Involvement Of CB1 Receptors Research Articles

Protective Effects of Cannabis sativa on chemotherapy-induced nausea in a rat: Involvement of CB1 receptors.

Cyclophosphamide is an anticancer and immunosuppressive agent used in the treatment of various malignancies but causing gastrointestinal distress. Cannabis sativa and its derivatives have been used for the treatment of human gastrointestinal disorders. A purpose of this study was to investigate the effect of C. sativa on nausea induced by cyclophosphamide in rats. The rats were divided into four groups (eight animals per group): Group 1: Normal control (saline i.p.). Group 2: Rats received cyclophosphamide (200 mg/kg i.p.) 3 consecutive days. Group 3 and 4: Rats received cyclophosphamide (200 mg/kg i.p.) across Days 1-7, and C. sativa (20 and 40 mg/kg s.c.) was administered on cyclophosphamide days 4-7. We examined intake of kaolin, normal food and changes in body weight, as an indicator of the emetic stimulus. Oxidative stress markers, antioxidant enzymes status, serotonin (5-HT), dopamine, noradrenaline and CB1R levels were evaluated in the intestinal homogenate. Moreover, histopathological study was performed. Results showed that C. sativa ameliorates cyclophosphamide-induced emesis by increasing in body weight and normal diet intake with a decrease in kaolin diet intake after 7 days. Moreover, C. sativa significantly decreases (serotonin) 5-HT, dopamine and noradrenaline, as well as decreasing oxidative stress and inflammation. Administration of C. sativa significantly increased the expression of CB1R in intestinal homogenate. Treatment with C. sativa also improved the histological feature of an intestinal tissue. These results suggested that C. sativa possess antiemetic, antioxidant and anti-inflammatory effects in chemotherapy-induced nausea in rats by activating CB1R.

ViphyllinTM, a Standardized Black Pepper Seed Extract Exerts Antinociceptive Effects in Murine Pain Models via Activation of Cannabinoid Receptor CB2, Peroxisome Proliferator-Activated Receptor-Alpha and TRPV1 Ion Channels.

PurposePlant-based natural products as anti-nociceptors have enormous potential as safer alternatives to conventional opiates and NSAIDS. Piper nigrum (black pepper) is one of the major culinary spices with medicinal attributes.MethodsIn the present study, the antinociceptive activity of a standardized black pepper seed extract (Viphyllin) containing not less than 30% β-caryophyllene (BCP) was evaluated using pain models in mice, namely acetic acid-induced writhing test, formalin-induced paw licking test, hot plate test and tail flick test. Further, the antagonists SR141716A (0.1 mg/kg i.p.), AM630 (5 mg/kg i.p.), capsazepine (0.1 mg/kg body weight i.p.), and GW6471 (1 mg/kg i.p.) were used to evaluate the involvement of cannabinoid receptors CB1 and CB2, TRPV1 ion channel and PPARα receptor, respectively. Molecular docking (AutoDock 4.2) was used to study the interaction of BCP with the agonist-binding sites of the selected pain receptors.ResultsViphyllin at 10 mg, 25 mg and 50 mg/kg (i.p.) significantly inhibited the writhings in mice as compared to untreated control group (p < 0.001). Further, Viphyllin at 50 mg/kg showed strong antinociceptive effect in formalin-induced paw licking test (p < 0.05). Pretreatment of mice with AM630 significantly reversed the antinociceptive activity of Viphyllin in both early and late phases of formalin test (p < 0.05). Administration of Viphyllin markedly increased the latency time of mice in hot plate test (p < 0.001). Further, Viphyllin markedly increased the latency time of tail flick compared to control group from 30 min to 90 min after treatment. AM630, Capsazepine, and GW6471 abolished the analgesic effect of Viphyllin. These findings clearly suggest the involvement of CB2 receptor, TRPV1 ion channel and PPARα receptor activation in Viphyllin-mediated antinociceptive activity. Docking score predictions further supported the possible involvement of BCP in the antinociceptive mechanism of Viphyllin.ConclusionIn conclusion, Viphyllin could be a natural pain-relieving agent involving safer pain signaling mechanisms, unlike conventional opiates and NSAIDs.

