Peripheral Endocannabinoid System Research Articles

Electroacupuncture attenuates inflammatory pain via peripheral cannabinoid receptor type 1 signaling pathway in mice

Pain is strongly associated with neuro-immune activation. Thus, the emerging role of the endocannabinoid system in neuro-inflammation is important. Acupuncture has been used for over 2500 years and is widely accepted for the management of pain. Our study aimed to investigate the effects of electroacupuncture on the regulation of cannabinoid receptor type 1 within the peripheral nervous system. Inflammatory pain was induced by injecting Complete Freund’s adjuvant to induce mechanical and thermal hyperalgesia. Electroacupuncture significantly attenuated the mechanical and thermal sensitivities, and AM251, a cannabinoid receptor type 1 antagonist, eliminated these effects. Dual immunofluorescence staining demonstrated that electroacupuncture elevated expression of cannabinoid receptor type 1, co-localized with Nav 1.8. Furthermore, electroacupuncture significantly reduced levels of Nav 1.8 and COX-2 by western blot analysis, but not vice versa as AM251 treatment. Our data indicate that electroacupuncture mediates antinociceptive effects through peripheral endocannabinoid system signaling pathway and provide evidence that electroacupuncture is beneficial for pain treatment.

The peripheral endocannabinoid system and its association with biomarkers of inflammation in untreated patients with multiple sclerosis.

The endocannabinoid system (ECS) has been found altered in patients with multiple sclerosis (MS). However, whether the ECS alteration is present in the early stage of MS remains unknown. First, we aimed to compare the ECS profile between newly diagnosed MS patients and healthy controls (HCs). Next, we explored the association of the ECS, biomarkers of inflammation, and clinical parameters in newly diagnosed MS patients. Whole blood gene expression of ECS components and levels of endocannabinoids in plasma were measured by real-time quantitative polymerase chain reaction and ultra-high-pressure liquid chromatography-mass spectrometry, respectively, in 66 untreated MS patients and 46 HCs. No differences were found in the gene expression or plasma levels of the selected ECS components between newly diagnosed MS patients and HCs. Interferon-γ, encoded by the gene IFNG, correlated positively (ρ = 0.60) with the expression of G protein-coupled receptor 55 (GPR55), and interleukin1β (IL1B) correlated negatively (ρ = -0.50) with cannabinoid receptor 2 (CNR2) in HCs. We found no alteration in the peripheral ECS between untreated patients with MS and HC. Furthermore, our results indicate that the ECS has a minor overall involvement in the early stage of MS on inflammatory markers and clinical parameters when compared with HCs.

Nicotine exposure during breastfeeding alters the expression of endocannabinoid system biomarkers in female but not in male offspring at adulthood.

Early nicotine exposure compromises offspring's phenotype at long-term in both sexes. We hypothesize that offspring exposed to nicotine during breastfeeding show deregulated central and peripheral endocannabinoid system (ECS), compromising several aspects of their metabolism. Lactating rats received nicotine (NIC, 6 mg/Kg/day) or saline from postnatal day (PND) 2 to 16 through implanted osmotic minipumps. Offspring were analyzed at PND180. We evaluated protein expression of N-acylphosphatidylethanolamide-phospholipase D (NAPE-PLD), fatty acid amide hydrolase (FAAH), diacylglycerol lipase (DAGL), monoacylglycerol lipase (MAGL) and cannabinoid receptors (CB1 and/or CB2) in lateral hypothalamus, paraventricular nucleus of the hypothalamus, liver, visceral adipose tissue (VAT), adrenal and thyroid. NIC offspring from both sexes did not show differences in hypothalamic ECS markers. Peripheral ECS markers showed no alterations in NIC males. In contrast, NIC females had lower liver DAGL and CB1, higher VAT DAGL, higher adrenal NAPE-PLD and higher thyroid FAAH. Endocannabinoids biosynthesis was affected by nicotine exposure during breastfeeding only in females; alterations in peripheral tissues suggest lower action in liver and higher action in VAT, adrenal and thyroid. Effects of nicotine exposure during lactation on ECS markers are sex- and tissue-dependent. This characterization helps understanding the phenotype of the adult offspring in this model and may contribute to the development of new pharmacological targets for the treatment of several metabolic diseases that originate during development.

