Role of neuronal nitric oxide synthase on cardiovascular functions in physiological and pathophysiological states

Synthesis, characterization and evaluation of new anti-inflammatory iron charge transfer complexes

The novelty and the essential purpose of this research is the preparation of new anti-inflammatory iron complexes in water green solvent using critical micelle concentration of anionic surface active agent (SAA). Three new anti-inflammatory iron complexes have been prepared. Thiophene-electron (es) donor (D) Schiff base (2-(2-OH-benzylidene)-amino)-4, 5, 6, 7-tetrah ydrobenzo[b] thiophene-3-carbonitrile) has been prepared. Molecular structures of all samples were confirmed based on CNH analysis, 1H NMR and 13C NMR spectra. The molecular structure of Schiff base is further confirmed by computational chemistry using the DFT-B3LYP method, 6-31G (d) basis set. Observed and simulated 1H NMR, UV-Vis. IR/Raman spectra confirmed the molecular structure of D. This Schiff base is intercalated to ferric chloride (FeCl3) giving pure iron charge transfer complex (CTCs). In vitro and kinetic studies confirmed Fe-CTC complexes had (concentration-dependent) potent antimicrobial-, good anti-inflammatory activities. Free radical scavenging activity nitrous oxide (NO.) of Fe (III)CTCs is attributed to geometry Fe(III) ions as distorted octahedral (either monoclinic or triclinic single crystals) via functional groups (-C]N-O, NH2). Elemental analysis and EDS spectra confirmed strong binding between iron and hetero atoms (N, S, O) of D molecules.

Enhancing the nitric oxide inhibitory activity using a combination of plant essential oils and mixture design approach

The synergistic effects of essential oils (EOs) from three aromatic plant species, Foeniculum vulgare subsp. piperitum (C.Presl) Bég. (FV), Origanum heracleoticum L. (OH) and Lavandula austroapennina N.G.Passal., Tundis & Upson. (LA), were evaluated for their inhibitory properties on nitric oxide production in RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS). We utilized a Design of Experiments (DoE) methodology to optimize a formulation by combining three Essential Oils (EOs), while simultaneously taking into account two response variables, maximization of NO inhibition with minimum cytotoxicity. The optimal blend of components was predicted, and the statistical outcome's efficacy was experimentally verified. The combination corresponding to 87.7 % FV, 12.3 % LA and 0.0 % OH showed high inhibitory effect (76.3 %) with negligible cytotoxicity (4.5 %). This research provides new information on the interactions among fennel, oregano and lavender essential oils and shows how they can synergistically inhibit in vitro LPS-induced NO production.

Regulatory effects of curcumin on nitric oxide signaling in the cardiovascular system

The continuously rising prevalence of cardiovascular disease (CVD) globally substantially impacts the economic growth of developing countries. Indeed, one of the leading causes of death worldwide is unfavorable cardiovascular events. Reduced nitric oxide (NO) generation is the pathogenic foundation of endothelial dysfunction, which is regarded as the first stage in the development of a number of CVDs. Nitric oxide exerts an array of biological effects, including vasodilation, the suppression of vascular smooth muscle cell proliferation and the functional control of cardiac cells. Numerous treatment strategies aim to increase NO synthesis or upregulate downstream NO signaling pathways. The major component of Curcuma longa, curcumin, has long been utilized in traditional medicine to treat various illnesses, especially CVDs. Curcumin improves CV function as well as having important pleiotropic effects, such as anti-inflammatory and antioxidant, through its ability to increase the bioavailability of NO and to positively impact NO-related signaling pathways. In this review, we discuss the scientific literature relating to curcumin's positive effects on NO signaling and vascular endothelial function.

Dysfunctional and Dysregulated Nitric Oxide Synthases in Cardiovascular Disease: Mechanisms and Therapeutic Potential

Nitric oxide (NO) plays an important and diverse signalling role in the cardiovascular system, contributing to the regulation of vascular tone, endothelial function, myocardial function, haemostasis, and thrombosis, amongst many other roles. NO is synthesised through the nitric oxide synthase (NOS)-dependent L-arginine-NO pathway, as well as the nitrate-nitrite-NO pathway. The three isoforms of NOS, namely neuronal (NOS1), inducible (NOS2), and endothelial (NOS3), have different localisation and functions in the human body, and are consequently thought to have differing pathophysiological roles. Furthermore, as we continue to develop a deepened understanding of the different roles of NOS isoforms in disease, the possibility of therapeutically modulating NOS activity has emerged. Indeed, impaired (or dysfunctional), as well as overactive (or dysregulated) NOS activity are attractive therapeutic targets in cardiovascular disease. This review aims to describe recent advances in elucidating the physiological role of NOS isoforms within the cardiovascular system, as well as mechanisms of dysfunctional and dysregulated NOS in cardiovascular disease. We then discuss the modulation of NO and NOS activity as a target in the development of novel cardiovascular therapeutics.

Management of Obesity-Related Inflammatory and Cardiovascular Diseases by Medicinal Plants: From Traditional Uses to Therapeutic Targets

Inflammation is a crucial factor in the development and progression of cardiovascular diseases (CVD). Cardiac remodeling in the presence of persistent inflammation leads to myocardial fibrosis and extracellular matrix changes, which reduce cardiac function, induce arrhythmias, and finally, cause heart failure. The majority of current CVD treatment plans concentrate on reducing risk factors such as hyperlipidemia, type 2 diabetes, and hypertension. One such strategy could be inflammation reduction. Numerous in vitro, animal, and clinical studies indicate that obesity is associated with low-grade inflammation. Recent studies have demonstrated the potential of medicinal plants and phytochemicals to cure and prevent obesity and inflammation. In comparison to conventional therapies, the synergistic effects of several phytochemicals boost their bioavailability and impact numerous cellular and molecular targets. Focusing on appetite, pancreatic lipase activity, thermogenesis, lipid metabolism, lipolysis and adipogenesis, apoptosis in adipocytes, and adipocyte life cycle by medicinal plants and phytochemicals represent an important goal in the development of new anti-obesity drugs. We conducted an extensive review of the literature and electronic databases, including Google Scholar, PubMed, Science Direct, and MedlinePlus, for collecting data on the therapeutic effects of medicinal plants/phytochemicals in curing obesity and its related inflammation and CVD diseases, including cellular and molecular mechanisms, cytokines, signal transduction cascades, and clinical trials.

