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At least 973 records · Page 54Linked to original sources
PubMed1998

Role of non-nitric oxide non-prostaglandin endothelium-derived relaxing factor(s) in bradykinin vasodilation.

The most conspicuous effect of bradykinin following its administration into the systemic circulation is a transient hypotension due to vasodilation. In the present study most of the available evidence regarding the mechanisms involved in bradykinin-induced arterial vasodilation is reviewed. It has become firmly established that in most species vasodilation in response to bradykinin is mediated by the release of endothelial relaxing factors following the activation of B2-receptors. Although in some cases the action of bradykinin is entirely mediated by the endothelial release of nitric oxide (NO) and/or prostacyclin (PGI2), a large amount of evidence has been accumulated during the last 10 years indicating that a non-NO/PGI2 factor accounts for bradykinin-induced vasodilation in a wide variety of perfused vascular beds and isolated small arteries from several species including humans. Since the effect of the non-NO/PGI2 endothelium-derived relaxing factor is practically abolished by disrupting the K+ electrochemical gradient together with the fact that bradykinin causes endothelium-dependent hyperpolarization of vascular smooth muscle cells, the action of such factor has been attributed to the opening of K+ channels in these cells. The pharmacological characteristics of these channels are not uniform among the different blood vessels in which they have been examined. Although there is some evidence indicating a role for KCa or KV channels, our findings in the mesenteric bed together with other reports indicate that the K+ channels involved do not correspond exactly to any of those already described. In addition, the chemical identity of such hyperpolarizing factor is still a matter of controversy. The postulated main contenders are epoxyeicosatrienoic acids or endocannabinoid agonists for the CB1-receptors. Based on the available reports and on data from our laboratory in the rat mesenteric bed, we conclude that the NO/PGI2-independent endothelium-dependent vasodilation induced by BK is unlikely to involve a cytochrome P450 arachidonic acid metabolite or an endocannabinoid agonist.

Animals↗
PubMed2003

Analyses of anandamide and endocannabinoid-like compounds using collision-induced dissociation in fast atom bombardment ionization-mass spectrometry and gas chromatography/chemical ionization-mass spectrometry.

The utility of the collision-induced dissociation (CID) of two different forms of precursor cations generated by the fast atom bombardment (FAB) ionization of N-arachidonylethanolamine (anandamide) and a series of endocannabinoid-like compounds, such as N-oleoylethanolamine, N-palmitoylethanolamine, N-stearoylethanolamine, N-linoleoylethanolamine, N-oleoylpropanolamine, and N-palmitoylpropanolamine, as a method of providing general information on their characterizations was examined. The CID spectra of lithium-adduct [M+Li]+ ions of the amines with unsaturated hydrocarbon chains were rich in structurally informative charge-site-remote (CSR) fragmentation patterns that provide information on the locations of double bonds in hydrocarbon chains. On the other hand, the CID reactions of [M+H]+ ions produced acylium ions that are derived from the cleavage of amide bonds, thus providing information on the size of the hydrocarbon chains, although CSR fragmentations were not observed. These compounds without derivatization were analyzed using gas chromatography/chemical ionization-mass spectrometry (GC/CI-MS) with a polyethylene glycol phased column with fused silica capillary pre-tubing. Identifiable molecular-related [M+H]+ ions were observed.

Arachidonic Acids↗
PubMed2005

Endocannabinoid-related enzymes as drug targets with special reference to N-acylphosphatidylethanolamine-hydrolyzing phospholipase D.

Anandamide (N-arachidonoylethanolamine) is the first discovered endocannabinoid (endogenous ligand of cannabinoid receptors). In animal tissues, anandamide is principally formed together with other bioactive long-chain N-acylethanolamines from membrane glycerophospholipid by two enzyme reactions. The first reaction is the transfer of a fatty acyl chain from the sn-1 position of glycerophospholipid to phosphatidylethanolamine by calcium-dependent N-acyltransferase, resulting in the generation of N-acylphosphatidylethanolamine (NAPE). The second reaction is catalyzed by a phosphodiesterase of the phospholipase D (PLD)-type, which releases N-acylethanolamines from their corresponding NAPEs. The produced N-acylethanolamines are hydrolyzed to fatty acids and ethanolamine by fatty acid amide hydrolase or an amidase acting exclusively at acidic pH. Our recent cDNA cloning of the NAPE-hydrolyzing PLD (NAPE-PLD) from mouse, rat and human revealed that NAPE-PLD is a novel enzyme which has no homology with any known PLD enzymes, but belongs to the zinc metallo-hydrolase family of the beta-lactamase fold. The recombinant enzyme hydrolyzed various NAPEs, including the anandamide precursor N-arachidonoylphosphatidylethanolamine at similar rates, but was inactive with phosphatidylcholine and phosphatidylethanolamine. Considering cannabimimetic activities of anandamide, the enzymes involved in the biosynthesis and degradation of anandamide, including NAPE-PLD, may be promising targets for therapeutic agents.

