Effects of long-chain N-acylethanolamines on lipid peroxidation in cardiac mitochondria

N-Stearoylethanolamine Inhibits Integrin-Mediated Activation, Aggregation, and Adhesion of Human Platelets

N-stearoylethanolamine (NSE), a lipid mediator that belongs to the N-acylethanolamine (NAE) family, has anti-inflammatory, antioxidant, and membranoprotective actions. In contrast to other NAEs, NSE does not interact with cannabinoid receptors. The exact mechanism of its action remains unclear. The aim of this study is to evaluate the action of NSE on activation, aggregation, and adhesion of platelets that were chosen as a model of cellular response. Aggregation of platelets was measured to analyze the action of NSE (10^-6-10^-10 M) on platelet reactivity. Changes in granularity and shape of resting platelets and platelets stimulated with ADP in the presence of NSE were monitored by flow cytometry, and platelet deganulation was monitored by spectrofluorimetry. In vivo studies were performed using obese insulin-resistant rats. Binding of fibrinogen to the GPIIb/IIIa receptor was estimated using indirect ELISA and a scanning electron microscopy (SEM). It was found that NSE inhibits the activation and aggregation of human platelets. Our results suggest that NSE may decrease the activation and subsequent aggregation of platelets induced by ristocetin, epinephrine, and low doses of ADP. NSE also reduced the binding of fibrinogen to GPIIb/IIIa on activated platelets. These effects could be explained by the inhibition of platelet activation mediated by integrin receptors: the GPIb-IX-V complex for ristocetin-induced activation and GPIIb/IIIa when epinephrine and low doses of ADP were applied. The anti-platelet effect of NSE complements its anti-inflammatory effect and allows us to prioritize studies of NSE as a potent anti-thrombotic agent. SIGNIFICANCE STATEMENT: N-stearoylethanolamine (NSE) was shown to possess inhibitory action on platelet activation, adhesion, and aggregation. The mechanism of inhibition possibly involves integrin receptors. This finding complements the known anti-inflammatory effects of NSE.

MicroRNA-155-5p modulates the progression of acute respiratory distress syndrome by targeting interleukin receptors

Acute respiratory distress syndrome (ARDS) is a multifactorial inflammatory lung failure with a high incidence and a high cost burden. However, the underlying pathogenesis of ARDS is still unclear. Recently, microRNA has been shown to have critical function in regulating the pathogenesis of ARDS development and inflammation. To identify the important microRNA in the serum from patients with ARDS that may be potential biomarkers for the disease and explore the underlying disease mechanism. We found significant upregulation of miR-155-5p expression in serum samples from patients with ARDS compared with the control group (p < 0.01). The levels of interleukin receptors and inflammatory cytokines were significantly increased in blood samples from patients with ARDS (p < 0.05). In the cell model, miR-155-5p had a binding site in the 3’-UTR of the three interleukin receptors. In LPS-simulated BEAS-2B cells, transfection of miR-155-5p mimic inhibited the expression levels of these interleukin receptors, and was found to directly target the inflammatory response of leukocyte nodulin receptor through NF-kB signaling. In conclusion, miR-155-5p can alleviate LPS-simulated injury that induces the expression of IL17RB, IL18R1, and IL22RA2 by affecting the NF-kB pathway; however, it cannot change the occurrence of inflammatory storms. Collectively, this suggests that the progression of ARDS is the result of effects of the multiple regulatory pathways, providing novel evidence for the therapy of ARDS.

Discovering a New Metabolic Pathway. Early Work with My Friend, Viswanathan Natarajan

This article summarizes our early work with Viswanathan Natarajan in the 1980s at the University of Minnesota's Hormel Institute, when he was at the beginning of his brilliant academic career. At that time most metabolic pathways for the biosynthesis and degradation of phospholipids were well established and known in considerable detail. Hence, it was exciting to discover a novel sequence of biochemical reactions, first in dog heart and later in various other vertebrate cells and tissues that became known as the transacylation-phosphodiesterase pathway of phospholipid metabolism. Because one of the metabolites, N-arachidonoylethanolamine, produced by this reaction sequence, was later found to bind to and activate cannabinoid receptors, investigations of this pathway became part of the rapidly growing field of endocannabinoid research. This is briefly summarized here as well.