CB2 Receptor Involvement in the Treatment of Substance Use Disorders.

The pharmacological modulation of the cannabinoid receptor 2 (CB2r) has emerged as a promising potential therapeutic option in addiction. The purpose of this review was to determine the functional involvement of CB2r in the effects produced by drugs of abuse at the central nervous system (CNS) level by assessing evidence from preclinical and clinical studies. In rodents, several reports suggest the functional involvement of CB2r in the effects produced by drugs of abuse such as alcohol, cocaine, or nicotine. In addition, the discovery of CB2r in brain areas that are part of the reward system supports the relevance of CB2r in the field of addiction. Interestingly, animal studies support that the CB2r regulates anxiety and depression behavioral traits. Due to its frequent comorbidity with neuropsychiatric disorders, these pharmacological actions may be of great interest in managing SUD. Preliminary clinical trials are focused on exploring the therapeutic potential of modulating CB2r in treating addictive disorders. These promising results support the development of new pharmacological tools regulating the CB2r that may help to increase the therapeutic success in the management of SUD.

Behavioral aspects and neurobiological properties underlying medical cannabis treatment in Shank3 mouse model of autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disease with a wide spectrum of manifestation. The core symptoms of ASD are persistent deficits in social communication, and restricted and repetitive patterns of behavior, interests, or activities. These are often accompanied by intellectual disabilities. At present, there is no designated effective treatment for the core symptoms and co-morbidities of ASD. Recently, interest is rising in medical cannabis as a treatment for ASD, with promising clinical data. However, there is a notable absence of basic pre-clinical research in this field. In this study, we investigate the behavioral and biochemical effects of long-term oral treatment with CBD-enriched medical cannabis oil in a human mutation-based Shank3 mouse model of ASD. Our findings show that this treatment alleviates anxiety and decreases repetitive grooming behavior by over 70% in treated mutant mice compared to non-treated mutant mice. Furthermore, we were able to uncover the involvement of CB1 receptor (CB1R) signaling in the Avidekel oil mechanism, alongside a mitigation of cerebrospinal fluid (CSF) glutamate concentrations. Subsequently, RNA sequencing (RNA seq) of cerebellar brain samples revealed changes in mRNA expression of several neurotransmission-related genes post-treatment. Finally, our results question the relevancy of CBD enrichment of medical cannabis for treating the core symptoms of ASD, and emphasize the importance of the THC component for alleviating deficits in repetitive and social behaviors in ASD.

Anticonvulsive and anti-epileptogenesis effects of Echinacea purpurea root extract, an involvement of CB2 receptor.

Phytocannabinoids beyond the Δ9-tetrahy-drocannabinol have shown anticonvulsive effects. Also, alkylamides from Echinacea purpurea have been proved as cannabinomimetics. We examined the effect of the hydroalcoholic root extract of E.purpurea on pentylenetetrazol (PTZ)-induced tonic-clonic seizures and kindling model of epileptogenesis and the involvement of CB2 receptors as the mediator of this effect. Male Wistar rats (200±20g) were used. Single intraperitoneal (i.p.) injection of PTZ (80mg/kg) was used to induce tonic-clonic seizures. The kindling model of epileptogenesis was induced by daily injections of PTZ (37mg/kg; i.p. for 15days). Latency and duration of the stages were monitored for analysis. The hydroalcoholic root extract of E.purpurea was injected (i.p.) 20min before seizure induction at the doses of 10, 50, 100 and 200mg/kg. CB2 receptor antagonist SR144528 was injected (0.1mg/kg; i.p.) 20min before the Echinacea injection. In the tonic-clonic model, pretreatment with E.purpurea at the doses of 100 and 200mg/kg significantly increased latencies to S2-S6, while it significantly decreased S6 duration and mortality rate. SR144528 injection before the injection of 100mg/kg of E.purpurea significantly prevented the effects of the extract on S4-S6 latencies. In the kindling model, E.purpurea at the doses of 100 and 200mg/kg significantly delayed epileptogenesis and decreased mortality rate, while SR144528 injection before the injection of 100mg/kg of E. purpurea significantly blocked this effect of the extract. These findings revealed the anticonvulsive and antiepileptogenesis effects of the E.purpurea root extract, which can be mediated by CB2 receptors.