Links between central CB1-receptor availability and peripheral endocannabinoids in patients with first episode psychosis

There is an established, link between psychosis and metabolic abnormalities, such as altered glucose metabolism and dyslipidemia, which often precede the initiation of antipsychotic treatment. It is known that obesity-associated metabolic disorders are promoted by activation of specific cannabinoid targets (endocannabinoid system (ECS)). Our recent data suggest that there is a change in the circulating lipidome at the onset of first episode psychosis (FEP). With the aim of characterizing the involvement of the central and peripheral ECSs, and their mutual associations; here, we performed a combined neuroimaging and metabolomic study in patients with FEP and healthy controls (HC). Regional brain cannabinoid receptor type 1 (CB1R) availability was quantified in two, independent samples of patients with FEP (n = 20 and n = 8) and HC (n = 20 and n = 10), by applying three-dimensional positron emission tomography, using two radiotracers, [11C]MePPEP and [18F]FMPEP-d2. Ten endogenous cannabinoids or related metabolites were quantified in serum, drawn from these individuals during the same imaging session. Circulating levels of arachidonic acid and oleoylethanolamide (OEA) were reduced in FEP individuals, but not in those who were predominantly medication free. In HC, there was an inverse association between levels of circulating arachidonoyl glycerol, anandamide, OEA, and palmitoyl ethanolamide, and CB1R availability in the posterior cingulate cortex. This phenomenon was, however, not observed in FEP patients. Our data thus provide evidence of cross talk, and dysregulation between peripheral endocannabinoids and central CB1R availability in FEP.

S7. INVESTIGATING THE LINK BETWEEN THE PERIPHERAL ENDOCANNABINOID SYSTEM AND CENTRAL GLUTAMATERGIC NEUROTRANSMISSION IN EARLY PSYCHOSIS: A 7T-MRS STUDY

BackgroundMeta-analytic evidence showed increased levels of peripheral endocannabinoid metabolites in psychotic illness. Alterations in the endocannabinoid system are believed to compromise glutamate and dopamine transmission, which play a central role in pathophysiological models of psychosis. I will present preliminary data from an ongoing high-field proton magnetic resonance spectroscopy (MRS) study aimed at investigating the association between peripheral levels of endocannabinoid system metabolites and central glutamate metabolism in individuals at their first non-affective psychotic episode (NA-FEP) and healthy controls.MethodsWe expect to recruit 17 NA-FEP and 20 healthy controls by January 2020. Currently, we recruited 12 NA-FEP and 18 healthy controls from two different research facilities (Imperial College London and University of Oxford) as part of a cross-sectional study. Participants underwent MRS scanning at 7-T with voxels placed in right dorsolateral prefrontal cortex (right-DLPFC), anterior cingulate cortex (ACC), and occipital cortex. Neuro-metabolites will be calculated using the unsuppressed water signal as reference. Endocannabinoid metabolites were quantified from serum samples, collected during the same imaging session.ResultsAnalyses are ongoing. Based on previous evidence, expected findings are: (i) reduced glutamate levels in the ACC and right-DLPFC of NA-FEP compared to controls; (ii) increased peripheral endocannabinoid metabolites in NA-FEP compared to controls; and (iii) inverse association between peripheral endocannabinoid metabolites and glutamate levels in ACC and right-DLPFC in NA-FEPDiscussionThis study will help clarifying the contribution of peripheral endocannabinoid system to central brain mechanisms of key relevance for psychotic illness. It will also add further evidence on the limited literature on high-resolution characterisation of brain metabolites in early psychosis. Strengths of the study include: (i) use of high-field MRS, which allows the estimation of glutamate-related compounds at higher precision than at lower field strength; (ii) reduced heterogeneity of the clinical sample (only male and NA-FEP). Limitations: small sample size and cross-sectional design.

