Comparative biology of the endocannabinoid system possible role in the immune response

Activation of central cannabinoid type 2 receptors, but not on peripheral immune cells, is required for endocannabinoid-mediated neuroprotection in Parkinson's disease

Neuroinflammation is a key feature of Parkinson's disease (PD). The cannabinoid receptor type 2 (CB2R) is expressed by cells of the innate and adaptive immune systems. Inhibition of monoacylglycerol lipase (MAGL) with JZL184 increases the levels of the endocannabinoid 2-arachidonoylglycerol (2-AG), which is neuroprotective for dopaminergic neurons. The aim of this study was to determine whether the neuroprotective effect of MAGL inhibition is mediated by CB2R activation on specific immune cell populations. Experimental parkinsonism was induced by chronic administration of MPTP and probenecid. A specific increase in CD4+ T cell infiltration was detected in the midbrain of parkinsonian mice and was reduced by administration of JZL184. JZL184 had no effect in CB2R KO mice, suggesting that CB2R is required for neuroprotection. In the brain, CB2R expression was restricted to myeloid cells and lymphocytes, and increased in microglia under parkinsonian conditions. Administration of a central CB2R agonist, JWH133, exerted a beneficial effect similar to that of JZL184, whereas the peripheral agonist RO304 lacked neuroprotective activity. These results were confirmed using chimeric mice. In silico analysis, showed that transcripts related to 2-AG biosynthesis are downregulated in the midbrain microglia from PD patients. Our results show that activation of CB2R in the brain prevents nigrostriatal degeneration, CD4+ T cell infiltration and TNFα production in the midbrain of parkinsonian mice. The reduced 2-AG signaling in microglia from PD patients suggests that activation of microglial CB2R may be an interesting strategy for the treatment of PD.

A high-resolution 13C NMR approach for profiling fatty acid unsaturation in lipid extracts and in live Caenorhabditiselegans

Unsaturated fatty acids (UFA) play a crucial role in central cellular processes in animals, including membrane function, development, and disease. Disruptions in UFA homeostasis can contribute to the onset of metabolic, cardiovascular, and neurodegenerative disorders. Consequently, there is a high demand for analytical techniques to study lipid compositions in live cells and multicellular organisms. Conventional analysis of UFA compositions in cells, tissues, and organisms involves solvent extraction procedures coupled with analytical techniques such as gas chromatography, MS and/or NMR spectroscopy. As a nondestructive and nontargeted technique, NMR spectroscopy is uniquely capable of characterizing the chemical profiling of living cells and multicellular organisms. Here, we use NMR spectroscopy to analyze Caenorhabditis elegans, enabling the determination of their lipid compositions and fatty acid unsaturation levels both in cell-free lipid extracts and in vivo. The NMR spectra of lipid extracts from WT and fat-3 mutant C. elegans strains revealed notable differences due to the absence of Δ-6 fatty acid desaturase activity, including the lack of arachidonic and eicosapentaenoic acyl chains. Uniform 13C-isotope labeling and high-resolution 2D solution-state NMR of live worms confirmed these findings, indicating that the signals originated from fast-tumbling lipid molecules within lipid droplets. Overall, this strategy permits the analysis of lipid storage in intact worms and has enough resolution and sensitivity to identify differences between WT and mutant animals with impaired fatty acid desaturation. Our results establish methodological benchmarks for future investigations of fatty acid regulation in live C. elegans using NMR.

Chronic exposure to a synthetic cannabinoid alters cerebral brain metabolism and causes long-lasting behavioral deficits in adult mice

In recent years, there has been growing evidence that cannabinoids have promising medicinal and pharmacological effects. However, the growing interest in medical cannabis highlights the need to better understand brain alterations linking phytocannabinoids or synthetic cannabinoids to clinical and behavioral phenotypes. Therefore, the aim of this study was to investigate the effects of long-term WIN 55,212-2 treatment-with and without prolonged abstinence-on cerebral metabolism and memory function in healthy wildtype mice. Adult C57BI/6J mice were divided into two treatment groups to study the acute effects of WIN 55,212-2 treatment as well the effects of WIN 55,212-2 treatment after an extended washout phase. We could demonstrate that 3 mg/kg WIN 55,212-2 treatment in early adulthood leads to a hypometabolism in several brain regions including the hippocampus, cerebellum, amygdala and midbrain, even after prolonged abstinence. Furthermore, prolonged acute WIN 55,212-2 treatment in 6-months-old mice reduced the glucose metabolism in the hippocampus and midbrain. In addition, Win 55,212-2 treatment during adulthood lead to spatial memory and recognition memory deficits without affecting anxiety behavior. Overall we could demonstrate that treatment with the synthetic CB1/CB2 receptor aganist Win 55,212-2 during adulthood causes persistent memory deficits, especially when mice were treated in early adulthood. Our findings highlight the risks of prolonged WIN 55,212-2 use and provide new insights into the mechanisms underlying the effects of chronic cannabinoid exposure on the brain and behavior.

Distribution of an analgesic palmitoylethanolamide and other N-acylethanolamines in human placental membranes

BACKGROUND

Human amniotic and amniochorionic membranes (AM, ACM) represent the most often used grafts accelerating wound healing. Palmitoylethanolamide, oleoylethanolamide and anandamide are endogenous bioactive lipid molecules, generally referred as N-acylethanolamines. They express analgesic, nociceptive, neuroprotective and anti-inflammatory properties. We assessed the distribution of these lipid mediators in placental tissues, as they could participate on analgesic and wound healing effect of AM/ACM grafts.

METHODS

Seven placentas were collected after caesarean delivery and fresh samples of AM, ACM, placental disc, umbilical cord, umbilical serum and vernix caseosa, and decontaminated samples (antibiotic solution BASE 128) of AM and ACM have been prepared. Ultra-high-performance liquid chromatography-tandem mass spectrometry was used for N-acylethanolamines analysis.

RESULTS

N-acylethanolamines were present in all studied tissues, palmitoylethanolamide being the most abundant and the anandamide the least. For palmitoylethanolamide the maximum average concentration was detected in AM (350.33 ± 239.26 ng/g), while oleoylethanolamide and anandamide were most abundant in placenta (219.08 ± 79.42 ng/g and 30.06 ± 7.77 ng/g, respectively). Low levels of N-acylethanolamines were found in serum and vernix. A significant increase in the levels of N-acylethanolamines (3.1-3.6-fold, P < 0.001) was observed in AM when the tissues were decontaminated using antibiotic solution. The increase in decontaminated ACM was not statistically significant.

CONCLUSIONS

The presence of N-acylethanolamines, particularly palmitoylethanolamide in AM and ACM allows us to propose these lipid mediators as the likely factors responsible for the anti-hyperalgesic, but also anti-inflammatory and neuroprotective, effects of AM/ACM grafts in wound healing treatment. The increase of N-acylethanolamines levels in AM and ACM after tissue decontamination indicates that tissue processing is an important factor in maintaining the analgesic effect.