Cannabidiol Enhancement of Exposure Therapy in Treatment Refractory Patients With Phobias: A Randomized Controlled Trial

In vivo exposure with response prevention is the current gold-standard treatment for anxiety disorders. However, many patients respond insufficiently. Given the involvement of CB1 receptors in conditioned fear extinction, influencing CB1 receptor signaling through the phytocannabinoid cannabidiol (CBD) may enhance treatment effects. We tested this hypothesis in a multi-site, outpatient, parallel randomized, double-blind, placebo-controlled fixed dose clinical trial.

Cannabinoid CB2receptors and spinal microglia are implicated in tingenone-mediated antinociception in mice

Objective: To investigate the antinociceptive effect of tingenone on inflammatory pain, as well as and the involvement of the cannabinoid receptors type 2 (CB2) and spinal microglia in this process. Methods: Male Swiss mice were subjected to inflammatory pain induced by intraplantar injection of carrageenan. The nociceptive threshold was measured by von Frey filaments test. Tingenone was administered orally 60 min before carrageenan injection. To evaluate the involvement of CB2 receptor, endocannabinoids, and microglia, AM630 (a CB2 receptor antagonist), MAFP (an inhibitor of an enzyme that hydrolyses endocannabinoids), and minocycline (a microglial inhibitor) were given intrathecally 20 min before tingenone administration. In addition, an immunofluorescence assay was used to evaluate CB2 receptor and CD11B (a microglial marker) expression in the spinal cord dorsal horn. Results: Tingenone significantly reduced carrageenan-induced hyperalgesia, which was reversed by pretreatment with AM630. MAFP and minocycline potentiated and prolonged the tingenone- induced antinociception. CD11B expression was increased in the spinal cord dorsal horn of mice with inflammatory pain pretreated with tingenone, which was reduced by AM630, MAFP, and minocycline. Conclusions: CB2 receptors and endocannabinoids participate in the tingenone-induced antinociception which may involve the inhibition of microglia at spinal level.

Effect of acute and subchronic administration of (R)-WIN55,212-2 induced neuroprotection and anti inflammatory actions in rat retina: CB1 and CB2 receptor involvement

Cannabinoids have been shown to protect the retina from ischemic/excitotoxic insults. The aim of the present study was to investigate the neuroprotective and anti-inflammatory properties of the synthetic cannabinoid (R)-WIN55,212-2 (CB1/CB2 receptor agonist) when administered acutely or subchronically in control and AMPA treated retinas. Sprague-Dawley rats were intravitreally administered (acutely) with vehicle or AMPA, in the absence or presence of (R)-WIN55,212-2 (10−7-10−4M) alone or in combination with AM251 [CB1 receptor antagonist/inverse agonist,10−4M] and AM630 (CB2 receptor antagonist,10−4M). In addition, AMPA was co-administered with the racemic (R,S)-WIN55,212 (10−4Μ). (R)-WIN55,212-2 was also administered subchronically (25,100 μg/kg,i.p.,4d) in control and AMPA treated rats. Immunohistochemical studies were performed using antibodies against the CB1R, and retinal markers for retinal neurons (brain nitric oxide synthetase, bNOS) and microglia (ionized calcium binding adaptor molecule 1, Iba1). ELISA assay was employed to assess TNFα levels in AMPA treated retinas. Intravitreal administration of (R)-WIN55,212-2 reversed the AMPA induced loss of bNOS expressing amacrine cells, an effect that was blocked by both AM251 and AM630. (R,S)WIN55,212 had no effect. (R)-WIN55,212-2 also reduced a) the AMPA induced activation of microglia, by activating CB2 receptors that were shown to be colocalized with Iba1+ reactive microglial cells, and b) TNFα levels in retina. (R)-WIN55,212-2 administered subchronically led to the downregulation of CB1 receptors at the high dose of 100 μg/kg(i.p.), and to the attenuation of the WIN55,212-2 induced neuroprotection of amacrine cells. At the same dose, (R)-WIN55,212-2 did not attenuate the AMPA induced increase in the number of reactive microglia cells, suggesting CB2 receptor downregulation under subchronic conditions. This study provides new findings regarding the role of CB1 and CB2 receptor activation by the synthetic cannabinoid (R)-WIN55,212-2, administered acutely or sub-chronically, on neuron viability and microglia activation in healthy and diseased retina.

