Swamp eel aldehyde reductase is involved in response to nitrosative stress via regulating NO/GSH levels

Aldehyde reductase (ALR) plays key roles in the detoxification of toxic aldehyde. In this study, the authors cloned the swamp eel ALR gene using rapid amplification of cDNA ends-PCR (RACE-PCR). The recombinant protein (rALR) was expressed in Escherichia coli and purified using a Ni2+ -NTA chelating column. The rALR protein exhibited efficient reductive activity towards several aldehydes, ketones and S-nitrosoglutathione (GSNO). A spot assay suggested that the recombinant E. coli strain expressing rALR showed better resistance to formaldehyde, sodium nitrite and GSNO stress, suggesting that swamp eel ALR is crucial for redox homeostasis in vivo. Consequently, the authors investigated the effect of rALR on the oxidative parameters of the liver in swamp eels challenged with Aeromonas hydrophila. The hepatic glutathione (GSH) content significantly increased, and the hepatic NO content and levels of reactive oxygen species and reactive nitrogen species significantly decreased when rALR was administered. In addition, the mRNA expression of hepatic Alr, HO1 and Nrf2 was significantly upregulated, whereas the expression levels of NF-κB, IL-1β and NOS1 were significantly downregulated in the rALR-administered group. Collectively, these results suggest that ALR is involved in the response to nitrosative stress by regulating GSH/NO levels in the swamp eel.

Nitric oxide in parasitic infections: a friend or foe?

The complex interaction between the host and the parasite remains a puzzling question. Control of parasitic infections requires an efficient immune response that must be balanced against destructive pathological consequences. Nitric oxide is a nitrogenous free radical which has many molecular targets and serves diverse functions. Apart from being a signaling messenger, nitric oxide is critical for controlling numerous infections. There is still controversy surrounding the exact role of nitric oxide in the immune response against different parasitic species. It proved protective against intracellular protozoa, as well as extracellular helminths. At the same time, it plays a pivotal role in stimulating detrimental pathological changes in the infected hosts. Several reports have discussed the anti-parasitic and immunoregulatory functions of nitric oxide, which could directly influence the control of the infection. Nevertheless, there is scarce literature addressing the harmful cytotoxic impacts of this mediator. Thus, this review provides insights into the most updated concepts and controversies regarding the dual nature and opposing sides of nitric oxide during the course of different parasitic infections.

The interaction between hippocampal cholinergic and nitrergic neurotransmission coordinates NMDA-dependent behavior and autonomic changes induced by contextual fear retrieval

RATIONALE

Re-exposing an animal to an environment previously paired with an aversive stimulus evokes large alterations in behavioral and cardiovascular parameters. Dorsal hippocampus (dHC) receives important cholinergic inputs from the basal forebrain, and respective acetylcholine (ACh) levels are described to influence defensive behavior. Activation of muscarinic M1 and M3 receptors facilitates autonomic and behavioral responses along threats. Evidence show activation of cholinergic receptors promoting formation of nitric oxide (NO) and cyclic guanosine monophosphate (cGMP) in dHC. Altogether, the action of ACh and NO on conditioned responses appears to converge within dHC.

OBJECTIVES

As answer about how ACh and NO interact to modulate defensive responses has so far been barely addressed, we aimed to shed additional light on this topic.

METHODS

Male Wistar rats had guide cannula implanted into the dHC before being submitted to the contextual fear conditioning (3footshocks/085 mA/2 s). A catheter was implanted in the femoral artery the next day for cardiovascular recordings. Drugs were delivered into dHC 10 min before contextual re-exposure, which occurred 48 h after the conditioning procedure.

RESULTS

Neostigmine (Neo) amplified the retrieval of conditioned responses. Neo effects (1 nmol) were prevented by the prior infusion of a M1-M3 antagonist (fumarate), a neuronal nitric oxide synthase inhibitor (NPLA), a NO scavenger (cPTIO), a guanylyl cyclase inhibitor (ODQ), and a NMDA antagonist (AP-7). Pretreatment with a selective M1 antagonist (pirenzepine) only prevented the increase in autonomic responses induced by Neo.

CONCLUSION

The results show that modulation in the retrieval of contextual fear responses involves coordination of the dHC M1-M3/NO/cGMP/NMDA pathway.

Inhibition of oocyte maturation by nitric oxide synthase 1 (NOS1) in zebrafish

It is well-documented that nitric oxide (NO) is an important regulator of oocyte maturation in mammals. Conversely, the function of NO during oocyte maturation has received little attention in nonmammalian vertebrates. NO is produced from L-arginine through the action of the enzyme NO synthase (NOS). Herein, we examined the expression, hormonal regulation, and involvement of NOS in meiotic signaling in zebrafish oocyte maturation. Three types of nos genes, nos1, nos2a, and nos2b, have been identified in zebrafish. We found that the expression of nos1 was highest in the ovary among the three nos genes, with maximal expression in full-grown (FG)-stage follicles during folliculogenesis. In addition, the concentration of NO was reduced during oocyte maturation and this corresponded with the decreased expression of nos1 in the follicular cell layers, suggesting that NOS1-derived NO may be one of the inhibitors of oocyte maturation in zebrafish. This is the first description of nos1 involvement in oocyte maturation in vertebrates. Moreover, the NO donor SNAP (S-nitroso-l-acetyl penicillamine) partially attenuates human chorionic gonadotropin (hCG)- and 17,20β-P-induced GVBD (germinal vesicle breakdown), perhaps by increasing cGMP levels during oocyte maturation. Finally, our results showed that SNAP and the cGMP analog 8-Br-cGMP inhibited hCG-induced mitogen-activated protein kinase (MAPK) activation, further indicating that NO and cGMP block oocyte maturation in zebrafish.

Role of nitric oxide in regulating epidermal permeability barrier function

Nitric oxide (NO), a free radical molecule synthesized by nitric oxide synthases (NOS), regulates multiple cellular functions in a variety of cell types. These NOS, including endothelial NOS (eNOS), inducible NOS (iNOS) and neural NOS (nNOS), are expressed in keratinocytes. Expression levels of both iNOS and nNOS decrease with ageing, and insufficient NO has been linked to the development of a number of disorders such as diabetes and hypertension, and to the severity of atherosclerosis. Conversely, excessive NO levels can induce cellular oxidative stress, but physiological levels of NO are required to maintain the normal functioning of cells, including keratinocytes. NO also regulates cutaneous functions, including epidermal permeability barrier homeostasis and wound healing, through its stimulation of keratinocyte proliferation, differentiation and lipid metabolism. Topical applications of a diverse group of agents which generate nitric oxide (called NO donors) such as S-nitroso-N-acetyl-D,L-penicillamine (SNAP) can delay permeability barrier recovery in barrier-disrupted skin, but iNOS is still required for epidermal permeability barrier homeostasis. This review summarizes the regulatory role that NO plays in epidermal permeability barrier functions and the underlying mechanisms involved.

The Role of PPAR Alpha in the Modulation of Innate Immunity

Peroxisome proliferator-activated receptor α is a potent regulator of systemic and cellular metabolism and energy homeostasis, but it also suppresses various inflammatory reactions. In this review, we focus on its role in the regulation of innate immunity; in particular, we discuss the PPARα interplay with inflammatory transcription factor signaling, pattern-recognition receptor signaling, and the endocannabinoid system. We also present examples of the PPARα-specific immunomodulatory functions during parasitic, bacterial, and viral infections, as well as approach several issues associated with innate immunity processes, such as the production of reactive nitrogen and oxygen species, phagocytosis, and the effector functions of macrophages, innate lymphoid cells, and mast cells. The described phenomena encourage the application of endogenous and pharmacological PPARα agonists to alleviate the disorders of immunological background and the development of new solutions that engage PPARα activation or suppression.

