Nitro-aspirin (NCX4016) reduces brain damage induced by focal cerebral ischemia in the rat

Selenium nanoparticles for targeted stroke therapy through modulation of inflammatory and metabolic signaling

Ischemic cerebral stroke is a major cause of death and morbidity. Currently, no neuroprotective agents have been shown to impact the clinical outcomes in cerebral stroke cases. Here, we report therapeutic effects of Se nanoparticles on ischemic stroke in a murine model. Anti-transferrin receptor monoclonal antibody (OX26)-PEGylated Se nanoparticles (OX26-PEG-Se NPs) were designed and synthesized and their neuroprotective effects were measured using in vitro and in vivo approaches. We demonstrate that administration of the biodegradable nanoparticles leads to resolution of brain edema, protection of axons in hippocampus region, and myelination of hippocampal area after cerebral ischemic stroke. Our nanoparticle design ensures efficient targeting and minimal side effects. Hematological and biochemical analyses revealed no undesired NP-induced changes. To gain mechanistic insights into the therapeutic effects of these particles, we characterized the changes to the relevant inflammatory and metabolic signaling pathways. We assessed metabolic regulator mTOR and related signaling pathways such as hippo, Ubiquitin-proteasome system (ERK5), Tsc1/Tsc2 complex, FoxO1, wnt/β-catenine signaling pathway. Moreover, we examined the activity of jak2/stat3 signaling pathways and Adamts1, which are critically involved in inflammation. Together, our study provides a promising treatment strategy for cerebral stroke based on Se NP induced suppression of excessive inflammation and oxidative metabolism.

Electro-acupuncture at Conception and Governor vessels and transplantation of umbilical cord blood-derived mesenchymal stem cells for treating cerebral ischemia/reperfusion injury

Mesenchymal stem cell transplantation is a novel means of treating cerebral ischemia/reperfusion, and can promote angiogenesis and neurological functional recovery. Acupuncture at Conception and Governor vessels also has positive effects as a treatment for cerebral ischemia/reperfusion. Therefore, we hypothesized that electro-acupuncture at Conception and Governor vessels plus mesenchymal stem cell transplantation may have better therapeutic effects on the promotion of angiogenesis and recovery of neurological function than either treatment alone. In the present study, human umbilical cord blood-derived mesenchymal stem cells were isolated, cultured, identified and intracranially transplanted into the striatum and subcortex of rats at 24 hours following cerebral ischemia/reperfusion. Subsequently, rats were electro-acupunctured at Conception and Governor vessels at 24 hours after transplantation. Modified neurological severity scores and immunohistochemistry findings revealed that the combined interventions of electro-acupuncture and mesenchymal stem cell transplantation clearly improved neurological impairment and up-regulated vascular endothelial growth factor expression around the ischemic focus. The combined intervention provided a better outcome than mesenchymal stem cell transplantation alone. These findings demonstrate that electro-acupuncture at Conception and Governor vessels and mesenchymal stem cell transplantation have synergetic effects on promoting neurological function recovery and angiogenesis in rats after cerebral ischemia/reperfusion.

Neuroprotective effect of a new synthetic aspirin-decursinol adduct in experimental animal models of ischemic stroke

Stroke is the second leading cause of death. Experimental animal models of cerebral ischemia are widely used for researching mechanisms of ischemic damage and developing new drugs for the prevention and treatment of stroke. The present study aimed to comparatively investigate neuroprotective effects of aspirin (ASA), decursinol (DA) and new synthetic aspirin-decursinol adduct (ASA-DA) against transient focal and global cerebral ischemic damage. We found that treatment with 20 mg/kg, not 10 mg/kg, ASA-DA protected against ischemia-induced neuronal death after transient focal and global ischemic damage, and its neuroprotective effect was much better than that of ASA or DA alone. In addition, 20 mg/kg ASA-DA treatment reduced the ischemia-induced gliosis and maintained antioxidants levels in the corresponding injury regions. In brief, ASA-DA, a new synthetic drug, dramatically protected neurons from ischemic damage, and neuroprotective effects of ASA-DA may be closely related to the attenuation of ischemia-induced gliosis and maintenance of antioxidants.