Subchronic Central Administration of Cannabinoid Ligands Modulates Nociception in Bulbectomized Rats.

Endocannabinoid system is involved in neuropsychiatric disorders such as major depression. The bilaterally olfactory bulbectomized rat is widely used as an animal model of depression. The removal of the olfactory bulbs produces behavioural, physiological, and neurochemical alterations resembling clinical depression. There is increasing evidence that highlights the important role of cannabinoid signalling in depression and nociception. To investigate the effect of CB1 receptor agonist HU 210 and CB1 receptor antagonist SR 141716A administered icv subchronically (for 7 days) on nociception of rats with model of depression - bilateral olfactory bulbectomy (OBX). Experimental model of depression - bilateral olfactory bulbectomy (OBX). Bilaterally olfactory bulbectomized rats were used as an experimental model of depression. HU 210 (5 µg) or SR 141716A (3 µg) were infused icv for 7 consecutive days, starting 15 days after the olfactory bulbectomy. Nociception was examined by applying paw pressure test (analgesy-meter) evaluating the rat pain threshold. On day 7, five minutes after the last microinjection, the rats were tested in an analgesy-meter and their mechanically evoked pain responses were measured in arbitrary units (AU). Microinjections of HU 210 (5 µg) significantly decreased the pain threshold in olfactory bulbectomized rats, while SR 141716A (3 µg) exerted antinociceptive effect by increasing the pain threshold. Data point to an involvement of CB1 receptors in depression-like behaviour and nociception in olfactory bulbectomized rats and support the data for the association between depressive disorder and pain pathways.

N-Linoleyltyrosine Protects against Transient Cerebral Ischemia in Gerbil via CB2 Receptor Involvement in PI3K/Akt Signaling Pathway.

Anandamide (AEA) played potent neuroprotective activities via cannabinoid type 1 (CB1) and 2 (CB2) receptor. N-Linoleyltyrosine (NITyr), as an AEA analogue, was synthesized in our laboratory and evaluated the neuroprotective effects and mechanisms for the first time. NITyr was synthesized via substitution reaction. The neuroprotective effects of NITyr were evaluated in a gerbil model of transient cerebral ischemia. Each gerbil was subjected to open field test (OFT), Rotard rod test (RRT), Morris water maze (MWM) successively and executed after animal behaviors. Part of the brain was stained with hematoxylin and eosin (HE) and Nissl staining, and the rest for biochemical analysis. NITyr could not increase spontaneous locomotor activity and ameliorate the anxiety behavior in the OFT but could improve the motor coordination in the RRT and the spatial memory impairment in the MWM. Immunohistochemically, NITyr could attenuate the ischemia-induced neural loss in the hippocampus. The Enzyme-linked immunosorbent assay (ELISA) suggested that NITyr ameliorated the inflammation and oxidative stress. Consistently, NITyr could up-regulate the expressions of p-phosphadylinositol 3-kinase (PI3K) and p-Akt but not PI3K and Akt in the hippocampus. In addition to oxidative stress, CB2 receptor antagonist AM630 but not CB1 receptor antagonist AM251 could reverse the above phenomena. However, CB1 receptor antagonist AM251 could reverse oxidative stress. Accordingly, NITyr could up-regulate the expressions of CB2 but not CB1. NITyr could improve the motor coordination, learning and memory impairments, neural loss in the hippocampus and the inflammation of the mice via CB2 receptor involvement of PI3K/Akt signaling pathway.