Endocannabinoids effect on oxidative status of human platelets

Reactive oxygen species (ROS) are known to regulate platelet activation. Since endocannabinoids behave as platelet agonists, we investigated the effect of two endocannabinoids, 2-arachidonoylglycerol (2AG) and anandamide (AEA) on the oxidative status of human platelets. We have demonstrated that 2AG and AEA stimulate ROS production, superoxide anion formation and lipid peroxidation. The effect is dose and time dependent and mainly occurs through the involvement of cannabinoid receptor 1 (CB1) since all tested parameters are greatly reduced by SR141716, the CB1 specific inhibitor. The specific inhibitor of cannabinoid receptor 2 (CB2) SR144528 produces a very small inhibition. The involvement of syk/PI3K/AKT/mTor pathway in oxidative stress induced by endocannabinoids is shown. Nicotinamide adenine dinucleotide phosphate oxidase seems to be poorly involved in the endocannabinoids effect. Concerning the aerobic metabolism, it has been demonstrated that endocannabinoids reduce the oxygen consumption and adenosine triphosphate synthesis, both in the presence of pyruvate + malate or succinate. In addition, endocannabinoids inhibit the activity of respiratory complexes II, III and IV and increase the activity of respiratory complex I. The endocannabinoids effect on aerobic metabolism seems to be also a CB1 mediated mechanism. Thus, in human platelets oxidative stress induced by endocannabinoids, mainly generated in the respiratory chain through the activation of complex I and the inhibition of complex II, III and IV, may lead to thrombotic events, contributing to cardiovascular diseases.

Exploration of Multiverse Activities of Endocannabinoids in Biological Systems

Over the last 25 years, the human endocannabinoid system (ECS) has come into the limelight as an imperative neuro-modulatory system. It is mainly comprised of endogenous cannabinoid (endocannabinoid), cannabinoid receptors and the associated enzymes accountable for its synthesis and deterioration. The ECS plays a proven role in the management of several neurological, cardiovascular, immunological, and other relevant chronic conditions. Endocannabinoid or endogenous cannabinoid are endogenous lipid molecules which connect with cannabinoid receptors and impose a fashionable impact on the behavior and physiological processes of the individual. Arachidonoyl ethanolamide or Anandamide and 2-arachidonoyl glycerol or 2-AG were the endocannabinoid molecules that were first characterized and discovered. The presence of lipid membranes in the precursor molecules is the characteristic feature of endocannabinoids. The endocannabinoids are released upon rapid enzymatic reactions into the extracellular space via activation through G-protein coupled receptors, which is contradictory to other neurotransmitter that are synthesized beforehand, and stock up into the synaptic vesicles. The current review highlights the functioning, synthesis, and degradation of endocannabinoid, and explains its functioning in biological systems.

Metabolomics reveal alterations in arachidonic acid metabolism in Schistosoma mekongi after exposure to praziquantel

BACKGROUND

Mekong schistosomiasis is a parasitic disease caused by the blood-dwelling fluke Schistosoma mekongi. This disease contributes to human morbidity and mortality in the Mekong region, posing a public health threat to people in the area. Currently, praziquantel (PZQ) is the drug of choice for the treatment of Mekong schistosomiasis. However, the molecular mechanisms of PZQ action remain unclear, and Schistosoma PZQ resistance has been reported occasionally. Through this research, we aimed to use a metabolomic approach to identify the potentially altered metabolic pathways in S. mekongi associated with PZQ treatment.

METHODOLOGY/PRINCIPAL FINDINGS

Adult stage S. mekongi were treated with 0, 20, 40, or 100 μg/mL PZQ in vitro. After an hour of exposure to PZQ, schistosome metabolites were extracted and studied with mass spectrometry. The metabolomic data for the treatment groups were analyzed with the XCMS online platform and compared with data for the no treatment group. After low, medium (IC50), and high doses of PZQ, we found changes in 1,007 metabolites, of which phosphatidylserine and anandamide were the major differential metabolites by multivariate and pairwise analysis. In the pathway analysis, arachidonic acid metabolism was found to be altered following PZQ treatment, indicating that this pathway may be affected by the drug and potentially considered as a novel target for anti-schistosomiasis drug development.

CONCLUSIONS/SIGNIFICANCE

Our findings suggest that arachidonic acid metabolism is a possible target in the parasiticidal effects of PZQ against S. mekongi. Identifying potential targets of the effective drug PZQ provides an interesting viewpoint for the discovery and development of new agents that could enhance the prevention and treatment of schistosomiasis.

The Endocannabinoid System in the Mediterranean Mussel Mytilus galloprovincialis: Possible Mediators of the Immune Activity?

Anandamide (AEA) is one of the best characterized members of the endocannabinoid family and its involvement in many pathophysiological processes has been well documented in vertebrates and invertebrates. Here, we report the biochemical and functional characterization of key elements of the endocannabinoid system in hemocytes isolated from the Mediterranean mussel Mytilus galloprovincialis. We also show the effects of exogenous AEA, as well as of capsaicin, on the cell ability to migrate and to activate the respiratory burst, upon in vitro stimulation of phagocytosis. Interestingly, our findings show that both AEA and capsaicin suppress the hemocyte response and that the use of selective antagonists of CB₂ and TRPV1 receptors revert their inhibitory effects. Overall, present data support previous evidence on the presence of endocannabinoid signaling in mollusks and advance our knowledge about the evolutionary origins of this endogenous system and its role in the innate response of mollusks.

The Endocannabinoid System and Invertebrate Neurodevelopment and Regeneration

Cannabis has long been used for its medicinal and psychoactive properties. With the relatively new adoption of formal medicinal cannabis regulations worldwide, the study of cannabinoids, both endogenous and exogenous, has similarly flourished in more recent decades. In particular, research investigating the role of cannabinoids in regeneration and neurodevelopment has yielded promising results in vertebrate models. However, regeneration-competent vertebrates are few, whereas a myriad of invertebrate species have been established as superb models for regeneration. As such, this review aims to provide a comprehensive summary of the endocannabinoid system, with a focus on current advances in the area of endocannabinoid system contributions to invertebrate neurodevelopment and regeneration.

Drosophila reward system - A summary of current knowledge

The fruit fly Drosophila melanogaster brain is the most extensively investigated model of a reward system in insects. Drosophila can discriminate between rewarding and punishing environmental stimuli and consequently undergo associative learning. Functional models, especially those modelling mushroom bodies, are constantly being developed using newly discovered information, adding to the complexity of creating a simple model of the reward system. This review aims to clarify whether its reward system also includes a hedonic component. Neurochemical systems that mediate the 'wanting' component of reward in the Drosophila brain are well documented, however, the systems that mediate the pleasure component of reward in mammals, including those involving the endogenous opioid and endocannabinoid systems, are unlikely to be present in insects. The mushroom body components exhibit differential developmental age and different functional processes. We propose a hypothetical hierarchy of the levels of reinforcement processing in response to particular stimuli, and the parallel processes that take place concurrently. The possible presence of activity-silencing and meta-satiety inducing levels in Drosophila should be further investigated.

