Nitric Oxide Signaling Pathway Research Articles

Roles of eNOS in atherosclerosis treatment.

Atherosclerosis (AS) is the main pathogeny of coronary heart disease, cerebral infarction and peripheral vascular disease. Endothelial dysfunction is one of the important pathogenesis of AS. As an important endothelium-derived relaxation factor, nitric oxide (NO) plays a role in cardiovascular protection and anti-AS function; but in the pathological state, endothelial nitric oxide synthase (eNOS) disorder causes an abnormal production of NO, which may damage endothelial function and trigger AS. This review summarized the research progresses in the treatment strategies for AS based on correcting the disordered eNOS/ NO signaling pathway. According to the topic, select the search terms 'atherosclerosis,' 'nitric oxide,' 'eNOS,' 'treatment,' 'management,' 'medication,' 'maintenance,' 'remission'. Using these terms, a structured literature search via multiple electronic databases was performed for the most recent trial evidence in recent years. We read and analyze these literatures carefully, classified these literatures according to their content, and then summarized and outlined the common main points in these classified literatures. Finally, literature data were organized to discuss these main points logically. We found that both aberrant expression and dysfunction of eNOS are closely related to AS development, and some new treatment strategies aimed at eNOS have been proposed, including upregulation of eNOS expression and inhibition of eNOS uncoupling. The former one is mainly related to inflammatory inhibition and protection of the PKB-eNOS signaling pathway; whereas the latter one is associated with the addition of the L-arginine substrate of eNOS, arginase inhibition, and the supplement of tetrahydrobiopterin, which can elevate no level. eNOS can be an important target for prevention and treatment of AS, and eNOS drugs may be another potent class of effective therapeutic treatment for AS following traditional lipid-lowering, anti-platelet, vasodilator drugs. But applying these experimental results to clinic treatment still requires further studies and development of biotechnology.

Abstract P151: Plasma Cyclic Guanosine Monophosphate (cGMP) and Heart Failure With Preserved Ejection Fraction: The Atherosclerosis Risk in Communities (ARIC) Study

Introduction: Cyclic guanosine monophosphate (cGMP) is an intracellular second messenger, synthesized through nitric oxide (NO) and natriuretic peptide (NP) pathways, with two different downstream effects on the cardiovascular system. Stimulators of cGMP are potential candidates in treating heart failure with preserved ejection fraction (HFpEF). However, the associations between plasma cGMP, HFpEF, and atherosclerotic cardiovascular disease (ASCVD) in the general population are unknown. We hypothesized that cGMP mediates HFpEF and ASCVD events, and that associations differ by sex. Methods: We included 1,034 ARIC participants selected by case-cohort design with over-sampling of participants with incident HFpEF. cGMP was measured using visit 4 plasma samples. Cox proportional hazard regression models were used to assess the relationship of cGMP with incident HFpEF, coronary heart disease (CHD), and ASCVD (CHD + stroke). Models were adjusted for sampling weights to provide estimates applicable to the overall ARIC population. Covariates included demographics and CVD risk factors. Models also adjusted for NT-proBNP, which is upstream of cGMP production in the NP regulated pathway. Results: Mean (SD) age was 63.2 (5.6) years and median (IQR) cGMP was 3.4 pmol/mL (2.4, 4.6). During 16.7 years of follow-up, there were 272 HFpEF, 179 ASCVD, and 129 CHD incident events. In models adjusted for CVD risk factors, the HRs (95% CI) comparing 3 rd tertile with 1 st tertile of cGMP for ASCVD, CHD and HF were 1.8 (1.1, 2.9), 1.9 (1.2, 3.0) and 2.0 (1.2, 3.3), respectively. In models further adjusted for NT-proBNP, associations were attenuated and not significant [HRs 1.2 (0.7, 2.0), 1.5 (0.96, 2.5) and 1.7 (0.98, 2.9), respectively]. There were no significant interactions by sex. Conclusions: cGMP levels are associated incident HFpEF, ASCVD, and CHD; however, after NT-proBNP adjustment, associations were attenuated, suggesting that plasma cGMP levels reflect a greater effect as a downstream messenger in NP than NO signaling pathways.

Chronic hypoxia changes gene expression profile of primary rat carotid body cells: consequences on the expression of NOS isoforms and ET-1 receptors.