Involvement of CB2 Receptors in the Neurobehavioral Effects of Catha Edulis (Vahl) Endl. (Khat) in Mice.

There is behavioral evidence for the interaction between crude khat extract and the endocannabinoid system, whereby the endocannabinoid system alters khat extract-mediated behavioral effects through modulation of the monoaminergic system. The objective of this study was to investigate the role of the endocannabinoid system on the neurobehavioral effect of khat extract in mice following concomitant administration of khat extract and the CB2R agonist, JWH133. Locomotor activity test, immunohistochemistry, and reverse transcriptase polymerase chain reaction technique were utilized to assess locomotor activity, tyrosine hydroxylase immunoreactivity, and expression of dopamine transporter mRNA gene. The results show sub-acute administration of khat extract alone increased locomotor activity in mice and co-administration of the CB2R agonist, JWH133, reduced khat extract induced hyperlocomotor activity. The data revealed that cell type specific deletion of CB2Rs on dopaminergic neurons increased the hyperlocomotor behavior of khat extract. Furthermore, the results revealed that khat extract attenuated MPTP induced motor deficits, which is enhanced by JWH133. Khat extract also increased expression of tyrosine hydroxylase positive cells and expression of dopamine transporter mRNA gene in wild type mice. Nevertheless, JWH133 did not alter the effect of khat extract on tyrosine hydroxylase immunoreactivity and dopamine transporter mRNA expression when given together with khat extract. Taken together, the results suggest that the CB2Rs selectively interact with khat extract-mediated locomotor effects and could be utilized as therapeutic target in central nervous system movement disorders associated with dopamine dysregulation.

Ximenia americana heteropolysaccharides ameliorate inflammation and visceral hypernociception in murine caerulein-induced acute pancreatitis: Involvement of CB2 receptors

BackgroundThis study aimed to investigate and characterize the anti-inflammatory and anti-hypernociceptive effects of the total polysaccharides of X. americana (TPL-Xa) bark in a mouse model of acute pancreatitis-induced by caerulein and the potential involvement of cannabinoid receptors. MethodsTPL-Xa was characterized by1H and 13C NMR spectroscopy. Animals received TPL-Xa (10 mg/kg, i.v.) 30 min before and after caerulein (50 μg/kg, 10×, i.p.) administration. To evaluate the involvement of cannabinoid receptors, AM281 (3 mg/kg, s.c.) and AM630 (1 mg/kg, s.c.) were administered 30 min before TPL-Xa. Plasma levels of amylase and lipase, pancreatic myeloperoxidase (MPO), histology, visceral hypernociception and motor coordination were evaluated 11 and 24 h after acute pancreatitis (AP) induction. ResultsTPL-Xa, containing a heteropolysaccharide composed of glucose, galactose, arabinose, rhamnose, fucose and galacturonic acid, reduced amylase and lipase levels, MPO activity, acinar cell necrosis, edema and neutrophil infiltration. TPL-Xa increased the threshold of visceral hypernociception, an effect reversed by AM630, an antagonist of cannabinoid receptor type 2 (CB2). In addition, TPL-Xa did not alter the animals’ motor coordination. ConclusionsTPL-Xa contains heteropolysaccharides that inhibit inflammation and hypernociception in the experimental model of caerulein-induced AP, by a mechanism involving type CB2 receptors.