Cannabis, the Endocannabinoid System and Immunity-the Journey from the Bedside to the Bench and Back

The Cannabis plant contains numerous components, including cannabinoids and other active molecules. The phyto-cannabinoid activity is mediated by the endocannabinoid system. Cannabinoids affect the nervous system and play significant roles in the regulation of the immune system. While Cannabis is not yet registered as a drug, the potential of cannabinoid-based medicines for the treatment of various conditions has led many countries to authorize their clinical use. However, the data from basic and medical research dedicated to medical Cannabis is currently limited. A variety of pathological conditions involve dysregulation of the immune system. For example, in cancer, immune surveillance and cancer immuno-editing result in immune tolerance. On the other hand, in autoimmune diseases increased immune activity causes tissue damage. Immuno-modulating therapies can regulate the immune system and therefore the immune-regulatory properties of cannabinoids, suggest their use in the therapy of immune related disorders. In this contemporary review, we discuss the roles of the endocannabinoid system in immunity and explore the emerging data about the effects of cannabinoids on the immune response in different pathologies. In addition, we discuss the complexities of using cannabinoid-based treatments in each of these conditions.

Cannabis, One Health, and Veterinary Medicine: Cannabinoids' Role in Public Health, Food Safety, and Translational Medicine

Public health is connected to cannabis with regard to food, animal feed (feed), and pharmaceuticals. Therefore, the use of phytocannabinoids should be examined from a One Health perspective. Current knowledge on medical cannabis treatment (MCT) does not address sufficiently diseases which are of epidemiological and of zoonotic concern. The use of cannabinoids in veterinary medicine is illegal in most countries, mostly due to lack of evidence-based medicine. To answer the growing need of scientific evidence-based applicable medicine in both human and veterinary medicine, a new approach for the investigation of the therapeutic potential of cannabinoids must be adopted. A model that offers direct study of a specific disease in human and veterinary patients may facilitate development of novel therapies. Therefore, we urge the regulatory authorities-the ministries of health and agriculture (in Israel and worldwide)-to publish guidelines for veterinary use due to its importance to public health, as well as to promote One Health-related preclinical translational medicine studies for the general public health.

Microglial Phenotypes and Their Relationship to the Cannabinoid System: Therapeutic Implications for Parkinson's Disease

Parkinson’s disease is a neurodegenerative disorder, the motor symptoms of which are associated classically with Lewy body formation and nigrostriatal degeneration. Neuroinflammation has been implicated in the progression of this disease, by which microglia become chronically activated in response to α-synuclein pathology and dying neurons, thereby acquiring dishomeostatic phenotypes that are cytotoxic and can cause further neuronal death. Microglia have a functional endocannabinoid signaling system, expressing the cannabinoid receptors in addition to being capable of synthesizing and degrading endocannabinoids. Alterations in the cannabinoid system—particularly an upregulation in the immunomodulatory CB₂ receptor—have been demonstrated to be related to the microglial activation state and hence the microglial phenotype. This paper will review studies that examine the relationship between the cannabinoid system and microglial activation, and how this association could be manipulated for therapeutic benefit in Parkinson’s disease.

Cannabinoid Actions on Neural Stem Cells: Implications for Pathophysiology

With the increase of life expectancy, neurodegenerative disorders are becoming not only a health but also a social burden worldwide. However, due to the multitude of pathophysiological disease states, current treatments fail to meet the desired outcomes. Therefore, there is a need for new therapeutic strategies focusing on more integrated, personalized and effective approaches. The prospect of using neural stem cells (NSC) as regenerative therapies is very promising, however several issues still need to be addressed. In particular, the potential actions of pharmacological agents used to modulate NSC activity are highly relevant. With the ongoing discussion of cannabinoid usage for medical purposes and reports drawing attention to the effects of cannabinoids on NSC regulation, there is an enormous, and yet, uncovered potential for cannabinoids as treatment options for several neurological disorders, specifically when combined with stem cell therapy. In this manuscript, we review in detail how cannabinoids act as potent regulators of NSC biology and their potential to modulate several neurogenic features in the context of pathophysiology.

Cannabis sativa: A comprehensive ethnopharmacological review of a medicinal plant with a long history

ETHNOPHARMACOLOGICAL RELEVANCE

Cannabis sativa L. (C. sativa) is an annual dioecious plant, which shares its origins with the inception of the first agricultural human societies in Asia. Over the course of time different parts of the plant have been utilized for therapeutic and recreational purposes, for instance, extraction of healing oils from seed, or the use of inflorescences for their psychoactive effects. The key psychoactive constituent in C. sativa is called Δ-9-tetrahydrocannabinol (D9-THC). The endocannabinoid system seems to be phylogenetically ancient, as it was present in the most primitive vertebrates with a neuronal network. N-arachidonoylethanolamine (AEA) and 2-arachidonoyl glycerol (2-AG) are the main endocannabinoids ligands present in the animal kingdom, and the main endocannabinoid receptors are cannabinoid type-1 (CB1) receptor and cannabinoid type-2 (CB2) receptor.

AIM OF THE STUDY

The review aims to provide a critical and comprehensive evaluation, from the ancient times to our days, of the ethnological, botanical, chemical and pharmacological aspects of C. sativa, with a vision for promoting further pharmaceutical research to explore its complete potential as a therapeutic agent.

MATERIALS AND METHODS

This study was performed by reviewing in extensive details the studies on historical significance and ethnopharmacological applications of C. sativa by using international scientific databases, books, Master's and Ph.D. dissertations and government reports. In addition, we also try to gather relevant information from large regional as well as global unpublished resources. In addition, the plant taxonomy was validated using certified databases such as Medicinal Plant Names Services (MPNS) and The Plant List.

RESULTS AND CONCLUSIONS

A detailed comparative analysis of the available resources for C. sativa confirmed its origin and traditional spiritual, household and therapeutic uses and most importantly its popularity as a recreational drug. The result of several studies suggested a deeper involvement of phytocannabinoids (the key compounds in C. sativa) in several others central and peripheral pathophysiological mechanisms such as food intake, inflammation, pain, colitis, sleep disorders, neurological and psychiatric illness. However, despite their numerous medicinal benefits, they are still considered as a menace to the society and banned throughout the world, except for few countries. We believe that this review will help lay the foundation for promoting exhaustive pharmacological and pharmaceutical studies in order to better understand the clinical relevance and applications of non-psychoactive cannabinoids in the prevention and treatment of life-threatening diseases and help to improve the legal status of C. sativa.