Targeting oxidative stress as a preventive and therapeutic approach for cardiovascular disease

Cardiovascular diseases (CVDs) continue to exert a significant impact on global mortality rates, encompassing conditions like pulmonary arterial hypertension (PAH), atherosclerosis (AS), and myocardial infarction (MI). Oxidative stress (OS) plays a crucial role in the pathogenesis and advancement of CVDs, highlighting its significance as a contributing factor. Maintaining an equilibrium between reactive oxygen species (ROS) and antioxidant systems not only aids in mitigating oxidative stress but also confers protective benefits on cardiac health. Herbal monomers can inhibit OS in CVDs by activating multiple signaling pathways, such as increasing the activity of endogenous antioxidant systems and decreasing the level of ROS expression. Given the actions of herbal monomers to significantly protect the normal function of the heart and reduce the damage caused by OS to the organism. Hence, it is imperative to recognize the significance of herbal monomers as prospective therapeutic interventions for mitigating oxidative damage in CVDs. This paper aims to comprehensively review the origins and mechanisms underlying OS, elucidate the intricate association between CVDs and OS, and explore the therapeutic potential of antioxidant treatment utilizing herbal monomers. Furthermore, particular emphasis will be placed on examining the cardioprotective effects of herbal monomers by evaluating their impact on cardiac signaling pathways subsequent to treatment.

Nitric Oxide Synthases in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by severe joint damage and disability. However, the specific mechanism of RA has not been thoroughly clarified over the past decade. Nitric oxide (NO), a kind of gas messenger molecule with many molecular targets, is demonstrated to have significant roles in histopathology and homeostasis. Three nitric oxide synthases (NOS) are related to producing NO and regulating the generation of NO. Based on the latest studies, NOS/NO signaling pathways play a key role in the pathogenesis of RA. Overproduction of NO can induce the generation and release of inflammatory cytokines and act as free radical gas to accumulate and trigger oxidative stress, which can involve in the pathogenesis of RA. Therefore, targeting NOS and its upstream and downstream signaling pathways may be an effective approach to managing RA. This review clearly summarizes the NOS/NO signaling pathway, the pathological changes of RA, the involvement of NOS/NO in RA pathogenesis and the conventional and novel drugs based on NOS/NO signaling pathways that are still in clinical trials and have good therapeutic potential in recent years, with an aim to provide a theoretical basis for further exploration of the role of NOS/NO in the pathogenesis, prevention and treatment of RA.

A mathematical model for intracellular NO and ROS dynamics in vascular endothelial cells activated by exercise-induced wall shear stress

Vascular endothelial cells (ECs) residing in the innermost layer of blood vessels are exposed to dynamic wall shear stress (WSS) induced by blood flow. The intracellular nitric oxide (NO) and reactive oxygen species (ROS) in ECs modulated by the dynamic WSS play important roles in endothelial functions. Mathematical modeling is a popular methodology for biophysical studies. It can not only explain existing cell experiments, but also reveal the underlying mechanism. However, the previous mathematical models of NO dynamics in ECs are limited to the static WSS induced by constant flow, while arterial blood flow is a periodic pulsatile flow with varying amplitude and frequency at different exercise intensities. In this study, a mathematical model of intracellular NO and ROS dynamics activated by dynamic WSS based on the in vitro cell experiments is developed. With the hypothesis of the viscoelastic body, the Kelvin model is adopted to simulate the mechanosensors on EC. Thus, the NO dynamics activated by dynamic shear stresses induced by constant flow, pulsatile flow, and oscillatory flow are analyzed and compared. Moreover, the roles of ROS have been considered for the first time in the modeling of NO dynamics in ECs based on the analysis of cell experiments. The predictions of the proposed model coincide fairly well with the experimental data when ECs are subjected to exercise-induced WSS. The mechanism is elucidated that WSS induced by moderate-intensity exercise is most favorable to NO production in ECs. This study can provide valuable insights for further study of NO and ROS dynamics in ECs and help develop appropriate exercise regimens for improving endothelial functions.

The Role of Nitric Oxide in the Micro- and Macrovascular Response to a 7-Day High-Salt Diet in Healthy Individuals

This study aimed to investigate the specific role of nitric oxide (NO) in micro- and macrovascular response to a 7-day high-salt (HS) diet, specifically by measuring skin microvascular local thermal hyperemia and the flow-mediated dilation of the brachial artery, as well as serum NO and three NO synthase enzyme (NOS) isoform concentrations in healthy individuals. It also aimed to examine the concept of non-osmotic sodium storage in the skin following the HS diet by measuring body fluid status and systemic hemodynamic responses, as well as serum vascular endothelial growth factor C (VEGF-C) concentration. Forty-six young, healthy individuals completed a 7-day low-salt diet, followed by a 7-day HS diet protocol. The 7-day HS diet resulted in impaired NO-mediated endothelial vasodilation in peripheral microcirculation and conduit arteries, in increased eNOS, decreased nNOS, and unchanged iNOS concentration and NO serum level. The HS diet did not change the volume of interstitial fluid, the systemic vascular resistance or the VEGF-C serum level. These results indicate that the 7-day HS-diet induces systemic impairment of NO-mediated endothelial vasodilation, while dissociation in the eNOS and nNOS response indicates complex adaptation of main NO-generating enzyme isoforms to HS intake in healthy individuals. Our results failed to support the concept of non-osmotic sodium storage.

Isodorsmanin A Prevents Inflammatory Response in LPS-Stimulated Macrophages by Inhibiting the JNK and NF-κB Signaling Pathways

Natural and synthetic chalcones exhibit anti-inflammatory, antitumoral, antibacterial, antifungal, antimalarial, and antitubercular activities. Isodorsmanin A (IDA), a chalcone, is a well-known constituent of the dried seeds of Psoralea corylifolia L. (PC). Although other constituents of PC have been widely investigated, there are no studies on the biological properties of IDA. In this study, we focused on the anti-inflammatory effects of IDA and evaluated its effects on lipopolysaccharide (LPS)-stimulated macrophages. The results showed that IDA suppressed the production of inflammatory mediators (nitric oxide [NO] and prostaglandin E₂ [PGE₂]) and proinflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-6 [IL-6], and interleukin-1β [IL-1β]) without cytotoxicity. In addition, it downregulated the mRNA levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) within the treatment concentrations. In our mechanistic studies, IDA inhibited the phosphorylation of the c-Jun N-terminal kinase (JNK), mitogen-activated protein kinase (MAPK), and protected the nuclear factor of the kappa light polypeptide gene enhancer in the B-cells' inhibitor, alpha (IκB-α), from degradation, thus preventing the activation of the nuclear factor kappa-light-chain-enhancer of activated B cells' (NF-κB) transcription factor. Our results suggest that IDA is a promising compound for attenuating excessive inflammatory responses.

