrite exchange shifted towards a net release indicating cerebrovascular NO production; this response was not evident following intravenous infusion of the non-selective NO synthase inhibitor N -monomethyl-l-arginine. NO synthase blockade did not alter cerebrovascular reactivity in the steady-state CO test; however, cerebral shear-mediated dilatation following a transient CO stimulus was reduced by ∼37% following intravenous infusion of N -monomethyl-l-arginine. NO is not obligatory for cerebrovascular reactivity to CO , but is a key contributor to cerebral shear-mediated dilatation.
Topics: Carbon Dioxide; Cerebrovascular Circulation; Dilatation; Enzyme Inhibitors; Humans; Nitric Oxide; Nitric Oxide Synthase; Nitrogen Dioxide; omega-N-Methylarginine
PubMed: 34904229
DOI: 10.1113/JP282427 -
Tumour Virus Research Jun 2023Kaposi's Sarcoma (KS) is a heterogenous, multifocal vascular malignancy caused by the human herpesvirus 8 (HHV8), also known as Kaposi's Sarcoma-Associated Herpesvirus...
Kaposi's Sarcoma (KS) is a heterogenous, multifocal vascular malignancy caused by the human herpesvirus 8 (HHV8), also known as Kaposi's Sarcoma-Associated Herpesvirus (KSHV). Here, we show that KS lesions express iNOS/NOS2 broadly throughout KS lesions, with enrichment in LANA positive spindle cells. The iNOS byproduct 3-nitrotyrosine is also enriched in LANA positive tumor cells and colocalizes with a fraction of LANA-nuclear bodies. We show that iNOS is highly expressed in the L1T3/mSLK tumor model of KS. iNOS expression correlated with KSHV lytic cycle gene expression, which was elevated in late-stage tumors (>4 weeks) but to a lesser degree in early stage (1 week) xenografts. Further, we show that L1T3/mSLK tumor growth is sensitive to an inhibitor of nitric oxide, L-NMMA. L-NMMA treatment reduced KSHV gene expression and perturbed cellular gene pathways relating to oxidative phosphorylation and mitochondrial dysfunction. These finding suggest that iNOS is expressed in KSHV infected endothelial-transformed tumor cells in KS, that iNOS expression depends on tumor microenvironment stress conditions, and that iNOS enzymatic activity contributes to KS tumor growth.
Topics: Animals; Humans; Mice; Antigens, Viral; Herpesvirus 8, Human; omega-N-Methylarginine; Sarcoma, Kaposi; Tumor Microenvironment
PubMed: 36863485
DOI: 10.1016/j.tvr.2023.200259 -
Nitric Oxide : Biology and Chemistry Nov 2020Nitric oxide synthase (NOS) inhibition with N(G)-monomethyl-l-arginine (L-NMMA) is often used to assess the role of NO in human cardiovascular function. However, the...
Nitric oxide synthase (NOS) inhibition with N(G)-monomethyl-l-arginine (L-NMMA) is often used to assess the role of NO in human cardiovascular function. However, the window of effect for L-NMMA on human vascular function is unknown, which is critical for designing and interpreting human-based studies. This study utilized the passive leg movement (PLM) assessment of vascular function, which is predominantly NO-mediated, in 7 young male subjects under control conditions, immediately following intra-arterial L-NMMA infusion (0.24 mg⋅dl⋅min), and at 45-60 and 90-105 min post L-NMMA infusion. The leg blood flow (LBF) and leg vascular conductance (LVC) responses to PLM, measured with Doppler ultrasound and expressed as the change from baseline to peak (ΔLBF and ΔLVC) and area under the curve (LBF and LVC), were assessed. PLM-induced robust control ΔLBF (1135 ± 324 ml⋅min) and ΔLVC (10.7 ± 3.6 ml⋅min⋅mmHg) responses that were significantly attenuated (704 ± 196 ml⋅min and 6.7 ± 2 ml⋅min⋅mmHg) immediately following L-NMMA infusion. Likewise, control condition PLM ΔLBF (455 ± 202 ml) and ΔLVC (4.0 ± 1.4 ml⋅mmHg) were significantly attenuated (141 ± 130 ml and 1.3 ± 1.2 ml⋅mmHg) immediately following L-NMMA infusion. However, by 45-60 min post L-NMMA infusion all PLM variables were not significantly different from control, and this was still the case at 90-105 min post L-NMMA infusion. These findings reveal that the potent reduction in NO bioavailability afforded by NOS inhibition with L-NMMA has a window of effect of less than 45-60 min in the human vasculature. These data are particularly important for the commonly employed approach of pharmacologically inhibiting NOS with L-NMMA in the human vasculature.
Topics: Adult; Enzyme Inhibitors; Femoral Artery; Hemodynamics; Humans; Leg; Male; Nitric Oxide; Nitric Oxide Synthase; Regional Blood Flow; Time Factors; Young Adult; omega-N-Methylarginine
PubMed: 32979497
DOI: 10.1016/j.niox.2020.09.001 -
The Journal of Toxicological Sciences 2020Bisphenol A (BPA) interferes the function and development of the central nervous system (CNS), resulting in behavioral abnormalities and memory loss. S-nitrosylation of...
Bisphenol A and rotenone induce S-nitrosylation of protein disulfide isomerase (PDI) and inhibit neurite outgrowth of primary cultured cells of the rat hippocampus and PC12 cells.
Bisphenol A (BPA) interferes the function and development of the central nervous system (CNS), resulting in behavioral abnormalities and memory loss. S-nitrosylation of protein disulfide isomerase (PDI) is increased in brains with sporadic Alzheimer's disease and Parkinson's disease. The aim of the present study was to clarify the role of nitric oxide (NO) in BPA-induced neurotoxicity. Since rotenone induces NO-mediated neurodegeneration through S-nitrosylation of PDI, it was used as a positive control. First, rats were treated with BPA and rotenone, and S-nitrosylation of PDI was detected in rat brain microsomes. BPA and rotenone decreased RNase oxidation activity of PDI concomitant with S-nitrosylation of PDI. Next, to clarify S-nitrosylation of PDI by BPA and rotenone in rat brains, we treated the rat pheochromocytoma cell line PC12 and primary cultured neuron cells from the rat hippocampus with BPA (5 and 10 μM) and rotenone (100 or 200 nM). BPA induced S-nitrosylation of PDI, while NG-monomethyl-L-arginine (L-NMMA), a NOS inhibitor, exerted the opposite effects. Finally, to evaluate the toxicity of BPA in the CNS, we investigated its effects on neurite outgrowth of PC12 and primary cultured neuron cells. BPA inhibited neurite outgrowth of these cells, while L-NMMA reversed this inhibition. The involvement of PDI activity in neurite outgrowth was also examined, and bacitracin, a PDI inhibitor, is shown to decrease neurite outgrowth. Furthermore, the overexpression of PDI, but not a catalytically inactive PDI mutant, enhanced neurite outgrowth. These results suggested that S-nitrosylation of PDI induced by excessive NO caused BPA-induced neurotoxicity.
Topics: Animals; Benzhydryl Compounds; Brain; Depression, Chemical; Hippocampus; Male; Neuronal Outgrowth; Neurotoxins; Nitric Oxide; Oxidation-Reduction; PC12 Cells; Phenols; Protein Disulfide-Isomerases; Rats; Rats, Sprague-Dawley; Ribonucleases; Rotenone; omega-N-Methylarginine
PubMed: 33268678
DOI: 10.2131/jts.45.783