Differential effects of endogenous, phyto and synthetic cannabinoids on thrombogenesis and platelet activity

This study analysed the impact of anandamide, cannabidiol (CBD), and WIN55,212-2 on platelet activity and thrombogenesis for the first time. The effects of the cannabinoids on venular thrombosis were studied in the ear of hairless mice. Cannabinoid treatment was performed either once or repetitive by a once-daily administration for three days. To assess the role of cyclooxygenase metabolites in the putative action of anandamide, in vivo studies likewise included a combined administration of anandamide with indomethacin. In vitro, the effect of the cannabinoids on human platelet activation was studied by means of P-selectin expression using flow cytometry. Platelets were analysed under resting or thrombin receptor activating peptide (TRAP)-stimulated conditions, both after cannabinoid treatment alone and after TRAP stimulation and subsequent cannabinoid exposure. Finally, platelet count was assessed after treatment with high concentrations of anandamide. Anandamide, but not CBD and WIN55,212-2, significantly accelerated thrombus growth after one-time treatment as compared to vehicle control. Co-administration with indomethacin neutralized this effect. However, thrombogenesis was not altered by repeated treatment with the cannabinoids. In vitro, anandamide was shown to elicit a concentration-dependent activation of resting human platelets. However, at higher concentrations anandamide reduced the response to TRAP activation associated with a decrease of platelet count. CBD and WIN55,212-2 neither increased nor reduced activation of platelets. Acute exposure to anandamide elicits a cyclooxygenase-dependent prothrombotic effect in vivo. Anandamide seems to affect human platelet activation by a concentration-dependent toxic effect. By contrast, CBD and WIN55,212-2 were not associated with induction of thrombosis or activation of platelets. © 2016 BioFactors, 42(6):581-590, 2016.

Evolution of the diacylglycerol lipases

Diacylglycerol lipases (DGLs) mainly catalyze "on-demand" biosynthesis of bioactive monoacylglycerols (MAGs) with different long fatty acyl chains, including 2-arachidonoylglycerol (2-AG), 2-linoleoylglycerol (2-LG), 2-oleoylglycerol (2-OG) and 2-palmitoylglycerol (2-PG). Enzymatic characterization of DGLs, their expression and distribution, and functional features has been elucidated from microorganisms to mammals in some extent. In mammals, biosynthesis, degradation and metabolism of these bioactive lipids intertwine and form a complicated biochemical pathway to affect the mammal neuromodulation of central nervous system and also other physiological processes in most peripheral organs and non-nervous tissue cells, and yet we still do not know if the neuromodulatory role of mammal DGL and MAGs is similar to invertebrates. Tracing the evolutionary history of DGLs from microorganisms to vertebrates will be an essential method to infer DGL and MAG research in organisms. In this review, we give an exhaustive explanation of the ancestral origin, divergence and evolutionary pattern through systemic searching of DGL orthologs in different species. Finally, we also summarize our recent work on the structural and functional studies of DGL in order to explore usage of DGLs in industry and the development of inhibitors for clinical intervention.

Regulation of cAMP Intracellular Levels in Human Platelets Stimulated by 2-Arachidonoylglycerol

We demonstrated that in human platelets the endocannabinoid 2-arachidonoylglycerol (2-AG) decreased dose- and time-dependently cAMP intracellular levels. No effect on cAMP decrease induced by 2-AG was observed in the presence of the adenylate cyclase inhibitor SQ22536 as well in platelets pretreated with the thromboxane A2 receptor antagonist, SQ29548 or with aspirin, inhibitor of arachidonic acid metabolism through the cyclooxygenase pathway. An almost complete recovering of cAMP level was measured in platelets pretreated with the specific inhibitor of phosphodiesterase (PDE) 3A, milrinone. In platelets pretreated with LY294002 or MK2206, inhibitors of PI3K/AKT pathway, and with U73122, inhibitor of phospholipase C pathway, only a partial prevention was shown. cAMP intracellular level depends on synthesis by adenylate cyclase and hydrolysis by PDEs. In 2-AG-stimulated platelets adenylate cyclase activity seems to be unchanged. In contrast PDEs appear to be involved. In particular PDE3A was specifically activated, as milrinone reversed cAMP reduction by 2-AG. 2-AG enhanced PDE3A activity through its phosphorylation. The PI3K/AKT pathway and PKC participate to this PDE3A phosphorylation/activation mechanism as it was greatly inhibited by platelet pretreatment with LY294002, MK2206, U73122, or the PKC specific inhibitor GF109203X. Taken together these data suggest that 2-AG potentiates its power of platelet agonist reducing cAMP intracellular level.

Endocannabinoids drive the acquisition of an alternative phenotype in microglia

The ability of microglia to acquire diverse states of activation, or phenotypes, reflects different features that are determinant for their contribution to homeostasis in the adult CNS, and their activity in neuroinflammation, repair or immunomodulation. Despite the widely reported immunomodulatory effects of cannabinoids in both the peripheral immune system and the CNS, less is known about how the endocannabinoid signaling system (eCBSS) influence the microglial phenotype. The general aim of the present study was to investigate the role of endocannabinoids in microglia polarization by using microglia cell cultures. We show that alternative microglia (M2a) and acquired deactivated microglia (M2c) exhibit changes in the eCB machinery that favor the selective synthesis of 2-AG and AEA, respectively. Once released, these eCBs might be able to act through CB1 and/or CB2 receptors in order to influence the acquisition of an M2 phenotype. We present three lines of evidence that the eCBSS is critical for the acquisition of the M2 phenotype: (i) M2 polarization occurs on exposure to the two main endocannabinoids 2-AG and AEA in microglia cultures; (ii) cannabinoid receptor antagonists block M2 polarization; and (iii) M2 polarization is dampened in microglia from CB2 receptor knockout mice. Taken together, these results indicate the interest of eCBSS for the regulation of microglial activation in normal and pathological conditions.

Effects of co-administration of 2-arachidonylglycerol (2-AG) and a selective µ-opioid receptor agonist into the nucleus accumbens on high-fat feeding behaviors in the rat

Previous research has demonstrated that the nucleus accumbens is a site where opioids and cannabinoids interact to alter feeding behavior. However, the influence of the endocannabinoid 2-arachidonylglycerol (2-AG) on the well-characterized model of intra-accumbens opioid driven high-fat feeding behavior has not been explored. The present experiments examined high-fat feeding associated behaviors produced by the interaction of 2-AG and the μ-opioid receptor agonist DAla(2),N,Me-Phe(4),Gly-ol(5)-enkaphalin (DAMGO) administered into the nucleus accumbens. Sprague-Dawley rats were implanted with bilateral cannulae aimed at the nucleus accumbens and were co-administered both a sub-threshold dose of 2-AG (0 or 0.25 μg/0.5 μl/side) and DAMGO (0, 0.025 μg or 0.25 μg/0.5 μl/side) in all dose combinations, and in a counterbalanced order. Animals were then immediately allowed a 2h-unrestricted access period to a palatable high-fat diet. Consumption, number and duration of food hopper entries, and locomotor activity were all monitored. DAMGO treatment led to an increase in multiple behaviors, including consumption, duration of food hopper entry, and locomotor activity. However, combined intra-accumbens administration of DAMGO and a subthreshold dose of 2-AG led to a significant increase in number of food hopper entries and locomotor activity, compared to DAMGO by itself. The results confirm that intra-accumbens administration of subthreshold dose of the endogenous cannabinoid 2-AG increases the DAMGO-induced approach and locomotor behaviors associated with high-fat feeding.