Acute beetroot juice consumption does not alter cerebral autoregulation or cardiovagal baroreflex sensitivity during lower-body negative pressure in healthy adults

Introduction

Beetroot juice (BRJ) improves peripheral endothelial function and vascular compliance, likely due to increased nitric oxide bioavailability. It is unknown if BRJ alters cerebrovascular function and cardiovagal baroreflex control in healthy individuals.

Purpose

We tested the hypotheses that BRJ consumption improves cerebral autoregulation (CA) and cardiovagal baroreflex sensitivity (cBRS) during lower-body negative pressure (LBNP).

Methods

Thirteen healthy adults (age: 26 ± 4 years; 5 women) performed oscillatory (O-LBNP) and static LBNP (S-LBNP) before (PRE) and 3 h after consuming 500 mL of BRJ (POST). Participants inhaled 3% CO2 (21% O2, 76% N2) during a 5 min baseline and throughout LBNP to attenuate reductions in end-tidal CO2 tension (PETCO2). O-LBNP was conducted at ∼0.02 Hz for six cycles (-70 mmHg), followed by a 3-min recovery before S-LBNP (-40 mmHg) for 7 min. Beat-to-beat middle cerebral artery blood velocity (MCAv) (transcranial Doppler) and blood pressure were continuously recorded. CA was assessed using transfer function analysis to calculate coherence, gain, and phase in the very-low-frequency (VLF; 0.020-0.070 Hz) and low-frequency bands (LF; 0.07-0.20 Hz). cBRS was calculated using the sequence method. Comparisons between POST vs. PRE are reported as mean ± SD.

Results

During O-LBNP, coherence VLF was greater at POST (0.55 ± 0.06 vs. 0.46 ± 0.08; P < 0.01), but phase VLF (P = 0.17) and gain VLF (P = 0.69) were not different. Coherence LF and phase LF were not different, but gain LF was lower at POST (1.03 ± 0.20 vs. 1.12 ± 0.30 cm/s/mmHg; P = 0.05). During S-LBNP, CA was not different in the VLF or LF bands (all P > 0.10). Up-cBRS and Down-cBRS were not different during both LBNP protocols.

Conclusion

These preliminary data indicate that CA and cBRS during LBNP in healthy, young adults is largely unaffected by an acute bolus of BRJ.

Role of Dietary Polyphenols in the Activity and Expression of Nitric Oxide Synthases: A Review

Nitric oxide (NO) plays several key roles in the functionality of an organism, and it is usually released in numerous organs and tissues. There are mainly three isoforms of the enzyme that produce NO starting from the metabolism of arginine, namely endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and neuronal nitric oxide synthase (nNOS). The expression and activity of these isoforms depends on the activation/deactivation of different signaling pathways at an intracellular level following different physiological and pathological stimuli. Compounds of natural origin such as polyphenols, which are obtainable through diet, have been widely studied in recent years in in vivo and in vitro investigations for their ability to induce or inhibit NO release, depending on the tissue. In this review, we aim to disclose the scientific evidence relating to the activity of the main dietary polyphenols in the modulation of the intracellular pathways involved in the expression and/or functionality of the NOS isoforms.

Peritraumatic physical symptoms and the clinical trajectory of PTSD after a terrorist attack: a network model approach

Introduction: Following a mass casualty event, such as the Paris terrorist attacks of 13 November 2015, first responders need to identify individuals at risk of PTSD. Physical peritraumatic symptoms involving the autonomic nervous system may be useful in this task.Objective: We sought to determine the trajectory of physical response intensity in individuals exposed to the Paris terrorist attacks using repeated measures, and to examine its associations with PTSD. Using network modelling, we examined whether peritraumatic physical symptom associations differed by PTSD status.Methods: Physical reactions were assessed using the Subjective Physical Reactions Scale at three time points: peritraumatic by retrospective recall, then current at one year (8-18 months) and three years (30-42 months) after the attacks. Interaction networks between peritraumatic physical reactions were compared according to PTSD status.Results: On the one hand, the reported intensity of physical reactions was significantly higher in the PTSD group at all time points. On the other hand, using the dynamic approach, more robust positive interactions between peritraumatic physical reactions were found in the PTSD group one and three years after the attacks. Negative interactions were found in the no-PTSD group at one year. Peritraumatic physical numbness was found to be the most central network symptom in the PTSD group, whereas it was least central in the no-PTSD group.Discussion: Network analysis of the interaction between peritraumatic physical subjective responses, particularly physical numbness, may provide insight into the clinical course of PTSD. Our knowledge of the brain regions involved in dissociation supports the hypothesis that the periaqueductal grey may contribute to the process leading to physical numbing.Conclusions: Our findings highlight the role of peritraumatic somatic symptoms in the course of PTSD. Peritraumatic physical numbness appears to be a key marker of PTSD and its identification may help to improve early triage.

Free radicals: Relationship to Human Diseases and Potential Therapeutic applications

Reactive species are highly-reactive enzymatically, or non-enzymatically produced compounds with important roles in physiological and pathophysiological cellular processes. Although reactive species represent an extensively researched topic in biomedical sciences, many aspects of their roles and functions remain unclear. This review aims to systematically summarize findings regarding the biochemical characteristics of various types of reactive species and specify the localization and mechanisms of their production in cells. In addition, we discuss the specific roles of free radicals in cellular physiology, focusing on the current lines of research that aim to identify the reactive oxygen species-initiated cascades of reactions resulting in adaptive or pathological cellular responses. Finally, we present recent findings regarding the therapeutic modulations of intracellular levels of reactive oxygen species, which may have substantial significance in developing novel agents for treating several diseases.

In silico model of atherosclerosis with individual patient calibration to enable precision medicine for cardiovascular disease

OBJECTIVE

Guidance for preventing myocardial infarction and ischemic stroke by tailoring treatment for individual patients with atherosclerosis is an unmet need. Such development may be possible with computational modeling. Given the multifactorial biology of atherosclerosis, modeling must be based on complete biological networks that capture protein-protein interactions estimated to drive disease progression. Here, we aimed to develop a clinically relevant scale model of atherosclerosis, calibrate it with individual patient data, and use it to simulate optimized pharmacotherapy for individual patients.

APPROACH AND RESULTS

The study used a uniquely constituted plaque proteomic dataset to create a comprehensive systems biology disease model for simulating individualized responses to pharmacotherapy. Plaque tissue was collected from 18 patients with 6735 proteins at two locations per patient. 113 pathways were identified and included in the systems biology model of endothelial cells, vascular smooth muscle cells, macrophages, lymphocytes, and the integrated intima, altogether spanning 4411 proteins, demonstrating a range of 39-96% plaque instability. After calibrating the systems biology models for individual patients, we simulated intensive lipid-lowering, anti-inflammatory, and anti-diabetic drugs. We also simulated a combination therapy. Drug response was evaluated as the degree of change in plaque stability, where an improvement was defined as a reduction of plaque instability. In patients with initially unstable lesions, simulated responses varied from high (20%, on combination therapy) to marginal improvement, whereas patients with initially stable plaques showed generally less improvement.