Sustained chronic hypoxia (CH) produces morphological and functional changes in the carotid body (CB). Nitric oxide (NO) and endothelin-1 (ET-1) play a major role as modulators of the CB oxygen chemosensory process. To characterize the effects of CH related to normoxia (Nx) on gene expression, particularly on ET-1 and NO pathways, primary cultures of rat CB cells were exposed to 7 days of CH. Total RNA was extracted, and cDNA-32P was synthesized and hybridized with 1,185 genes printed on a nylon membrane Atlas cDNA Expression Array. Out of 324 differentially expressed genes, 184 genes were upregulated, while 140 genes were downregulated. The cluster annotation and protein network analyses showed that both NO and ET-1 signaling pathways were significantly enriched and key elements of each pathway were differentially expressed. Thus, we assessed the effect of CH at the protein level of nitric oxide synthase (NOS) isoforms and ET-1 receptors. CH induced an increase in the expression of endothelial NOS, inducible NOS, and ETB. During CH, the administration of SNAP, a NO donor, upregulated ETB. Treatment with Tezosentan (ET-1 receptor blocker) during CH upregulated all three NOS isoforms, while the NOS blocker L-NAME induced upregulation of iNOS and ETB and downregulated the protein levels of ETA. These results show that CH for 7 days changed the cultured cell CB gene expression profile, the NO and ET-1 signaling pathways were highly enriched, and these two signaling pathways interfered with the protein expression of each other.

Chronic Ethanol Consumption Impairs the Tactile-Evoked Long-Term Depression at Cerebellar Molecular Layer Interneuron-Purkinje Cell Synapses in vivo in Mice

The cerebellum is sensitive to ethanol (EtOH) consumption. Chronic EtOH consumption impairs motor learning by modulating the cerebellar circuitry synaptic transmission and long-term plasticity. Under in vitro conditions, acute EtOH inhibits both parallel fiber (PF) and climbing fiber (CF) long-term depression (LTD). However, thus far it has not been investigated how chronic EtOH consumption affects sensory stimulation-evoked LTD at the molecular layer interneurons (MLIs) to the Purkinje cell (PC) synapses (MLI-PC LTD) in the cerebellar cortex of living animals. In this study, we investigated the effect of chronic EtOH consumption on facial stimulation-evoked MLI-PC LTD, using an electrophysiological technique as well as pharmacological methods, in urethane-anesthetized mice. Our results showed that facial stimulation induced MLI–PC LTD in the control mice, but it could not be induced in mice with chronic EtOH consumption (0.8 g/kg; 28 days). Blocking the cannabinoid type 1 (CB1) receptor activity with AM-251, prevented MLI-PC LTD in the control mice, but revealed a nitric oxide (NO)-dependent long-term potentiation (LTP) of MLI–PC synaptic transmission (MLI-PC LTP) in the EtOH consumption mice. Notably, with the application of a NO donor, S-nitroso-N-Acetyl-D, L-penicillamine (SNAP) alone prevented the induction of MLI–PC LTD, but a mixture of SNAP and AM-251 revealed an MLI-PC LTP in control mice. In contrast, inhibiting NO synthase (NOS) revealed the facial stimulation-induced MLI-PC LTD in EtOH consumption mice. These results indicate that long-term EtOH consumption can impair the sensory stimulation-induced MLI–PC LTD via the activation of a NO signaling pathway in the cerebellar cortex in vivo in mice. Our results suggest that the chronic EtOH exposure causes a deficit in the cerebellar motor learning function and may be involved in the impaired MLI–PC GABAergic synaptic plasticity.

The protein S-nitrosylation of splicing and translational machinery in vascular endothelial cells is susceptible to oxidative stress induced by oxidized low-density lipoprotein