Inflammatory Cytokines are in Action: Brain Plasticity and Recovery after Brain Ischemia Due to Delayed Melatonin Administration

OBJECTIVES

Post-ischemic inflammation leads to apoptosis as an indirect cause of functional disabilities after the stroke. Melatonin may be a good candidate for the stroke recovery because of its anti-inflammatory effects. Therefore, we investigated the effect of melatonin on inflammation in the functional recovery of brain by evaluating ipsilesional and contralesional alterations.

MATERIALS AND METHODS

Melatonin (4 mg/kg/day) was intraperitoneally administered into the mice from the 3^rd to the 55^th day of the post-ischemia after 30 min of middle cerebral artery occlusion.

RESULTS

Melatonin produced a functional recovery by reducing the emigration of the circulatory leukocytes and the local microglial activation within the ischemic brain. Overall, the expression of the inflammation-related genes reduced upon melatonin treatment in the ischemic hemisphere. On the other hand, the expression level of the inflammatory cytokine genes raised in the contralateral hemisphere at the 55^th day of the post-ischemia. Furthermore, melatonin triggers an increase in the iNOS expression and a decrease in the nNOS expression in the ipsilateral hemisphere at the earlier times in the post-ischemic recovery. At the 55^th day of the post-ischemic recovery, melatonin administration enhanced the eNOS and nNOS protein expressions.

CONCLUSIONS

The present molecular, biological, and histological data have revealed broad anti-inflammatory effects of melatonin in both hemispheres with distinct temporal and spatial patterns at different phases of post-stroke recovery. These outcomes also established that melatonin act recruitment of contralesional rather than of ipsilesional.

The Nitric Oxide Pathway in Pulmonary Arterial Hypertension: Pathomechanism, Biomarkers and Drug Targets

The altered Nitric Oxide (NO) pathway in the pulmonary endothelium leads to increased vascular smooth muscle tone and vascular remodelling, and thus contributes to the development and progression of pulmonary arterial hypertension (PAH). The pulmonary NO signalling is abrogated by the decreased expression and dysfunction of the endothelial NO synthase (eNOS) and the accumulation of factors blocking eNOS functionality. The NO deficiency of the pulmonary vasculature can be assessed by detecting nitric oxide in the exhaled breath or measuring the degradation products of NO (nitrite, nitrate, S-nitrosothiol) in blood or urine. These non-invasive biomarkers might show the potential to correlate with changes in pulmonary haemodynamics and predict response to therapies. Current pharmacological therapies aim to stimulate pulmonary NO signalling by suppressing the degradation of NO (phosphodiesterase- 5 inhibitors) or increasing the formation of the endothelial cyclic guanosine monophosphate, which mediates the downstream effects of the pathway (soluble guanylate cyclase sensitizers). Recent data support that nitrite compounds and dietary supplements rich in nitrate might increase pulmonary NO availability and lessen vascular resistance. This review summarizes current knowledge on the involvement of the NO pathway in the pathomechanism of PAH, explores novel and easy-to-detect biomarkers of the pulmonary NO.

Involvement of nitric oxide during in vitro oocyte maturation, sperm capacitation and in vitro fertilization in pig

The importance of porcine species for meat production is undeniable. Due to the genetic, anatomical, and physiological similarities with humans, from a biomedical point of view, pig is considered an ideal animal model for the study and development of new therapies for human diseases. The in vitro production (IVP) of porcine embryos has become widespread as a result of these qualities and there is significant demand for these embryos for research purposes. However, the efficiency of porcine embryo IVP remains very low, which hinders its use as a model for research. The high degree of polyspermic fertilization is the main problem that affects in vitro fertilization (IVF) in porcine species. Furthermore, oocyte in vitro maturation (IVM) is another important step that could be related to polyspermic fertilization and low embryo production. The presence of nitric oxide synthase (NOS), the enzyme that produces nitric oxide (NO), has been detected in the oviduct, the ovary, the oocyte and the sperm cell of porcine species. Its functions include regulating oviductal activity, ovulation, acquisition of meiotic competence, oocyte activation, sperm capacitation, and gamete interaction. Therefore, in this review, we summarize the current knowledge on the role of NO/NOS system in each of the steps that lead to the production of porcine embryos in an in vitro environment, i.e. IVM, sperm capacitation, IVF, and embryo culture. We also discuss the possible ways in which the NO/NOS system could be used to enhance IVP of porcine embryos.

Activation of ATM/Akt/CREB/eNOS Signaling Axis by Aphidicolin Increases NO Production and Vessel Relaxation in Endothelial Cells and Rat Aortas

Although DNA damage responses (DDRs) are reported to be involved in nitric oxide (NO) production in response to genotoxic stresses, the precise mechanism of DDR-mediated NO production has not been fully understood. Using a genotoxic agent aphidicolin, we investigated how DDRs regulate NO production in bovine aortic endothelial cells. Prolonged (over 24 h) treatment with aphidicolin increased NO production and endothelial NO synthase (eNOS) protein expression, which was accompanied by increased eNOS dimer/monomer ratio, tetrahydrobiopterin levels, and eNOS mRNA expression. A promoter assay using 5'-serially deleted eNOS promoters revealed that Tax-responsive element site, located at -962 to -873 of the eNOS promoter, was responsible for aphidicolin-stimulated eNOS gene expression. Aphidicolin increased CREB activity and ectopic expression of dominantnegative inhibitor of CREB, A-CREB, repressed the stimulatory effects of aphidicolin on eNOS gene expression and its promoter activity. Co-treatment with LY294002 decreased the aphidicolin-stimulated increase in p-CREB-Ser133 level, eNOS expression, and NO production. Furthermore, ectopic expression of dominant-negative Akt construct attenuated aphidicolin-stimulated NO production. Aphidicolin increased p-ATM-Ser1981 and the knockdown of ATM using siRNA attenuated all stimulatory effects of aphidicolin on p-Akt-Ser473, p-CREB-Ser133, eNOS expression, and NO production. Additionally, these stimulatory effects of aphidicolin were similarly observed in human umbilical vein endothelial cells. Lastly, aphidicolin increased acetylcholine-induced vessel relaxation in rat aortas, which was accompanied by increased p-ATM-Ser1981, p-Akt-Ser473, p-CREB-Ser133, and eNOS expression. In conclusion, our results demonstrate that in response to aphidicolin, activation of ATM/Akt/CREB/eNOS signaling cascade mediates increase of NO production and vessel relaxation in endothelial cells and rat aortas.

Remote ischemic conditioning counteracts the intestinal damage of necrotizing enterocolitis by improving intestinal microcirculation

Necrotizing enterocolitis (NEC) is a devastating disease of premature infants with high mortality rate, indicating the need for precision treatment. NEC is characterized by intestinal inflammation and ischemia, as well derangements in intestinal microcirculation. Remote ischemic conditioning (RIC) has emerged as a promising tool in protecting distant organs against ischemia-induced damage. However, the effectiveness of RIC against NEC is unknown. To address this gap, we aimed to determine the efficacy and mechanism of action of RIC in experimental NEC. NEC was induced in mouse pups between postnatal day (P) 5 and 9. RIC was applied through intermittent occlusion of hind limb blood flow. RIC, when administered in the early stages of disease progression, decreases intestinal injury and prolongs survival. The mechanism of action of RIC involves increasing intestinal perfusion through vasodilation mediated by nitric oxide and hydrogen sulfide. RIC is a viable and non-invasive treatment strategy for NEC.