CONCLUSION

In this pilot study, proteomics-based system biology modeling was shown to simulate drug response based on atherosclerotic plaque instability with a power of 90%, providing a potential strategy for improved personalized management of patients with cardiovascular disease.

Ancient Chinese Herbal Recipe Huanglian Jie Du Decoction for Ischemic Stroke: An Overview of Current Evidence

Ischemic stroke is a major cause of mortality and neurological morbidity worldwide. The underlying pathophysiology of ischemic stroke is highly complicated and correlates with various pathological processes, including neuroinflammation, oxidative stress injury, altered cell apoptosis and autophagy, excitotoxicity, and acidosis. The current treatment for ischemic stroke is limited to thrombolytic therapy such as recombinant tissue plasminogen activator. However, tissue plasminogen activator is limited by a very narrow therapeutic time window (<4.5 hours), selective efficacy, and hemorrhagic complication. Hence, the development of novel therapies to prevent ischemic damage to the brain is urgent. Chinese herbal medicine has a long history in treating stroke and its sequela. In the past decades, extensive studies have focused on the neuroprotective effects of Huanglian Jie Du decoction (HLJDD), an ancient and classical Chinese herbal formula that can treat a wide spectrum of disorders including ischemic stroke. In this review, the current evidence of HLJDD and its bioactive components for ischemic stroke is comprehensively reviewed, and their potential application directions in ischemic stroke management are discussed.

The role of nitric oxide in the dorsomedial periaqueductal gray (dmPAG) column in cardiovascular responses in urethane-anesthetized male rats

BACKGROUND

The dorsomedial periaqueductal gray (dmPAG) is a mesencephalic area and has numerous functions including cardiovascular regulation. Because nitric oxide (NO) is present in the dmPAG, here we investigate, the probable cardiovascular effect of NO in the dmPAG.

METHODS

Five groups (n = 6 for each group) were used as follows: (1) control; (2) L-NAME (N^G -nitro-L-arginine methyl ester, a NO synthase inhibitor, 90 nmol); (3) L-arginine (L-Arg, a precursor for NO, 60 nmol); (4) Sodium nitroprusside (SNP, a NO donor, 27 nmol); and (5) L-Arg + L-NAME. The cardiovascular parameters were recorded by a Power Lab device after cannulation of the femoral artery. Drugs were injected using a stereotaxic instrument. The changes (∆) in systolic blood pressure (SBP), mean arterial pressure (MAP), and heart rate (HR) were calculated at different times and compared to the control group.

RESULTS

Microinjection of L-NAME significantly increased ∆SBP, ∆MAP, and ∆HR more than saline (from p < 0.05 to p < 0.001). L-Arg only significantly increased ∆HR (p < 0.05). In the L-Arg + L-NAME group, the above parameters also significantly increased (from p < 0.01 to p < 0.05) but not as significantly as with L-NAME alone. Microinjection of SNP significantly decreased ∆SBP and ∆MAP more than in the control and L-NAME groups (from p < 0.01 to p < 0.001), but ∆HR did not change significantly.

CONCLUSION

The results indicated that NO in dmPAG has an inhibitory effect on cardiovascular responses in anesthetized rats.

UBIAD1 protects against oxygen-glucose deprivation/reoxygenation injury via nNOS/NO pathway

OBJECTIVES

Cerebral infarction is a subtype of stroke with high incidence and disability rate. Ischemia reperfusion injury (IRI) is the key point of cerebral infarction treatment. UbiA prenyltransferase domain containing 1 (UBIAD1) is a kind of enzyme with various biological functions including electron transport in mitochondrial respiratory chain, lipid metabolism, and oxidative stress which are related to IRI. The purpose of this study aims to determine the neuroprotective effects and the underlying mechanisms of UBIAD1 in cerebral IRI.

METHODS

We employed oxygen-glucose deprivation/reoxygenation (OGD/R) model in mouse neuroblastoma Neuro2a (N2a) cells to mimic cerebral IRI. Lentivirus vector over-expressed UBIAD1 was transfacted into N2a cells to maintain high and stable expression of UBIAD1. In the first part of the experiment, N2a cells were divided into 5 groups: A non-OGD (N2a cells without exposure to OGD) group, groups of reoxygenation 0, 4, 12 and 24 h after 4 h of OGD, respectively. In the second part of the experiment, N2a cells were divided into 6 groups: A Con (normal cell)+non-OGD group, an EV (cell transfected with empty vector)+non-OGD group, an OE (over-expressed UBIAD1)+non-OGD group, a Con+OGD/R group, an EV+OGD/R group, and an OE+OGD/R group. In the third part, the N2a cells were divided into 8 groups: A Con+non-OGD group, an OE+non-OGD group, a Con+non-OGD+nNOS inhibitior 7-nitroindazole (7-NI) group, an OE+non-OGD+7-NI group, a Con+OGD/R group, an OE+OGD/R group, a Con+OGD/R+7-NI group, and an OE+OGD/R+7-NI group. The morphological changes of Golgi apparatus were observed under the confocal laser scanning microscope. The mRNA and protein levels of UBIAD1, secretory pathway Ca2+-ATPase isoform 1 (SPCA1), and NOS were determined by real-time PCR and Western blotting, respectively. Cell apoptosis rate was detected with flow cytometry; cell viability was detected with MTT assay, and NO release was determined with Griess assay.

RESULTS

Compared with the non-OGD group, the expression levels of UBIAD1 mRNA and protein in N2a cells in the groups of 0, 4, 12 and 24 h reoxygenation after OGD 4 h decreased significantly (P<0.05 or P<0.01), and the longer the reoxygenation time, the more significant the reduction of UBIAD1 expression. Compared with the Con+OGD/R group and the EV+OGD/R group, mRNA and protein levels of UBIAD1 and SPCA1 were increased (P<0.05 or P<0.01), the apoptosis rate was decreased (all P<0.01), and the cell viability was increased (all P<0.01) in the OE+OGD/R group. The Golgi fragmentation was less in the OE+OGD/R group than that in the Con+ OGD/R group and the EV+OGD/R group. The mRNA and protein levels of endothelial NOS (eNOS) and neuronal NOS (nNOS) were decreased (P<0.05 or P<0.01), and the level of NO was decreased (all P<0.01) in the groups over-expressed UBIAD1 (OE+non-OGD group vs Con+non-OGD group, OE+OGD/R group vs Con+OGD/R group). The level of NO and apoptosis rate of N2a cells were decreased (all P<0.01) in the the groups pretreated with 7-NI (Con+OGD/R+7-NI group vs Con+OGD/R group, OE+OGD/R+7-NI group vs OE+OGD/R group).