Oxidized low-density lipoprotein (ox-LDL) can impair endothelial function and lead to the atherosclerosis development. Protein S-nitrosylation is sensitive to cellular redox state and acts as a crucial regulator and executor of nitric oxide (NO) signaling pathways. Aberrant S-nitrosylation contributes to the pathogenesis of cardiovascular and cerebrovascular diseases. However, the effect of ox-LDL on S-nitrosylation and its significance for endothelial dysfunction have not been studied at proteome level. Herein, the combined quantitative analysis of proteome and S-nitrosoproteome was performed using an integrated biotin switch and iTRAQ labeling approach in EA.hy926 cell line derived from human umbilical vein endothelial cell (HUVEC) treated with ox-LDL. A total of 2204 S-nitrosylated (SNO) peptides of 1318 SNO-proteins were quantified. Notably, 352 SNO-peptides of 262 SNO-proteins were significantly regulated after excluding S-nitrosylation changes caused by protein expression alterations. Many of them belonged to mRNA splicing, ribosomal structure and translational regulatory proteins, covering the entire translation process. The results indicated that S-nitrosylation of the splicing and translational machinery in vascular endothelial cells was susceptible to ox-LDL. Abnormal protein S-nitrosylation may be one pivotal mechanism underlying endothelial dysfunction induced by ox-LDL. This study potentially enriches the present understanding of pro-atherogenic effect of ox-LDL from the perspective of S-nitrosylation. SignificanceThe role of ox-LDL in endothelial dysfunction and atherosclerosis development has been recognized from the aspect of impaired NO production. However, its effect on S-nitrosylation, which is directly related to NO signaling pathway, still remains largely unexplored. Our work initially provided a systematic characterization of S-nitrosoproteome in ox-LDL-treated endothelial cells after ruling out the changes of S-nitrosylation modification caused by protein expression alone. MS-based approach coupled with iTRAQ technique indicated 262 SNO-proteins were significantly regulated. Functional enrichment and interaction network analysis revealed that proteins involved in mRNA splicing and translational machinery were susceptible to abnormal S-nitrosylation under ox-LDL treatment. This achievement suggested one potential mechanism underlying endothelial dysfunction induced by ox-LDL from the perspective of S-nitrosoproteome.

Application of chitosan on plant responses with special reference to abiotic stress.

Chitosan is a natural biopolymer modified from chitins which act as a potential biostimulant and elicitor in agriculture. It is non-toxic, biodegradable and biocompatible which favors potentially broad application. It enhances the physiological response and mitigates the adverse effect of abiotic stresses through stress transduction pathway via secondary messenger(s). Chitosan treatment stimulates photosynthetic rate, stomatal closure through ABA synthesis; enhances antioxidant enzymes via nitric oxide and hydrogen peroxide signaling pathways, and induces production of organic acids, sugars, amino acids and other metabolites which are required for the osmotic adjustment, stress signaling, and energy metabolism under stresses. It is also known to form complexes with heavy metals and used as tool for phytoremediation and bioremediation of soil. Besides, this is used as antitranspirant compound through foliar application in many plants thus reducing water use and ensures protection from other negative effects. Based on such beneficial properties, chitosan is utilized in sustainable agricultural practices owing to changing climates. Our review gathers the recent information on chitosan centered upon the abiotic stress responses which could be useful in future crop improvement programs.

Ad libidum exercise improves functional sympatholysis in rats with spontaneous hypertension via the nitric oxide signal pathway

Objective To explore the effect of exercise on functional sympatholysis in rats modeling spontaneous hypertension and the role of the nitric oxide signal pathway. Methods Thirty Wistar rats with spontaneous hypertension were randomly divided into a sedentary group and an exercise group, each of 15, while another fifteen healthy rats acted as controls. The exercise group performed eight weeks of voluntary wheel running exercise while the other two groups did not. The rats were instrumented to stimulate the lumbar sympathetic chain (at 1 Hz, 2.5 Hz or 5 Hz) to induce vasoconstriction and the triceps surae muscle group was forced to contract by stimulating the tibial nerve electrically. The change in the femoral artery vascular conductance (FAVC) in response to sympathetic stimulation was recorded at rest and during contraction. The functional sympatholysis was calculated as the percentage difference in FAVC (△%FAVC) in response to sympathetic stimulation during muscular contraction and at rest (△%FAVC=%FAVC during contraction-%FAVC at rest). After administration of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), changes in FAVC were repeatedly determined. Results The average △%FAVC of the sedentary group was significantly lower than that of the control group at all stimulation frequencies, while the average △%FAVC in the exercise group was significantly higher than in the sedentary group. There were no significant differences between the exercise and control groups. After the administration of L-NAME, significant decrease was observed in the average △%FAVCs of the control and exercise groups, but there was no significant change in the sedentary group. Conclusion Voluntary exercise may improve functional sympatholysis in rats with spontaneous hypertension through improving NO-dependent signalling. Key words: Exercise; Hypertension; Functional sympatholysis; Nitric oxide

DDAH2 alleviates myocardial fibrosis in diabetic cardiomyopathy through activation of the DDAH/ADMA/NOS/NO pathway in rats.