Necrotizing enterocolitis (NEC) is one of the most lethal gastrointestinal emergencies in neonates needing precision treatment. Here the authors show that remote ischemic conditioning is a non-invasive therapeutic method that enhances blood flow in the intestine, reduces damage, and improves NEC outcome.

eNOS deletion impairs mitochondrial quality control and exacerbates Western diet-induced NASH

Dysregulated mitochondrial quality control leads to mitochondrial functional impairments that are central to the development and progression of hepatic steatosis to nonalcoholic steatohepatitis (NASH). Here, we identify hepatocellular localized endothelial nitric oxide synthase (eNOS) as a novel master regulator of mitochondrial quality control. Mice lacking eNOS were more susceptible to Western diet-induced hepatic inflammation and fibrosis in conjunction with decreased markers of mitochondrial biogenesis and turnover. The hepatocyte-specific influence was verified via magnetic activated cell sorting purified primary hepatocytes and in vitro siRNA-induced knockdown of eNOS. Hepatic mitochondria from eNOS knockout mice revealed decreased markers of mitochondrial biogenesis (PPARγ coactivator-1α, mitochondrial transcription factor A) and autophagy/mitophagy [BCL-2-interacting protein-3 (BNIP3), 1A/1B light chain 3B (LC3)], suggesting decreased mitochondrial turnover rate. eNOS knockout in primary hepatocytes exhibited reduced fatty acid oxidation capacity and were unable to mount a normal BNIP3 response to a mitophagic challenge compared with wild-type mice. Finally, we demonstrate that eNOS is required in primary hepatocytes to induce activation of the stress-responsive transcription factor nuclear factor erythroid 2-related factor 2 (NRF2). Thus, our data demonstrate that eNOS is an important regulator of hepatic mitochondrial content and function and NASH susceptibility.

Physiological relevance of nitric oxide in ovarian functions: An overview

Nitric oxide (NO, nitrogen monoxide), a short-lived, free radical carrying an unpaired electron, is one of the smallest molecules synthesized in the biological system. In addition to its role in angiogenesis, neuronal function and inflammatory response, NO has wide-spread significance in regulation of ovarian function in vertebrates. Based on tissue-specific expression, three different nitric oxide synthase (NOS) isoforms, neuronal (nNOS) or NOS1, inducible (iNOS) or NOS2 and endothelial (eNOS) or NOS3 have been identified. While expression of both inducible (iNOS) and constitutive NOS (eNOS) isoforms varies considerably in the ovary at various stages of follicular growth and development, selective binding of NO with proteins containing heme moieties have significant influence on ovarian steroidogenesis. Besides, NO modulation of ovulatory response suggests physiological significance of NO/NOS system in mammalian ovary. Compared to the duality of NO action on follicular development, steroidogenesis and meiotic maturation in mammalian models, participation of NO/NOS system in teleost ovary is less investigated. Genes encoding nos1 and nos2 have been identified in fish; however, presence of nos3 is still ambiguous. Interestingly, two distinct nos2 genes, nos2a and nos2b in zebrafish, possibly arose through whole genome duplication. Differential expression of major NOS isoforms in catfish ovary, NO inhibition of meiosis resumption in Anabas testudineus follicle-enclosed oocytes and NO/sGC/cGMP modulation of oocyte maturation in zebrafish are some of the recent advancements. The present overview is an update on the advancements made and shortfalls still remaining in NO/NOS modulation of intercellular communication in teleost vis-à-vis mammalian ovary.

Limited effects of early life manipulations on sex-specific gene expression and behavior in adulthood

Exposure to childhood adversity is associated with increased vulnerability to stress-related disorders in adulthood which has been replicated in rodent stress models, whereas environmental enrichment has been suggested to have beneficial effects. However, the exact neurobiological mechanisms underlying these environment influences on adult brain and behavior are not well understood. Therefore, we investigated the long-term effects of maternal separation (MS) or environmental enrichment (EE) in male and female CD1 mice. We found clear sex-specific effects, but limited influence of environmental manipulations, on adult behavior, fecal corticosterone metabolite (FCM) levels and stress- and plasticity related gene expression in discrete brain regions. In detail, adult females displayed higher locomotor activity and FCM levels compared to males and EE resulted in attenuation in both measures, but only in females. There were no sex- or postnatal manipulation-dependent differences in anxiety-related behaviors in either sex. Gene expression analyses revealed that adult males showed higher Fkbp5 mRNA levels in hippocampus, hypothalamus and raphe nuclei, and higher hippocampal Nos1 levels. Interestingly, MS elevated Nos1 levels in hippocampus but reduced Fkbp5 expression in hypothalamus of males. Finally, we also found higher Maoa expression in the hypothalamus of adult females, however no differences were observed in the expression levels of Bdnf, Crhr1, Nr3c1 and Htr1a. Our findings further contribute to sex-dependent differences in behavior, corticosterone and gene expression and reveal that the effects of postnatal manipulations on these parameters in outbred CD1 mice are limited.

Loss of endothelial nitric oxide synthase exacerbates intestinal and lung injury in experimental necrotizing enterocolitis

BACKGROUND

Necrotizing enterocolitis (NEC) continues to be a devastating condition among preterm infants. Nitric oxide, which is synthesized in the intestine by endothelial nitric oxide synthase (eNOS), acts as a potent vasodilator and antioxidant within the mesentery and may play a role in prevention of NEC. We hypothesized that loss of endothelial nitric oxide would worsen both intestinal and associated lung injury and increase local and systemic inflammation during experimental NEC.

METHODS

NEC was induced in five-day-old wild type (WT) and eNOS-knockout (eNOSKO) mouse pups. Experimental groups (n=10) were formula fed and subjected to intermittent hypoxic and hypothermic stress, while control groups (n=10) remained with their mother to breastfeed. Pups were monitored by daily clinical assessment. After sacrifice on day nine, intestine and lung were assessed for injury, and cytokines were measured in tissue homogenates by ELISA. Data were compared with Mann-Whitney, and p<0.05 was significant.

RESULTS

Each NEC group was compared to its respective strain's breastfed control to facilitate comparisons between the groups. Both NEC groups were significantly sicker than their breastfed controls. eNOSKO NEC animals had a median clinical assessment score of 3 (IQR=1-5), and the WT NEC animal's median score was 3 (IQR=2-5). Despite similar clinical scores, intestinal injury was significantly worse in the eNOSKO NEC groups compared to WT NEC groups (median injury scores of 3.25 (IQR=2.25-3.625) and 2 (IQR=1-3), respectively (p=0.0474). Associated lung injury was significantly worse in the eNOSKO NEC group as compared to the WT NEC group (median scores of 8.5 (IQR=6.75-11.25) and 6.5 (IQR=5-7.5), respectively, p=0.0391). Interestingly, cytokines in both tissues were very different between the two groups, with varying effects noted for each cytokine (IL-6, IL-1β, VEGF, and IL-12) in both tissues.

CONCLUSION

Nitric oxide from eNOS plays a key role in preventing the development of NEC. Without eNOS function, both intestinal and lung injuries are more severe, and the inflammatory cascade is significantly altered. Further studies are needed to determine how eNOS-derived nitric oxide facilitates these beneficial effects.

Redox Signaling Mediated by Thioredoxin and Glutathione Systems in the Central Nervous System

SIGNIFICANCE

The thioredoxin (Trx) and glutathione (GSH) systems play important roles in maintaining the redox balance in the brain, a tissue that is prone to oxidative stress due to its high-energy demand. These two disulfide reductase systems are active in various areas of the brain and are considered to be critical antioxidant systems in the central nervous system (CNS). Various neuronal disorders have been characterized to have imbalanced redox homeostasis. Recent Advances: In addition to their detrimental effects, recent studies have highlighted that reactive oxygen species/reactive nitrogen species (ROS/RNS) act as critical signaling molecules by modifying thiols in proteins. The Trx and GSH systems, which reversibly regulate thiol modifications, regulate redox signaling involved in various biological events in the CNS.

CRITICAL ISSUES

In this review, we focus on the following: (i) how ROS/RNS are produced and mediate signaling in CNS; (ii) how Trx and GSH systems regulate redox signaling by catalyzing reversible thiol modifications; (iii) how dysfunction of the Trx and GSH systems causes alterations of cellular redox signaling in human neuronal diseases; and (iv) the effects of certain small molecules that target thiol-based signaling pathways in the CNS.

FUTURE DIRECTIONS

Further study on the roles of thiol-dependent redox systems in the CNS will improve our understanding of the pathogenesis of many human neuronal disorders and also help to develop novel protective and therapeutic strategies against neuronal diseases. Antioxid. Redox Signal. 27, 989-1010.

