The Endocannabinoid System in Energy Homeostasis and the Etiopathology of Metabolic Disorders

Endocannabinoids and cannabinoid CB1 receptors are known to play a generalized role in energy homeostasis. However, clinical trials with the first generation of CB1 blockers, now discontinued due to psychiatric side effects, were originally designed to reduce food intake and body weight rather than the metabolic risk factors associated with obesity. In this review, we discuss how, in addition to promoting energy intake, endocannabinoids control lipid and glucose metabolism in several peripheral organs, particularly the liver and adipose tissue. Direct actions in skeletal muscle and pancreas are also emerging. This knowledge may help in the design of future therapies for the metabolic syndrome

From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Pharmacology

Apart from having been used and misused for at least four millennia for, among others, recreational and medicinal purposes, the cannabis plant and its most peculiar chemical components, the plant cannabinoids (phytocannabinoids), have the merit to have led humanity to discover one of the most intriguing and pleiotropic endogenous signaling systems, the endocannabinoid system (ECS). This review article aims to describe and critically discuss, in the most comprehensive possible manner, the multifaceted aspects of 1) the pharmacology and potential impact on mammalian physiology of all major phytocannabinoids, and not only of the most famous one Δ9-tetrahydrocannabinol, and 2) the adaptive pro-homeostatic physiological, or maladaptive pathological, roles of the ECS in mammalian cells, tissues, and organs. In doing so, we have respected the chronological order of the milestones of the millennial route from medicinal/recreational cannabis to the ECS and beyond, as it is now clear that some of the early steps in this long path, which were originally neglected, are becoming important again. The emerging picture is rather complex, but still supports the belief that more important discoveries on human physiology, and new therapies, might come in the future from new knowledge in this field

Phytocannabinoids promote viability and functional adipogenesis of bone marrow-derived mesenchymal stem cells through different molecular targets.

Abstract The cellular microenvironment plays a critical role in the maintenance of bone marrow-derived mesenchymal stem cells (BM-MSCs) and their subsequent cell lineage differentiation. Recent studies suggested that individuals with adipocyte-related metabolic disorders have altered function and adipogenic potential of adipose stem cell subpopulations, primarily BM-MSCs, increasing the risk of heart attack, stroke or diabetes. In this study, we explored the potential therapeutic effect of some of the most abundant non-euphoric compounds derived from the Cannabis sativa plant (or phytocannabinoids) including tetrahydrocannabivarin (THCV), cannabidiol (CBD), cannabigerol (CBG), cannabidiolic acid (CBDA) and cannabigerolic acid (CBGA), by analysing their pharmacological activity on viability of endogenous BM-MSCs as well as their ability to alter BM-MSC proliferation and differentiation into mature adipocytes. We provide evidence that CBD, CBDA, CBGA and THCV (5 µM) increase the number of viable BM-MSCs; whereas only CBG (5 µM) and CBD (5 µM) alone or in combination promote BM-MSCs maturation into adipocytes via distinct molecular mechanisms. These effects were revealed both in vitro and in vivo. In addition, phytocannabinoids prevented the insulin signalling impairment induced by palmitate in adipocytes differentiated from BM-MSCs. Our study highlights phytocannabinoids as a potential novel pharmacological tool to regain control of functional adipose tissue in unregulated energy homeostasis often occurring in metabolic disorders including type 2 diabetes mellitus (T2DM), aging and lipodystrophy

Two novel classes of neuroactive fatty acid amides are substrates for mouse neuroblastoma ‘anandamide amidohydrolase’

AbstractThe endogenous cannabimimetic substance, anandamide (N-arachidonoyl-ethanolamine) and the recently isolated sleep-inducing factor, oleoyl-amide (cis-9,10-octadecenoamide), belong to two neuroactive fatty acid amide classes whose action in mammals has been shown to be controlled by enzymatic amide bond hydrolysis. Here we report the partial characterisation and purification of ‘anandamide amidohydrolase’ from membrane fractions of N18 neuroblastoma cells, and provide evidence for a further and previously unsuspected role of this enzyme. An enzymatic activity catalysing the hydrolysis of [14C]anandamide was found in both microsomal and 10,000 × g pellet fractions. The latter fractions, which displayed the highest Vmax for anandamide, were used for further characterisation of the enzyme, and were found to catalyse the hydrolysis also of [14C]oleoyl-amide, with an apparent Km of 9.0 ± 2.2 μM. [14C]anandamide- and [14C]oleoyl-amide-hydrolysing activities: (i) exhibited identical pH- and temperature-dependency profiles; (ii) were inhibited by alkylating agents; (iii) were competitively inhibited by the phospholipase A2 inhibitor arachidonyl-trifluoromethyl-ketone with the same IC50 (3 μM); (iv) were competitively inhibited by both anandamide (or other polyunsaturated fatty acid-ethanolamides) and oleoyl-amide. Proteins solubilised from 10,000 × g pellets were directly analysed by isoelectric focusing, yielding purified fractions capable of catalysing the hydrolysis of both [14C]anandamide and [14C]oleoyl-amide. These data suggest that ‘anandamide amidohydrolase’ enzymes, such as that characterised in this study, may be used by neuronal cells also to hydrolyse the novel sleep-inducing factor oleoyl-amide