Targeting gaseous molecules to protect against cerebral ischaemic injury: mechanisms and prospects

1. Ischaemic brain injury is a leading cause of death and disability in many countries. However, the pathological mechanisms underlying ischaemic brain injury, including oxidative stress, calcium overload, excitotoxicity and neuronal apoptosis, are perplexing and this makes it difficult to find effective novel drugs for the treatment of the condition. 2. Recently, gaseous molecules such as nitric oxide (NO), carbon monoxide (CO), hydrogen sulphide (H(2)S) and hydrogen (H(2)) have attracted considerable interest because of their physiological and pathophysiological roles in various body systems. Emerging evidence indicates that gaseous molecules are involved in the pathological processes of ischaemic brain damage. 3. In the present review, we summarize evidence regarding the involvement of gaseous molecules in ischaemic brain injury and discuss the therapeutic potential of targeting gaseous molecules. 4. Collectively, the available data suggest that the application of these biological gas molecules and their pharmacological regulators may be a potential therapeutic approach for the treatment of ischaemic brain injury.

Regulation of injury-induced neurogenesis by nitric oxide

The finding that neural stem cells (NSCs) are able to divide, migrate, and differentiate into several cellular types in the adult brain raised a new hope for restorative neurology. Nitric oxide (NO), a pleiotropic signaling molecule in the central nervous system (CNS), has been described to be able to modulate neurogenesis, acting as a pro- or antineurogenic agent. Some authors suggest that NO is a physiological inhibitor of neurogenesis, while others described NO to favor neurogenesis, particularly under inflammatory conditions. Thus, targeting the NO system may be a powerful strategy to control the formation of new neurons. However, the exact mechanisms by which NO regulates neural proliferation and differentiation are not yet completely clarified. In this paper we will discuss the potential interest of the modulation of the NO system for the treatment of neurodegenerative diseases or other pathological conditions that may affect the CNS.

Intravenous administration of pravastatin immediately after middle cerebral artery occlusion reduces cerebral oedema in spontaneously hypertensive rats

3-hydroxy-3-methyl-glutaryl-coenzyme-A (HMG-CoA) reductase inhibitors (statins) have been shown to protect against ischemic stroke by mechanisms that are independent of lowering serum cholesterol levels. In this study we investigated the potential neuroprotective effect of a single i.v. treatment with four increasing doses of pravastatin on permanent occlusion of middle cerebral artery (MCAo) in spontaneously hypertensive rats. Pravastatin was given 10 min after MCAo and its effect was determined 24 h later. Treatment results were evaluated in terms of infarct volume, homolateral hemisphere oedema, glial fibrillary acid (GFAP), vimentin (Vim) and endothelial NO synthase (eNOS) immunoreactivity and TUNEL positivity. Cerebral levels of eNOS were measured by western blot analysis. Pravastatin did not reduce cerebral infarct while it mitigated homolateral hemisphere oedema in a dose-dependent manner with respect to controls. No differences among groups were found regarding GFAP and Vim immunoreactivity and TUNEL positivity. Instead, pravastatin-treated animals presented a more marked cerebral eNOS immunoreactivity as compared with controls. In agreement with immunohistochemistry, immunoblot revealed dose-dependent increases in cerebral levels of eNOS in pravastatin rats. Our data confirm statin neuroprotection in cerebral ischemia. In particular, it is of great interest that a single i.v. Pravastatin administration reduced cerebral oedema by upregulating eNOS expression/activity. This, by increasing vascular NO bioavailability, could have produced proximal vasodilation and contributed to reducing perfusional deficit. It is worthy stressing how important the anti-oedema action is that pravastatin seems to exert. Indeed, cerebral oedema, when widespread and beyond limits of physiological compensation, causes endocranic hypertension and additional cerebral damage over time.

Nitric oxide: new evidence for novel therapeutic indications

BACKGROUND

Nitric oxide (NO) deficiency is implicated in many pathophysiological processes in mammals. NO is a ubiquitous molecule involved in multiple cellular functions. Uncontrolled or inappropriate production of NO may lead to several disease states including septic shock, rheumatoid and inflammatory arthropathies, and expansion of cerebral damage after stroke. However, to date, there are no therapeutic agents available that can overcome these conditions. Similarly, underproduction of NO by NO synthase or enhanced breakdown of NO also leads to diseases such as hypertension, ischemic conditions, pre-eclampsia, premature delivery, among others. NO donor therapies are indicated in these conditions.