The endocannabinoid-alcohol crosstalk: Recent advances on a bi-faceted target.

Increasing evidence has focusesed on the endocannabinoid system as a relevant player in the induction of aberrant synaptic plasticity and related addictive phenotype following chronic excessive alcohol drinking. In addition, the endocannabinoid system is implicated in the pathogenesis of alcoholic liver disease. Interestingly, whereas the involvement of CB1 receptors in alcohol rewarding properties is established, the central and peripheral action of CB2 signalling is still to be elucidated. This review aims at giving the input to deepen knowledge on the role of the endocannabinoid system, highlighting the advancing evidence that suggests that CB1 and CB2 receptors may play opposite roles in the regulation of both the reinforcing properties of alcohol in the brain and the mechanisms responsible for cell injury and inflammation in the hepatic tissue. The manipulation of the endocannabinoid system could represent a bi-faceted strategy to counteract alcohol-related dysfunction in central transmission and liver structural and functional disarrangement.

Biological characterization of PM226, a chromenoisoxazole, as a selective CB2 receptor agonist with neuroprotective profile

Cannabinoids have emerged as promising neuroprotective agents due to their capability to activate specific targets, which are involved in the control of neuronal homeostasis and survival. Specifically, those ligands that selectively target and activate the CB2 receptor may be useful for their anti-inflammatory and neuroprotective properties in various neurological disorders, with the advantage of being devoid of psychotropic effects associated with the activation of CB1 receptors. The aim of this work has been to investigate the neuroprotective properties of 7-(1,1-dimethylheptyl)-4,4-dimethyl-9-methoxychromeno[3,4-d]isoxazole (PM226), a compound derived from a series of chromeno-isoxazoles and −pyrazoles, which seems to have a promising profile related to the CB2 receptor. The compound binds selectively to this receptor with an affinity in the nanomolar range (Ki=12.8±2.4nM). It has negligible affinity for the CB1 receptor (Ki>40000nM) and no activity at the GPR55. PM226 was also evaluated in GTPγS binding assays specific to the CB2 receptor showing agonist activity (EC50=38.67±6.70nM). In silico analysis of PM226 indicated that it has a good pharmacokinetic profile and a predicted ability to cross the blood-brain barrier. Next, PM226 was investigated in an in vitro model to explore its anti-inflammatory/neuroprotective properties. Conditioned media were collected from LPS-stimulated cultures of BV2 microglial cell line in the absence or presence of different doses of PM226, and then media were added to cultured M213-2O neuronal cells to record their influence on cell viability evaluated using MTT assays. As expected, cell viability was significantly reduced by the exposure to these conditioned media, while the addition of PM226 attenuated this reduction in a dose-dependent manner. This effect was reversed by co-incubating with the CB2 antagonist SR144528, thus confirming the involvement of CB2 receptors, whereas the addition of PM226 to neuronal cultures instead cultured BV2 cells was not effective. PM226 has also been studied in an in vivo model of mitochondrial damage generated by intrastriatal application of malonate in rats. MRI analysis showed that PM226 administration decreased the volume of the striatal lesion caused by malonate, effect that was confirmed after the histopathological evaluation (Nissl staining, Iba-1 immunostaining and TUNEL assay) of striatal sections derived from malonate-lesioned rats in the absence or presence of PM226. Again, the beneficial effects of PM226 were dependent on the activation of CB2 receptors as they were reversed by blocking these receptors with AM630. Overall, PM226 has shown to have a promising neuroprotective profile derived from its ability to selectively activate CB2 receptor, so that it could be a useful disease-modifying agent in those neurodegenerative pathologies in which the activation of these receptors may have therapeutic value.

Enhanced Glutamatergic Synaptic Plasticity in the Hippocampal CA1 Field of Food-Restricted Rats: Involvement of CB1 Receptors.