Amino Acid Sequence↗
PubMed2006

Therapeutic potential of targeting the endocannabinoids: implications for the treatment of obesity, metabolic syndrome, drug abuse and smoking cessation.

Rimonabant (SR141716, Acomplia) has been described as an antagonist/inverse agonist at the cannabinoid receptor type 1 (CB1). It has been widely used as a tool to evaluate the mechanisms by which cannabinoid agonists produce their pharmacological effects and to elucidate the respective physiological or pathophysiological roles of the CB1 receptor. It has become increasingly clear that rimonabant can exert its own intrinsic actions. These may be viewed as evidence of either the inverse agonist nature of rimonabant or of tonic activity of the endocannabinoid system. To date, data obtained from clinical trials (RIO North America, RIO Europe and RIO Lipid) indicate that rimonabant may have clinical benefits in relation to its anti-obesity properties and as a novel candidate for the treatment of metabolic and cardiovascular disorders associated with overweight and obesity. Other clinical trials, such as the STRATUS study, have also shown that rimonabant may be effective in smoking cessation, and that the drug has a reasonable safety profile. Recently, it has been shown that rimonabant prevents indomethacin-induced intestinal injury by decreasing the levels of pro-inflammatory cytokine tumour necrosis factor alpha (TNFalpha), thus indicating that CB1 receptor antagonists might exhibit potential anti-inflammatory activity in acute and chronic diseases.

Animals↗
PubMed2004

Oxidative metabolism of endocannabinoids by COX-2.

The last decade has witnessed a rapid expansion in our understanding of the mammalian endogenous cannabinoid system. In just a few short years since the discovery of endogenous lipids that serve as cannabinoids in vivo, these molecules have been shown to participate in a broad array of physiological and pathological processes. Consequently, attention has been directed at defining the proteins responsible for endocannabinoid synthesis, transport, and metabolism. Recently, multiple fatty acid oxygenases including, most notably, cyclooxygenase-2 (COX-2), have been implicated in endocannabinoid metabolism. This review will highlight connections between COX-2 and the endogenous cannabinoid system. The available biochemical evidence supporting a role for COX-2 in endocannabinoid metabolism will be presented. Finally, the potential biological consequences of COX-2-mediated endocannabinoid oxygenation will be discussed.

Binding Sites↗
PubMed2005

Focus on the three key enzymes hydrolysing endocannabinoids as new drug targets.

The family of endocannabinoids (i.e., the endogenous agonists of cannabinoid receptors) contains several polyunsaturated fatty acid amides such as anandamide (AEA) and oleamide but also esters such as 2-arachidonoylglycerol (2-AG). These compounds are the subject of growing interest in pharmacology for their multiple therapeutic potentials. Unfortunately, they are rapidly inactivated by enzymatic hydrolysis, which prevents their effective medical use. Inhibitors of endocannabinoid degradation seem to be necessary tools for the development of endocannabinoid therapeutics. But hitting this target is inconceivable without good knowledge of the enzymes. Fatty acid amide hydrolase (FAAH) is the oldest and the best characterised enzyme involved in the degradation of endocannabinoids. Cloning, distribution in the body and crystal structure of FAAH have been described. A large number of FAAH inhibitors have also been synthesised and tested. For a long time, FAAH was considered as the only key enzyme hydrolysing endocannabinoids. But recent findings indicate that at least two other enzymes have critical role in the endocannabinoids degradation. Monoglyceride lipase participates in 2-AG degradation and some data indicate that it is the primary mechanism for 2-AG inactivation in intact neurons. N-palmitoylethanolamine-selective acid amidase (NPAA) is a second fatty acid amide hydrolase more active with N-palmitoylethanolamine, an anti-inflammatory substance. The purpose of this review is to collect and compare the catalytic properties of these 3 key enzymes hydrolysing endocannabinoids.

Amidohydrolases↗
PubMed2006

Fatty acid amide hydrolase: a potential target for next generation therapeutics.