RESULTS

Nitroglycerin and nitrates (NO donors) have been used as therapeutic agents for the past century, particularly to treat vascular disease, and the only significant adverse effects are headaches. NO donors are highly cost-effective and have beneficial effects in multiple body systems. When the body cannot generate NO via NO synthase or due to rapid turnover leading to inadequate amounts of NO available for biological homeostasis, administration of exogenous NO, or prolongation of the actions of endogenous NO, are practical ways to supplement NO.

CONCLUSION

Recipients of such therapy include patients with angina pectoris, coronary artery disease, hypertension, osteoporosis, gastrointestinal motility disorders, pregnancy-related disorders including premature delivery, pre-eclampsia, vulvodynia, and erectile dysfunction in men. Postmenopausal NO deficiency is rectified with hormone replacement therapy, which enhances local production of NO. Declining local NO production secondary to estrogen deficiency in postmenopausal women and perhaps in older men could be one of the reasons for age-related increased incidences of cardiovascular events and sexual dysfunction. Thus, in addition to supplementation of NO compounds in acute situations like alleviating angina and erectile dysfunction, chronic NO therapy is cost-effective in decreasing cardiovascular events, and improving the urogenital system and skeletal health.

Nitric oxide, ischaemia and brain inflammation

Cerebral ischaemia results in the activation of three isoforms of NOS (nitric oxide synthase) that contribute to the development of and recovery from stroke pathology. This review discusses, in particular, the role of the transcriptionally activated NOS-2 (inducible NOS) isoform and summarizes the outcomes of experimental stroke studies with regard to the therapeutic utility of nitric oxide donors and NOS inhibitors.

Targeting Nitric Oxide With Drug Therapy

Increasing knowledge of the role of nitric oxide (NO) in physiology and disease has stimulated efforts to target the NO pathway pharmacologically. These therapeutic strategies include NO donors that directly or indirectly release NO and agents that increase NO bioactivity. Traditional organic nitrates such as nitroglycerin, which indirectly release NO, were believed to have limited long-term efficacy and tolerability, chiefly because of nitrate tolerance. Recent studies, however, suggest more effective ways of using these agents and new applications for them. Nicorandil, a hybrid organic nitrate that also activates potassium channels, has demonstrated significant benefits in acute coronary syndromes. Other nitrates are being investigated for use in neurodegenerative diseases. Direct NO donors include NO gas, which is useful in respiratory disorders, and the more recent classes of diazeniumdiolates, sydnonimines, and S-nitrosothiols. Preliminary data suggest that these agents may be effective as antiatherosclerotic agents as well as in other disease states. In addition, hybrid agents that consist of an NO donor coupled with a parent anti-inflammatory drug, including nonsteroidal anti-inflammatory drugs, have demonstrated enhanced efficacy and tolerability compared with the anti-inflammatory parent drug alone in diverse experimental models. Established drugs that enhance NO bioactivity include antihypertensive agents, particularly angiotensin-converting enzyme inhibitors, calcium channel blockers, and newer vasodilating beta-blockers. In addition, 3-methylglutaryl coenzyme A reductase inhibitors (statins) promote NO bioactivity, both through and independent of lipid lowering. The NO-promoting actions of these established drugs provide some insight into their known benefits and suggest possible therapeutic potential.

Prevention of Postischemic Myocardial Reperfusion Injury by the Combined Treatment of NCX-4016 and Tempol

Nitric oxide (NO) plays a protective role in myocardial ischemia-reperfusion (I/R) injury. However, the concomitant production of superoxide and other reactive oxygen species (ROS) during I/R may diminish the bioavailability of NO and hence compromise the beneficial effects. The objective of this study was to investigate the protective effect of the coadministration of NCX-4016 [2-(acetyloxy)benzoic acid 3-(nitrooxymethyl)phenyl ester] (an NO donor) with antioxidants Tempol, superoxide dismutase (SOD), or urate on I/R injury. Isolated rat hearts, perfused with Krebs-Henseleit buffer, were subjected to 30 minutes of global ischemia, followed by 45 minutes of reperfusion. Before the induction of ischemia, the hearts were infused for 1 minute with NCX-4016 (100 microM) either alone or in combination with Tempol (100 microM), SOD (200 U/mL), or urate (100 microM). Hearts pretreated with NCX-4016 showed a significantly enhanced recovery of function and decreased infarct size and LDH/CK release compared with the controls. However, treatment of hearts with NCX-4016 + Tempol, SOD, or urate showed a significantly enhanced recovery of heart function compared with NCX-4016 alone. The treatment of hearts with NCX-4016 + Tempol showed significantly enhanced NO generation and decreased ROS and dityrosine (a marker of peroxynitrite) formation. In conclusion, NCX-4016 in combination with Tempol demonstrated significant cardioprotection and, thus, may offer a novel therapeutic strategy to prevent I/R-mediated myocardial injury.