CONCLUSIONS

UBIAD1 may exerts protective effects on OGD/R induced N2a cells by ameliorating Golgi apparatus dysfunction via the nNOS/NO pathway.

Biofunctional roles of estrogen in coronavirus disease 2019: Beyond a steroid hormone

The coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), epidemic poses a major global public health threat with more than one million daily new infections and hundreds of deaths. To combat this global pandemic, efficient prevention and management strategies are urgently needed. Together with the main characteristics of COVID-19, impaired coagulation with dysfunctions of the immune response in COVID-19 pathophysiology causes high mortality and morbidity. From recent clinical observations, increased expression of specific types of estrogen appears to protect patients from SARS-CoV-2 infection, thereby, reducing mortality. COVID-19 severity is less common in women than in men, particularly in menopausal women. Furthermore, estrogen levels are negatively correlated with COVID-19 severity and mortality. These findings suggest that estrogen plays a protective role in the pathophysiology of COVID-19. In this review, we discuss the potential roles of estrogen in blocking the SARS-CoV-2 from invading alveolar cells and replicating, and summarize the potential mechanisms of anti-inflammation, immune modulation, reactive oxygen species resistance, anti-thrombosis, vascular dilation, and vascular endothelium protection. Finally, the potential therapeutic effects of estrogen against COVID-19 are reviewed. This review provides insights into the role of estrogen and its use as a potential strategy to reduce the mortality associated with COVID-19, and possibly other viral infections and discusses the possible challenges and pertinent questions.

Disparate Roles of Oxidative Stress in Rostral Ventrolateral Medulla in Age-Dependent Susceptibility to Hypertension Induced by Systemic l-NAME Treatment in Rats

This study aims to investigate whether tissue oxidative stress in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons reside, plays an active role in age-dependent susceptibility to hypertension in response to nitric oxide (NO) deficiency induced by systemic l-NAME treatment, and to decipher the underlying molecular mechanisms. Systolic blood pressure (SBP) and heart rate (HR) in conscious rats were recorded, along with measurements of plasma and RVLM level of NO and reactive oxygen species (ROS), and expression of mRNA and protein involved in ROS production and clearance, in both young and adult rats subjected to intraperitoneal (i.p.) infusion of l-NAME. Pharmacological treatments were administered by oral gavage or intracisternal infusion. Gene silencing of target mRNA was made by bilateral microinjection into RVLM of lentivirus that encodes a short hairpin RNA (shRNA) to knock down gene expression of NADPH oxidase activator 1 (Noxa1). We found that i.p. infusion of l-NAME resulted in increases in SBP, sympathetic neurogenic vasomotor activity, and plasma norepinephrine levels in an age-dependent manner. Systemic l-NAME also evoked oxidative stress in RVLM of adult, but not young rats, accompanied by augmented enzyme activity of NADPH oxidase and reduced mitochondrial electron transport enzyme activities. Treatment with L-arginine via oral gavage or infusion into the cistern magna (i.c.), but not i.c. tempol or mitoQ₁₀, significantly offset the l-NAME-induced hypertension in young rats. On the other hand, all treatments appreciably reduced l-NAME-induced hypertension in adult rats. The mRNA microarray analysis revealed that four genes involved in ROS production and clearance were differentially expressed in RVLM in an age-related manner. Of them, Noxa1, and GPx2 were upregulated and Duox2 and Ucp3 were downregulated. Systemic l-NAME treatment caused greater upregulation of Noxa1, but not Ucp3, mRNA expression in RVLM of adult rats. Gene silencing of Noxa1 in RVLM effectively alleviated oxidative stress and protected adult rats against l-NAME-induced hypertension. These data together suggest that hypertension induced by systemic l-NAME treatment in young rats is mediated primarily by NO deficiency that occurs both in vascular smooth muscle cells and RVLM. On the other hand, enhanced augmentation of oxidative stress in RVLM may contribute to the heightened susceptibility of adult rats to hypertension induced by systemic l-NAME treatment.

Biological Sensing of Nitric Oxide in Macrophages and Atherosclerosis Using a Ruthenium-Based Sensor

Macrophage-derived nitric oxide (NO) plays a critical role in atherosclerosis and presents as a potential biomarker. We assessed the uptake, distribution, and NO detection capacity of an irreversible, ruthenium-based, fluorescent NO sensor (Ru-NO) in macrophages, plasma, and atherosclerotic plaques. In vitro, incubation of Ru-NO with human THP1 monocytes and THP1-PMA macrophages caused robust uptake, detected by Ru-NO fluorescence using mass-cytometry, confocal microscopy, and flow cytometry. THP1-PMA macrophages had higher Ru-NO uptake (+13%, p < 0.05) than THP1 monocytes with increased Ru-NO fluorescence following lipopolysaccharide stimulation (+14%, p < 0.05). In mice, intraperitoneal infusion of Ru-NO found Ru-NO uptake was greater in peritoneal CD11b+F4/80+ macrophages (+61%, p < 0.01) than CD11b+F4/80− monocytes. Infusion of Ru-NO into Apoe−/− mice fed high-cholesterol diet (HCD) revealed Ru-NO fluorescence co-localised with atherosclerotic plaque macrophages. When Ru-NO was added ex vivo to aortic cell suspensions from Apoe−/− mice, macrophage-specific uptake of Ru-NO was demonstrated. Ru-NO was added ex vivo to tail-vein blood samples collected monthly from Apoe−/− mice on HCD or chow. The plasma Ru-NO fluorescence signal was higher in HCD than chow-fed mice after 12 weeks (37.9%, p < 0.05). Finally, Ru-NO was added to plasma from patients (N = 50) following clinically-indicated angiograms. There was lower Ru-NO fluorescence from plasma from patients with myocardial infarction (−30.7%, p < 0.01) than those with stable coronary atherosclerosis. In conclusion, Ru-NO is internalised by macrophages in vitro, ex vivo, and in vivo, can be detected in atherosclerotic plaques, and generates measurable changes in fluorescence in murine and human plasma. Ru-NO displays promising utility as a sensor of atherosclerosis.

Endothelial Dysfunction in Heart Failure With Preserved Ejection Fraction: What are the Experimental Proofs?