Anandamide rescues retinal barrier properties in Müller glia through nitric oxide regulation

The blood retinal barrier (BRB) can mitigate deleterious immune response. Dysfunction at the BRB can affect disease progression. Under inflammatory conditions Müller glia produce increased pro-inflammatory factors, like nitric oxide (NO). In this study we describe molecular events at the Müller glia during inflammation which could affect inner BRB properties. Griess assay and 4,5-diaminofluorescein diacetate (DAF-2DA) time-lapse fluorescence were used to measure NO production. Western blot was used to analyze the expression of inducible nitric oxide synthase (iNOS) and mitogen-activated protein kinases (MAPK) components. Lucifer Yellow was used to measure permeability. Griess assay and DAF-2DA time-lapse fluorescence images revealed that lipopolysaccharide (LPS) induced inflammation and increased NO production. In parallel, changes were observed in tight junction proteins, zona occludens 1 (ZO-1), connexin 43 (Cx43), and permeability. This was mediated through activation of iNOS and mitogen-activated protein kinase phosphatase-1 (MKP-1), implicated in immune response. Endocannabinoids can exert a protective and anti-inflammatory effect. Exogenous arachidonoyl ethanolamide (AEA) inhibited NO generation and also abolished LPS-induced increase in permeability. Our work suggests that subtle changes in Müller glia function, which act as part of the BRB, could contribute to retinal health. AEA which can reduce inflammatory cytotoxicity has potential as treatment in several ocular manifestations where the integrity of the BRB is crucial.

What we know and do not know about the cannabinoid receptor 2 (CB2)

It has been well appreciated that the endocannabinoid system can regulate immune responses via the cannabinoid receptor 2 (CB2), which is primarily expressed by cells of the hematopoietic system. The endocannabinoid system is composed of receptors, ligands and enzymes controlling the synthesis and degradation of endocannabinoids. Along with endocannabinoids, both plant-derived and synthetic cannabinoids have been shown to bind to and signal through CB2 via G proteins leading to both inhibitory and stimulatory signals depending on the biological process. Because no cannabinoid ligand has been identified that only binds to CB2, the generation of mice deficient in CB2 has greatly expanded our knowledge of how CB2 contributes to immune cell development and function in health and disease. In regards to humans, genetic studies have associated CB2 with a variety of human diseases. Here, we review the endocannabinoid system with an emphasis on CB2 and its role in the immune system.

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.

Cannabinoid CB2 receptor gene (CNR2) polymorphism is associated with chronic childhood immune thrombocytopenia in Egypt

Immune thrombocytopenia (ITP) is a heterogeneous autoimmune disorder characterized by thrombocytopenia with or without mucocutaneous bleeding manifestations. ITP patients have significant defects in immune self-tolerance: autoreactive T-lymphocyte clones are capable of directly damaging platelets and possibly megakaryocytes and are likely to proliferate under the influence of Th lymphocytes. The CB2 receptor is thought to be the principal cannabinoid receptor that mediates immune modulation by endocannabinoid. The later has shown a complex range of immunomodulatory effects, primarily suppressive effects on leukocytes and immune functions, including modulation of Th cell development, chemotaxis and cytokine secretion. In this study, we investigated the association between cannabinoid CB2 receptor gene (CNR2) Q63R polymorphism and the susceptibility to childhood ITP in Egyptian population. CNR2 genotyping in ITP patients revealed that 41% of patients had the QR(AA/GG) heterotype and 49% had the RR(AA/AA) homotype. There was a significantly higher frequency of homomutant genotype (RR) in ITP patients than in controls, which conferred more than two-fold increased risk of ITP among Egyptian children [odds ratio (OR) 2.352, 95% confidence interval (CI) 1.313-4.215]. There was a significant statistical difference in the distribution of CNR2 Q63R genotypes between chronic ITP patients group and the control groups. The homomutant genotype carried nearly three-fold increased risk for chronic ITP (OR 2.701, 95% CI 1.462-5.009). In conclusion, CNR2 Q63R polymorphism may represent a novel genetic risk factor in the pathophysiology of chronicity development of ITP in Egyptian children.

Unraveling the complexities of cannabinoid receptor 2 (CB2) immune regulation in health and disease

It has become clear that the endocannabinoid system is a potent regulator of immune responses, with the cannabinoid receptor 2 (CB2) as the key component due to its high expression by all immune subtypes. CB2 has been shown to regulate immunity by a number of mechanisms including development, migration, proliferation, and effector functions. In addition, CB2 has been shown to modulate the function of all immune cell types examined to date. CB2 is a G(i)-protein-coupled receptor and thus exhibits a complex pharmacology allowing both stimulatory and inhibitory signaling that depends on receptor expression levels, ligand concentration, and cell lineage specificities. Here, we discuss both in vitro and in vivo experimental evidence that CB2 is a potent regulator of immune responses making it a prime target for the treatment of inflammatory diseases.

The anandamide effect on NO/cGMP pathway in human platelets

In this study the effect of the endocannabinoid anandamide on platelet nitric oxide (NO)/cGMP pathway was investigated. Data report that anandamide in a dose-and time-dependent manner increased NO and cGMP levels and stimulated endothelial nitric oxide synthase (eNOS) activity. These parameters were significantly reduced by LY294002, selective inhibitor of PI3K and by MK2206, specific inhibitor of AKT. Moreover anandamide stimulated both eNOSser1177 and AKTser473 phosphorylation. Finally the anandamide effect on NO and cGMP levels, eNOS and AKT phosphorylation/activation were inhibited by SR141716, specific cannabinoid receptor 1 antagonist, supporting the involvement of anandamide binding to this receptor. Overall data of this report indicate that low concentrations of anandamide, through PI3K/AKT pathway activation, stimulates eNOS activity and increases NO levels in human platelets. In such way anandamide contributes to extend platelet survival.

Multiple changes in peptide and lipid expression associated with regeneration in the nervous system of the medicinal leech

BACKGROUND

The adult medicinal leech central nervous system (CNS) is capable of regenerating specific synaptic circuitry after a mechanical lesion, displaying evidence of anatomical repair within a few days and functional recovery within a few weeks. In the present work, spatiotemporal changes in molecular distributions during this phenomenon are explored. Moreover, the hypothesis that neural regeneration involves some molecular factors initially employed during embryonic neural development is tested.

