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The Journal of Physiology Nov 2021The importance of nitric oxide (NO) in regulating cerebral blood flow (CBF) remains unresolved, due in part to methodological approaches, which lack a comprehensive... (Randomized Controlled Trial)
Randomized Controlled Trial
The importance of nitric oxide (NO) in regulating cerebral blood flow (CBF) remains unresolved, due in part to methodological approaches, which lack a comprehensive assessment of both global and regional effects. Importantly, NO synthase (NOS) expression and activity appear greater in some anterior brain regions, suggesting region-specific NOS influence on CBF. We hypothesized that NO contributes to basal CBF in healthy adults, in a regionally distinct pattern that predominates in the anterior circulation. Fourteen healthy adults (7 females; 24 ± 5 years) underwent two magnetic resonance imaging (MRI) study visits with saline (placebo) or the NOS inhibitor, L-NMMA, administered in a randomized, single-blind approach. 4D flow MRI quantified total and regional macrovascular CBF, whereas arterial spin labelling (ASL) MRI quantified total and regional microvascular perfusion. L-NMMA (or volume-matched saline) was infused intravenously for 5 min prior to imaging. L-NMMA reduced CBF (L-NMMA: 722 ± 100 vs. placebo: 771 ± 121 ml/min, P = 0.01) with similar relative reductions (5-7%) in anterior and posterior cerebral circulations, due in part to the reduced cross-sectional area of 9 of 11 large cerebral arteries. Global microvascular perfusion (ASL) was reduced by L-NMMA (L-NMMA: 42 ± 7 vs. placebo: 47 ± 8 ml/100g/min, P = 0.02), with 7-11% reductions in both hemispheres of the frontal, parietal and temporal lobes, and in the left occipital lobe. We conclude that NO contributes to macrovascular and microvascular regulation including larger artery resting diameter. Contrary to our hypothesis, the influence of NO on cerebral perfusion appears regionally uniform in healthy young adults. KEY POINTS: Cerebral blood flow (CBF) is vital for brain health, but the signals that are key to regulating CBF remain unclear. Nitric oxide (NO) is produced in the brain, but its importance in regulating CBF remains controversial since prior studies have not studied all regions of the brain simultaneously. Using modern MRI approaches, a drug that inhibits the enzymes that make NO (L-NMMA) reduced CBF by up to 11% in different brain regions. NO helps maintain proper CBF in healthy adults. These data will help us understand whether the reductions in CBF that occur during ageing or cardiovascular disease are related to shifts in NO signalling.
Topics: Adult; Cerebrovascular Circulation; Female; Humans; Male; Nitric Oxide; Nitric Oxide Synthase; Perfusion; Regional Blood Flow; Single-Blind Method; Young Adult; omega-N-Methylarginine
PubMed: 34587648
DOI: 10.1113/JP281975 -
The American Journal of Pathology Dec 2021Bone homeostasis depends on the balance between bone resorption by osteoclasts (OCs) and bone formation by osteoblasts. Bone resorption can become excessive under...
Bone homeostasis depends on the balance between bone resorption by osteoclasts (OCs) and bone formation by osteoblasts. Bone resorption can become excessive under various pathologic conditions, including rheumatoid arthritis. Previous studies have shown that OC formation is promoted under hypoxia. However, the precise mechanisms behind OC formation under hypoxia have not been elucidated. The present study investigated the role of inducible nitric oxide synthase (iNOS) in OC differentiation under hypoxia. Primary bone marrow cells obtained from mice were stimulated with receptor activator of NF-κB ligand and macrophage colony-stimulating factor to induce OC differentiation. The number of OCs increased in culture under hypoxia (oxygen concentration, 5%) compared with that under normoxia (oxygen concentration, 20%). iNOS gene and protein expression increased in culture under hypoxia. Addition of an iNOS inhibitor under hypoxic conditions suppressed osteoclastogenesis. Addition of a nitric oxide donor to the normoxic culture promoted osteoclastogenesis. Furthermore, insulin-like growth factor 2 expression was significantly altered in both iNOS inhibition experiments and nitric oxide donor experiments. These data might provide clues to therapies for excessive osteoclastogenesis under several hypoxic pathologic conditions, including rheumatoid arthritis.
Topics: Animals; Bone Resorption; Cell Differentiation; Cell Hypoxia; Cells, Cultured; Enzyme Induction; Hypoxia; Male; Mice; Mice, Inbred C57BL; Nitric Oxide Synthase Type II; Osteoclasts; Osteogenesis; Oxygen; Signal Transduction; omega-N-Methylarginine
PubMed: 34560064
DOI: 10.1016/j.ajpath.2021.08.014 -
Tissue & Cell Dec 2021Puerarin regulates the osteoblast differentiation of umbilical cord mesenchymal stem cells. This study, hereby, explored the effects of puerarin on the osteogenic...