N-Oleoyl-Phosphatidyl-Ethanolamine and Epigallo Catechin-3-Gallate Mitigate Oxidative Stress in Overweight and Class I Obese People on a Low-Calorie Diet

Oxidative stress and lipid peroxidation are considered key factors linking obesity with its associated complications. Epigallo catechin-3-gallate (EGCG) and oleoylethanolamide, together with its phospholipid precursor N-oleoyl-phosphatidylethanolamine (NOPE), are nutritional compounds that might improve the oxidative stress status of obese people. Unfortunately, the bioavailability of these compounds is low; however, the coadministration of NOPE with EGCG has been shown to ameliorate both the plasma availability of EGCG and the intestinal levels of NOPE in rats. This double-blind placebo-controlled study investigated the effects of 2 months' supplementation with EGCG complexed with NOPE, combined with moderate energy restriction, on plasma oxidative status of overweight and class I obese subjects. A total of 138 subjects (body mass index: 25-35 kg/m²) were recruited and randomized into two groups: the first (n = 67) received caps of placebo and the second (n = 71) caps of an oily dispersion of EGCG complexed with NOPE for 2 months. Subjects' supplementation was combined with moderate energy restriction (-800 kcal/day). Plasma oxidative status was determined by measuring the levels of oxidized low-density lipoprotein (Ox-LDL), malondialdehyde and reactive oxygen metabolites, and by calculating the lag time and the slope of Cu-induced lipid peroxidation kinetics. In total 116 subjects (27 M/89 F) completed the supplementation period, 49 in the placebo group and 67 in the treated group. Treatment induced a similar significant weight reduction in the two groups. Moreover, we found the mean changes of Ox-LDL significantly lower and the mean changes of antioxidant capacity (lag time) significantly higher in NOPE-EGCG group than in placebo group (treatment effect mean difference: -3.15 UL, P < .044 and +5.37 min, P < .0347, respectively). EGCG plasma levels were detectable only after 2 months of NOPE-EGCG diet. The NOPE-EGCG integration to a low-energy diet seems, therefore, useful for ameliorating oxidative stress-related markers, which are concomitant causes of obesity-induced disorders.

Modulation of the Oxidative Stress and Lipid Peroxidation by Endocannabinoids and Their Lipid Analogues

Growing evidence supports the pivotal role played by oxidative stress in tissue injury development, thus resulting in several pathologies including cardiovascular, renal, neuropsychiatric, and neurodegenerative disorders, all characterized by an altered oxidative status. Reactive oxygen and nitrogen species and lipid peroxidation-derived reactive aldehydes including acrolein, malondialdehyde, and 4-hydroxy-2-nonenal, among others, are the main responsible for cellular and tissue damages occurring in redox-dependent processes. In this scenario, a link between the endocannabinoid system (ECS) and redox homeostasis impairment appears to be crucial. Anandamide and 2-arachidonoylglycerol, the best characterized endocannabinoids, are able to modulate the activity of several antioxidant enzymes through targeting the cannabinoid receptors type 1 and 2 as well as additional receptors such as the transient receptor potential vanilloid 1, the peroxisome proliferator-activated receptor alpha, and the orphan G protein-coupled receptors 18 and 55. Moreover, the endocannabinoids lipid analogues N-acylethanolamines showed to protect cell damage and death from reactive aldehydes-induced oxidative stress by restoring the intracellular oxidants-antioxidants balance. In this review, we will provide a better understanding of the main mechanisms triggered by the cross-talk between the oxidative stress and the ECS, focusing also on the enzymatic and non-enzymatic antioxidants as scavengers of reactive aldehydes and their toxic bioactive adducts.

Relationship between seminal plasma levels of anandamide congeners palmitoylethanolamide and oleoylethanolamide and semen quality

OBJECTIVE

To determine whether changes in seminal plasma concentrations of the endogenous lipid signaling molecules palmitoylethanolamide (PEA) and oleoylethanolamide (OEA) have significant effects on sperm quality.

DESIGN

Biochemical and physiological studies of human seminal plasma and spermatozoa.

SETTING

Academic tertiary care medical center.