Diabetic cardiomyopathy (DCM) is a form of idiopathic heart disease, with signs including hypertrophy of myocardial cells, hypertension-independent fibrosis and coronary artery disease. Considering the involvement of dimethylarginine dimethylaminohydrolase 2 (DDAH2) in diabetes, it was hypothesized that DDAH2 may be beneficial to cardiac function and myocardial fibrosis during the progression of DCM with involvement of the DDAH/asymmetric NG, NGdimethyl-L-arginine (ADMA)/nitric oxide synthase (NOS)/nitric oxide (NO) signaling pathway. Following establishment of diabetic rat models, diabetes-related blood biochemical indices and cardiac function were measured in diabetic rats treated with lentivirus expressing DDAH2, short hairpin RNA against DDAH2, or L-NNA (inhibitor of NOS) to identify the roles of DDAH2 in DCM. The functional roles of DDAH2 in DCM were further determined through detection of the levels of collagen I, matrix metalloproteinase 2 (MMP2) and tissue inhibitor of metalloproteinase 2 (TIMP2). The H9C2 myocardial cell line was selected for in vitro experiments. The effects of DDAH2 on the migration of myocardial cells under high glucose conditions were also examined. To further investigate the underlying regulatory mechanism of DDAH2 in DCM, the contents of ADMA and NO, and the activities of DDAH and NOS were observed. The DCM model rats treated with DDAH2 exhibited reduced left ventricular end-diastolic pressure, and decreased blood glucose, total cholesterol, triglyceride, fasting blood glucose, and fasting insulin levels, but exhibited increased left ventricular systolic pressure and maximum rate of left ventricular pressure rise/fall levels in myocardial tissues. Myocardial cells under high glucose conditions treated with DDAH2 showed reductions in collagen I, MMP2 and TIMP2, indicating that DDAH2 reduced cell migration. Decreased levels of ADMA and NO but increased levels of DDAH and NOS were observed following treatment with DDAH2, indicating that the DDAH/ADMA/NOS/NO pathway was activated. These results reveal that the overexpression of DDAH2 attenuates myocardial fibrosis and protects against DCM through activation of the DDAH/ADMA/NOS/NO pathway in DCM rats. These results indicate that DDAH2 is a potential therapeutic candidate for the treatment of DCM.

Puncta of Neuronal Nitric Oxide Synthase (nNOS) Mediate NMDA Receptor Signaling in the Auditory Midbrain.

Nitric oxide (NO) is a neurotransmitter synthesized in the brain by neuronal nitric oxide synthase (nNOS). Using immunohistochemistry and confocal imaging in the inferior colliculus (IC, auditory midbrain) of the guinea pig (Cavia porcellus, male and female), we show that nNOS occurs in two distinct cellular distributions. We confirm that, in the cortices of the IC, a subset of neurons show cytoplasmic labeling for nNOS, whereas in the central nucleus (ICc), such neurons are not present. However, we demonstrate that all neurons in the ICc do in fact express nNOS in the form of discrete puncta found at the cell membrane. Our multi-labeling studies reveal that nNOS puncta form multiprotein complexes with NMDA receptors, soluble guanylyl cyclase (sGC), and PSD95. These complexes are found apposed to glutamatergic terminals, which is indicative of synaptic function. Interestingly, these glutamatergic terminals express both vesicular glutamate transporters 1 and 2 denoting a specific source of brainstem inputs. With in vivo electrophysiological recordings of multiunit activity in the ICc, we found that local application of NMDA enhances sound-driven activity in a concentration-dependent and reversible fashion. This response is abolished by blockade of nNOS or sGC, indicating that the NMDA effect is mediated solely via the NO and cGMP signaling pathway. This discovery of a ubiquitous, but highly localized, expression of nNOS throughout the ICc and demonstration of the dramatic influence of the NMDA activated NO pathway on sound-driven neuronal activity imply a key role for NO signaling in auditory processing.SIGNIFICANCE STATEMENT We show that neuronal nitric oxide synthase (nNOS), the enzyme that synthesizes nitric oxide (NO), occurs as puncta in apparently all neurons in the central nucleus of the inferior colliculus (ICc) in the auditory midbrain. Punctate nNOS appears at glutamatergic synapses in a complex with glutamate NMDA receptors (NMDA-Rs), soluble guanylyl cyclase (sGC, the NO receptor), and PSD95 (a protein that anchors receptors and enzymes at the postsynaptic density). We show that NMDA-R modulation of sound-driven activity in the ICc is solely mediated by activation of nNOS and sGC. The presence of nNOS throughout this sensory nucleus argues for a major role of NO in hearing. Furthermore, this punctate form of nNOS expression may exist and have gone unnoticed in other brain regions.