Cellular and plasma nitrite levels in myeloid leukemia: a pathogenetic decrease

Nitric oxide (NO) has a contributory role in hemopoietic cell growth and differentiation. The effects of NO on leukemic cell growth have been predominantly studied inin vitrosettings. This study was done to assess the alterations in nitrite level in myeloid leukemias. Thirty-six newly diagnosed cases of myeloid leukemia (16 AML and 20 CML) were enrolled in the study. Neutrophil precursors from the marrow aspirate and peripheral blood were separated into cell bands using the Percoll density gradient method of Borregard and Cowland. The blood plasma and marrow fluid was also collected. Nitrite (stable non-volatile end product of NO) was estimated in the cell bands, blood plasma and marrow fluid using Griess reagent. The mean nitrite level in all cell bands from peripheral blood, bone marrow, blood plasma, and marrow fluid of cases was significantly lower as compared to corresponding value in the controls. No significant difference between AML and CML was seen. On follow-up, analysis of 13 CML patients higher nitrite levels were seen (p>0.05). The significant decrease in nitrite levels in myeloid leukemia suggests a decrease in nitric oxide synthase (NOS) activity. Further work may unfold molecular targets for therapeutic role of NO modulators.

Withania somniferaphytochemicals confer neuroprotection by selective inhibition of nNos: Anin silicostudy to search potent and selective inhibitors for human nNOS

Neuronal nitric oxide synthase (nNOS or NOS1) is an important therapeutic target for the treatment of various neurological diseases. A major challenge faced in the design of nNOS inhibitors emphasizes on potency in humans and selectivity over other NOS isoforms — eNOS and iNOS. The present structural-based in silico study was carried out to search potent and selective inhibitor for human nNOS from a set of 40 Withania somnifera phytochemicals structure. Ten phytochemicals appear as dual-selective inhibitors of nNOS over both iNOS and eNOS. Here we report five potent and selective human nNOS inhibitors, namely, Chlorogenic Acid, Withanolide B, Withacnistin Pelletierine, and Calystegine B2 based on their selectivity, binding energy and nNOS active site residues interaction profile. These phytochemicals have nNOS selectivity higher than 4-methyl-6-(2-(5-(3-(methylamino)propyl)pyridin-3-yl)-ethyl)pyridin-2-amine inhibitor and have potential as an oral neurotherapeutic agent to combat neurological disorders mediated by nNOS activation.

[Tthe efficacy and safety of drug therapy divaza in patients with chronic cerebral ischemia]

AIM

To evaluate the efficacy and safety of divazа in the treatment of cognitive and emotional disorders in patients with chronic cerebral ischemia (CCI) based on clinical findings and laboratory markers of endothelial dysfunction.

MATERIAL AND METHODS

Thirty patients with CCI, aged 40 to 70 years, were examined. All patients were treated with divazа (2 tablets 3 times a day) for 12 weeks. Cognitive functions and markers of endothelial dysfunction (the activity of endothelial NO-synthase (eNOS), the number of circulating desquamated endothelial cells in blood plasma) were measured at baseline and after treatment.

RESULTS

Divazа significantly reduced the severity of clinical symptoms and had a positive effect on endothelial dysfunction normalizing the tone of cerebral vessels and preventing deendotheliazation.

CONCLUSION

The use of divazа resulted in clinical improvement and normalization of markers of endothelial dysfunction as well.

Ischemic brain injury: New insights on the protective role of melatonin

Stroke represents one of the most common causes of brain's vulnerability for many millions of people worldwide. The plethora of physiopathological events associated with brain ischemia are regulate through multiple signaling pathways leading to the activation of oxidative stress process, Ca²⁺ dyshomeostasis, mitochondrial dysfunction, proinflammatory mediators, excitotoxicity and/or programmed neuronal cell death. Understanding this cascade of molecular events is mandatory in order to develop new therapeutic strategies for stroke. In this review article, we have highlighted the pleiotropic effects of melatonin to counteract the multiple processes of the ischemic cascade. Additionally, experimental evidence supports its actions to ameliorate ischemic long-term behavioural and neuronal deficits, preserving the functional integrity of the blood-brain barrier, inducing neurogenesis and cell proliferation through receptor-dependent mechanism, as well as improving synaptic transmission. Consequently, the synthesis of melatonin derivatives designed as new multitarget-directed products has focused a great interest in this area. This latter has been reinforced by the low cost of melatonin and its reduced toxicity. Furthermore, its spectrum of usages seems to be wide and with the potential for improving human health. Nevertheless, the molecular and cellular mechanisms underlying melatonin´s actions need to be further exploration and accordingly, new clinical studies should be conducted in human patients with ischemic brain pathologies.

Ketamine upregulates eNOS expression in human astroglial A172 cells: Possible role in its antidepressive properties

Ketamine is a potent anti-depressive agent. Nitric oxide plays an essential role in neuronal transmission and cerebral blood flow and has been implicated in the pathophysiology of major depressive disorder as well as cardiovascular functioning. We investigated the effect of ketamine on eNOS expression in human A172 astroglial cells. Ketamine (50-500μM) increased eNOS expression at 4-24h in a concentration-dependent manner. This effect was mediated by NMDA receptor, Akt inhibition and ERK1/2 activation and was synergistically augmented by rapamycin. The combined effect on the vascular, immune and neuronal systems may be relevant to the rapid antidepressive effect of ketamine.

Contribution of inducible and neuronal nitric oxide synthases to mitochondrial damage and melatonin rescue in LPS-treated mice

NOS isoform activation is related to liver failure during sepsis, but the mechanisms driving mitochondrial impairment remain unclear. We induced sepsis by LPS administration to inducible nitric oxide synthase (iNOS^-/-) and neuronal nitric oxide synthase (nNOS^-/-) mice and their respective wild-type controls to examine the contribution of iNOS to mitochondrial failure in the absence of nNOS. To achieve this goal, the determination of messenger RNA (mRNA) expression and protein content of iNOS in cytosol and mitochondria, the mitochondrial respiratory complex content, and the levels of nitrosative and oxidative stress (by measuring 3-nitrotyrosine residues and carbonyl groups, respectively) were examined in the liver of control and septic mice. We detected strongly elevated iNOS mRNA expression and protein levels in liver cytosol and mitochondria of septic mice, which were related to enhanced oxidative and nitrosative stress, and with fewer changes in respiratory complexes. The absence of the iNOS, but not nNOS, gene absolutely prevented mitochondrial impairment during sepsis. Moreover, the nNOS gene did not modify the expression and the effects of iNOS here shown. Melatonin administration counteracted iNOS activation and mitochondrial damage and enhanced the expression of the respiratory complexes above the control values. These effects were unrelated to the presence or absence of nNOS. iNOS is a main target to prevent liver mitochondrial impairment during sepsis, and melatonin represents an efficient antagonist of these iNOS-dependent effects whereas it may boost mitochondrial respiration to enhance liver survival.

Role of Nitric Oxide in Cardiovascular Adaptation to Intermittent Hypoxia

Hypoxia is one of the most frequently encountered stresses in health and disease. The duration, frequency, and severity of hypoxic episodes are critical factors determining whether hypoxia is beneficial or harmful. Adaptation to intermittent hypoxia has been demonstrated to confer cardiovascular protection against more severe and sustained hypoxia, and, moreover, to protect against other stresses, including ischemia. Thus, the direct and cross protective effects of adaptation to intermittent hypoxia have been used for treatment and prevention of a variety of diseases and to increase efficiency of exercise training. Evidence is mounting that nitric oxide (NO) plays a central role in these adaptive mechanisms. NO-dependent protective mechanisms activated by intermittent hypoxia include stimulation of NO synthesis as well as restriction of NO overproduction. In addition, alternative, nonenzymic sources of NO and negative feedback of NO synthesis are important factors in optimizing NO concentrations. The adaptive enhancement of NO synthesis and/or availability activates or increases expression of other protective factors, including heat shock proteins, antioxidants and prostaglandins, making the protection more robust and sustained. Understanding the role of NO in mechanisms of adaptation to hypoxia will support development of therapies to prevent and treat hypoxic or ischemic damage to organs and cells and to increase adaptive capabilities of the organism.