Endocannabinoids are amides, esters and ethers of long chain polyunsaturated fatty acids, which act as new lipid mediators. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol are the main endogenous agonists of cannabinoid receptors, able to mimic several pharmacological effects of Delta(9)-tetrahydrocannabinol, the active principle of Cannabis sativa preparations like hashish and marijuana. The activity of AEA at its receptors is limited by cellular uptake through a specific membrane transporter, followed by intracellular degradation by a fatty acid amide hydrolase (FAAH). Growing evidence demonstrates that FAAH is the critical regulator of the endogenous levels of AEA, suggesting that it may serve as an attractive therapeutic target for the treatment of human disorders. In particular, FAAH inhibitors may be next generation therapeutic drugs of potential value for the treatment of pathologies in the central nervous system and in the periphery. Here, the potential applications of these inhibitors for human disease will be reviewed, with an emphasis on the properties of hydro(pero)xy-anandamides. In fact, these oxygenated derivatives of AEA are the most powerful inhibitors of FAAH of natural origin as yet discovered. In addition, new insights into the promoter region of FAAH gene will be presented, and the therapeutic potential of mimetics of transcription factors of this gene in the management of human infertility will be discussed.

Amidohydrolases↗
PubMed2006

New insights into endocannabinoid degradation and its therapeutic potential.

Endocannabinoids are amides, esters and ethers of long chain polyunsaturated fatty acids, which act as new lipidic mediators. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol (2-AG) are the main endogenous agonists of cannabinoid receptors, able to mimic several pharmacological effects of (-)-Delta9-tetrahydrocannabinol (THC), the active principle of Cannabis sativa preparations like hashish and marijuana. The activity of AEA and 2-AG at their receptors is limited by cellular uptake through an anandamide membrane transporter (AMT), followed by intracellular degradation. A fatty acid amide hydrolase (FAAH) is the main AEA hydrolase, whereas a monoacylglycerol lipase (MAGL) is critical in degrading 2-AG. Here, we will review growing evidence that demonstrates that these hydrolases are pivotal regulators of the endogenous levels of AEA and 2-AG in vivo, overall suggesting that specific inhibitors of AMT, FAAH or MAGL may serve as attractive therapeutic targets for the treatment of human disorders. Recently, the N-acylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD), which synthesizes AEA from N-arachidonoylphosphatidylethanolamine (NArPE), and the diacylglycerol lipase (DAGL), which generates 2-AG from diacylglycerol (DAG) substrates, have been characterized. The role of these synthetic routes in maintaining the endocannabinoid tone in vivo will be discussed. Finally, the effects of inhibitors of endocannabinoid degradation in animal models of human disease will be reviewed, with an emphasis on their ongoing applications in anxiety, cancer and neurodegenerative disorders.

Arachidonic Acid↗
PubMed2003

The endocannabinoid system and Huntington's disease.

The research in Huntington's disease (HD) has been growing exponentially during the last decade, since the discovery of the genetic basis that leads to neurodegeneration. HD is one of several progressive neurodegenerative disorders, in which the underlying mutation is a CAG expansion encoding a polyglutamine tract in a specific protein, which in the case of HD, is called huntingtin. The first clinical symptoms of HD are generally psychiatric abnormalities, most commonly depression and mood disturbances. Involuntary choreiform movements and dementia develop over the next 15-20 years, and death generally results from complications derived from immobility. There is currently no cure, or even an effective therapy to offset the decline in mental and motor capabilities suffered by those affected by HD, but recent studies have started to examine the usefulness of different classes of new compounds. Among these, plant-derived, synthetic or endogenous cannabinoids have been proposed to have therapeutic value for the treatment of HD, since they act on cannabinoid CB(1) receptors located in the basal ganglia circuitry, that is affected by the striatal atrophy typical of HD. Recent studies have characterized the changes in these receptors, as well as their endogenous ligands, in the basal ganglia in a variety of animal models of HD. The results are indicative that the endocannabinoid system becomes hypofunctional in this disease, which could be related to the hyperkinesia typical of the earliest phases of this disease. In addition, it has been proposed that the loss of these receptors might be involved in the process of pathogenesis itself. This, together with the well-known protective properties of cannabinoid-related compounds, suggest that, in addition to a symptomatic usefulness, cannabinoids might also serve to delay or to arrest the development of this disease. The present article will review all recent data dealing with the biochemical, pharmacological and therapeutic bases that support a potential role of cannabinoids in the pathogenesis and/or therapeutic treatment of this motor disorder.

Animals↗
PubMed2005

Endocannabinoids in neuroimmunology and stress.