RESULTS

Imaging mass spectrometry coupled to peptidomic and lipidomic methodologies allowed the selection of molecules whose spatiotemporal pattern of expression was of potential interest. The identification of peptides was aided by comparing MS/MS spectra obtained for the peptidome extracted from embryonic and adult tissues to leech transcriptome and genome databases. Through the parallel use of a classical lipidomic approach and secondary ion mass spectrometry, specific lipids, including cannabinoids, gangliosides and several other types, were detected in adult ganglia following mechanical damage to connected nerves. These observations motivated a search for possible effects of cannabinoids on neurite outgrowth. Exposing nervous tissues to Transient Receptor Potential Vanilloid (TRPV) receptor agonists resulted in enhanced neurite outgrowth from a cut nerve, while exposure to antagonists blocked such outgrowth.

CONCLUSION

The experiments on the regenerating adult leech CNS reported here provide direct evidence of increased titers of proteins that are thought to play important roles in early stages of neural development. Our data further suggest that endocannabinoids also play key roles in CNS regeneration, mediated through the activation of leech TRPVs, as a thorough search of leech genome databases failed to reveal any leech orthologs of the mammalian cannabinoid receptors but revealed putative TRPVs. In sum, our observations identify a number of lipids and proteins that may contribute to different aspects of the complex phenomenon of leech nerve regeneration, establishing an important base for future functional assays.

Hydrolysis of 2-arachidonoylglycerol in Tetrahymena thermophila. Identification and partial characterization of a Monoacylglycerol Lipase-like enzyme

Tetrahymena thermophila is a model organism for molecular and cellular biology. Previous studies from our group showed that Tetrahymena contains major components of the endocannabinoid system, such as various endocannabinoids and FAAH. In mammalian cells the endocannabinoid 2-arachidonoylglycerol is inactivated mainly by MAGL. In this study we showed that 2-arachidonoylglycerol and 2-oleoylglycerol are hydrolyzed by the combined actions of MAGL and FAAH. MAGL-like activity was examined in the presence of FAAH specific inhibitors, URB597 or AM374 and showed optimum pH of 8-9, apparent K(M) of 14.1μM and V(max) of 5.8nmol/min×mg. The enzyme was present in membrane bound and cytosolic isoforms; molecular mass was determined at ∼45 and ∼40kDa. MAGL and FAAH could also inactivate endogenous signaling lipids, which might play an important role in Tetrahymena as suggested in mammals. Tetrahymena could be used as a model system for testing drugs targeting enzymes of the endocannabinoid system.

Properties of cannabinoid-dependent long-term depression in the leech

Previously, a cannabinoid-dependent form of long-term depression (LTD) was discovered at the polysynaptic connection between the touch mechanosensory neuron and the S interneuron (Li and Burrell in J Comp Physiol A 195:831-841, 2009). In the present study, the physiological properties of this cannabinoid-dependent LTD were examined. Increases in intracellular calcium in the S interneuron are necessary for this form of LTD in this circuit. Calcium signals contributing to cannabinoid-dependent LTD are mediated by voltage-dependent calcium channel and release of calcium from intracellular stores. Inositol triphosphate receptors, but not ryanodine receptors, appear to mediate this store-released calcium signal. Cannabinoid-dependent LTD also requires activation of metabotropic serotonin receptors, possibly a serotonin type 2-like receptor. Finally, this form of LTD involves the stimulation of nitric oxide synthase and a decrease in cyclic adenosine monophosphate signaling, both of which appeared to be downstream of cannabinoid receptor activation. Based on these findings, the cellular signaling mechanisms of cannabinoid-dependent LTD in the leech are remarkably similar to vertebrate forms of cannabinoid-dependent synaptic plasticity.

Cannabinoids and the immune system: an overview

Cannabinoids can influence the immune network. Data on the impact of exogenous cannabinoid ligands on immune function serve not only to understand how the endocannabinoid system modulates immune phenomena associated with infection or inflammation, but also to identify therapeutic targets for immune diseases. Cannabinoids can modulate immune reactions in the periphery but also in the brain, influence T cell subset balance and cytokine expression and play a role in the balance between neuroinflammation and neurodegeneration. Immune cells can synthesize endocannabinoids and also be influenced by cannabinoid analogues. Cannabinoid receptors show different expression on immune cells depending on activation status and stimuli. The complexity of relation between cannabinoid ligands of various classes and cannabinoid receptors brought the need to refine the simple conceptual frame of agonist-antagonists and offered potential implications for understanding interactions in pathological conditions. The immune influence of cannabinoid ligands is not fully elucidated. However, aspects of their immunomodulatory effects provide the basis for a context-dependent targeted therapeutic approach, thus leading to the possibility for the use of cannabinoids in the treatment of inflammatory disease.

Cannabinoid system in the skin - a possible target for future therapies in dermatology

Cannabinoids and their derivatives are group of more than 60 biologically active chemical agents, which have been used in natural medicine for centuries. The major agent of exogenous cannabinoids is Delta(9)-tetrahydrocannabinol (Delta(9)-THC), natural psychoactive ingredient of marijuana. However, psychoactive properties of these substances limited their use as approved medicines. Recent discoveries of endogenous cannabinoids (e.g. arachidonoylethanolamide, 2-arachidonoylglycerol or palmithyloethanolamide) and their receptors initiated discussion on the role of cannabinoid system in physiological conditions as well as in various diseases. Based on the current knowledge, it could be stated that cannabinoids are important mediators in the skin, however their role have not been well elucidated yet. In our review, we summarized the current knowledge about the significant role of the cannabinoid system in the cutaneous physiology and pathology, pointing out possible future therapeutic targets.

Effects of cannabinoids on caffeine contractures in slow and fast skeletal muscle fibers of the frog

The effect of cannabinoids on caffeine contractures was investigated in slow and fast skeletal muscle fibers using isometric tension recording. In slow muscle fibers, WIN 55,212-2 (10 and 5 μM) caused a decrease in tension. These doses reduced maximum tension to 67.43 ± 8.07% (P = 0.02, n = 5) and 79.4 ± 14.11% (P = 0.007, n = 5) compared to control, respectively. Tension-time integral was reduced to 58.37 ± 7.17% and 75.10 ± 3.60% (P = 0.002, n = 5), respectively. Using the CB₁ cannabinoid receptor agonist ACPA (1 μM) reduced the maximum tension of caffeine contractures by 68.70 ± 11.63% (P = 0.01, n = 5); tension-time integral was reduced by 66.82 ± 6.89% (P = 0.02, n = 5) compared to controls. When the CB₁ receptor antagonist AM281 was coapplied with ACPA, it reversed the effect of ACPA on caffeine-evoked tension. In slow and fast muscle fibers incubated with the pertussis toxin, ACPA had no effect on tension evoked by caffeine. In fast muscle fibers, ACPA (1 μM) also decreased tension; the maximum tension was reduced by 56.48 ± 3.4% (P = 0.001, n = 4), and tension-time integral was reduced by 57.81 ± 2.6% (P = 0.006, n = 4). This ACPA effect was not statistically significant with respect to the reduction in tension in slow muscle fibers. Moreover, we detected the presence of mRNA for the cannabinoid CB₁ receptor on fast and slow skeletal muscle fibers, which was significantly higher in fast compared to slow muscle fiber expression. In conclusion, our results suggest that in the slow and fast muscle fibers of the frog cannabinoids diminish caffeine-evoked tension through a receptor-mediated mechanism.