Differential Expression of Endothelial Nitric Oxide Synthase in Coronary and Cardiac Tissue in Hypoxic Fetal Guinea Pig Hearts

OBJECTIVE

The purpose of the present study was to quantify the effect of chronic hypoxia on endothelial nitric oxide synthase (eNOS) gene and protein expression of fetal coronary artery segments and cardiac tissue of fetal guinea pig hearts.

METHODS

Time-mated pregnant guinea pigs (term = 65 days) were housed in room air (NMX, n = 6) or in a hypoxic chamber containing 10.5% O2 for 14 days (HPX14, n = 6). At near term (60 days gestation), fetuses were excised from anesthetized animals via hysterotomy and hearts were removed and weighed. Both coronary artery segments and cardiac ventricle were excised from the same hearts, frozen, and stored at -80 C until ready for study. eNOS mRNA was quantified using real-time polymerase chain reaction (PCR) based on SYBR Green I labeling (BioRad Laboratories, Hercules, CA) using eNOS primers obtained from GeneBank normalized to 18S. eNOS proteins were quantified by Western immunoblotting using eNOS antibody (1:200) and normalized to normoxic controls. eNOS cell-specific localization in the fetal guinea pig heart was performed by double immunofluorescence staining.

RESULTS

Both coronary artery endothelial cells (EC) and cardiomyocytes (CM) but not vascular smooth muscle cells of normoxic hearts exhibited positive immunostaining of eNOS protein. Chronic hypoxia significantly (P < .05) increased both eNOS mRNA and protein levels of coronary artery segments (by 210.6% and 51.4%, respectively) but decreased (P < .05) mRNA and protein of cardiac tissue (by 50.0% and 40.6%, respectively) in the same hearts.

CONCLUSIONS

Chronic fetal hypoxia, after 14 days, induces sustained changes in eNOS gene and eNOS protein expression that differ between coronary and cardiac tissue in the fetal guinea pig heart. This study suggests that while the functional roles of altered eNOS expression in hypoxic fetal hearts remain unclear, the site at which eNOS expression is altered may be important in the adaptive response of the fetal heart to hypoxia.

Melatonin rescues zebrafish embryos from the parkinsonian phenotype restoring the parkin/PINK1/DJ-1/MUL1 network

Multiple studies reporting mitochondrial impairment in Parkinson's disease (PD) involve knockout or knockdown models to inhibit the expression of mitochondrial-related genes, including parkin, PINK1, and DJ-1 ones. Melatonin has significant neuroprotective properties, which have been related to its ability to boost mitochondrial bioenergetics. The meaning and molecular targets of melatonin in PD are yet unclear. Zebrafish are an outstanding model of PD because they are vertebrates, their dopaminergic system is comparable to the nigrostriatal system of humans, and their brains express the same genes as mammals. The exposure of 24 hpf zebrafish embryos to MPTP leads to a significant inhibition of the mitochondrial complex I and the induction of sncga gene, responsible for enhancing γ-synuclein accumulation, which is related to mitochondrial dysfunction. Moreover, MPTP inhibited the parkin/PINK1/DJ-1 expression, impeding the normal function of the parkin/PINK1/DJ-1/MUL1 network to remove the damaged mitochondria. This situation remains over time, and removing MPTP from the treatment did not stop the neurodegenerative process. On the contrary, mitochondria become worse during the next 2 days without MPTP, and the embryos developed a severe motor impairment that cannot be rescued because the mitochondrial-related gene expression remained inhibited. Melatonin, added together with MPTP or added once MPTP was removed, prevented and recovered, respectively, the parkinsonian phenotype once it was established, restoring gene expression and normal function of the parkin/PINK1/DJ-1/MUL1 loop and also the normal motor activity of the embryos. The results show, for the first time, that melatonin restores brain function in zebrafish suffering with Parkinson-like disease.

Increased Expression of Endothelial and Neuronal Nitric Oxide Synthase In Dura and Pia Mater After Air Stress

Stress is the leading precipitating factor for migraine attacks but the underlying mechanism is currently unknown. Nitric oxide (NO) has been implicated in migraine pathogenesis based on the ability of NO donors to induce migraine attacks. In the present study, we investigated in Wistar rats the effect of air stress on nitric oxide synthase (NOS) mRNA and protein expression in dura and pia mater using real-time polymerase chain reaction and Western blotting, respectively. Endothelial (e)NOS protein expression was significantly increased in dura and pia mater after air stress. Significantly augmented neuronal (n)NOS protein expression was detected in pia mater after air stress but not in dura mater. Inducible NOS mRNA and protein expression levels in dura and pia mater were unaffected by stress. The increased expression of eNOS in dura mater and eNOS and nNOS in pia mater seen after stress could not be antagonized by treatment with the migraine drug sumatriptan. These findings point towards the involvement of increased NO concentrations in dura and pia mater in response to air stress. However, the role of these findings in relation to migraine pathophysiology remains unclear.

Immediate Remote Ischemic Postconditioning Reduces Brain Nitrotyrosine Formation in a Piglet Asphyxia Model

Remote ischemic postconditioning (RIPostC) is a promising therapeutic intervention that could be administered as an alternative to cooling in cases of perinatal hypoxia-ischemia (HI). In the current study we hypothesized that RIPostC in the piglet model of birth asphyxia confers protection by reducing nitrosative stress and subsequent nitrotyrosine formation, as well as having an effect on glial immunoreactivity. Postnatal day 1 (P1) piglets underwent HI brain injury and were randomised to HI (control) or HI + RIPostC. Immunohistochemistry assessment 48 hours after HI revealed a significant decrease in brain nitrotyrosine deposits in the RIPostC-treated group (p = 0.02). This was accompanied by a significant increase in eNOS expression (p < 0.0001) and decrease in iNOS (p = 0.010), with no alteration in nNOS activity. Interestingly, RIPostC treatment was associated with a significant increase in GFAP (p = 0.002) and IBA1 (p = 0.006), markers of astroglial and microglial activity, respectively. The current study demonstrates a beneficial effect of RIPostC therapy in the preclinical piglet model of neonatal asphyxia, which appears to be mediated by modulation of nitrosative stress, despite glial activation.

The antioxidative property of melatonin against brain ischemia

INTRODUCTION

This review briefly summarizes some of the large amount of data documenting the ability of melatonin to limit molecular and organ tissue damage in neural ischemia-reperfusion injury (stroke), where free radicals are generally considered as being responsible for much of the resulting tissue destruction.

AREA COVERED

Melatonin actions that have been identified include its ability to directly neutralize a number of toxic reactants and stimulate antioxidative enzymes. Furthermore, several of its metabolites such as N(1)-acetyl-N(2)-formyl-5- methoxykynuramine (AFMK) and N(1)-acetyl-5-methoxykynuramine (AMF), are themselves scavengers suggesting that there is a cascade of reactions that greatly increase the efficacy of melatonin. Expert Commentary: However, the mechanisms by which melatonin is protective in such widely diverse areas of the cell and different organs are likely not yet all identified.

Inherent physical characteristics and gene expression differences between alveolar and basal bones

OBJECTIVES

The objective of this study was to evaluate the baseline differences between alveolar and basal areas of the rat mandible.

STUDY DESIGN

Rat mandibular alveolar and basal bones were evaluated using histology and micro-computed tomography to compare osteocyte number as well as bone density and architecture and polymerase chain reaction to measure gene expression levels.

RESULTS

Micro-computed tomography data indicated that basal bone is denser and less porous than alveolar bone. Histologic analysis showed that alveolar bone has more osteocytes per unit area compared with basal bone. Real-time polymerase chain reaction results showed higher levels of expression of the following genes in basal bone than in alveolar bone: SOST, E-11, DMP-1, and MEPE.