PATIENT(S)

Ninety men attending an infertility clinic for semen analysis.

INTERVENTION(S)

Palmitoylethanolamide and OEA extracted from seminal plasma were quantified by ultra high-performance liquid chromatography (HPLC)-tandem mass spectrometry. Patient sperm from semen with normal parameters were exposed in vitro to PEA or OEA to determine effects on sperm motility, viability, and mitochondrial activity.

MAIN OUTCOME MEASURE(S)

The relationship between seminal plasma concentrations of PEA and OEA and sperm quality and the effect of these compounds on sperm motility, viability, and mitochondria activity in vitro.

RESULT(S)

Palmitoylethanolamide and OEA concentrations in seminal plasma were lower in men with asthenozoospermia and oligoasthenoteratozospermia compared with men with normal semen parameters. Palmitoylethanolamide and OEA rapidly and significantly improved sperm motility and maintained viability without affecting mitochondria activity in vitro.

CONCLUSION(S)

Maintenance of normal PEA and OEA tone in human seminal plasma may be necessary for the preservation of normal sperm function and male fertility. Exocannabinoids found in Cannabis, such as delta-9-tetrahydrocannabinol and cannabidiol, could compete with these endocannabinoids upsetting their finely balanced, normal functioning and resulting in male reproductive failure.

Roles of fatty acid ethanolamides (FAE) in traumatic and ischemic brain injury

Ethanolamides of long-chain fatty acids are a class of endogenous lipid mediators generally referred to as N-acylethanolamines (NAEs). NAEs include anti-inflammatory and analgesic palmitoylethanolamide, anorexic oleoylethanolamide, stearoylethanolamide, and the endocannabinoid anandamide. Traumatic brain injury (TBI), associated with a high morbidity and mortality and no specific therapeutic treatment, has become a pressing public health and medical problem. TBI is a complex process evoking systemic immune responses as well as direct local responses in the brain tissues. The direct (primary) damage disrupts the blood-brain barrier (BBB), injures the neurons and initiates a cascade of inflammatory reactions including chemokine production and activation of resident immune cells. The effect of TBI is not restricted to the brain; it can cause multi-organ damage and evoke systemic immune response with cytokine and chemokine production. This facilitates the recruitment of immune cells to the site of injury and progression of the inflammatory reaction. Depending on severity, TBI induces immediate neuropathologic effects that, for the mildest form, may be transient; however, with increasing severity, these injuries cause cumulative neural damage and degeneration. Moreover, TBI leads to increased catabolism of phospholipids, resulting in a series of phospholipid breakdown products, some of which have potent biological activity. Ischemia-reperfusion (I/R) injury resulting from stroke leads to metabolic distress, oxidative stress and neuroinflammation, making it likely that multiple therapeutic intervention strategies may be needed for successful treatment. Current therapeutic strategies for stroke need complimentary neuroprotective treatments to provide a better outcome. Prior studies on NAEs have demonstrated neurotrophic/neuroprotective activities across a broad spectrum of cellular and animal models of neurodegenerative and acute cerebrovascular disorders. The present review will summarize our knowledge of the biological role of these lipid signaling molecules in brain and highlights their therapeutic effect from multipotential actions on neuronal cell death and neuroinflammatory pathways.

Reduction of ischemic brain injury by administration of palmitoylethanolamide after transient middle cerebral artery occlusion in rats

Stroke is the third leading cause of death and the leading cause of long-term disability in adults. Current therapeutic strategies for stroke, including thrombolytic drugs, such as tissue plasminogen activator offer great promise for the treatment, but complimentary neuroprotective treatments are likely to provide a better outcome. To counteract the ischemic brain injury in mice, a new therapeutic approach has been employed by using palmitoylethanolamide (PEA). PEA is one of the members of N-acyl-ethanolamine family maintain not only redox balance but also inhibit the mechanisms of secondary injury on ischemic brain injury. Treatment of the middle cerebral artery occlusion (MCAo)-induced animals with PEA reduced edema and brain infractions as evidenced by decreased 2,3,5-triphenyltetrazolium chloride (TTC) staining across brain sections. PEA-mediated improvements in tissues histology shown by reduction of lesion size and improvement in apoptosis level (assayed by Bax and Bcl-2) further support the efficacy of PEA therapy. We demonstrated that PEA treatment blocked infiltration of astrocytes and restored MCAo-mediated reduced expression of PAR, nitrotyrosine, iNOS, chymase, tryptase, growth factors (BDNF and GDNF) and GFAP. PEA also inhibited the MCAo-mediated increased expression of pJNK, NF-κB, and degradation of IκB-α. PEA-treated injured animals improved neurobehavioral functions as evaluated by motor deficits. Based on these findings we propose that PEA would be useful in lowering the risk of damage or improving function in ischemia-reperfusion brain injury-related disorders.