Puerarin regulates the osteoblast differentiation of umbilical cord mesenchymal stem cells. This study, hereby, explored the effects of puerarin on the osteogenic differentiation of dental follicle cells (DFCs) for the first time. Rat DFCs (rDFCs) were isolated and identified. After the rDFCs were treated by Puerarin and cultured in osteogenic induction medium, the viability, osteogenic differentiation, and the activities of alkaline phosphatase (ALP) and nitric oxide (NO) were detected. Besides, the secretion of cyclic guanosine monophosphate (cGMP) and expressions of collagen I, osteocalcin (OC), osteopontin (OPN), runt-related transcription factor 2 (RUNX2), soluble guanylate cyclase (SGC), and protein kinase G 1 (PKG-1) were further determined or quantified. Puerarin enhanced the viability and osteogenic differentiation, and increased the activities of ALP, NO, and cGMP and the expressions of Collagen I, OC, OPN, RUNX2, SGC, and PKG-1 in rDFCs. After the co-treatment with puerarin and L-NMMA (NO synthase inhibitor), the promotive effects of Puerarin on cell viability, osteogenic differentiation, and the expressions of collagen I, OC, OPN, RUNX2, SGC, and PKG-1 in rDFCs were reversed by L-NMMA. Puerarin boosted the osteogenic differentiation of rDFCs by activating the NO pathway.
Topics: Alkaline Phosphatase; Animals; Animals, Newborn; Cell Differentiation; Cell Survival; Cells, Cultured; Collagen Type I; Core Binding Factor Alpha 1 Subunit; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Dental Sac; Guanylate Cyclase; Isoflavones; Nitric Oxide; Osteocalcin; Osteogenesis; Osteopontin; Rats, Sprague-Dawley; Solubility; omega-N-Methylarginine; Rats
PubMed: 34371290
DOI: 10.1016/j.tice.2021.101601 -
The Journal of Biological Chemistry Dec 2020Cancer cachexia is characterized by reductions in peripheral lean muscle mass. Prior studies have primarily focused on increased protein breakdown as the driver of...
Cancer cachexia is characterized by reductions in peripheral lean muscle mass. Prior studies have primarily focused on increased protein breakdown as the driver of cancer-associated muscle wasting. Therapeutic interventions targeting catabolic pathways have, however, largely failed to preserve muscle mass in cachexia, suggesting that other mechanisms might be involved. In pursuit of novel pathways, we used untargeted metabolomics to search for metabolite signatures that may be linked with muscle atrophy. We injected 7-week-old C57/BL6 mice with LLC1 tumor cells or vehicle. After 21 days, tumor-bearing mice exhibited reduced body and muscle mass and impaired grip strength compared with controls, which was accompanied by lower synthesis rates of mixed muscle protein and the myofibrillar and sarcoplasmic muscle fractions. Reductions in protein synthesis were accompanied by mitochondrial enlargement and reduced coupling efficiency in tumor-bearing mice. To generate mechanistic insights into impaired protein synthesis, we performed untargeted metabolomic analyses of plasma and muscle and found increased concentrations of two methylarginines, asymmetric dimethylarginine (ADMA) and N-monomethyl-l-arginine, in tumor-bearing mice compared with control mice. Compared with healthy controls, human cancer patients were also found to have higher levels of ADMA in the skeletal muscle. Treatment of C2C12 myotubes with ADMA impaired protein synthesis and reduced mitochondrial protein quality. These results suggest that increased levels of ADMA and mitochondrial changes may contribute to impaired muscle protein synthesis in cancer cachexia and could point to novel therapeutic targets by which to mitigate cancer cachexia.
Topics: Animals; Arginine; Cachexia; Female; Heterografts; Humans; Male; Mice; Mice, Inbred C57BL; Mitochondria, Muscle; Muscle Proteins; Neoplasms; omega-N-Methylarginine
PubMed: 33453990
DOI: 10.1074/jbc.RA120.014884 -
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 -
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 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 -
Journal of the American Heart... Aug 2020Background Basal release of nitric oxide (NO) from the vascular endothelium regulates the tone of muscular arteries and resistance vasculature. Effects of NO on muscular... (Randomized Controlled Trial)
Randomized Controlled Trial
Background Basal release of nitric oxide (NO) from the vascular endothelium regulates the tone of muscular arteries and resistance vasculature. Effects of NO on muscular arteries could be particularly important during exercise when shear stress may stimulate increased NO synthesis. Methods and Results We investigated acute effects of NO synthase inhibition on exercise hemodynamics using N-monomethyl-l-arginine (l-NMMA), a nonselective NO synthase -inhibitor. Healthy volunteers (n=10, 5 female, 19-33 years) participated in a 2-phase randomized crossover study, receiving l-NMMA (6 mg/kg, iv over 5 minutes) or placebo before bicycle exercise (25-150 W for 12 minutes). Blood pressure, cardiac output (measured by dilution of soluble and inert tracers) and femoral artery diameter were measured before, during, and after exercise. At rest, l-NMMA reduced heart rate (by 16.2±4.3 bpm relative to placebo, <0.01), increased peripheral vascular resistance (by 7.0±1.4 mmHg per L/min, <0.001), mean arterial blood pressure (by 8.9±3.5 mmHg, <0.05), and blunted an increase in femoral artery diameter that occurred immediately before exercise (change in diameter: 0.14±0.04 versus 0.32±0.06 mm after l-NMMA and placebo, <0.01). During/after exercise l-NMMA had no significant effect on peripheral resistance, cardiac output, or on femoral artery diameter. Conclusions These results suggest that NO plays little role in modulating muscular artery function during exercise but that it may mediate changes in muscular artery tone immediately before exercise.