Crosstalk Between Nitric Oxide and Endocannabinoid Signaling Pathways in Normal and Pathological Placentation.

Endocannabinoids are a group of endogenous lipid mediators that act as ligands of cannabinoid and vanilloid receptors, activating multiple signal transduction pathways. Together with enzymes responsible for their synthesis and degradation, these compounds constitute the endocannabinoid system (ECS), which is involved in different physiological processes in reproduction. The placenta, which is essential for the success of gestation and optimal fetal growth, undergoes constant tissue remodeling. ECS members are expressed in trophoblast cells, and current evidence suggests that this system is involved in placental development, apoptosis, and syncytialization. Impairment of endocannabinoid signaling has been associated with several pathological conditions such as intrauterine growth restriction and preeclampsia. Both clinical entities are characterized by dysregulation on vascular perfusion where nitrergic system performs a pivotal role. Nitric oxide (NO) is a potent local vasodepressor that exerts a critical role in the regulation of hemodynamic flow, contributing to the maintenance of low vascular resistance in the feto-placental circulation. NO production could be affected by different factors and growing evidence suggests that the endocannabinoid mediators may regulate nitrergic signaling. Herein, we review emerging knowledge supporting ECS-mediated regulation of NO production in normal placentation. Finally, we discuss how alterations in these systems could affect homoeostasis and contribute to the occurrence of placental-mediated pregnancy complications. Given the impact on women and perinatal heath, we will focus on current knowledge regarding the effects of ECS on nitrergic system in normal and pathological placentation.

Dysfunction of Cerebrovascular Endothelial Cells: Prelude to Vascular Dementia.

Vascular dementia (VaD) is the second most common type of dementia after Alzheimer’s disease (AD), characterized by progressive cognitive impairment, memory loss, and thinking or speech problems. VaD is usually caused by cerebrovascular disease, during which, cerebrovascular endothelial cells (CECs) are vulnerable. CEC dysfunction occurs before the onset of VaD and can eventually lead to dysregulation of cerebral blood flow and blood–brain barrier damage, followed by the activation of glia and inflammatory environment in the brain. White matter, neuronal axons, and synapses are compromised in this process, leading to cognitive impairment. The present review summarizes the mechanisms underlying CEC impairment during hypoperfusion and pathological role of CECs in VaD. Through the comprehensive examination and summarization, endothelial nitric oxide synthase (eNOS)/nitric oxide (NO) signaling pathway, Ras homolog gene family member A (RhoA) signaling pathway, and CEC-derived caveolin-1 (CAV-1) are proposed to serve as targets of new drugs for the treatment of VaD.

Phoenixin Expression Is Regulated by the Fatty Acids Palmitate, Docosahexaenoic Acid and Oleate, and the Endocrine Disrupting Chemical Bisphenol A in Immortalized Hypothalamic Neurons

Phoenixin (PNX) is a newly identified reproductive peptide required for the estrous cycle. It is most highly expressed in the hypothalamus, where it is a positive regulator of gonadotropin-releasing hormone (GnRH) and kisspeptin. However, it is unknown what signals lie upstream of Pnx to coordinate its effects on GnRH and kisspeptin. We investigated the effects of the hormones, estrogen and leptin; the fatty acids, palmitate, docosahexaenoic acid (DHA), oleate and palmitoleate; and the endocrine disrupting chemical BPA on Pnx mRNA levels. We also examined whether the signaling pathways of nitric oxide, lipopolysaccharide, cAMP and protein kinase C could alter Pnx expression. Immortalized hypothalamic neurons were treated from 2 to 24 h with these compounds and Pnx mRNA levels were measured with RT-qPCR. Unexpectedly, only BPA as well as the fatty acids, palmitate, DHA and oleate, could alter Pnx expression; therefore suggesting that Pnx may fulfill a nutrient-sensing role in the hypothalamus. Our study is the first to delineate potential regulators of this novel neuropeptide, and our findings provide some insight into the functional role of PNX in the hypothalamus.