SAT-LB100 Central and Peripheral Endocannabinoid Levels in Obese Versus Lean Women

The endocannabinoid system (ECS) is thought to be involved in obesity because its activation increases appetite and weight gain (Pagotto et al 2006). The ECS is hyperactivated in the hypothalamus of obese mice, and peripheral overactivation has been observed in humans; circulating 2-arachidonoyl glycerol (2-AG) levels positively correlated with body fat, visceral fat and fasting glucose (Osei-Hyiaman et al 2005) (Bluher et al 2006) (Motaghedi and McGraw 2008) (Cavuoto et al 2007) (Artmann et al 2008) (Bermudez-Silva 2009). The aim of this study was to evaluate whether differential activation of the peripheral versus the central ECS occurred in humans and to test the hypothesis that the ECS is hyperactivated in the human central nervous system (CNS).Cerebral spinal fluid (CSF) and blood samples were collected from 13 obese and 11 lean control women to measure 2-AG and anandamide (AEA) levels.AEA levels were higher in the plasma of obese women (obese: 4.03 ± 0.91 pmol/mL, N=13; lean: 1.84 ± 0.21 pmol/mL, N=10; p<0.05) but were lower in the CSF of obese women. The plasma/CSF ratio was 41.58 ± 5.78 (N=10) in lean women and 103.0 ± 37.36 (N=6) in obese women (p=0.054). There were no correlations between plasma and CSF AEA levels or with any biochemical parameter. The 2-AG analysis was not possible because of technical problems.Our data suggested that in human obesity, the peripheral ECS may be more active than the central ECS. Indeed, the system appeared to be suppressed in the CNS of obese women. Therefore, the peripheral activation of the ECS may be more relevant for obesity. Keywords: Anandamide, 2-arachidonoyl glycerol, obesity, endocannabinoid, endocannabinoid system, cb1 receptor.

Cannabis: From a Plant That Modulates Feeding Behaviors toward Developing Selective Inhibitors of the Peripheral Endocannabinoid System for the Treatment of Obesity and Metabolic Syndrome.

In this review, we discuss the role of the endocannabinoid (eCB) system in regulating energy and metabolic homeostasis. Endocannabinoids, via activating the cannabinoid type-1 receptor (CB1R), are commonly known as mediators of the thrifty phenotype hypothesis due to their activity in the central nervous system, which in turn regulates food intake and underlies the development of metabolic syndrome. Indeed, these findings led to the clinical testing of globally acting CB1R blockers for obesity and various metabolic complications. However, their therapeutic potential was halted due to centrally mediated adverse effects. Recent observations that highlighted the key role of the peripheral eCB system in metabolic regulation led to the preclinical development of various novel compounds that block CB1R only in peripheral organs with very limited brain penetration and without causing behavioral side effects. These unique molecules, which effectively ameliorate obesity, type II diabetes, fatty liver, insulin resistance, and chronic kidney disease in several animal models, are likely to be further developed in the clinic and may revive the therapeutic potential of blocking CB1R once again.

Impact of maternal western diet-induced obesity on offspring mortality and peripheral endocannabinoid system in mice.

Over two-thirds of adults in the United States are obese or overweight, which is largely due to chronic overconsumption of diets high in fats and sugars (i.e., Western diet). Recent studies reveal that maternal obesity may predispose offspring to development of obesity and other metabolic diseases; however, the molecular underpinnings of these outcomes are largely unknown. The endocannabinoid system is an important signaling pathway that controls feeding behavior and energy homeostasis, and its activity becomes upregulated in the upper small intestinal epithelium of Western diet-induced obese mice, which drives overeating. In the current investigation, we examined the impact of chronic maternal consumption of Western diet on the expression and function of the endocannabinoid system in several peripheral organs important for food intake and energy homeostasis in offspring. Female C57BL/6Tac mice were fed a Western diet or low-fat/no-sucrose control chow for 10 weeks, then males were introduced for mating. Dams were maintained on their respective diets through weaning of pups, at which time pups were maintained on low-fat/no-sucrose chow for 10 weeks. Neonates born from dams fed Western diet, when compared to those born from mice fed control chow, unexpectedly displayed increases in mortality that occurred exclusively within six days following birth (greater than 50% mortality). Males comprised a larger fraction of surviving offspring from obese dams. Furthermore, surviving offspring displayed transient increases in body mass for first two days post weaning, and no marked changes in feeding patterns and endocannabinoid levels in upper small intestinal epithelium, pancreas, and plasma, or in expression of key endocannabinoid system genes in the upper small intestinal epithelium and pancreas at 10 weeks post-weaning. Collectively, these results suggest that maternal diet composition greatly influences survival of neonate C57BL/6Tac mice, and that surviving offspring from dams chronically fed a Western diet do not display marked changes in body mass, eating patterns, or expression and function of the endocannabinoid system in several peripheral organs important for feeding behavior and energy homeostasis.