Overexpression of a fatty acid amide hydrolase compromises innate immunity in Arabidopsis

N-acylethanolamines are a group of lipid mediators that accumulate under a variety of neurological and pathological conditions in mammals. N-acylethanolamine signaling is terminated by the action of diverse hydrolases, among which fatty acid amide hydrolase (FAAH) has been well characterized. Here, we show that transgenic Arabidopsis lines overexpressing an AtFAAH are more susceptible to the bacterial pathogens Pseudomonas syringae pv. tomato and P. syringae pv. maculicola. AtFAAH overexpressors also were highly susceptible to non-host pathogens P. syringae pv. syringae and P. syringae pv. tabaci. AtFAAH overexpressors had lower amounts of jasmonic acid, abscisic acid and both free and conjugated salicylic acid (SA), compared with the wild-type. Gene expression studies revealed that transcripts of a number of plant defense genes, as well as genes involved in SA biosynthesis and signaling, were lower in AtFAAH overexpressors than wild-type plants. Our data suggest that FAAH overexpression alters phytohormone accumulation and signaling which in turn compromises innate immunity to bacterial pathogens.

CD4 T cells: Balancing the coming and going of autoimmune-mediated inflammation in the CNS

The regulation of the inflammatory response is often viewed as very complex with many cellular players. The type of immune response generated is dependent upon the nature of the immune stimulation. In autoimmunity, one of the most important players is the CD4 T cell. The CD4 T cell lineage consists of a number of phenotypically and functionally distinct subsets. The unique functions of CD4 T cells are often mediated by soluble factors, which shape the nature of the immune response. In a T cell-mediated autoimmune response, such as in multiple sclerosis (MS), the CD4 T cell is thought to orchestrate and drive the immune response resulting in inflammation within the central nervous system (CNS). The extent of the inflammation must be tightly controlled or permanent tissue damage will occur. In MS, progressive debilitating disease is thought to be due to such damage. In addition to promoting inflammation, the CD4 T cell lineage also has the capacity to prevent and downmodulate inflammation. This is accomplished by specific CD4 T regulatory (Treg) cells and other regulatory feedback mechanisms. Thus although the complexity of the immune system is often viewed as too complicated for a nonimmunologist to fully understand, there are patterns that emerge that make the system clearer. One such pattern is the balance that the immune system must always maintain. A weak or slow immune response to a pathogen can lead to sickness and even death, while a too robust or uncontrolled immune response can lead to tissue damage, and for autoimmune diseases, ultimately death. How CD4 T cells maintain this balance will be discussed in the context of the CNS autoimmune disease MS.

The peripheral cannabinoid receptor knockout mice: an update

This review gives an overview of the CB2 receptor (CB2R) knockout (CB2R-/-) mice phenotype and the work that has been carried out using this mutant mouse. Using the CB2R-/- mice, investigators have discovered the involvement of CB2R on immune cell function and development, infection, embryonic development, bone loss, liver disorders, pain, autoimmune inflammation, allergic dermatitis, atherosclerosis, apoptosis and chemotaxis. Using the CB2R-/- mice, investigators have also found that this receptor is not involved in cannabinoid-induced hypotension. In addition, the CB2R-/- mice have been used to determine specific tissue CB2R expression. The specificity of synthetic cannabinoid agonists, antagonists and anti-CB2R antibodies has been screened using tissues from CB2R-/- mice. Thus, the use of this mouse model has greatly helped reveal the diverse events involving the CB2R, and has aided in drug and antibody screening.

Review of factors essential for blastocyst implantation for their modulating effects on the maternal immune system

Pituitary and ovarian hormones prepare the endometrium for successful blastocyst implantation and support its process directly or indirectly through the action of growth factors, cytokines and other molecules. Many of the blastocyst implantation essential factors (BIEFs) are modulators of the maternal immune system. Since little is known as to the action of these molecules on the uterine lymphocytes, its clarification is imperative to the understanding of the process of blastocyst implantation.

Direct suppression of autoreactive lymphocytes in the central nervous system via the CB2 receptor

The cannabinoid system is now recognized as a regulator of both the nervous and immune systems. Although marijuana has been used for centuries for the treatment of a variety of disorders, its therapeutic mechanisms are only now being understood. The best-studied plant cannabinoid, delta9-tetrahydrocannabinol (THC), produced by Cannabis sativa and found in marijuana, has shown evidence of being immunosuppressive in both in vivo and in vitro. Since THC binds to at least two receptors that are differentially expressed by the immune and nervous systems, it has not been possible to clearly discriminate the biological effects it exerts in the two systems. In addition, endogenous cannabinoids have also been described that bind to both receptors and exert both neuronal and immune modulatory activity. The generation of mice deficient in specific cannabinoid receptors has facilitated studies to discriminate cannabinoid-specific functions. This review focuses on the function of the cannabinoid receptor 2 (CB2), primarily expressed in the immune system, in regulating T cell effector functions associated with autoimmune inflammation in the central nervous system (CNS).

Direct suppression of CNS autoimmune inflammation via the cannabinoid receptor CB1 on neurons and CB2 on autoreactive T cells

The cannabinoid system is immunomodulatory and has been targeted as a treatment for the central nervous system (CNS) autoimmune disease multiple sclerosis. Using an animal model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), we investigated the role of the CB(1) and CB(2) cannabinoid receptors in regulating CNS autoimmunity. We found that CB(1) receptor expression by neurons, but not T cells, was required for cannabinoid-mediated EAE suppression. In contrast, CB(2) receptor expression by encephalitogenic T cells was critical for controlling inflammation associated with EAE. CB(2)-deficient T cells in the CNS during EAE exhibited reduced levels of apoptosis, a higher rate of proliferation and increased production of inflammatory cytokines, resulting in severe clinical disease. Together, our results demonstrate that the cannabinoid system within the CNS plays a critical role in regulating autoimmune inflammation, with the CNS directly suppressing T-cell effector function via the CB(2) receptor.