Heart failure with preserved ejection fraction (HFpEF) has been recognized as the greatest single unmet need in cardiovascular medicine. Indeed, the morbi-mortality of HFpEF is high and as the population ages and the comorbidities increase, so considerably does the prevalence of HFpEF. However, HFpEF pathophysiology is still poorly understood and therapeutic targets are missing. An unifying, but untested, theory of the pathophysiology of HFpEF, proposed in 2013, suggests that cardiovascular risk factors lead to a systemic inflammation, which triggers endothelial cells (EC) and coronary microvascular dysfunction. This cardiac small vessel disease is proposed to be responsible for cardiac wall stiffening and diastolic dysfunction. This paradigm is based on the fact that microvascular dysfunction is highly prevalent in HFpEF patients. More specifically, HFpEF patients have been shown to have decreased cardiac microvascular density, systemic endothelial dysfunction and a lower mean coronary flow reserve. Importantly, impaired coronary microvascular function has been associated with the severity of HF. This review discusses evidence supporting the causal role of endothelial dysfunction in the pathophysiology of HFpEF in human and experimental models.

Lipopolysaccharide-induced inflammation increases nitric oxide production in taste buds

Inducible nitric oxide synthase (iNOS) is expressed when cells are induced or stimulated by proinflammatory cytokines and/or bacterial lipopolysaccharide (LPS). iNOS is a downstream gene of the NF-κB pathway. Our previous studies demonstrated that five Nfkb genes are expressed in mouse taste epithelium and taste organoids. However, it is unclear whether activation of the NF-κB pathway could induce iNOS gene expression and increase nitric oxide (NO) production in taste buds. In this study, we investigated the expression of iNOS mRNA and protein after LPS stimulation. Our results showed that a subset of taste bud cells and taste neurons express iNOS proteins after LPS stimulation. In addition, isolated mouse taste epithelium can release NO after exposure to LPS ex vivo. In taste behavioral tests, the NO donor nitroprusside enhanced mouse aversive responses to salty, bitter, and sour taste compounds. The enhanced aversive responses were especially strong for salty taste. In conclusion, our results suggest that iNOS and NO may play a role in the inflammation-associated taste disturbances.

The Differences of Metabolites in Different Parts of the Brain Induced by Shuxuetong Injection against Cerebral Ischemia-Reperfusion and Its Corresponding Mechanism

Ischemic stroke is often associated with a large disease burden. The existence of ischemia-reperfusion injury brings great challenges to the treatment of ischemic stroke. The purpose of this study was to explore the differences of metabolites in different parts of the brain induced by Shuxuetong injection against cerebral ischemia-reperfusion and to extend the corresponding mechanism. The rats were modeled by transient middle cerebral artery occlusion (t-MCAO) operation, and the success of modeling was determined by neurological function score and TTC staining. UPLC-Q/TOF-MS metabolomics technique and multivariate statistical analysis were used to analyze the changes and differences of metabolites in the cortex and hippocampus of cerebral ischemia-reperfusion rats. Compared with the model group, the neurological function score and cerebral infarction volume of the Shuxuetong treatment group were significantly different. There were differences and changes in the metabolic distribution of the cortex and hippocampus in each group, the distribution within the group was relatively concentrated. The separation trend between the groups was obvious, and the distribution of the Shuxuetong treatment group was similar to that of the sham operation group. We identified 13 metabolites that were differentially expressed in the cortex, including glutamine, dihydroorotic acid, and glyceric acid. We also found five differentially expressed metabolites in the hippocampus, including glutamic acid and fumaric acid. The common metabolic pathways of Shuxuetong on the cortex and hippocampus were D-glutamine and D-glutamate metabolism and nitrogen metabolism, which showed inhibition of cortical glutamine and promotion of hippocampal glutamic acid. Specific pathways of Shuxuetong enriched in the cortex included glyoxylate and dicarboxylate metabolism and pyrimidine metabolism, which showed inhibition of glyceric acid and dihydroorotic acid. Specific pathways of Shuxuetong enriched in the hippocampus include arginine biosynthesis and citrate cycle (TCA cycle), which promotes fumaric acid. Shuxuetong injection can restore and adjust the metabolic disorder of the cortex and hippocampus in cerebral ischemia-reperfusion rats. The expression of Shuxuetong in different parts of the brain is different and correlated.

Animal models of hypertension: The status of nitric oxide and oxidative stress and the role of the renal medulla

Hypertension significantly contributes to overall morbidity and mortality worldwide, and animal models of hypertension provide important tools to verify the physiological and molecular mechanisms underlying the development of the disease. A review of the most important models available would provide an insight into the appropriate targets to be addressed in the treatment of different forms of human hypertension. In the animal models discussed a special attention is given to the status and pathophysiological role of nitric oxide and its interaction with reactive oxygen species and oxidative stress. Another focus of the review are the processes running in the renal medulla which are still insufficiently explored. Deficient nitric oxide synthesis and its reduced bioavailability are important determinants of hypertension since NO is recognized as a major control factor of vascular tone homeostasis. For decades perfusion of the renal medulla has also been regarded as one of the blood pressure control factors and, noteworthily, the renal medulla belongs to the tissues with the highest NO content. The list of most often applied animal hypertension models reviewed here includes variants of salt-induced hypertension, the models with genetic background: such as spontaneously hypertensive rats (SHR) and Dahl salt sensitive (SS/SR) rats, Goldblatt 2K-1C hypertensive rats, and also the pharmacologically-plus-dietary salt-induced model known as DOCA-salt hypertension.

Interactions among Endothelial Nitric Oxide Synthase, Cardiovascular System, and Nociception during Physiological and Pathophysiological States

Nitric oxide synthase (NOS) plays important roles within the cardiovascular system in physiological states as well as in pathophysiologic and specific cardiovascular (CV) disease states, such as hypertension (HTN), arteriosclerosis, and cerebrovascular accidents. This review discusses the roles of the endothelial NOS (eNOS) and its effect on cardiovascular responses that are induced by nociceptive stimuli. The roles of eNOS enzyme in modulating CV functions while experiencing pain will be discussed. Nociception, otherwise known as the subjective experience of pain through sensory receptors, termed “nociceptors”, can be stimulated by various external or internal stimuli. In turn, events of various cascade pathways implicating eNOS contribute to a plethora of pathophysiological responses to the noxious pain stimuli. Nociception pathways involve various regions of the brain and spinal cord, including the dorsolateral periaqueductal gray matter (PAG), rostral ventrolateral medulla (RVLM), caudal ventrolateral medulla, and intermediolateral column of the spinal cord. These pathways can interrelate in nociceptive responses to pain stimuli. The alterations in CV responses that affect GABAergic and glutamatergic pathways will be discussed in relation to mechanical and thermal (heat and cold) stimuli. Overall, this paper will discuss the aggregate recent and past data regarding pain pathways and the CV system.