Changes in the Peripheral Endocannabinoid System as a Risk Factor for the Development of Eating Disorders

Eating Disorder (ED) is characterized by persistently and severely disturbed eating behaviours. They arise from a combination of long-standing behavioural, emotional, psychological, interpersonal, and social factors and result in insufficient nutrient ingestion and/or adsorption. The three main EDs are: anorexia nervosa, bulimia nervosa, and binge eating disorder. We review the role of peripheral endocannabinoids in eating behaviour. The neuronal pathways involved in feeding behaviours are closely related to catecholaminergic, serotoninergic and peptidergic systems. Accordingly, feeding is promoted by serotonin, dopamine, and prostaglandin and inhibited by neuropeptide Y, norepinephrine, GABA, and opioid peptides. The endocannabinoid system plays a role in EDs, and multiple lines of evidence indicate that the cannabinoid signalling system is a key modulatory factor of the activity in the brain areas involved in EDs as well as in reward processes. Besides their central role in controlling food behaviours, peripheral cannabinoids are also involved in regulating adipose tissue and insulin signalling as well as cell metabolism in peripheral tissues such as liver, pancreas, fatty tissue, and skeletal muscle. Altogether, these data indicate that peripheral cannabinoids can provide new therapeutic targets not only for EDs but also for metabolic disease.

42.4 THE ENDOCANNABINOID SYSTEM IN FIRST-EPISODE PSYCHOSIS

BackgroundThe endocannabinoid (EC) system comprises of fatty acid neurotransmitters such as anandamide and 2-acylglycerol, at least two specific cannabinoid (CB) receptor subtypes and enzyme machinery for synthesis and degradation of ECs. The EC system regulates a wide array of functions in central nervous system and peripheral tissues such as brain development, plasticity, reward and stress sensitivity as well as metabolic functions a such as energy/lipid metabolism including liver function and insulin resistance (1). One of the aims of the METSY project (www.metsy.eu) is to study the central and peripheral EC system in FEPs and their involvement in brain mechanisms in psychosis as well as related metabolic co-morbidities. The cannabinoid CB1 receptor (CB1R) is the most abundant cannabinoid receptor subtype in the human brain and is the predominant mediator of various EC effects. In this first series of METSY experiments we report in vivo brain CB1R binding characteristics in patients with first-episode psychosis (FEP) and controls.MethodsBrain CB1R availability was measured using [18F]-FMPEP-d2 and 3D ECAT HRRT positron emission tomography (PET) using distribution volume (DVt) as a proxy for CB1R availability. Our studies in healthy volunteers revealed a marked sex difference in [18F]-FMPEP DVt with males having higher CB1R availability. The overall CB1R sex difference was widespread but also regionally different with most significant effects in the occipital cortex. Therefore, subsequent studies focused first on male patients with FEP and controls (n=18).ResultsThe results indicate a significant and relatively widespread decrease in CB1R DVt in patients with FEP in fronto-temporal regions, putamen, posterior cingulate as well as parietal regions with large effect sizes. Largely similar results were seen in an independent sample of medication-free male patients with FEP (n=17, the other METSY PET site, King’s College, London, UK) (2). Those studies used another validated CB1R tracer, the [11C]-MePPEP. The reduced CB1R in patients was also state-dependent as [18F]-FMPEP DVt correlated negatively with psychotic symptoms (BPRS) in a highly significant manner.DiscussionEpidemiological studies have convincingly shown that cannabis use is associated with an increased risk of both psychotic symptoms and schizophrenia-like psychoses. We now provide direct in vivo evidence for a robust and partly state-dependent dysregulation of the endocannabinoid system in first-episode psychosis. This is well in line with a recent PET study with CB1R tracer, [11C]-OMAR in patients with schizophrenia (3). Based on previous experimental data the reduced CB1R availability is indicative of an increased endocannabinoid drive in psychosis.AcknowledgementsFunding from the EU’s 7th Framework Programme; METSY - Neuroimaging platform for characterization of metabolic co-morbidities in psychotic disorders (no. 602478).References1) Eriksson O et al The Cannabinoid Receptor-1 Is an Imaging Biomarker of Brown Adipose Tissue. J Nucl Med. 2015 Dec;56(12):1937–41.2) METSY: Endocannabinoid pathways in early psychosis – brain imaging studies (Hietala J, Howes O, Laurikainen H, Borgan F and the METSY PET Imaging group).3) Ranganathan M et al Reduced Brain Cannabinoid Receptor Availability in Schizophrenia. Biol Psychiatry. 2016 Jun 15;79(12):997–1005.