CONCLUSIONS

Three of these gene products are associated with mature osteocytes, and this suggests that basal bone has more mature osteocyte phenotypes compared with alveolar bone. These findings are suggestive of fewer bone mineralization units and therefore a slower remodeling rate.

The role of nitric oxide in neurovascular coupling

Nitric oxide (NO) is a neurotransmitter known to act as a potent cerebral vasodilator. Its role in neurovascular coupling (NVC) is discussed controversially and one of the main unanswered questions is which cell type provides the governing source of NO for the regulation of vasodynamics. Mathematical modelling can be an appropriate tool to investigate the contribution of NO towards the key components of NVC and analyse underlying mechanisms. The lumped parameter model of a neurovascular unit, including neurons (NE), astrocytes (AC), smooth muscle cells (SMC) and endothelial cells (EC), was extended to model the NO signalling pathway. Results show that NO leads to a general shift of the resting regional blood flow by dilating the arteriolar radius. Furthermore, dilation during neuronal activation is enhanced. Simulations show that potassium release is responsible for the fast onset of vascular response, whereas NO-modulated mechanisms maintain dilation. Wall shear stress-activated NO release from the EC leads to a delayed return to the basal state of the arteriolar radius. The governing source of vasodilating NO that diffuses into the SMC, which determine the arteriolar radius, depends on neuronal activation. In the resting state the EC provides the major contribution towards vasorelaxation, whereas during neuronal stimulation NO produced by the NE dominates.

Effects of intratracheally instilled laser printer-emitted engineered nanoparticles in a mouse model: A case study of toxicological implications from nanomaterials released during consumer use

Incorporation of engineered nanomaterials (ENMs) into toners used in laser printers has led to countless quality and performance improvements. However, the release of ENMs during printing (consumer use) has raised concerns about their potential adverse health effects. The aim of this study was to use "real world" printer-emitted particles (PEPs), rather than raw toner powder, and assess the pulmonary responses following exposure by intratracheal instillation. Nine-week old male Balb/c mice were exposed to various doses of PEPs (0.5, 2.5 and 5 mg/kg body weight) by intratracheal instillation. These exposure doses are comparable to real world human inhalation exposures ranging from 13.7 to 141.9 h of printing. Toxicological parameters reflecting distinct mechanisms of action were evaluated, including lung membrane integrity, inflammation and regulation of DNA methylation patterns. Results from this in vivo toxicological analysis showed that while intratracheal instillation of PEPs caused no changes in the lung membrane integrity, there was a pulmonary immune response, indicated by an elevation in neutrophil and macrophage percentage over the vehicle control and low dose PEPs groups. Additionally, exposure to PEPs upregulated expression of the Ccl5 (Rantes), Nos1 and Ucp2 genes in the murine lung tissue and modified components of the DNA methylation machinery (Dnmt3a) and expression of transposable element (TE) LINE-1 compared to the control group. These genes are involved in both the repair process from oxidative damage and the initiation of immune responses to foreign pathogens. The results are in agreement with findings from previous in vitro cellular studies and suggest that PEPs may cause immune responses in addition to modifications in gene expression in the murine lung at doses that can be comparable to real world exposure scenarios, thereby raising concerns of deleterious health effects.

G894T and 4a/b polymorphisms of NOS3 gene are not associated with cancer risk: a meta-analysis

Endothelial nitric oxide synthase (eNOS or NOS3) produces nitric oxide and genetic polymorphisms of NOS3 gene play significant roles in various processes of carcinogenesis. The results from published studies on the association between NOS3 G894T and NOS3 intron 4 (4a/b) polymorphisms and cancer risk are conflicting and inconclusive. However, i n order to assess this relationship more precisely, a meta-analysis was performed with PubMed (Medline), EMBASE and Google web searches until February 2014 to select all published case- control and cohort studies. Genotype distribution data were collected to calculate the pooled odd ratios (ORs) and 95% confidence intervals (CIs) to evaluate the strength of association. A total of 10,546 cancer cases and 10,550 controls were included from twenty four case-control studies for the NOS3 G894T polymorphism. The results indicated no significant association with cancer risk as observed in allelic (T vs G: OR=1.024, 95%CI=0.954 to 1.099, p=0.508), homozygous (TT vs GG: OR=1.137, 95%CI=0.944 to 1.370, p=0.176), heterozygous (GT vs GG: OR=0.993, 95%CI=0.932 to 1.059, p=0.835), recessive (TT vs GG+GT: OR=1.100, 95%CI=0.936 to 1.293, p=0.249) and dominant (TT+GT vs GG: OR=1.012, 95%CI=0.927 to 1.105, p=0.789) genetic models. Similarly, a total of 3,449 cancer cases and 3,691 controls were recruited from fourteen case-control studies for NOS3 4a/b polymorphism. Pooled results indicated no significant association under allelic (A vs B: OR=0.981, 95%CI=0.725 to 1.329, p=0.902), homozygous (AA vs BB: OR=1.166, 95%CI=0.524 to 2.593, p=0.707), heterozygous (BA vs BB: OR=1.129, 95%CI=0.896 to 1.422, p=0.305), dominant (AA+BA vs BB: OR=1.046, 95%CI=0.779 to 1.405, p=0.763) and recessive (AA vs BB+BA: OR=1.196, 95%CI=0.587 to 2.439, p=0.622) genetic contrast models. This meta-analysis suggests that G894T and 4a/b polymorphisms of NOS3 gene are not associated with increased or decreased risk of overall cancer.

Stretch and/or oxygen glucose deprivation (OGD) in an in vitro traumatic brain injury (TBI) model induces calcium alteration and inflammatory cascade

The blood-brain barrier (BBB), made up of endothelial cells of capillaries in the brain, maintains the microenvironment of the central nervous system. During ischemia and traumatic brain injury (TBI), cellular disruption leading to mechanical insult results to the BBB being compromised. Oxygen glucose deprivation (OGD) is the most commonly used in vitro model for ischemia. On the other hand, stretch injury is currently being used to model TBI in vitro. In this paper, the two methods are used alone or in combination, to assess their effects on cerebrovascular endothelial cells cEND in the presence or absence of astrocytic factors. Applying severe stretch and/or OGD to cEND cells in our experiments resulted to cell swelling and distortion. Damage to the cells induced release of lactate dehydrogenase enzyme (LDH) and nitric oxide (NO) into the cell culture medium. In addition, mRNA expression of inflammatory markers interleukin (I L)-6, IL-1α, chemokine (C-C motif) ligand 2 (CCL2) and tumor necrosis factor (TNF)-α also increased. These events could lead to the opening of calcium ion channels resulting to excitotoxicity. This could be demonstrated by increased calcium level in OGD-subjected cEND cells incubated with astrocyte-conditioned medium. Furthermore, reduction of cell membrane integrity decreased tight junction proteins claudin-5 and occludin expression. In addition, permeability of the endothelial cell monolayer increased. Also, since cell damage requires an increased uptake of glucose, expression of glucose transporter glut1 was found to increase at the mRNA level after OGD. Overall, the effects of OGD on cEND cells appear to be more prominent than that of stretch with regards to TJ proteins, NO, glut1 expression, and calcium level. Astrocytes potentiate these effects on calcium level in cEND cells. Combining both methods to model TBI in vitro shows a promising improvement to currently available models.

Redox regulation of metabolic and signaling pathways by thioredoxin and glutaredoxin in NOS-3 overexpressing hepatoblastoma cells

Nitric oxide (NO) plays relevant roles in signal transduction in physiopathology and its effects are dependent on several environmental factors. NO has both pro-apoptotic and anti-apoptotic functions but the molecular mechanisms responsible for these opposite effects are not fully understood. The action of NO occurs mainly through redox changes in target proteins, particularly by S-nitrosylation of reactive cysteine residues. Thioredoxin (Trx) and glutaredoxin (Grx) systems are the main cellular controllers of the thiolic redox state of proteins exerting controversial effects on apoptosis with consequences for the resistance to or the development of cancer.

The aim of this study was to ascertain whether Trx and/or Grx systems mediate the antiproliferative effect of NO on hepatoblastoma cells by modulating the redox-state of key proteins.