Olfactory dysfunction and potential mechanisms caused by volatile organophosphate dichlorvos in the silkworm as a model animal

Volatile pesticides impair olfactory function in workers/farmers and insects, but data on molecular responses and mechanisms are poorly understood. This study aims to reveal the mechanisms of olfactory dysfunction in the silkworm after exposure to volatile dichlorvos. Our results demonstrated that acute exposure for 12 h significantly reduced electroantennogram responses, and over 62.50% of the treated male moths cannot locate the pheromone source. Transcriptional and proteomic responses of the antennae and heads were investigated. A total of 101 differentially expressed genes (DEGs) in the antennae, 138 DEGs in the heads, and 43 differentially expressed proteins (DEPs) in the heads including antennae were revealed. We discovered that upregulations of Arrestin1 and nitric oxide synthase1 (NOS1) may inhibit cyclic nucleotide-gated channels and hinder calcium influx in the antennae. In the central nervous systems (CNS), downregulations of tyrosine hydroxylase (TH) and tyrosine decarboxylase (TDC) may inhibit olfactory signal transduction by reducing the second messenger biosynthesis. Meanwhile, an abnormal increase of brain cell apoptosis was revealed by Annexin V-mCherry staining, often leading to persistent neurologic impairment. Taken together, this study highlighted olfactory dysfunction caused by dichlorvos, which may provide a novel perspective for understanding the toxicity mechanism of volatile pesticides in other organisms.

Anti-Inflammatory Activity and Mechanism of Cryptochlorogenic Acid from Ageratina adenophora

Ageratina adenophora is an invasive plant known for its toxicity to livestock. Current research on this plant has shifted from toxicity prevention to the beneficial utilization of plant resources. This study was performed to investigate the effects and mechanisms of cryptochlorogenic acid (CCGA) isolated from Ageratina adenophora on the inflammatory responses induced by lipopolysaccharide (LPS) in RAW264.7 cells. RAW264.7 cells were pretreated with CCGA (200, 100, and 50 μg/mL) and subsequently stimulated with LPS (1 μg/mL) for 16 h. The cytotoxicity of CCGA was tested using the Cell Counting Kit (CCK8). The mechanism of action of CCGA in attenuating inflammation was also identified using enzyme-linked immunosorbent assay (ELISA), quantitative reverse transcription-polymerase chain reaction, and Western blot. The results showed that CCGA had a maximal safe concentration of 200 mg/mL. Moreover, CCGA reduced the level of nitric oxide (NO) and iNOS in LPS-induced RAW264.7 cells (p < 0.01). In addition, CCGA reduced the levels of pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IL-8) and cyclooxygenase-2 (COX-2) in LPS-induced RAW264.7 cells at both the mRNA and protein levels (p < 0.01). CCGA prevented the activation of nuclear factor-kappa B (NF-kB) in LPS-induced RAW264.7 cells via the inhibition of IKK and IκB phosphorylation and the degradation of IκB proteins (p < 0.01). This finding indicated that CCGA isolated from A. adenophora may be a potential candidate for the treatment of inflammation-related diseases.

Endothelial Nitric Oxide Synthase (eNOS) and the Cardiovascular System: in Physiology and in Disease States

Endothelial nitric oxide synthase (eNOS) plays a critical role in regulating and maintaining a healthy cardiovascular system. The importance of eNOS can be emphasized from the genetic polymorphisms of the eNOS gene, uncoupling of eNOS dimerization, and its numerous signaling regulations. The activity of eNOS on the cardiac myocytes, vasculature, and the central nervous system are discussed. The effects of eNOS on the sympathetic autonomic nervous system (SANS) and the parasympathetic autonomic nervous system (PANS), both of which profoundly influence the cardiovascular system, will be elaborated. The relationship between the eNOS protein with cardiovascular autonomic reflexes such as the baroreflex and the Exercise Pressor Reflex will be discussed. For example, the effects of endogenous nitric oxide (NO) are shown to be mediated by the eNOS protein and that eNOS-derived endothelial NO is most effective in regulating blood pressure oscillations via modulating the baroreflex mechanisms. The protective action of eNOS on the CVS is emphasized here because dysfunction of the eNOS enzyme is intricately correlated with the pathogenesis of several cardiovascular diseases such as hypertension, arteriosclerosis, myocardial infarction, and stroke. Overall, our current understanding of the eNOS protein with a focus on its role in the modulation, regulation, and control of the cardiovascular system in a normal physiological state and in cardiovascular diseases are discussed.

Intrauterine L-NAME Exposure Weakens the Development of Sympathetic Innervation and Induces the Remodeling of Arterial Vessels in Two-Week-Old Rats

Nitric oxide (NO) has been shown to stimulate differentiation and increase the survival of ganglionic sympathetic neurons. The proportion of neuronal NOS-immunoreactive sympathetic preganglionic neurons is particularly high in newborn rats and decreases with maturation. However, the role of NO in the development of vascular sympathetic innervation has never been studied before. We tested the hypothesis that intrauterine NO deficiency weakened the development of vascular sympathetic innervation and thereby changed the contractility of peripheral arteries and blood pressure level in two-week-old offspring. Pregnant rats consumed NOS inhibitor L-NAME (250 mg/L in drinking water) from gestational day 10 until delivery. Pups in the L-NAME group had a reduced body weight and blood level of NO metabolites at 1–2 postnatal days. Saphenous arteries from two-week-old L-NAME offspring demonstrated a lower density of sympathetic innervation, a smaller inner diameter, reduced maximal active force and decreased α-actin/β-actin mRNA expression ratio compared to the controls. Importantly, pups in the L-NAME group exhibited decreased blood pressure levels before, but not after, ganglionic blockade with chlorisondamine. In conclusion, intrauterine L-NAME exposure is followed by the impaired development of the sympathetic nervous system in early postnatal life, which is accompanied by the structural and functional remodeling of arterial blood vessels.