Reductions in circulating endocannabinoid 2-arachidonoylglycerol levels in healthy human subjects exposed to chronic stressors

Increasing evidence indicates that chronic stress, such as social isolation, plays an important role in the development of a variety of psychiatric and somatic disorders. Meanwhile, chronic stress imposed by prolonged isolation and confinement in the spacecraft is also one of the major concerns for the health of future interplanetary space travelers. Preclinical studies suggest that the peripheral endocannabinoid (eCB) system is involved in the regulation of the stress response and eCB signaling is implicated in the pathogenesis of stress-related diseases. However, there are only few human studies addressing this topic, of which most focusing on patients who have already developed a certain type of disorder. It remains unknown whether chronic stress may affect eCB signaling in healthy humans. A 520-d isolation and confinement study simulating a flight to Mars provided an extraordinary chance to study the effects of prolonged stress in healthy humans. During the study period, the participants lived in confinement and could not meet their families, friends, or strangers for more than 500days. We examined the impact of chronic exposure to isolation and confinement through monitoring their psychological state, brain cortical activity, sympathetic adrenal–medullary system response and eCB signaling response. We observed reduced positive emotion ratings, decreased brain cortical activities and high levels of catecholamine release, indicating that prolonged exposure to isolation and confinement stressors may bring about changes both psychologically and physiologically. Importantly, for eCB signaling response, blood concentrations of eCB 2-arachidonoylglycerol (2-AG), but not anandamide (AEA), were significantly reduced (p<0.001), suggesting that dysregulation of 2-AG signaling might be specifically implicated in the response to chronic stressors.

Dysregulated peripheral endocannabinoid system signaling is associated with cognitive deficits in first-episode psychosis

Among etiological explanations for psychosis, several hypotheses involving alterations on the immune/inflammatory system have been proposed. The endocannabinoid system (ECS) is an endogenous neuroprotective, anti-inflammatory system that modulates cognitive processes. Its altered expression has been associated with psychotic disorders. 73 patients with a first episode of psychoses (FEP) and 67 healthy controls were recruited in 5 university centers in Spain. The protein expression of the main peripheral ECS components was determined in peripheral blood mononuclear cells. The cognition function was assessed following the MATRICS consensus. After controlling for potential confounding factors, working memory statistically correlated to the peripheral N-acyl phosphatidylethanolamine phospholipase expression (p = 0.039). The short-term verbal memory correlated to the Diacylglycerol lipase (p = 0.043) and the fatty acid amide hydrolase (p = 0.026) expression. Finally, attention measures correlated to the Monoacylglycerol lipase expression, by means of the CPT-II commissions (p = 0.036) and detectability (p = 0.026) scores. The ECS may regulate the activation of key mediators in immune and inflammatory responses that may be involved in the primary neuronal stress phenomenon that occurs from the onset of psychotic illness. This study points a relationship between the ECS and the cognitive function in early psychosis and suggests the use of some of the ECS elements as biomarkers and/or pharmacological targets for FEP.