A systematic review of nitric oxide donors and L-arginine in experimental stroke; effects on infarct size and cerebral blood flow

BACKGROUND

Nitric oxide (NO) is a candidate treatment for acute ischaemic stroke, however published studies in experimental stroke have given conflicting results.

METHODS

We performed a systematic review of published controlled studies of L-arginine (the precursor for NO) and NO donors in experimental stroke. Data were analysed using the Cochrane Collaboration Review Manager software. Standardised mean difference (SMD) and 95% confidence intervals (95% CI) were calculated.

RESULTS

Altogether, 25 studies(s) were identified. L-Arginine and NO donors reduced total cerebral infarct volume in permanent (SMD -1.21, 95% CI -1.69 to -0.73, p < 0.01, s = 10) and transient models of ischaemia (SMD -0.78, 95% CI -1.21 to -0.35, p < 0.01, s = 7). Drug administration increased cortical CBF in permanent (SMD +0.86, 95% CI 0.52-1.21, p < 0.01, s = 8) but not transient models (SMD +0.34, 95% CI -0.02 to 0.70, p = 0.07, s = 4).

CONCLUSIONS

Administration of NO in experimental stroke reduces stroke lesion volume in permanent and transient models. This may be mediated, in part, by increased cerebral perfusion in permanent models. These data support clinical trials in stroke patients, although the presence of a narrow therapeutic time window may be a limiting factor.

Modulation of prostaglandin biosynthesis by nitric oxide and nitric oxide donors

The biosynthesis and release of nitric oxide (NO) and prostaglandins (PGs) share a number of similarities. Two major forms of nitric-oxide synthase (NOS) and cyclooxygenase (COX) enzymes have been identified to date. Under normal circumstances, the constitutive isoforms of these enzymes (constitutive NOS and COX-1) are found in virtually all organs. Their presence accounts for the regulation of several important physiological effects (e.g. antiplatelet activity, vasodilation, and cytoprotection). On the other hand, in inflammatory setting, the inducible isoforms of these enzymes (inducible NOS and COX-2) are detected in a variety of cells, resulting in the production of large amounts of proinflammatory and cytotoxic NO and PGs. The release of NO and PGs by the inducible isoforms of NOS and COX has been associated with the pathological roles of these mediators in disease states as evidenced by the use of selective inhibitors. An important link between the NOS and COX pathways was made in 1993 by Salvemini and coworkers when they demonstrated that the enhanced release of PGs, which follows inflammatory mechanisms, was nearly entirely driven by NO. Such studies raised the possibility that COX enzymes represent important endogenous "receptor" targets for modulating the multifaceted roles of NO. Since then, numerous papers have been published extending the observation across various cellular systems and animal models of disease. Furthermore, other studies have highlighted the importance of such interaction in physiology as well as in the mechanism of action of drugs such as organic nitrates. More importantly, mechanistic studies of how NO switches on/off the PG/COX pathway have been undertaken and additional pathways through which NO modulates prostaglandin production unraveled. On the other hand, NO donors conjugated with COX inhibitors have recently found new interest in the understanding of NO/COX reciprocal interaction and potential clinical use. The purpose of this article is to cover the advances which have occurred over the years, and in particular, to summarize experimental data that outline how the discovery that NO modulates prostaglandin production has impacted and extended our understanding of these two systems in physiopathological events.

Glial nitric oxide and ischemia

One of the responses to cerebral ischemia is an increase in the production of nitric oxide, catalyzed by enzymes expressed in both resident and infiltrating cells. The nitric oxide that is generated does contribute to the ensuing pathology, but it can also be beneficial. The effects of nitric oxide depend on the cell site of production, the amount generated, and the chemical nature of the products of further oxidation. Understanding how nitric oxide production from microglia and astrocytes contributes to ischemic pathology is important for the development and application of future therapeutics based on inhibiting or amplifying its production in the injured brain.