Anandamide as an intracellular messenger regulating ion channel activity.

Abstract The endocannabinoid anandamide (N-arachidonoylethanolamine) was proposed to be an extracellular retrograde messenger, which regulates excitability of neurons by cannabinoid CB 1 receptordependent inhibition of neurotransmitter release. Recent findings indicate that the neuromodulatory actions of anandamide might be more complex. Anandamide has been shown to directly modulate various ion channels, such as ␣7-nicotinic acetylcholine receptors, T-type Ca 2+ channels, voltage-gated and background K + -channels and Transient Receptor Potential Vanilloid type 1 (TRPV1) channels. The binding site of anandamide at some of these ion channels appears to be intracellular or at the bilayer interface. This rises the intriguing possibility that anandamide, prior to its release into the synaptic cleft, may regulate ion homeostasis and excitability of neurons as an intracellular modulator of ion channels independent of its action at cannabinoid CB 1 receptors. This possibility might extend the concept of anandamide as an endocannabinoid retrograde messenger and may have profound implications for its role in neurotransmission and neuronal function. Here, we will review the evidence for this hypothesis

Anti-inflammatory Properties of Cannabidiol, a Nonpsychotropic Cannabinoid, in Experimental Allergic Contact Dermatitis

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Increased levels of palmitoylethanolamide and other bioactive lipid mediators and enhanced local mast cell proliferation in canine atopic dermatitis

Background: Despite the precise pathogenesis of atopic dermatitis (AD) is unknown, an immune dysregulation that causes Th2-predominant inflammation and an intrinsic defect in skin barrier function are currently the two major hypotheses, according to the so-called outside-inside-outside model. Mast cells (MCs) are involved in AD both by releasing Th2 polarizing cytokines and generating pruritus symptoms through release of histamine and tryptase. A link between MCs and skin barrier defects was recently uncovered, with histamine being found to profoundly contribute to the skin barrier defects. Palmitoylethanolamide and related lipid mediators are endogenous bioactive compounds, considered to play a protective homeostatic role in many tissues: evidence collected so far shows that the anti-inflammatory effect of palmitoylethanolamide depends on the down-modulation of MC degranulation. Based on this background, the purpose of the present study was twofold: (a) to determine if the endogenous levels of palmitoylethanolamide and other bioactive lipid mediators are changed in the skin of AD dogs compared to healthy animals; (b) to examine if MC number is increased in the skin of AD dogs and, if so, whether it depends on MC in-situ proliferation. Results: The amount of lipid extract expressed as percent of biopsy tissue weight was significantly reduced in AD skin while the levels of all analyzed bioactive lipid mediators were significantly elevated, with palmitoylethanolamide showing the highest increase. In dogs with AD, the number of MCs was significantly increased in both the subepidermal and the perifollicular compartments and their granule content was significantly decreased in the latter. Also, in situ proliferation of MCs was documented. Conclusions: The levels of palmitoylethanolamide and other bioactive lipid mediators were shown to increase in AD skin compared to healthy samples, leading to the hypothesis that they may be part of the body's innate mechanisms to maintain cellular homeostasis when faced with AD-related inflammation. In particular, the increase may be considered a temptative response to down-regulating the observed elevation in the number, functionality and proliferative state of MCs in the skin of AD dogs. Further studies are warranted to confirm the hypothesis