N-Methyl-D-aspartate Glutamate Receptor Modulates Cardiovascular and Neuroendocrine Responses Evoked by Hemorrhagic Shock in Rats

Here, we report the participation of N-methyl-D-aspartate (NMDA) glutamate receptor in the mediation of cardiovascular and circulating vasopressin responses evoked by a hemorrhagic stimulus. In addition, once NMDA receptor activation is a prominent mechanism involved in nitric oxide (NO) synthesis in the brain, we investigated whether control of hemorrhagic shock by NMDA glutamate receptor was followed by changes in NO synthesis in brain supramedullary structures involved in cardiovascular and neuroendocrine control. Thus, we observed that intraperitoneal administration of the selective NMDA glutamate receptor antagonist dizocilpine maleate (MK801, 0.3 mg/kg) delayed and reduced the magnitude of hemorrhage-induced hypotension. Besides, hemorrhage induced a tachycardia response in the posthemorrhage period (i.e., recovery period) in control animals, and systemic treatment with MK801 caused a bradycardia response during hemorrhagic shock. Hemorrhagic stimulus increased plasma vasopressin levels during the recovery period and NMDA receptor antagonism increased concentration of this hormone during both the hemorrhage and postbleeding periods in relation to control animals. Moreover, hemorrhagic shock caused a decrease in NOx levels in the paraventricular nucleus of the hypothalamus (PVN), amygdala, bed nucleus of the stria terminalis (BNST), and ventral periaqueductal gray matter (vPAG). Nevertheless, treatment with MK801 did not affect these effects. Taken together, these results indicate that the NMDA glutamate receptor is involved in the hemorrhagic shock by inhibiting circulating vasopressin release. Our data also suggest a role of the NMDA receptor in tachycardia, but not in the decreased NO synthesis in the brain evoked by hemorrhage.

Acupuncture Attenuates Blood Pressure via Inducing the Expression of nNOS

Background

Sympathetic activation leads to elevated blood pressure. Neuronal nitric oxide synthase (nNOS) inhibits sympathetic nervous system activity, thereby decreasing blood pressure (BP). nNOS is highly expressed in the arcuate nucleus (ARC) and ventrolateral periaqueductal gray (vlPAG), which play essential roles in the regulation of the cardiovascular and sympathetic nervous systems.

Objective

This study was designed to verify the hypothesis that acupuncture exerts an antihypertensive effect via increasing the expression of nNOS in ARC and vlPAG of spontaneously hypertensive (SHR) rats.

Methods

Rats without anesthesia were subject to daily acupuncture for 2 weeks. BP was monitored by the tail-cuff method. nNOS expressions in the ARC and vlPAG were detected by western blot and immunofluorescence. BP was measured after 7-Nitroindazole (7-NI), a specific nNOS inhibitor, was microinjected into ARC or vlPAG in SHR rats treated with acupuncture.

Results

Acupuncture for 14 days significantly attenuated BP, and the Taichong (LR3) acupoint was superior to Zusanli (ST36) and Fengchi (GB20) in lowering BP. In addition, acupuncture at Taichong (LR3) induced an increase of nNOS expression in ARC and vlPAG, whereas microinjection of 7-NI into ARC or vlPAG reversed the antihypertensive effect of acupuncture.

Conclusions

This study indicates that acupuncture at Taichong (LR3) induces a better antihypertensive effect than at Zusanli (ST36) or at Fengchi (GB20) in SHR rats, and enhancement of nNOS in ARC and vlPAG probably contributes to the antihypertensive effect of acupuncture.

Protective Effects of Estrogen on Cardiovascular Disease Mediated by Oxidative Stress

Perimenopause is an important stage of female senescence. Epidemiological investigation has shown that the incidence of cardiovascular disease in premenopausal women is lower than that in men, and the incidence of cardiovascular disease in postmenopausal women is significantly higher than that in men. This phenomenon reveals that estrogen has a definite protective effect on the cardiovascular system. In the cardiovascular system, oxidative stress is considered important in the pathogenesis of atherosclerosis, myocardial dysfunction, cardiac hypertrophy, heart failure, and myocardial ischemia. From the perspective of oxidative stress, estrogen plays a regulatory role in the cardiovascular system through the estrogen receptor, providing strategies for the treatment of menopausal women with cardiovascular diseases.

The Roles of Nitric Oxide Synthase/Nitric Oxide Pathway in the Pathology of Vascular Dementia and Related Therapeutic Approaches

Vascular dementia (VaD) is the second most common form of dementia worldwide. It is caused by cerebrovascular disease, and patients often show severe impairments of advanced cognitive abilities. Nitric oxide synthase (NOS) and nitric oxide (NO) play vital roles in the pathogenesis of VaD. The functions of NO are determined by its concentration and bioavailability, which are regulated by NOS activity. The activities of different NOS subtypes in the brain are partitioned. Pathologically, endothelial NOS is inactivated, which causes insufficient NO production and aggravates oxidative stress before inducing cerebrovascular endothelial dysfunction, while neuronal NOS is overactive and can produce excessive NO to cause neurotoxicity. Meanwhile, inflammation stimulates the massive expression of inducible NOS, which also produces excessive NO and then induces neuroinflammation. The vicious circle of these kinds of damage having impacts on each other finally leads to VaD. This review summarizes the roles of the NOS/NO pathway in the pathology of VaD and also proposes some potential therapeutic methods that target this pathway in the hope of inspiring novel ideas for VaD therapeutic approaches.

Nitric oxide synthase (NOS) inhibitor L-NAME activates inducible NOS/NO system and drives multidimensional regulation of Na+ /K+ -ATPase in ionocyte epithelia of immersion-stressed air-breathing fish (Anabas testudineus Bloch)

Nitric oxide (NO) has been implicated in Na⁺  homeostatic control in water-breathing fishes. It is, however, uncertain whether air-breathing fish relies on NO to coordinate Na⁺ /K⁺ -ATPase (NKA)-driven Na⁺  transport during acute hypoxemia. We, thus, examined the action of nitric oxide synthase (NOS) inhibitor, L-NAME on NO availability, inducible NOS (iNOS) protein abundance and the regulatory dynamics of NKA in osmoregulatory epithelia of Anabas testudineus kept at induced hypoxemia. As expected in nonstressed fish, in vivo L-NAME (100 ng g^-1 ) challenge for 30 min declined NO production in serum (40%) and osmoregulatory tissues (average 51.6%). Surprisingly, the magnitude of such reduction was less in hypoxemic fish after L-NAME challenge due to the net gain of NO (average 23.7%) in these tissues. Concurrently, higher iNOS protein abundance was found in branchial and intestinal epithelia of these hypoxemic fish. In nonstressed fish, L-NAME treatment inhibited the NKA activity in branchial and intestinal epithelia while stimulating its activity in renal epithelia. Interestingly in hypoxemic fish, L-NAME challenge restored the hypoxemia-inhibited NKA activity in branchial and renal epithelia. Similar recovery response was evident in the NKAα protein abundance in immunoblots and immunofluorescence images of branchial epithelia of these fish. Analysis of Nkaα1 isoform transcript abundance (Nkaα1a, α1b, α1c) also showed spatial and preferential regulation of Nkaα1 isoform switching. Collectively, the data indicate that L-NAME challenge activates iNOS/NO system in the branchial ionocyte epithelia of hypoxemia-stressed Anabas and demands multidimensional regulation of NKA to restore the Na⁺  transport rate probably to defend against acute hypoxemia.