Systematic review and metaanalysis of the efficacy of FK506 in experimental stroke

FK506 is a candidate drug for acute stroke. For such drugs, any decision to proceed to clinical trial should be based on a full and unbiased assessment of the animal data, and consideration should be given to the limitations of those data. Such an assessment should include not only the efficacy of a drug but also the in vivo characteristics and limits to that efficacy. Here we use systematic review and meta-analysis to assess the evidence for a protective effect of FK506 in animal models of stroke. In all, 29 studies were identified describing procedures involving 1759 animals. The point estimate for the effect of FK506 was a 31.3% (95% confidence interval 27.2% to 35.4%) improvement in outcome. Efficacy was higher with ketamine anaesthesia and temporary ischaemia and was lower in rats, in animals with comorbidities, and where outcome was measured as infarct size alone. Reported study quality was modest by clinical trial standards, and efficacy was lower in high-quality studies. These findings show a substantial efficacy for FK506 in experimental stroke, but raise concerns that our estimate of effect size might be too high because of factors such as study quality and possible publication bias.

Nitrates and NO release: contemporary aspects in biological and medicinal chemistry

Nitroglycerine has been used clinically in the treatment of angina for 130 years, yet important details on the mechanism of action, biotransformation, and the associated phenomenon of nitrate tolerance remain unanswered. The biological activity of organic nitrates can be said to be nitric oxide mimetic, leading to recent, exciting progress in realizing the therapeutic potential of nitrates. Unequivocally, nitroglycerine and most other organic nitrates, including NO-NSAIDs, do not behave as NO donors in the most fundamental action: in vitro activation of sGC to produce cGMP. The question as to whether the biological activity of nitrates results primarily or exclusively from NO donation will not be satisfactorily answered until the location, the apparatus, and the mechanism of reduction of nitrates to NO are defined. Similarly, the therapeutic potential of nitrates will not be unlocked until this knowledge is attained. Aspects of the therapeutic and biological activity of nitrates are reviewed in the context of the chemistry of nitrates and the elusive efficient 3e- reduction required to generate NO.

Nitric oxide-releasing aspirin derivative, NCX 4016, promotes reparative angiogenesis and prevents apoptosis and oxidative stress in a mouse model of peripheral ischemia

BACKGROUND

Recently, nitric oxide (NO) donors have been developed that mimic the physiological intracellular release of NO. We evaluated whether one of these new compounds, consisting of aspirin coupled to an NO-releasing moiety (NCX 4016), would protect limbs from supervening arterial occlusion.

METHODS AND RESULTS

Mice were assigned to receive regular chow or chow containing NCX 4016 or aspirin (both at 300 mumol/kg body weight, daily) throughout the 3-week experimental period. One week after randomization, they underwent surgical excision of the left femoral artery. Limb blood flow recovery (laser Doppler flowmetry) was accelerated by NCX 4016 as compared with aspirin or vehicle (P<0.05). In controls, histological analysis revealed a 35% increase in the capillary density of ischemic muscles compared with contralateral ones, indicative of spontaneous angiogenesis. Neovascularization was enhanced by NCX 4016 (91%; P<0.05 versus vehicle), but not by aspirin (51%; P=NS versus vehicle). Furthermore, NCX 4016 reduced endothelial cell (EC) apoptosis (4.3+/-1.0 versus 8.7+/-2.0 in aspirin and 12.6+/-3.3 ECs/1000 cap in vehicle; P<0.05 for either comparison) as well as caspase-3 mRNA levels in ischemic muscles ([caspase-3/GAPDH]*100 = 0.09+/-0.04 versus 2.30+/-0.44 in aspirin and 2.30+/-0.32 in vehicle; P<0.01 for either comparison). Nitrite levels and the ratio of reduced to oxidized glutathione were selectively increased in ischemic muscles by NCX 4016. Vascular endothelial growth factor-A expression was reduced by aspirin, with this effect being blunted by NCX 4016.