Anandamide Uptake by Human Endothelial Cells and Its Regulation by Nitric Oxide

Anandamide (AEA) has vasodilator activity, which can be terminated by cellular re-uptake and degradation. Here we investigated the presence and regulation of the AEA transporter in human umbelical vein endothelial cells (HUVECs). HUVECs take up AEA by facilitated transport (apparent K(m) = 190 +/- 10 nm and V(max) = 45 +/- 3 pmol. min(-1).mg(-1) protein), which is inhibited by alpha-linolenoyl-vanillyl-amide and N-(4-hydroxyphenyl)-arachidonoylamide, and stimulated up to 2.2-fold by nitric oxide (NO) donors. The NO scavenger hydroxocobalamin abolishes the latter effect, which is instead enhanced by superoxide anions but inhibited by superoxide dismutase and N-acetylcysteine, a precursor of glutathione synthesis. Peroxynitrite (ONOO(-)) causes a 4-fold activation of AEA transport into cells. The HUVEC AEA transporter contributes to the termination of a typical type 1 cannabinoid receptor (CB(1)) -mediated action of AEA, i.e. the inhibition of forskolin-stimulated adenylyl cyclase, because NO/ONOO(-) donors and alpha-linolenoyl-vanillyl-amide/N-(4-hydroxyphenyl)-arachidonoylamide were found to attenuate and enhance, respectively, this effect of AEA. Consistently, activation of CB(1) cannabinoid receptors by either AEA or the cannabinoid HU-210 caused a stimulation of HUVEC inducible NO synthase activity and expression up to 2.9- and 2. 6-fold, respectively. Also these effects are regulated by the AEA transporter. HU-210 enhanced AEA uptake by HUVECs in a fashion sensitive to the NO synthase inhibitor Nomega-nitro-l-arginine methyl ester. These findings suggest a NO-mediated regulatory loop between CB(1) cannabinoid receptors and AEA transporter

Endocannabinoid signalling in the blood of patients with schizophrenia

AIM: To test the hypothesis that schizophrenia might be associated with alterations of the endogenous cannabinoid system in human blood. RESULTS: Blood from 20 healthy volunteers and 12 patients with schizophrenia, 5 of which both before and after a successful antipsychotic treatment, was analysed for: 1) the amounts of the endocannabinoid anandamide; 2) the levels of cannabinoid CB(1 )and CB(2 )receptor mRNAs, and 3) the levels of the mRNA encoding the enzyme fatty acid amide hydrolase (FAAH), responsible for anandamide degradation. The amounts of anandamide were significantly higher in the blood of patients with acute schizophrenia than in healthy volunteers (7.79 ± 0.50 vs. 2.58 ± 0.28 pmol/ml). Clinical remission was accompanied by a significant decrease of the levels of anandamide (3.88 ± 0.72 pmol/ml) and of the mRNA transcripts for CB(2 )receptors and FAAH. CONCLUSION: These findings indicate that endocannabinoid signalling might be altered during the acute phase of schizophrenia not only in the central nervous system but also in the blood. These changes might be related to the several immunological alterations described in schizophrenia

The Activity of Anandamide at Vanilloid VR1 Receptors Requires Facilitated Transport across the Cell Membrane and Is Limited by Intracellular Metabolism

The endogenous ligand of CB(1) cannabinoid receptors, anandamide, is also a full agonist at vanilloid VR1 receptors for capsaicin and resiniferatoxin, thereby causing an increase in cytosolic Ca(2+) concentration in human VR1-overexpressing (hVR1-HEK) cells. Two selective inhibitors of anandamide facilitated transport into cells, VDM11 and VDM13, and two inhibitors of anandamide enzymatic hydrolysis, phenylmethylsulfonyl fluoride and methylarachidonoyl fluorophosphonate, inhibited and enhanced, respectively, the VR1-mediated effect of anandamide, but not of resiniferatoxin or capsaicin. The nitric oxide donor, sodium nitroprusside, known to stimulate anandamide transport, enhanced anandamide effect on the cytosolic Ca(2+) concentration. Accordingly, hVR1-HEK cells contain an anandamide membrane transporter inhibited by VDM11 and VDM13 and activated by sodium nitroprusside, and an anandamide hydrolase activity sensitive to phenylmethylsulfonyl fluoride and methylarachidonoyl fluorophosphonate, and a fatty acid amide hydrolase transcript. These findings suggest the following. (i) Anandamide activates VR1 receptors by acting at an intracellular site. (ii) Degradation by fatty acid amide hydrolase limits anandamide activity on VR1; and (iii) the anandamide membrane transporter inhibitors can be used to distinguish between CB(1) or VR1 receptor-mediated actions of anandamide. By contrast, the CB(1) receptor antagonist SR141716A inhibited also the VR1-mediated effect of anandamide and capsaicin on cytosolic Ca(2+) concentration, although at concentrations higher than those required for CB(1) antagonism