Cyclosporin A attenuating morphine tolerance through inhibiting NO/ERK signaling pathway in human glioblastoma cell line: the involvement of calcineurin.

Cyclosporin A (CsA) is known to have an immunosuppressive action. However, it is also attracting attention due to its effects on the nervous system, such as inhibiting the development and expression of morphine-induced tolerance and dependence through unknown mechanisms. It has been shown that CsA modulates the nitric oxide (NO) synthesis and extracellular signal-regulated kinases (ERK) activation, which are potentially involved in signaling pathways in morphine-induced tolerance in cellular models. Therefore, the current study was designed to evaluate the modulatory role of CsA on the MOR tolerance, by targeting the downstream signaling pathway of NO and ERK using an in vitro model. For this purpose, T98G cells were pretreated with CsA, calcineurin autoinhibitory peptide (CAIP), and NG-nitro-l-arginine methyl ester (L-NAME) 30 min before 18 h exposure to MOR. Then, we analyzed the intracellular cyclic adenosine monophosphate (cAMP) levels and also the expression of phosphorylated ERK and nitric oxide synthase (nNOS) proteins. Our results showed that CsA (1 nM, 10 nM, and 100 nM) and CAIP (50 µM) have significantly reduced cAMP and nitrite levels as compared to MOR-treated (2.5 µM) T98G cells. This clearly revealed the attenuation of MOR tolerance by CsA. The expression of nNOS and p-ERK proteins were down-regulated when the T98G cells were pretreated with CsA (1 nM, 10 nM, and 100 nM), CAIP (50 µM), and L-NAME (0.1 mM) as compared to MOR. In conclusion, the CsA pretreatment had a modulatory role in MOR-induced tolerance, which was possibly mediated through NO/ERK signaling pathway.

Pharmacogenetic relevance of endothelial nitric oxide synthase polymorphisms and gene interactions.

Endothelial nitric oxide synthase (NOS3) is a key enzyme responsible for nitric oxide (NO) generation in the vascular endothelium. Endothelial dysfunction is characterized by reduced NO production, and is a hallmark of cardiovascular diseases. Drugs with cardiovascular action may activate NOS3 and result in NO release and vasodilation. Moreover, genetic variations affect NOS3 expression and activity, and may partially explain the variability in the responses to cardiovascular drugs. We reviewed NO signaling and genetic effects on NO formation, and the effects of NOS3 polymorphisms, haplotypes and gene-gene interactions within NO signaling pathways on the responses to cardiovascular drugs. We discuss the role of rare NOS3 variants and further gene-gene interactions analysis for the development of novel therapies for cardiovascular diseases.

Impact of nitrate therapy on the expression of caveolin-1 and its phosphorylated isoform in lungs in the model of monocrotaline induced pulmonary hypertension

Abstract Aim: Nitric oxide signalling pathway showed to be one of the crucial factors in the treatment and pathogenesis of pulmonary arterial hypertension. The aim of this study was to determine the effect of administration of inorganic nitrate, NaNO3, on the expression of caveolin-1 and its phosphorylated isoform (pTyr14Cav-1) in lungs in the experimental model of monocrotaline induced pulmonary hypertension. Methods: 10 weeks old male Wistar rats were subcutaneously injected with 60 mg/kg dose of monocrotaline (MCT) or vehicle (CON). Twelve days after the injection, part of the MCT group was receiving 0.3 mM NaNO3 (MCT+N0.3) daily in the drinking water and rest was receiving 0.08% NaCl solution. Four weeks after MCT administration, the rats were sacrificed in CO2. Protein expression in lungs was determined by western blot. Results: We observed a significant decrease in the caveolin-1 expression and a significant shift towards the expression of pTyr14Cav-1 in the group treated with nitrate (p < 0.05). Conclusion: NaNO3 administration affected the expression of caveolin-1 and the ratio of its active (phosphorylated) isoform increased.