CONCLUSIONS

Pretreatment with the new oral NO-releasing aspirin derivative stimulates reparative angiogenesis and prevents apoptosis and oxidative stress, thereby alleviating the consequences of supervening arterial occlusion.

Antioxidant activity of nitro derivative of aspirin against ischemia-reperfusion in hamster cheek pouch microcirculation

Aspirin that has been chemically combined with a nitric oxide (NO) donor (NCX-4016) has been shown to inhibit cyclooxygenase and prostaglandin generation while maintaining the inhibitory effects of aspirin. The possible role of reactive oxygen species (ROS) in the action of NCX-4016 in ischemia-reperfusion (I/R) has not been studied. Furthermore, we were interested in comparing the effects of a conventional NO donor [2,2'-hydroxynitrosohydrazino-bis-etanamine (DETA/NO)] and NCX-4016 at the microvascular level in the hamster cheek pouch visualized by using an intravital fluorescent microscopy technique. Microvascular injury was assessed by measuring diameter change, the perfused capillary length (PCL), and leukocyte adhesion. Animals were treated with NCX-4016 (100 mg/kg or 30 mg.kg(-1).day(-1) for 5 days po) or DETA-NO (0.5 mg/kg). Mean arterial blood pressure increased slightly but significantly after NCX-4016 treatment. During 5- and 15-min reperfusion, lipid peroxides in the systemic blood increased by 72 and 89% vs. baseline, respectively, and were still higher than in basal conditions after 30-min reperfusion in the I/R group. Pretreatment with NCX-4016 maintained ROS at normal levels; increased arteriolar diameter, blood flow, and PCL; and decreased leukocyte adhesion (P < 0.05). DETA-NO decreased ROS during 30-min reperfusion; however, later there was a significant increase during reperfusion. DETA-NO decreased leukocyte adhesion (P < 0.05) but microvascular permeability increased after 30 min of reperfusion. In conclusion, NCX-4016 attenuates oxidative stress and prevents arteriolar constriction during I/R, whereas DETA-NO increases lipid peroxides in the systemic blood and permeability after reperfusion.

Nitric oxide-releasing drugs

Pharmacological compounds that release nitric oxide (NO) have been useful tools for evaluating the broad role of NO in physiology and therapeutics. NO deficiency has been implicated in the genesis and evolution of several disease states. Both medical needs and commercial opportunities have fostered attempts to modulate NO in the human body for therapeutic gain. Strategies for NO modulation encompass antiinflammatory, sexual dysfunction, and cardiovascular indications. Apart from newly developed drugs, several commonly used cardiovascular drugs exert their beneficial action, at least in part, by modulating the NO pathway. This review discusses the fundamental pharmacological properties and mechanisms of action of NO-releasing drugs. Some of these compounds may enter in the clinical arena providing important therapeutic benefits in human diseases.

Acetylsalicylic acid reduces perfusion deficit in ischemic injured brain in rats

Acetylsalicylic acid (ASA) is an antiplatelet agent which has been used in treatment and prevention of stroke in humans. In the present study, the effects of ASA on perfusion deficits in the brain have been studied in an embolic model of stroke. Data showed that perfusion deficits were observed in all rats sacrificed immediately after middle cerebral artery (MCA) occlusion. Treatment with ASA significantly reduced perfusion deficits 1 h but not 3 h after the MCA occlusion. These findings thus support that ASA is useful agent in treatment and prevention of stroke, and show that its mechanism of action is likely through the reopening of cerebral microvessels.

[3-(1H-imidazol-4-yl)propyl]guanidines containing furoxan moieties: a new class of H3-antagonists endowed with NO-donor properties

Synthesis and pharmacological characterisation of a series of products obtained by coupling the H(3)-antagonist SKF 91486 through appropriate spacers with the NO-donor 3-phenylfuroxan-4-yloxy and 3-benzenesulfonylfuroxan-4-yloxy moieties, as well as with the corresponding furazan substructures, devoid of NO-donating properties, are reported. All the products were tested for their H(3)-antagonistic and H(2)-agonistic properties on electrically-stimulated guinea-pig ileum segments and guinea-pig papillary muscle, respectively. The whole series of compounds displayed good H(3)-antagonist behaviour and feeble partial H(2)-agonist activity. Among furoxan derivatives, the benzenesulfonyl hybrid 28, a good NO-donor, triggered a dual NO-dependent muscle relaxation and H(3)-antagonistic effect on guinea-pig intestine.