Two topics are presented in this review. In the first section, we review data regarding the effects of the endocannabinoids (eCBs) and cannabinoid receptors on neuroimmune function. The function of eCBs in the interaction between the immune system and the central nervous system (CNS) is of particular interest, since the CNS itself is a rich source of eCBs while being exquisitely sensitive to inflammation. There are several sites at which cannabinoids can influence neuroinflammation. Microglial cells express both CB receptors and make eCBs. Activation of CB receptors on these cells seems to promote migration and proliferation but to reduce activation to macrophages. In several neurodegenerative diseases, up-regulation of microglial CB2 receptors have been observed. It is our hypothesis that microglial CB receptor activity is anti-inflammatory and could be exploited to manipulate neuroinflammatory processes with a minimum of unwanted effects. The second topic discussed suggests that the eCB/CB1 receptor pair is involved in the responses of animals to acute, repeated and variable stress. The roles of this pair are complex and dependent upon previous stress, among other things. Dysfunctional responding to stress is a component of several human neuropsychiatric disorders, including anxiety and panic disorders, post-traumatic stress disorders, premenstrual dysphoria and quite possibly, drug abuse. While it is too early to say with certainty, it is very possible that either inhibition or potentiation of endocannabinoid signaling will be an efficacious novel therapeutic approach to more than one human psychiatric disease.

Animals↗
PubMed2005

Therapeutic perspectives of inhibitors of endocannabinoid degradation.

The study of the cannabinoids can be established in the middle sixties with the elucidation of the structure of the active principle of Cannabis sativa plant, the delta9-tetrahydrocannabinol. However, the existence of an endogenous cannabinoid system (ECS) has not been unequivocally accepted until recently. The last two decades have witnessed an impressive advance in the knowledge about cannabinoids, their chemistry, the enzymes involved in their metabolism, and their physiological and pathological roles. In particular, we have made progress in modifying the activity of the ECS with selective compounds, validating the ECS as a new therapeutic target. Endocannabinoids play a role in physiological and pathological processes, and their levels are affected in several disorders. Therefore, it should be possible to ameliorate these pathologies by correcting their altered levels. This review focuses on the current therapeutic opportunities of endocannabinoid-directed drugs, and pays special attention to the therapeutic possibilities underlying the inhibition of the endocannabinoid inactivation. The strategy of manipulating the ECS might open new avenues in the development of therapeutic approaches for a number of disorders, both central and peripheral, that lack as yet effective treatments.

Animals↗
PubMed2005

Pharmacological properties and therapeutic possibilities for drugs acting upon endocannabinoid receptors.

Clinical trial data are beginning to emerge with respect to the therapeutic efficacy of cannabis extracts for the treatment of chronic pain. Although there is some evidence of efficacy, a major issue concerns the narrow margin between doses producing therapeutic effects and those producing the "highs" associated with cannabis misuse. In addition, long-term use is associated with an increased risk of psychiatric illness. These negative aspects constrain the doses of cannabis extracts and psychoactive cannabinoids that can be given to patients, and raise the risk that properly conducted clinical trials with too low dosages will impact negatively on subsequent drug development in this field. However, recent research has opened up a number of avenues whereby compounds acting directly upon cannabinoid (CB) receptors may have therapeutic potential. In this review, two such areas are discussed, namely a) the possible use of peripherally acting CB agonists and CB2 receptor-selective agonists for the treatment of pain, and b) the possible utility of CB2 receptor agonists for the prevention of stress-induced exacerbations of skin disorders such as psoriasis. A second area of drug development at present is that of CB1 receptor antagonists/inverse agonists, spearheaded by rimonabant, for the treatment of obesity and as an aid for smoking cessation. An important aspect of these compounds is their efficacy and selectivity, and this is discussed in detail in the present review.

Animals↗
PubMed2005

Molecular biology of the enzymes that degrade endocannabinoids.

Endocannabinoid circuits have been shown to regulate a number of important pathways including pain, feeding, memory and motor coordination. Direct manipulation of endocannabinoid tone, therefore, may relieve disease symptoms related to analgesia, obesity, Alzheimer's and Parkinson's in humans. The endocannabinoid circuit involves two cloned receptors: CB1 in the CNS and CB2 in the periphery; endogenously produced ligands including anandamide, 2-arachidonylglycerol and palmitoylethanolamide; and enzymes that degrade endocannabinoid ligands to terminate signaling. Currently, three enzymes have been characterized with the ability to hydrolyze endocannabinoids: fatty acid amide hydrolase (FAAH), monoglyceride lipase (MGL) and N-acylethanolamine-hydrolyzing acid amidase (NAAA). The purpose of this review is to examine the molecular biology for the enzymes that hydrolyze endocannabinoids covering the protein activity and expression, mRNA characterization, genomic locus organization, promoter analysis and knockout phenotypes.