Lauroylethanolamide and linoleoylethanolamide improve functional outcome in a rodent model for stroke

Ischemic stroke is a significant health problem affecting over 6 million people in the United States alone. In addition to surgical and thrombolytic therapeutic strategies for stroke, neuroprotective therapies may offer additional benefit. N-acylethanolamines (NAEs) are signaling lipids whose synthesis is upregulated in response to ischemia, suggesting that they may be neuroprotective. To date only three NAEs, arachidonylethanolamide (NAE 20:4), palmitoylethanolamide (NAE 16:0) and oleoylethanolamide (NAE 18:1) have shown to exert neuroprotective effect in animal models for stroke. Here, we describe neuroprotective effects of the hitherto uncharacterized NAEs, lauroylethanolamide (NAE 12:0) and linoleoylethanolamide (NAE 18:2) in a middle cerebral artery occlusion model of stroke. Pretreatment with NAE 18:2 prior to ischemia/reperfusion (I/R) injury resulted in both significantly reduced cortical infarct volume and improved functional outcome as determined using the neurological deficit score. NAE 12:0 improved neurological deficits without a significant reduction lesion size. Our results suggest that NAEs, as a whole, provide neuroprotection during I/R injury and may have therapeutic benefit when used as complementary treatment with other therapies to improve stroke outcome.

Synthesis of new plant growth regulator: N-(fatty acid) O-aryloxyacetyl ethanolamine

N-(fatty acyl) O-aryloxyacetyl ethanolamines, prepared from N-acylethanolamine (NAE) and aryloxyacetic acid, were tested for plant growth regulating activity. Compared with N-stearoylethanolamine, most compounds exhibit improved plant growth stimulating activity. In particular, those with chlorine on aryl ring show better activity than 2,4-dichlorophenyloxyacetic acid in stimulating hypocotyls elongation of rape which indicates that chlorine on aryl ring appears significant. Moreover, these derivatives display improved solubility.

Oleoylethanolamide protects human sperm cells from oxidation stress: studies on cases of idiopathic infertility

N-acylethanolamides are naturally occurring hydrophobic molecules usually present in a very small amount in many mammalian tissues and cells. The presence of N-acylethanolamides has also been demonstrated in human reproductive tracts and fluids, although their biological effects and molecular mechanisms of action are not yet completely elucidated. It is known that some N-acylethanolamides, such as oleoylethanolamide, have antioxidative properties. The aim of this study was to test whether oleoylethanolamide could protect sperm cells from reactive oxygen species-induced oxidative damage in cases of idiopathic infertility, because the excessive generation of these radicals was associated with this pathology. Our results show that 2.5 nM oleoylethanolamide in vitro supplementation significantly reduces DNA strand breaks both in fertile and infertile subjects. Moreover, oleoylethanolamide increases kinematic parameters, such as curvilinear velocity and amplitude of lateral head displacement and hyperactivation, both in the presence and in the absence of oxidative stress. Results of this study support the hypothesis of a possible protective action of oleoylethanolamide against reactive oxygen species, which could explain its beneficial effects on in vitro capacitated spermatozoa.