Proliferation decreased and apoptosis increased in HepG2 cells overexpressing Nitric Oxide Synthase-3 (NOS-3) as a result of multilevel cellular responses to the oxidative environment generated by NO. Enzyme levels and cysteine redox state at several metabolic checkpoints were consistent with prominence of the pentose phosphate pathway to direct the metabolic flux toward NADPH for antioxidant defense and lowering of nucleotide biosynthesis and hence proliferation. Proteins involved in cell survival pathways, proteins of the redoxin systems and phosphorylation of MAPK were all significantly increased accompanied by a shift of the thiolic redox state of Akt1, Trx1 and Grx1 to more oxidized.

Silencing of Trx1 and Grx1 neutralized the increases in CD95, Akt1 and pAkt levels induced by NO and produced a marked increase in caspase-3 and -8 activities in both control and NOS-3 overexpressing cells concomitant with a decrease in the number of cells.

These results demonstrate that the antiproliferative effect of NO is actually hampered by Trx1 and Grx1 and support the strategy of weakening the thiolic antioxidant defenses when designing new antitumoral therapies.

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Endogenous NO induces NADPH and reduces nucleotide biosynthesis in HepG2 cells.

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Trx1 and Grx1 have a pro-oxidant action on key proteins under nitrosative conditions.

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Trx1 and Grx1 hamper the antiproliferative action of NO in tumoral cells.

•

Weakening of thiolic antioxidant defenses could help in the design of anti-tumoral therapies.

A novel long non-coding natural antisense RNA is a negative regulator of Nos1 gene expression

Long non-coding natural antisense transcripts (NATs) are widespread in eukaryotic species. Although recent studies indicate that long NATs are engaged in the regulation of gene expression, the precise functional roles of the vast majority of them are unknown. Here we report that a long NAT (Mm-antiNos1 RNA) complementary to mRNA encoding the neuronal isoform of nitric oxide synthase (Nos1) is expressed in the mouse brain and is transcribed from the non-template strand of the Nos1 locus. Nos1 produces nitric oxide (NO), a major signaling molecule in the CNS implicated in many important functions including neuronal differentiation and memory formation. We show that the newly discovered NAT negatively regulates Nos1 gene expression. Moreover, our quantitative studies of the temporal expression profiles of Mm-antiNos1 RNA in the mouse brain during embryonic development and postnatal life indicate that it may be involved in the regulation of NO-dependent neurogenesis.

Glucagon induces airway smooth muscle relaxation by nitric oxide and prostaglandin E₂

Glucagon is a hyperglycemic pancreatic hormone that has been shown to provide a beneficial effect against asthmatic bronchospasm. We investigated the role of this hormone on airway smooth muscle contraction and lung inflammation using both in vitro and in vivo approaches. The action of glucagon on mouse cholinergic tracheal contraction was studied in a conventional organ bath system, and its effect on airway obstruction was also investigated using the whole-body pletysmographic technique in mice. We also tested the effect of glucagon on lipopolysaccharide (LPS)-induced airway hyperreactivity (AHR) and inflammation. The expression of glucagon receptor (GcgR), CREB, phospho-CREB, nitric oxide synthase (NOS)-3, pNOS-3 and cyclooxygenase (COX)-1 was evaluated by western blot, while prostaglandin E₂ (PGE₂) and tumour necrosis factor-α were quantified by enzyme-linked immunoassay and ELISA respectively. Glucagon partially inhibited carbachol-induced tracheal contraction in a mechanism clearly sensitive to des-His1-[Glu9]-glucagon amide, a GcgR antagonist. Remarkably, GcgR was more expressed in the lung and trachea with intact epithelium than in the epithelium-denuded trachea. In addition, the glucagon-mediated impairment of carbachol-induced contraction was prevented by either removing epithelial cells or blocking NOS (L-NAME), COX (indomethacin) or COX-1 (SC-560). In contrast, inhibitors of either heme oxygenase or COX-2 were inactive. Intranasal instillation of glucagon inhibited methacholine-induced airway obstruction by a mechanism sensitive to pretreatment with L-NAME, indomethacin and SC-560. Glucagon induced CREB and NOS-3 phosphorylation and increased PGE₂ levels in the lung tissue without altering COX-1 expression. Glucagon also inhibited LPS-induced AHR and bronchoalveolar inflammation. These findings suggest that glucagon possesses airway-relaxing properties that are mediated by epithelium-NOS-3-NO- and COX-1-PGE₂-dependent mechanisms.

RNA-stabilizing proteins as molecular targets in cardiovascular pathologies

The stability of mRNA has emerged as a key step in the regulation of eukaryotic gene expression and function. RNA stabilizing proteins (RSPs) contain several RNA recognition motifs, and selectively bind to adenylate-uridylate-rich elements in the 3' untranslated region of several mRNAs leading to altered processing, stability, and translation. These post-transcriptional gene regulations play a critical role in cellular homeostasis; therefore act as molecular switch between 'normal cell' and 'disease state.' Many mRNA binding proteins have been discovered to date, which either stabilize (HuR/HuA, HuB, HuC, HuD) or destabilize (AUF1, tristetraprolin, KSRP) the target transcripts. Although the function of RSPs has been widely studied in cancer biology, its role in cardiovascular pathologies is only beginning to evolve. The current review provides an overall understanding of the potential role of RSPs, specifically HuR-mediated mRNA stability in myocardial infarction, hypertension and hypertrophy. Also, the effect of RSPs on various cellular processes including inflammation, fibrosis, angiogenesis, cell-death, and proliferation and its relevance to cardiovascular pathophysiological processes is presented. We also discuss the potential clinical implications of RSPs as therapeutic targets in cardiovascular diseases.

Nitric oxide synthase in innate and adaptive immunity: an update

Thirty years after the discovery of its production by activated macrophages, our appreciation of the diverse roles of nitric oxide (NO) continues to grow. Recent findings have not only expanded our understanding of the mechanisms controlling the expression of NO synthases (NOS) in innate and adaptive immune cells, but have also revealed new functions and modes of action of NO in the control and escape of infectious pathogens, in T and B cell differentiation, and in tumor defense. I discuss these findings, in the context of a comprehensive overview of the various sources and multiple reaction partners of NO, and of the regulation of NOS2 by micromilieu factors, antisense RNAs, and 'unexpected' cytokines.

Traditional Chinese medicine's intervention in endothelial nitric oxide synthase activation and nitric oxide synthesis in cardiovascular system

Cardiovascular disease (CVD) is one of the most dangerous diseases which has become a major cause of human death. Many researches evidenced that nitric oxide (NO)/endothelial nitric oxide synthase (eNOS) system plays a significant role in the occurrence and development of CVD. NO, an important signaling molecule, closely associated with the regulation of vasodilatation, blood rheology, blood clotting and other physiological and pathological processes. The synthesis of NO in the endothelial cells primarily depends on the eNOS activity, thus the exploration of the mechanisms and effects of the eNOS activation on NO production is of great significance. Recently, studies on the effects of traditional Chinese medicine (TCM) and its extracts on eNOS activation and NO synthesis have gradually attracted more and more attentions. In this paper, we reviewed the mechanisms of NO synthesis and eNOS activation in the vascular endothelial cells (VECs) and intervention of TCM, so as to provide reference and train of thought to the intensive study of NO/eNOS system and the research and development of new drug for the treatment of CVD.