Amidohydrolases↗
PubMed2005

From cannabis to endocannabinoids in multiple sclerosis: a paradigm of central nervous system autoimmune diseases.

An increasing body of evidence suggests that cannabinoids have beneficial effects on the symptoms of multiple sclerosis, including spasticity and pain. Endogenous molecules with cannabinoid-like activity, such as the "endocannabinoids", have been shown to mimic the anti-inflammatory properties of cannabinoids through the cannabinoid receptors. Several studies suggest that cannabinoids and endocannabinoids may have a key role in the pathogenesis and therapy of multiple sclerosis. Indeed, they can down regulate the production of pathogenic T helper 1-associated cytokines enhancing the production of T helper 2-associated protective cytokines. A shift towards T helper 2 has been associated with therapeutic benefit in multiple sclerosis. In addition, cannabinoids exert a neuromodulatory effect on neurotransmitters and hormones involved in the neurodegenerative phase of the disease. In vivo studies using mice with experimental allergic encephalomyelitis, an animal model of multiple sclerosis, suggest that the increase of the circulating levels of endocannabinoids might have a therapeutic effect, and that agonists of endocannabinoids with low psychoactive effects could open new strategies for the treatment of multiple sclerosis.

Animals↗
PubMed2005

Partial QSAR analysis of some selected natural inhibitors of FAAH suggests a working hypothesis for the development of endocannabinoid-based drugs.

The endogenous cannabinoids (endocannabinoids) are bioactive signaling molecules, that show diverse cellular and physiological effects and play various roles in the central nervous system, as well as in the periphery. The discovery of N-arachidonoylethanolamine (anandamide, AEA) and of the enzyme that terminates its signaling, i. e. fatty acid amide hydrolase (FAAH), has inspired pharmacological strategies to augment endocannabinoid tone and biological activity through inhibition of FAAH. Here we discuss the role of natural endocannabinoid derivatives, like the hydroxy-anandamides (OH-AEAs) generated from AEA via lipoxygenase activity, as powerful inhibitors of FAAH. We propose that these compounds, by reversibly inhibiting FAAH, may control in vivo the endocannabinoid tone. We consider the theoretical structural properties of OH-AEAs and other natural inhibitors of FAAH, based on the calculation of theoretical molecular descriptors commonly used in Quantitative Structure Activity Relationship (QSAR) studies. The QSAR properties of OH-AEAs and congeners suggest that they could act at different specific sites of FAAH, thus confirming their potential value as templates for the development of next-generation therapeutics.

Amidohydrolases↗
PubMed2005

Endocannabinoid metabolic pathways and enzymes.

Endocannabinoids, defined in 1995 as endogenous agonists of cannabinoid receptors, their anabolic and catabolic pathways, and the enzymes involved in these pathways (the "endocannabinoid enzymes"), are the subject of this review. A general strategy seems to apply to the regulation of the levels of the two major endocannabinoids, anandamide and 2-arachidonoylglycerol (2-AG). Five endocannabinoid enzymes have been cloned to date: two are responsible for the biosynthesis and degradation of anandamide, the NAPE-selective phospholipase D and the fatty acid amide hydrolase, respectively; the other three catalyse the biosynthesis and degradation of 2-AG, the sn-1-selective diacylglycerol lipases alpha and beta and the monoacylglycerol lipase, respectively. The major features of these five proteins, their relative weight in determining endocannabinoid levels, and the possible targeting of some of them for therapeutic purpose, as well as the possibility of the existence of alternative anabolic and catabolic pathways are discussed.

Animals↗
PubMed2006

Cardiac and vascular changes in cirrhosis: pathogenic mechanisms.

Cardiovascular abnormalities accompany both portal hypertension and cirrhosis. These consist of hyperdynamic circulation, defined as reduced mean arterial pressure and systemic vascular resistance, and increased cardiac output. Despite the baseline increased cardiac output, ventricular inotropic and chronotropic responses to stimuli are blunted, a condition known as cirrhotic cardiomyopathy. Both conditions may play an initiating or aggravating pathogenic role in many of the complications of liver failure or portal hypertension including ascites, variceal bleeding, hepatorenal syndrome and increased postoperative mortality after major surgery or liver transplantation. This review briefly examines the major mechanisms that may underlie these cardiovascular abnormalities, concentrating on nitric oxide, endogenous cannabinoids, central neural activation and adrenergic receptor changes. Future work should address the complex interrelationships between these systems.

Blood Circulation↗