The potential of nitric oxide therapeutics in stroke

The therapeutic modulation of the nitric oxide (NO) system has generated considerable interest as a new way for managing many disease processes. In stroke, a useful strategy is to increase NO availability and thereby exploit its beneficial antiplatelet, antiatherosclerotic, haemodynamic and neuroprotective properties. Pharmacologically, this can be achieved by providing NO substrate, using NO donors or by upregulating nitric oxide synthase. Alternatively, one can reduce NO availability by inhibiting NO synthase and thereby limiting its pro-inflammatory and neurotoxic properties. This article reviews developments in NO-related therapeutics for treatment of stroke, with a particular emphasis on compounds that are in the clinical research and development pipeline. Although the routine use of NO therapeutics for the prevention or treatment of stroke cannot currently be recommended, we are evidently at an exciting stage in their pharmacological development. Definitive randomised controlled trials in stroke patients are required as a matter of urgency.

Pharmacology and potential therapeutic applications of nitric oxide-releasing non-steroidal anti-inflammatory and related nitric oxide-donating drugs

This review examines the biological significance, therapeutic potential and mechanism(s) of action of a range of nitric oxide-releasing non-steroidal anti-inflammatory drugs (NO-NSAID) and related nitric oxide-releasing donating drugs (NODD). The slow release of nitric oxide (NO) from these compounds leads to subtle changes in the profile of pharmacological activity of the parent, non-steroidal anti-inflammatory drugs (NSAID). For example, compared with NSAID, NO-NSAID cause markedly diminished gastrointestinal toxicity and improved anti-inflammatory and anti-nociceptive efficacy. In addition, nitroparacetamol exhibits hepatoprotection as opposed to the hepatotoxic activity of paracetamol. The possibility that NO-NSAID or NODD may be of therapeutic benefit in a wide variety of disease states including pain and inflammation, thrombosis and restenosis, neurodegenerative diseases of the central nervous system, colitis, cancer, urinary incontinence, liver disease, impotence, bronchial asthma and osteoporosis is discussed.

Nitric oxide donor drugs: current status and future trends

Nitric oxide synthesised in endothelial cells that line blood vessels has a wide range of functions that are vital for maintaining a healthy cardiovascular system. Reduced nitric oxide availability is implicated in the initiation and progression of many cardiovascular diseases and delivery of supplementary nitric oxide to help prevent disease progression is an attractive therapeutic option. Nitric oxide donor drugs represent a useful means of systemic nitric oxide delivery and organic nitrates have been used for many years as effective therapies for symptomatic relief from angina. However, nitrates have limitations and a number of alternative nitric oxide donor classes have emerged since the discovery that nitric oxide is a crucial biological mediator. This review focuses on novel advances and possible future directions in nitric oxide donor drug development.

Colon cancer prevention with NO-releasing NSAIDs

A seminal advance in the prevention of colon cancer has been the observation that nonsteroidal antiinflammatory drugs (NSAIDs) reduce the incidence of and mortality from colon cancer by about half. Among current efforts to overcome the side effects of NSAIDs, an important limitation for their application as chemopreventive agents, is the synthesis of nitric oxide-releasing NSAIDs. These novel compounds may display greater safety and greater efficacy compared to their parent traditional NSAIDs and thus hold significant promise as chemopreventive agents against human colon cancer. In this review we discuss salient features of their pharmacology, in vitro and animal data pertaining to colon cancer, their mechanisms of action, and assess their potential in the chemoprevention of colon cancer.

Nitric oxide donors and cardiovascular agents modulating the bioactivity of nitric oxide: an overview

Nitric oxide (NO) mediates multiple physiological and pathophysiological processes in the cardiovascular system. Pharmacological compounds that release NO have been useful tools for evaluating the pivotal role of NO in cardiovascular physiology and therapeutics. These agents constitute two broad classes of compounds, those that release NO or one of its redox congeners spontaneously and those that require enzymatic metabolism to generate NO. In addition, several commonly used cardiovascular drugs exert their beneficial action, in part, by modulating the NO pathway. Here, we review these classes of agents, summarizing their fundamental chemistry and pharmacology, and provide an overview of their cardiovascular mechanisms of action.