Hydroxyurea therapy modulates sickle cell anemia red blood cell physiology: Impact on RBC deformability, oxidative stress, nitrite levels and nitric oxide synthase signalling pathway

Hydroxyurea (HU) has been suggested to act as a nitric oxide (NO) donor in sickle cell anemia (SCA). However, little is known about the HU NO-related effects on red blood cell (RBC) physiology and NO signalling pathway.Thirty-four patients with SCA (22 under HU treatment (HU+) and 12 without (HU-)) and 17 healthy subjects (AA) were included. RBC nitrite content, deformability and reactive oxygen species (ROS) levels were measured. RBC NO-synthase (RBC-NOS) signalling pathway was assessed by the measurement of RBC-NOS serine1177 and RBC-AKT serine473 phosphorylation. We also investigated the in vitro effects of Sodium Nitroprusside (SNP), a NO donor, on the same parameters in SCA RBC.RBC nitrite content was higher in HU+ than in HU- and AA. RBC deformability was decreased in SCA patients compared to AA but the decrease was more pronounced in HU-. RBC ROS level was increased in SCA compared to AA but the level was higher in HU- than in HU+. RBC-NOS serine1177 and RBC-AKT serine473 phosphorylation were decreased in HU+ compared to HU- and AA. SCA RBC treated with SNP showed increased deformability, reduced ROS content and a decrease in AKT and RBC-NOS phosphorylation.Our study suggests that HU, through its effects on foetal hemoglobin and possibly on NO delivery, would modulate RBC NO signalling pathway, RBC rheology and oxidative stress.

Ablation alleviates atrial fibrillation by regulating the signaling pathways of endothelial nitric oxide synthase/nitric oxide via miR-155-5p and miR-24-3p.

This study aimed to identify the microRNAs implicated in atrial fibrillation (AF) to investigate the molecular mechanisms underlying the role of microRNAs in ablation-based AF treatment. Real-time polymerase chain reaction (PCR)and microRNA microarrays were utilized to measure the profiles of microRNA expression in AF to identify differentially expressed microRNAs. Enzyme-linked immunosorbent assay, real-time PCR, Western blot analysis, and immunohistochemistry assays were also performed to investigate the regulatory relationships among various factors implicated in AF. Finally, bioinformatic tools and luciferase assays were used to confirm the roles of miR-155-5p, miR-24-3p, endothelial nitric oxide synthase (eNOS), and nitric oxide (NO) in the pathogenesis of AF. We demonstrated that the levels of miR-155-5p and miR-24-3p were greatly reduced in postablation AF patients compared with those AF patients not treated by ablation. Furthermore, the NO level in the AF+ group was much lower than that of the AF- group. Finally, in a swine model of AF, evident upregulation of miR-155-5p and miR-24-3p was found in AF pigs, whereas the ablation treatment reduced the levels of miR-155-5p and miR-24-3p in AF pigs. On contrary, as targets of miR-155-5p and miR-24-3p, the levels of eNOS and NO increased when the expression of miR-155-5p and miR-24-3p decreased. MiR-155-5p and miR-24-3p are involved in the pathogenesis of AF via regulating the expression of eNOS and the production of NO. In addition, ablation treatment helps the recovery from AF by reducing the expression of miR-155-5p and miR-24-3p.

NO-sGC-cGMP signaling influence the anxiolytic like effect of lithium in mice in light and dark box and elevated plus maze