Changes of gonadal CB1 cannabinoid receptor mRNA in the gilthead seabream, Sparus aurata, during sex reversal

Two cannabinoid receptor-like genes (CB1-like), named CB1A and CB1B, have been isolated in teleost fish, specifically in the puffer fish, Fugu rubripes. However, information on the physiological roles, such as the control of reproduction and development in fish is still scarce. Therefore, the aim of the present study was to investigate the presence of CB1-like mRNA in the gonads of a marine teleost species, the gilthead seabream, Sparus aurata, a hermaphrodite species in which the gonadal tissues first develop as testes, and then as functional ovary. We isolated an 890 bp fragment (GenBank accession number ); that corresponded to the open reading frame of the teleost CB1 receptor gene, encoding for the central portion of the protein, which was aligned with the other bony fish sequence. Using "in situ" hybridization, CB1-like mRNA was localized in both mature and sex-reversing gonads, and relative changes in CB1-like expression levels were detected through semi-quantitative RT-PCR. In the mature testis and in the testicular part of the sex-reversing gonad, CB1 expression levels were found to be much higher compared to the ovarian portion. This suggests that the CB1 signaling is likely involved in the process of testicular regression of the S. aurata, but its actual role has yet to be determined.

Cannabinoids and cancer: pros and cons of an antitumour strategy

In the last two decades, research has dramatically increased the knowledge of cannabinoids biology and pharmacology. In mammals, compounds with properties similar to active components of Cannabis sativa, the so called 'endocannabinoids', have been shown to modulate key cell-signalling pathways involved in cancer cell growth, invasion and metastasis. To date, cannabinoids have been licensed for clinical use as palliative treatment of chemotherapy, but increased evidences showed direct antiproliferative actions of cannabinoid agonists on several tumour cells in vitro and in animal models. In this article, we will review the principal molecular pathways modulated by cannabinoids on cancer and summarize pros and cons evidence on the possible future use of endocannabinoid-based drugs in cancer therapy.

The Endocannabinoid System as a Target for the Treatment of Visceral Obesity and Metabolic Syndrome

The endogenous cannabinoid system is a novel, remarkably elaborate physiological signaling system, comprising the recently identified endogenous cannabinoid ligands, their corresponding selective receptors, and the machinery of proteins and enzymes that is involved in their biosynthesis, release, transport, and degradation. This system extends widely in both the central nervous system (CNS) and the periphery and exhibits a variety of actions implicated in vital functions (e.g., behavioral, antinociceptive, neuroprotective, immunosuppressive, cardiovascular, and metabolic). Particular interest has been focused on the apparent participation of endocannabinoids in metabolic homeostasis by modulating the activity of CNS circuits that control food intake and energy expenditure, the neuroendocrine response of the stress system, and the metabolic functions of crucial peripheral tissues, such as the adipose tissue, the gastrointestinal tract, the liver, and the skeletal muscles. These effects are predominantly CB(1) receptor mediated and, thus, selective antagonists of this receptor subtype are being vigorously investigated as potential therapeutic agents for the treatment of various metabolic derangements (e.g., obesity, insulin resistance, dyslipidemia, and metabolic syndrome). The first selective CB(1) receptor antagonist, rimonabant, has already successfully completed phase III clinical trials as adjunctive obesity treatment, with significant improvements in several associated metabolic and cardiovascular risk factors that led to the recent approval of its clinical use by the Food and Drug Administration.

Neuronal cytoskeleton and synaptic densities are altered after a chronic treatment with the cannabinoid receptor agonist WIN 55,212-2

Cannabinoid CB1 receptors are the most abundant G-protein-coupled receptors in the brain. Its presynaptic location suggests a role for cannabinoids in modulating the release of neurotransmitters from axon terminals by retrograde signaling. The neuroprotective effects of cannabinoid agonists in animal models of ischemia, seizures, hypoxia, Multiple Sclerosis, Huntington and Parkinson disease have been demonstrated in several reports. The proposed mechanism for the neuroprotection ranges from antioxidant effects, reduction of microglial activation and anti-inflammatory reaction to receptor-mediated reduction of glutamate release. In the present work, we analyzed the morphological changes induced by a chronic treatment with the synthetic cannabinoid receptor agonist, WIN 55,212-2, in four brain regions where the CB1 cannabinoid receptor is present in high density: the CA1 hippocampal area, corpus striatum, cerebellum and frontal cortex. After a twice-daily treatment for 14 days with the cannabinoid receptor agonist (3 mg/kg sc, each dose) to male Wistar rats (150-170 g), the expression of neurofilaments (Nf-160 and Nf-200), microtubule-associated protein-2 (MAP-2), synaptophysin (Syn) and glial fibrillary acidic protein (GFAP) was studied by immunohistochemistry and digital image analysis. Ultrastructural study of the synapses was done using electron microscopy. After the treatment, a significant increase in the expression of neuronal cytoskeletal proteins (Nf-160, Nf-200, MAP-2) was observed, but we did not find changes in the expression of GFAP, the main astroglial cytoskeletal protein. In cerebellum, there was an increase in Syn expression and in the number of synaptic vesicles, while, in the hippocampus, an increase in the Syn expression and in the thickness of the postsynaptic densities was observed. The results obtained from these studies provide evidences on the absence of astroglial reaction and a sprouting phenomena induced by the WIN treatment that might be a key contributor to the long-term neuroprotective effects observed after cannabinoid treatments in different models of central nervous system (CNS) injury reported in the literature.

Effects of delta-9-tetrahydrocannabinol, the primary psychoactive cannabinoid in marijuana, on human sperm function in vitro

OBJECTIVE

To investigate effects of delta-9-tetrahydrocannabinol (THC) on human sperm function in vitro.

DESIGN

Laboratory analysis of sperm motility after exposure to THC using computer-assisted semen analysis and acrosome reaction by fluoroscein isothiocyanate-labeled peanut agglutinin staining.

SETTING

An assisted reproductive technology unit.

PATIENT(S)

Seventy-eight male patients.

INTERVENTION(S)

Sperm were divided into 90% (the best fertilizing potential used in assisted conception) and 45% (the poorer subpopulation) fractions by density centrifugation and incubated with THC at concentrations equivalent to therapeutic (0.032 microM) and recreational (0.32 and 4.8 microM) plasma levels at 37 degrees C for 3 h.

MAIN OUTCOME MEASURE(S)

Sperm motility and spontaneous and induced acrosome reactions.

RESULT(S)

Percentage progressive motility was decreased dose dependently in the 90% fraction (by 2%-21%; P<.05; P<.001). The 45% fraction showed a greater decrease in percentage progressive motility (by 28% at 0.032 microM; 56% at 4.8 microM; P=.004 and P=.01 res). Straight line velocity and the average path velocity also were reduced (by 10%, in the 90% LAYER) in both fractions. Spontaneous acrosome reactions were reduced in the 90% (17% at 0.032 microM, 35% at 4.8 microM P=.004 and P<.001 resp) and more markedly in the 45% fractions (17%-35%; P<.001). When the acrosome reaction was artificially induced (90% fraction) by A23187, THC (4.8 microM) resulted in a 57% inhibition (P<.001).

CONCLUSION(S)

The use of THC as a recreational drug may adversely affect male fertility.