Increased plasma concentrations of Palmitoylethanolamide, an endogenous fatty acid amide, affect oxidative damage of human low-density lipoproteins: An in vitro study

Fatty acid ethanolamides (NAEs) are naturally occurring hydrophobic molecules usually present in a very small amount in many mammalian tissues and cells. Moreover, these compounds have been isolated in mammalian biological fluids, such as blood. Palmitoylethanolamide (C16:0) (PEA) is a fully saturated NAE, which presents some possible pharmaceutical activities, such as anti-inflammatory and antinociceptive effects. PEA is physiologically present in the mammalian blood at concentrations ranging from 9.4 to 16.7 pmol/ml. Since increasing evidence indicates that oxidative modification of low-density lipoproteins (LDL) is an important determinant in atherogenesis, the aim of this study was to evaluate the effect of physiologically relevant concentrations of PEA on Cu2+-induced LDL oxidation (measured as conjugated dienes formation). Our experiments indicate both anti-oxidative and slightly pro-oxidative effects of PEA. The anti-oxidative effect is obtained at low PEA concentrations (0.01 and 0.1 microM), while the pro-oxidative effect is obtained at a higher PEA concentration (1 microM). Fluorescence and circular dichroism data indicate that the effect of PEA occurs mainly by affecting the conformational features of ApoB-100.

Plant-derived, synthetic and endogenous cannabinoids as neuroprotective agents. Non-psychoactive cannabinoids, 'entourage' compounds and inhibitors of N-acyl ethanolamine breakdown as therapeutic strategies to avoid pyschotropic effects

There is good evidence that plant-derived and synthetic cannabinoids possess neuroprotective properties. These compounds, as a result of effects upon CB(1) cannabinoid receptors, reduce the release of glutamate, and in addition reduce the influx of calcium following NMDA receptor activation. The major obstacle to the therapeutic utilization of such compounds are their psychotropic effects, which are also brought about by actions on CB(1) receptors. However, synthesis of the endogenous cannabinoids anandamide and 2-arachidonoylglycerol, which also have neuroprotective properties, are increased under conditions of severe inflammation and ischemia, raising the possibility that compounds that prevent their metabolism may be of therapeutic utility without having the drawback of producing psychotropic effects. In this review, the evidence indicating neuroprotective actions of plant-derived, synthetic and endogenous cannabinoids is presented. In addition, the pharmacological properties of endogenous anandamide-related compounds that are not active upon cannabinoid receptors, but which are also produced during conditions of severe inflammation and ischemia and may contribute to a neuroprotective action are reviewed.

Putative neuroprotective actions of N-acyl-ethanolamines

N-Acyl-ethanolamines (NAEs) and their precursors, N-acyl-ethanolamine phospholipids (NAPEs), are present in the mammalian brain at levels of a few hundred picomoles/gram tissue and a few nanomoles/gram tissue, respectively. NAE-containing arachidonic acid is called anandamide, and it has attracted particular attention since it is a partial agonist for the cannabinoid receptors, for which 2-arachidonoylglycerol is the full agonist. In addition, anandamide may also activate the vanilloid receptor. Anandamide usually amounts to 1-10% of NAEs, as the vast majority of N-acyl groups are saturated and monounsaturated fatty acids. Formation of NAPE and NAE is catalyzed by an N-acyltransferase and an NAPE-hydrolyzing phospholipase D, respectively, two enzymes that have been characterized only preliminary. Interestingly, NAPEs and NAEs accumulate in the brain in response to neurodegenerative insults at a time when other phospholipids are subjected to rapid degradation. This is an important biosynthetic aspect of NAPE and NAE, as NAEs may be neuroprotective by a number of different mechanisms involving both receptor activation and non-receptor-mediated effects, e.g. by binding to cannabinoid receptors and interfering with ceramide turnover, respectively.

Cannabinoid receptor-inactive N-acylethanolamines and other fatty acid amides: metabolism and function

Although it is now generally accepted that long-chain N-acylethanolamines and their precursors, N-acylethanolamine phospholipids, exist as trace constituents in virtually all vertebrate cells and tissues, their possible biological functions are just emerging. While anandamide (N-arachidonoylethanolamine) has received much attention due to its ability to bind to and activate cannabinoid receptors, the saturated and monounsaturated N-acylethanolamines, which usually represent the vast majority, are cannabinoid receptor-inactive but appear to interact with endocannabinoids and to have other signaling functions as well. Also, primary fatty acid amides, including the amide of oleic acid, which acts as a sleep-inducing agent, do not interact with cannabinoid receptors but are catabolically related to endocannabinoids. Here we review published information on the occurrence, metabolism, and possible signaling functions of the cannabinoid receptor-inactive N-acylethanolamines and primary fatty acid amides.