URB937, a peripherally restricted inhibitor for fatty acid amide hydrolase, reduces prostaglandin E2 -induced bladder overactivity and hyperactivity of bladder mechano-afferent nerve fibres in rats.

To determine if inhibition of the endocannabinoid-degrading enzyme fatty acid amide hydrolase (FAAH) can counteract the changes in urodynamic variables and bladder afferent activities induced by intravesical prostaglandin E2 (PGE2 ) instillation in rats. In female Sprague-Dawley rats we studied the effects of URB937, a peripherally restricted FAAH inhibitor, on single-unit afferent activity (SAA) during PGE2 -induced bladder overactivity (BO). SAA measurements were made in urethane-anaesthetised rats and Aδ- and C-fibres were identified by electrical stimulation of the pelvic nerve and by bladder distention. Cystometry (CMG) in conscious animals and during SAA measurements was performed during intravesical instillation of PGE2 (50 or 100μm) after intravenous administration of URB937 (0.1 and 1mg/kg) or vehicle. In separate experiments, the comparative expressions of FAAH and cannabinoid receptors, CB1 and CB2 , in microsurgically removed L6 dorsal root ganglion (DRG) were studied by immunofluorescence. During CMG, 1mg/kg URB937, but not vehicle or 0.1mg/kg URB937, counteracted the PGE2 -induced changes in urodynamic variables. PGE2 increased the SAAs of C-fibres, but not Aδ-fibres. URB937 (1mg/kg) depressed Aδ-fibre SAA and abolished the facilitated C-fibre SAA induced by PGE2 . The DRG nerve cells showed strong staining for FAAH, CB1 and CB2 , with a mean (sem) of 77 (2)% and 87 (3)% of FAAH-positive nerve cell bodies co-expressing CB1 or CB2 immunofluorescence, respectively. The present results show that URB937, a peripherally restricted FAAH inhibitor, reduces BO and C-fibre hyperactivity in the rat bladder provoked by PGE2 , suggesting an important role of the peripheral endocannabinoid system in BO and hypersensitivity.

Inhibition of anandamide hydrolysis attenuates nociceptor sensitization in a murine model of chemotherapy-induced peripheral neuropathy.

Painful neuropathy frequently develops as a consequence of commonly used chemotherapy agents for cancer treatment and is often a dose-limiting side effect. Currently available analgesic treatments are often ineffective on pain induced by neurotoxicity. Although peripheral administration of cannabinoids, endocannabinoids, and inhibitors of endocannabinoid hydrolysis has been effective in reducing hyperalgesia in models of peripheral neuropathy, including chemotherapy-induced peripheral neuropathy (CIPN), few studies have examined cannabinoid effects on responses of nociceptors in vivo. In this study we determined whether inhibition of fatty acid amide hydrolase (FAAH), which slows the breakdown of the endocannabinoid anandamide (AEA), reduced sensitization of nociceptors produced by chemotherapy. Over the course of a week of daily treatments, mice treated with the platinum-based chemotherapy agent cisplatin developed robust mechanical allodynia that coincided with sensitization of cutaneous C-fiber nociceptors as indicated by the development of spontaneous activity and increased responses to mechanical stimulation. Administration of the FAAH inhibitor URB597 into the receptive field of sensitized C-fiber nociceptors decreased spontaneous activity, increased mechanical response thresholds, and decreased evoked responses to mechanical stimuli. Cotreatment with CB1 (AM281) or CB2 (AM630) receptor antagonists showed that the effect of URB597 was mediated primarily by CB1 receptors. These changes following URB597 were associated with an increase in the endocannabinoid anandamide in the skin. Our results suggest that enhanced signaling in the peripheral endocannabinoid system could be utilized to reduce nociceptor sensitization and pain associated with CIPN.