Topics: Adult; Arterial Pressure; Arteries; Cardiac Output; Cross-Over Studies; Enzyme Inhibitors; Exercise; Exercise Test; Female; Femoral Artery; Humans; Male; Muscle, Skeletal; Nitric Oxide; Nitric Oxide Synthase; Placebos; Pulse Wave Analysis; Vascular Resistance; Vasodilation; Young Adult; omega-N-Methylarginine
PubMed: 32781940
DOI: 10.1161/JAHA.119.013849 -
Molecules (Basel, Switzerland) May 2020(QM)-a member of the Fagaceae family-has been used as traditional medicine in Korea, China and Mongolia as a treatment for inflammation of oral, genital or anal mucosa...
(QM)-a member of the Fagaceae family-has been used as traditional medicine in Korea, China and Mongolia as a treatment for inflammation of oral, genital or anal mucosa and for external inflammation of skin. To treat acne vulgaris (AV), we evaluated the inhibition of inflammatory cytokines (IL-6 and IL-8) of QM leaf extract (QML) and its main compound, pedunculagin (PD) in vitro and 5α-reductase inhibitory activity by western blotting. As results, QML and PD showed potent NO production inhibitory activity compared with the positive control (PC), NG-monomethyl-L-arginine (L-NMMA). QML and PD was also showed the decreases of IL-6 and IL-8 compared with the PC, EGCG and exhibited potent 5α-reductase type 1 inhibitory activities compared with the PC, dutasteride.
Topics: 5-alpha Reductase Inhibitors; Acne Vulgaris; Anti-Inflammatory Agents; Cell Line; Cholestenone 5 alpha-Reductase; Down-Regulation; Humans; Interleukin-6; Interleukin-8; Lipopolysaccharides; Medicine, Traditional; Nitric Oxide; Plant Extracts; Plant Leaves; Quercus; Tannins; omega-N-Methylarginine
PubMed: 32380665
DOI: 10.3390/molecules25092154 -
Oxidative Medicine and Cellular... 2020() is one of the most important agents of dermatophyte infection in humans. The aim of this experiment was to evaluate the effect of HaCaT cells on , investigate the...
() is one of the most important agents of dermatophyte infection in humans. The aim of this experiment was to evaluate the effect of HaCaT cells on , investigate the responsible mechanism of action, and explore the role of reactive oxygen species (ROS) and nitric oxide (NO) in the inhibition of growth by HaCaT cells. The viability of fungi treated with HaCaT cells alone and with HaCaT cells combined with pretreatment with the NADPH oxidase inhibitor (DPI) or the nitric oxide synthase (NOS) inhibitor L-NMMA was determined by enumerating the colony-forming units. NOS, ROS, and NO levels were quantified using fluorescent probes. The levels of the NOS inhibitor asymmetric dimethylarginine (ADMA) were determined by enzyme-linked immunosorbent assay (ELISA). Micromorphology was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, fungal keratinase activity was assessed by measuring dye release from keratin azure. In vitro fungal viability, keratinase activity, and ADMA content decreased after HaCaT cell intervention, whereas the levels of ROS, NO, and NOS increased. The micromorphology was abnormal. Fungi pretreated with DPI and L-NMMA exhibited opposite effects. HaCaT cells inhibited the growth and pathogenicity of in vitro. A suggested mechanism is that ROS and NO play an important role in the inhibition of growth by HaCaT cells.
Topics: Arginine; Catecholamines; Cell Line; Enzyme Inhibitors; Humans; Imidazolines; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; NADPH Oxidases; Nitric Oxide; Nitric Oxide Synthase; Peptide Hydrolases; Reactive Oxygen Species; Trichophyton; omega-N-Methylarginine
PubMed: 32104540
DOI: 10.1155/2020/8548619