Pathways and mechanisms of N-acylethanolamine biosynthesis: can anandamide be generated selectively?

Long-chain N-acylethanolamines (NAEs) and their precursors, N-acylethanolamine phospholipids, are ubiquitous trace constituents of animal and human cells, tissues and body fluids. Their cellular levels appear to be tightly regulated and they accumulate as the result of injury. Saturated and monounsaturated congeners which represent the vast majority of cellular NAEs can have cytoprotective effects while polyunsaturated NAEs, especially 20:4n-6 NAE (anandamide), elicit physiological effects by binding to and activating cannabinoid receptors. It is the purpose of this article to review published data on the pathways and mechanisms of NAE biosynthesis in mammals and to evaluate this information for its physiological significance. The generation and turnover of NAE via N-acyl PE through the transacylation-phosphodiesterase pathway may represent a novel cannabinoid receptor-independent signalling system, analogous to and possibly related to ceramide-mediated cell signalling.

N-Acylethanolamines and precursor phospholipids - relation to cell injury

The present review focuses on the relationship between formation of N-acylethanolamine phospholipids (NAPEs) and N-acyletransferase (NAEs) catalyzed by N-acyltranferase and NAPE-hydrolyzing phospholipase D, respectively, and cell injury in tissues like brain, heart, and testis. A number of mechanisms are proposed by which these two groups of lipids may have cytoprotective properties. The mechanisms may involve activation of cannabinoid receptors, as well as non-receptor-mediated effects such as stabilization of membrane bilayers, antioxidant mechanisms, inhibition of calcium leakage from mitochondria, and direct inhibition of ceramidase. Anandamide (20:4-NAE) is formed as a minor component along with other NAEs during cell injury. Whether 20:4-NAE has a separate physiological role is at present not known, but some data suggest that 20:4-NAE may be formed, e.g. in the uterus, by a more selective mechanism without being accompanied by a vast majority of saturated and monounsaturated NAEs.

Derivatised lipids in membranes. Physico-chemical aspects of N-biotinyl phosphatidylethanolamines, N-acyl phosphatidylethanolamines and N-acyl ethanolamines

The physical properties of N-biotinyl phosphatidylethanolamines, N-acyl phosphatidylethanolamines and of N-acyl ethanolamines, in aqueous dispersions, are reviewed. Emphasis is placed on the calorimetric (i.e. chain melting) properties, the thermotropic phase behaviour, certain aspects of the structure and dynamics, and the miscibility with other membrane lipids. In the case of N-biotinyl phosphatidylethanolamines, the specific binding of avidin, and in the case of N-acyl ethanolamines, the function of the third chain, is also considered. All of these properties are relevant to the role of these rather unusual lipids in membranes.

Long-chain N-acylethanolamines inhibit lipid peroxidation in rat liver mitochondria under acute hypoxic hypoxia

Two long-chain N-acylethanolamines (NAEs), N-palmitoyl- (NPE) and N-stearoylethanolamine (NSE), are shown to inhibit an in vitro non-enzymatic Fe(2+)-induced free radical oxidation of lipids in the liver mitochondria of rats with hypoxic hypoxia. NSE appeared to be more effective than NPE in suppressing some kinetic parameters of the Fe(2+)-induced chemiluminescence. The inhibitory action of NAEs on non-enzymatic lipid peroxidation supports the idea that they possess membrane protective properties.

Accumulation of various N-acylethanolamines including N-arachidonoylethanolamine (anandamide) in cadmium chloride-administered rat testis