Glutamate is an excitatory neurotransmitter implicated in the pathogenesis of psychiatric disorders. Glutamate results in the activation of an enzyme called glycogen synthase kinase-3 (GSK-3) acting through N-methyl-d-aspartate (NMDA) receptors. Impaired expression of GSK-3 affects behavior and neurochemicals level in the brain responsible for the pathogenesis of mood disorders. It has been reported that lithium acts as an inhibitor of GSK-3 and inhibit the enzyme GSK-3 in an uncompetitive manner. In the present study, anxiolytic like effect of lithium in mice is investigated through light and dark box (LDB) and elevated plus maze (EPM). Lithium (50, 100 and 200 mg/kg, i.p.) was administered to the mice to determine the anxiety related behavior. Results obtained suggests that the administration of lithium (100 mg/kg, i.p.) reversed the anxiety related behavior of mice and decreased the levels of glutamate and nitrite as compared to control. Glutamate acting through the NMDA receptor has been found to regulate the expression of enzyme neuronal nitric oxide synthase (nNOS), which is responsible for the release of nitric oxide (NO), suggesting a possible link between NO and GSK-3 also. Therefore, to determine the possible interaction with NO, sub-effective dose of lithium was administered in combination with NO donor i.e. l-Arginine (50 mg/kg, i.p.), NOS and soluble guanylate cyclase (sGC) inhibitor i.e. methylene blue (1 mg/kg, i.p.) and phosphodiesterase inhibitor i.e. sildenafil (1 mg/kg, i.p.). The results obtained demonstrated that the anxiolytic like effect of lithium was abolished by the pretreatment with NO donor and potentiated by the pretreatment with NOS inhibitor. Therefore, it is suggested that NO signaling pathway influence the anxiolytic like activity of lithium in mice, further suggesting the link between the GSK-3 and NO signaling in the regulation of anxiety related behavior.

Nitric oxide functions in stromal cell-derived factor-1-induced cytoskeleton changes and the migration of Jurkat cells.

Stromal cell-derived factor-1 (SDF-1) regulates multiple cell signal pathways in a variety of cellular functions, including cell migration, proliferation, survival and angiogenesis. SDF-1-induced chemotaxis is an important step of lymphocyte migration. However, the molecular mechanisms that modulate SDF-1-mediated lymphocyte migration are not well identified. Nitric oxide (NO) has been found to function as a signaling molecule in a number of signaling pathways, including migration. In the present study, the potential role of NO in SDF-1-induced migration and the association between NO and the cytoskeletal changes of Jurkat cells was investigated. The present study demonstrated that Jurkat cells induced the production of NO by SDF-1 stimulation, using Griess reaction method and western blot analysis, and that NO was involved in SDF-1-induced rearrangement and polymerization of the cytoskeleton, using NOS inhibitor L-NMMA. Furthermore, NO was required for the migration of Jurkat cells. The research suggested that NO signaling pathways exerted a critical role in SDF-1-induced cytoskeleton changes and the migration of Jurkat cells. This work provides insight into the migration mechanism of acute lymphoblastic leukemia and provides an effective theoretical basis for therapy strategies for acute lymphoblastic leukemia.

The protective effects of a novel synthetic β-elemene derivative on human umbilical vein endothelial cells against oxidative stress-induced injury: Involvement of antioxidation and PI3k/Akt/eNOS/NO signaling pathways

Antioxidant therapy is considered as promising strategy for treating oxidative stress-induced cardiovascular disease. Bis (β-elemene-13-yl) glutarate (BEG) is a novel β-elemene derivative. Herein, we examined the antioxidant activity of BEG on human umbilical vein endothelial cells (HUVECs) after injury with hydrogen peroxide (H2O2) and investigated the mechanism involved. HUVECs were divided into the following groups: control group (untreated cells); treated groups (cells treated with 0.1, 1, 10 μmol/L of BEG); positive control group (cells treated with 0.1 mM Vitamin E); model group (cells treated with 0.5 mM H2O2 alone). Cells were pre-incubated with or without BEG for 24 h and then incubated for a further 2 h with 0.5 mM H2O2. Our results showed that BEG significantly reduced H2O2 induced loss in endothelial cell viability, reactive oxygen species (ROS) production, reduced lactate dehydrogenase (LDH) release, and malonyldialdehyde (MDA) level in a concentration-dependent manner. Also, BEG increased the cellular the superoxide dismutase (SOD) activity. Moreover, we found that H2O2 decreased Akt and eNOS phosphorylation, which perhaps, indirectly reduced nitric oxide (NO) production. These effects induced by H2O2, however, were reduced by pre-treatment with BEG. BEG effects were inhibited by a PI3K inhibitor (wortmannin) and eNOS inhibitor (L-NAME). In conclusion, the present study demonstrated that BEG has antioxidant activity. Furthermore, BEG reduced H2O2-induced endothelial cells injury by the involvement of antioxidation and PI3K/Akt/eNOS/NO signaling pathways.