Supplementary dietary nitric oxide donor (sodium nitroprusside) or inhibitor (NG-nitro-L-arginine methyl ester) depressed growth performance and ovarian primordial and primary follicles in Japanese quail (Coturnix coturnix japonica) in a dose-dependent manner

1. The aim of the study was to determine the effects of dietary supplementation with sodium nitroprusside (SNP), a nitric oxide (NO) exogenous donor, and N(G)-nitro-L-arginine methyl ester (l-NAME), a NO inhibitor, on growth performance, some biochemical parameters and ovarian primordial and primary follicles of quail. 2. A total of 480 Japanese quail (Coturnix coturnix japonica), one-day-old, including both males and females, were randomly allocated into one control group and 4 treatment groups each consisting of 96 birds. The control group was fed on the basal diet, whereas the experimental groups were fed on the basal diet supplemented with 50 mg SNP/kg, 200 mg SNP/kg, 50 mg L-NAME/kg or 200 mg L-NAME/kg. In the group receiving 200 mg SNP/kg, BW was lower on d 28 and d 42 compared to the control group and body weight gain (BWG) was lower between weeks 2 and 4 compared to the control group. In the same group, BWG and feed consumption were lower compared with the control group. 3. In the group receiving 200 mg L-NAME/kg, BW on d 42 and BWG were lower, whereas feed consumption and FCR was higher than in the control group. 4. In the groups supplemented with SNP at 50 and 200 mg/kg, serum total protein and albumin were higher than the control group; however, serum lipid profile, and liver and kidney enzymes were not affected by supplementation with SNP or l-NAME. 5. The numbers of ovarian primordial and primary follicles were greater in the group fed on the diet supplemented with 200 mg SNP/kg compared with the control group. Supplementation at 200 mg L-NAME/kg diet reduced the number of primary follicles compared to the controls, whereas the diameter of primordial and primary follicles increased. 6. In conclusion, supplementation with SNP and L-NAME depressed quail growth. Furthermore, the increase in NO following dietary supplementation with the NO-donor SNP delayed the growth process from primordial to primary and primary to secondary follicle transition in quail.

Carbon monoxide increases inducible NOS expression that mediates CO-induced myocardial damage during ischemia-reperfusion

We investigated the role of inducible nitric oxide (NO) synthase (iNOS) on ischemic myocardial damage in rats exposed to daily low nontoxic levels of carbon monoxide (CO). CO is a ubiquitous environmental pollutant that impacts on mortality and morbidity from cardiovascular diseases. We have previously shown that CO exposure aggravates myocardial ischemia-reperfusion (I/R) injury partly because of increased oxidative stress. Nevertheless, cellular mechanisms underlying cardiac CO toxicity remain hypothetical. Wistar rats were exposed to simulated urban CO pollution for 4 wk. First, the effects of CO exposure on NO production and NO synthase (NOS) expression were evaluated. Myocardial I/R was performed on isolated perfused hearts in the presence or absence of S-methyl-isothiourea (1 μM), a NOS inhibitor highly specific for iNOS. Finally, Ca(2+) handling was evaluated in isolated myocytes before and after an anoxia-reoxygenation performed with or without S-methyl-isothiourea or N-acetylcystein (20 μM), a nonspecific antioxidant. Our main results revealed that 1) CO exposure altered the pattern of NOS expression, which is characterized by increased neuronal NOS and iNOS expression; 2) cardiac NO production increased in CO rats because of its overexpression of iNOS; and 3) the use of a specific inhibitor of iNOS reduced myocardial hypersensitivity to I/R (infarct size, 29 vs. 51% of risk zone) in CO rat hearts. These last results are explained by the deleterious effects of NO and reactive oxygen species overproduction by iNOS on diastolic Ca(2+) overload and myofilaments Ca(2+) sensitivity. In conclusion, this study highlights the involvement of iNOS overexpression in the pathogenesis of simulated urban CO air pollution exposure.

Significance of nitric oxide synthases: Lessons from triple nitric oxide synthases null mice

Nitric oxide (NO) is synthesized by three distinct NO synthases (neuronal, inducible, and endothelial NOSs), all of which are expressed in almost all tissues and organs in humans. The regulatory roles of NOSs in vivo have been investigated in pharmacological studies with non-selective NOS inhibitors. However, the specificity of the inhibitors continues to be an issue of debate, and the authentic significance of NOSs is still poorly understood. To address this issue, we generated mice in which all three NOS genes are completely disrupted. The triple NOSs null mice exhibited cardiovascular abnormalities, including hypertension, arteriosclerosis, myocardial infarction, cardiac hypertrophy, diastolic heart failure, and reduced EDHF responses, with a shorter survival. The triple NOSs null mice also displayed metabolic abnormalities, including metabolic syndrome and high-fat diet-induced severe dyslipidemia. Furthermore, the triple NOSs null mice showed renal abnormalities (nephrogenic diabetes insipidus and pathological renal remodeling), lung abnormalities (accelerated pulmonary fibrosis), and bone abnormalities (increased bone mineral density and bone turnover). These results provide evidence that NOSs play pivotal roles in the pathogenesis of a wide variety of disorders. This review summarizes the latest knowledge on the significance of NOSs in vivo, based on lessons learned from experiments with our triple mutant model.

eNOS plays an important role in the regulation of colonic inflammation: a novel therapeutic target and a predictive marker for the prognosis of ulcerative colitis

BACKGROUND

We reported that deficiency of the eNOS protein exacerbates colitis induced by dextran sodium sulfate (DSS-induced colitis). However, the role of eNOS in colitis remains controversial. Therefore, we studied how over-expression of eNOS affected this inflammatory condition, using vascular endothelial cells and mice as in vitro and in vivo models, respectively. Furthermore, we investigated the influence of a polymorphism in the eNOS gene on the clinical features of ulcerative colitis (UC).

METHODS

We examined the effect of eNOS overexpression on the expression of adhesion molecules in the endothelium and assessed the degree of DSS-induced colitis in eNOS transgenic (eNOS-Tg) mice. We also investigated the relationship between a polymorphism in the eNOS gene and clinical features of patients with UC.

RESULTS

The expression of adhesion molecules, under inflammatory conditions, was attenuated in eNOS gene-transfected vascular endothelial cells, as measured by western blot analysis. Symptoms of DSS-induced colitis were likewise attenuated in eNOS-Tg mice, which exhibited lower weight loss, mortality, histological damage (by inflammation score and crypt damage score), and colonic myeloperoxidase activity, tumor necrosis factor-α expression, and MAdCAM-1 expression than in wild-type mice. Furthermore, there was a significant relationship between intractable cases of UC and a polymorphism in the eNOS gene promoter (c.-786 T > C) that decreases eNOS expression.

CONCLUSION

The eNOS gene plays an important role in the regulation of colonic inflammation. The level of eNOS expression may be a predictive marker for prognosis of UC, and eNOS expression may be a novel therapeutic target.

Nitric oxide-induced murine hematopoietic stem cell fate involves multiple signaling proteins, gene expression, and redox modulation

There are a growing number of reports showing the influence of redox modulation in cellular signaling. Although the regulation of hematopoiesis by reactive oxygen species (ROS) and reactive nitrogen species (RNS) has been described, their direct participation in the differentiation of hematopoietic stem cells (HSCs) remains unclear. In this work, the direct role of nitric oxide (NO(•)), a RNS, in the modulation of hematopoiesis was investigated using two sources of NO(•) , one produced by endothelial cells stimulated with carbachol in vitro and another using the NO(•)-donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP) in vivo. Two main NO(•) effects were observed: proliferation of HSCs-especially of the short-term HSCs-and its commitment and terminal differentiation to the myeloid lineage. NO(•)-induced proliferation was characterized by the increase in the number of cycling HSCs and hematopoietic progenitor cells positive to BrdU and Ki-67, upregulation of Notch-1, Cx43, PECAM-1, CaR, ERK1/2, Akt, p38, PKC, and c-Myc. NO(•)-induced HSCs differentiation was characterized by the increase in granulocytic-macrophage progenitors, granulocyte-macrophage colony forming units, mature myeloid cells, upregulation of PU.1, and C/EBPα genes concomitantly to the downregulation of GATA-3 and Ikz-3 genes, activation of Stat5 and downregulation of the other analyzed proteins mentioned above. Also, redox status modulation differed between proliferation and differentiation responses, which is likely associated with the transition of the proliferative to differentiation status. Our findings provide evidence of the role of NO(•) in inducing HSCs proliferation and myeloid differentiation involving multiple signaling.