Activation of adipose tissue cannabinoid receptors 1 (CB1R) alters antilipolytic action of insulin and increases lipolysis in mice

Objectives: Recent data indicate that activation of peripheral endocannabinoid system (ECS) in tissues such as liver, muscle or adipose tissue may directly influence carbohydrate and lipid metabolism. The existence of cannabinoid receptors 1 (CB1R) and ECS enzymatic machinery has been demonstrated in mature adipocytes, nevertheless studies regarding their role in lipogenesis and lipolysis control are often conflicting.

Cognitive performance and peripheral endocannabinoid system receptor expression in schizophrenia

Schizophrenia is a chronic psychiatric syndrome characterized by generalized cognitive deficits that are associated with functional impairment. The endocannabinoid system (ECS) modulates neurotransmission and neuronal plasticity and is important for cognitive functioning. Evidence points to the involvement of this neuromodulatory system in the pathophysiology of schizophrenia and that alteration of the ECS on peripheral lymphocytes could reflect central changes. The objective of this study was to compare levels of peripheral endocannabinoid receptor expression in patients with schizophrenia and healthy subjects and find evidence of association between peripheral expression of those receptors and cognitive performance. Patients with stabilized schizophrenia (N=53) and controls (N=22) underwent clinical and cognitive evaluation, and assessment of cannabinoid receptor expression on the surface of peripheral immune cells (lymphocytes, natural killer cells and monocytes) by flow cytometry. Patients with schizophrenia had lower levels of cannabinoid receptor expression on total T lymphocytes, but after controlling for possible confounders this difference did not remain significant. In patients, increased cannabinoid receptor expression on lymphocytes and monocytes was significantly correlated with worst cognitive performance. These data provide additional evidence of the involvement of the ECS in the pathophysiology of cognitive deficits in schizophrenia.

Docosahexaenoyl ethanolamide improves glucose uptake and alters endocannabinoid system gene expression in proliferating and differentiating C2C12 myoblasts

Skeletal muscle is a major storage site for glycogen and a focus for understanding insulin resistance and type-2-diabetes. New evidence indicates that overactivation of the peripheral endocannabinoid system (ECS) in skeletal muscle diminishes insulin sensitivity. Specific n-6 and n-3 polyunsaturated fatty acids (PUFA) are precursors for the biosynthesis of ligands that bind to and activate the cannabinoid receptors. The function of the ECS and action of PUFA in skeletal muscle glucose uptake was investigated in proliferating and differentiated C2C12 myoblasts treated with either 25 μM of arachidonate (AA) or docosahexaenoate (DHA), 25 μM of EC [anandamide (AEA), 2-arachidonoylglycerol (2-AG), docosahexaenoylethanolamide (DHEA)], 1 μM of CB1 antagonist NESS0327, and CB2 inverse agonist AM630. Compared to the BSA vehicle control cell cultures in both proliferating and differentiated myoblasts those treated with DHEA, the EC derived from the n-3 PUFA DHA, had higher 24 h glucose uptake, while AEA and 2-AG, the EC derived from the n-6 PUFA AA, had lower basal glucose uptake. Adenylyl cyclase mRNA was higher in myoblasts treated with DHA in both proliferating and differentiated states while those treated with AEA or 2-AG were lower compared to the control cell cultures. Western blot and qPCR analysis showed higher expression of the cannabinoid receptors in differentiated myoblasts treated with DHA while the opposite was observed with AA. These findings indicate a compensatory effect of DHA and DHEA compared to AA-derived ligands on the ECS and associated ECS gene expression and higher glucose uptake in myoblasts.

Peripheral endocannabinoid system dysregulation in first-episode psychosis.