Changes in the levels of various molecular species of N-acylethanolamine in CdCl2-administered rat testis were examined. We found that the levels of various N-acylethanolamines including anandamide (N-arachidonoylethanolamine), an endogenous cannabinoid receptor ligand, were dramatically increased in CdCl2-admin-istered rat testis. Such changes were particularlyprominent for saturated and monoenoic species such as N-palmitoyl species (39-fold at 9 h) and N-stearoyl species (21-fold at 9 h), compared with unsaturated fatty acid-containing species such as anandamide (5-fold at 9 h). Noticeably, increased levels were observed of not only N-acylethanolamines but also several species of N-acylphosphatidylethanolamine, potential precursors for N-acylethanolamines. We confirmed that the rat testis microsomal fraction contains phosphodiesterase activity catalyzing the release of N-acylethanolamine from N-acylphosphatidylethanolamine and transacylase activity catalyzing the formation of N-acylphosphatidylethanolamine from phosphatidylethanolamine and phosphatidylcholine. These enzyme activities were not dramatically different in the microsomal fraction obtained from CdCl2-administered rat testis compared with that in the case of control rat testis, at least when estimated in cell-free assay systems, suggesting that the accessibility of the substrates to the enzymes may be increased in CdCl2-administered rat testis to generate a large amount of N-acylethanolamine. Possible pathophysiological implications of the augmented generation of N-acylethanolamine including anandamide in CdCl2-administered rat testis were discussed.

Differential scanning calorimetric studies on the thermotropic phase transitions of dry and hydrated forms of N-acylethanolamines of even chainlengths

N-acylethanolamines (NAEs) have attracted the attention of researchers in the last two decades due to their occurrence in biological membranes under conditions of stress as well as under normal conditions. Differential scanning calorimetric studies have been carried out on dry and hydrated samples of a homologous series of N-acylethanolamines containing saturated acyl chains of even number of carbon atoms (n = 8-20). In both cases a major sharp endothermic transition was observed which occurs at the melting point for the dry NAEs whereas for the hydrated samples it occurs at considerably lower temperatures. The enthalpies and entropies corresponding to this transition could be fitted, in each case, to a straight line suggesting that the transition enthalpy and transition entropy consist of a fixed component from the polar head group and the terminal methyl group, whereas the contribution of the methylene groups, (CH2)n, is linearly proportional to the number of carbon atoms in it. The contributions of each methylene unit to the transition enthalpy and transition entropy of NAEs were found to be deltaH(inc) = 0.82 (+/-0.02) and 0.96 (+/-0.06) kcal mol(-1), and deltaS(inc) = 2.01 (+/- 0.06) and 2.37 (+/-0.17) cal mol(-1) K(-1), respectively, for the dry and hydrated samples of NAEs, whereas the end contributions arising from the head group and the terminal methyl group were determined to be deltaH(o) = -0.10 (+/-0.26) and -0.52 (+/-0.82) kcal mol(-1) and deltaS(o) = 2.12 (+/-0.71) and 3.1 (+/-2.3) cal mol(-1) K(-1), respectively, for the dry and hydrated samples of NAEs. These results are relevant to an understanding of the thermodynamics of the phase properties of NAEs in membranes.

The N-acylation-phosphodiesterase pathway and cell signalling

Long-chain N-acylethanolamines (NAEs) elicit a variety of biological and pharmacological effects. Anandamide (20:4n-6 NAE) and other polyunsaturated NAEs bind to the cannabinoid receptor and may thus serve as highly specific lipid mediators of cell signalling. NAEs can be formed by phospholipase D-catalyzed hydrolysis of N-acylethanolamine phospholipids or by direct condensation of ethanolamine and fatty acid. So far, most of the latter biosynthetic activity has been shown to be the reverse reaction of the NAE amidohydrolase that catalyzes NAE degradation. Thus, increasing evidence supports the hypothesis that the N-acylation-phosphodiesterase pathway yields not only saturated-monounsaturated NAEs, but polyunsaturated ones, including anandamide, as well.

The effect of long-chain N-acylethanolamines on some membrane-associated functions of neuroblastoma C1300 N18 cells

As reported earlier (Gulaya, N.M., Vaskovsky, V.E., Vystosky, M.V., Volkov, G.L., Govseeva, N.N. and Artemenko, I.P. (1988) Ukr. Biochim. J. 60, 58-63), N-acylphosphatidylethanolamines (NAPE) and products of their catabolism, N-acylethanolamines (NAE), are present in the lipids of neuroblastoma C1300 N18 undifferentiated cells. The present paper describes the distribution of NAE added to culture medium of differentiated cells and its effect on the fast sodium channels and some other membrane characteristics. It is shown that NAE inhibits the destroying action of veratridine on membranes.