Several hypotheses involving alterations of the immune system have been proposed among etiological explanations for psychotic disorders. The endocannabinoid system (ECS) has a homeostatic role as an endogenous neuroprotective and anti-inflammatory system. Alterations of this system have been associated with psychosis. Cannabis use is a robust risk factor for these disorders that could alter the ECS signalling. In this study, 95 patients with a first episode of psychosis (FEP) and 90 healthy controls were recruited. Protein expression of cannabinoid receptor 2 (CB2), the protein levels of the main endocannabinoid synthesizing enzymes N-acyl phosphatidylethanolamine phospholipase (NAPE) and diacylglycerol lipase (DAGL), and of degradation enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) were determined by western blot analysis in peripheral blood mononuclear cells (PBMCs). Patients with a FEP showed a decreased expression of CB2 and of both endocannabinoids synthesizing enzymes (NAPE and DAGL) in comparison to healthy controls. After controlling for age, gender, body mass index, and cannabis use, NAPE and DAGL expression remained significantly decreased, whereas FAAH and MAGL expression were increased. On the other hand, FEP subjects with history of severe cannabis use showed a larger ECS dysregulation compared with healthy controls. These results indicate an ECS dysregulation in PBMC of FEP patients. The alteration of the ECS presented at the initial phases of psychosis could be contributing to the pathophysiology of the disease and constitutes a possible biomarker of psychotic disorders and an interesting pharmacological target to take into account for therapeutic purposes.

Ghrelin-Induced Orexigenic Effect in Rats Depends on the Metabolic Status and Is Counteracted by Peripheral CB1 Receptor Antagonism

Ghrelin is an endogenous regulator of energy homeostasis synthesized by the stomach to stimulate appetite and positive energy balance. Similarly, the endocannabinoid system is part of our internal machinery controlling food intake and energy expenditure. Both peripheral and central mechanisms regulate CB1-mediated control of food intake and a functional relationship between hypothalamic ghrelin and cannabinoid CB1 receptor has been proposed. First of all, we investigated brain ghrelin actions on food intake in rats with different metabolic status (negative or equilibrate energy balance). Secondly, we tested a sub-anxiogenic ultra-low dose of the CB1 antagonist SR141716A (Rimonabant) and the peripheral-acting CB1 antagonist LH-21 on ghrelin orexigenic actions. We found that: 1) central administration of ghrelin promotes food intake in free feeding animals but not in 24 h food-deprived or chronically food-restricted animals; 2) an ultra-low dose of SR141716A (a subthreshold dose 75 folds lower than the EC50 for induction of anxiety) completely counteracts the orexigenic actions of central ghrelin in free feeding animals; 3) the peripheral-restricted CB1 antagonist LH-21 blocks ghrelin-induced hyperphagia in free feeding animals. Our study highlights the importance of the animaĺs metabolic status for the effectiveness of ghrelin in promoting feeding, and suggests that the peripheral endocannabinoid system may interact with ghrelińs signal in the control of food intake under equilibrate energy balance conditions.

DHA dampens endocannabinoid tone related to cannabinoid receptor expression in proliferating C2C12 myoblasts

Emerging evidence indicates that the peripheral endocannabinoid signaling system (ECS) has a pronounced effect on health status, specifically glucose homeostasis. Focus on skeletal muscle is of great interest as it is a major storage for glycogen in the body. However, overactivation of the ECS in skeletal muscle has been shown to diminish insulin sensitivity. In particular, an elevation of CB1 activity has been reported in diabetic rodent models. Our research intends to identify changes in ECS tone by fatty acid (FA) enrichment. Proliferating C2C12 myoblasts were cultured until 50% confluency and treated with either 25 μM of AA, EPA, AEA, 2‐AG, or a BSA control for 24 h. Cells were collected and labeled with antibodies for CB1 and CB2 for FACS flow cytometry and FA analysis by GC. Compared to the control, FACS revealed a significant reduction in CB1 abundance with DHA treatment, while a significantly higher expression of CB1 was found with AA. No difference in CB2 level was observed. FA composition of myoblasts reflected their respective FA treatment. Interestingly, between the two AA‐derived ECS ligands, only 2‐AG enrichment had a doubling of its precursor, AA, but not with AEA. These findings suggest that DHA may dampen an overactive EC tone.Grant Funding Source: Diet and Health Initiative, UConn, Storrs, CT, USA