The endogenous endocannabinoid system has a crucial role in regulating appetite and feeding behavior in mammals, as well as working memory and reward mechanisms. In order to elucidate the possible role of cannabinoid type-1 receptors (CB1Rs) in the regulation of hippocampal plasticity in animals exposed to food restriction (FR), we limited the availability of food to a 2-h daily period for 3 weeks in Sprague-Dawley rats. FR rats showed a higher long-term potentiation at hippocampal CA1 excitatory synapses with a parallel increase in glutamate release when compared with animals fed ad libitum. FR rats showed a significant increase in the long-term spatial memory determined by Barnes maze. FR was also associated with a decreased inhibitory effect of the CB1R agonist win55,212-2 on glutamatergic field excitatory postsynaptic potentials, together with a decrease in hippocampal CB1R protein expression. In addition, hippocampal brain-derived neurotrophic factor protein levels and mushroom dendritic spine density were significantly enhanced in FR rats. Altogether, our data suggest that alterations of hippocampal CB1R expression and function in FR rats are associated with dendritic spine remodeling and functional potentiation of CA1 excitatory synapses, and these findings are consistent with increasing evidence supporting the idea that FR may improve cognitive functions.

Neuroprotective Effect of JZL184 in MPP(+)-Treated SH-SY5Y Cells Through CB2 Receptors.

Growing evidence suggests that the endocannabinoid system plays a role in neuroprotection in Parkinson's disease. Recently, we have shown the neuroprotective effect of monoacylglycerol lipase (MAGL) inhibition with JZL184 in the chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model. However, further investigation is needed to determine the neuroprotective mechanisms of the endocannabinoid system on the nigrostriatal pathway. The aim of this work was to investigate whether the neuroprotective effect of JZL184 in mice could be extended to an in vitro cellular model to further understand the mechanism of action of the drug. The SH-SY5Y cell line was selected based on its dopaminergic-like phenotype and its susceptibility to 1-methyl-4-phenylpyridinium iodide (MPP(+)) toxicity. Furthermore, SH-SY5Y cells express both cannabinoid receptors, CB1 and CB2. The present study describes the neuroprotective effect of MAGL inhibition with JZL184 in SH-SY5Y cells treated with MPP(+). The effect of JZL184 in cell survival was blocked by AM630, a CB2 receptor antagonist, and it was mimicked with JWH133, a CB2 receptor agonist. Rimonabant, a CB1 receptor antagonist, did not affect JZL184-induced cell survival. These results demonstrate that the neuroprotective effect of MAGL inhibition with JZL184 described in animal models of Parkinson's disease could be extended to in vitro models such as SH-SY5Y cells treated with MPP(+). This represents a useful tool to study mechanisms of neuroprotection mediated by MAGL inhibition, and we provide evidence for the possible involvement of CB2 receptors in the improvement of cell survival.

Inhibition of COX-2-mediated eicosanoid production plays a major role in the anti-inflammatory effects of the endocannabinoid N-docosahexaenoylethanolamine (DHEA) in macrophages.

N-docosahexaenoylethanolamine (DHEA) is the ethanolamine conjugate of the long-chain polyunsaturated n-3 fatty acid docosahexaenoic (DHA; 22: 6n-3). Its concentration in animal tissues and human plasma increases when diets rich in fish or krill oil are consumed. DHEA displays anti-inflammatory properties in vitro and was found to be released during an inflammatory response in mice. Here, we further examine possible targets involved in the immune-modulating effects of DHEA. Antagonists for cannabinoid (CB)1 and CB2 receptors and PPARγ were used to explore effects of DHEA on NO release by LPS-stimulated RAW264.7 cells. The possible involvement of CB2 receptors was studied by comparing effects in LPS-stimulated peritoneal macrophages obtained from CB2 (-/-) and CB2 (+/+) mice. Effects on NF-κB activation were determined using a reporter cell line. To study DHEA effects on COX-2 and lipoxygenase activity, 21 different eicosanoids produced by LPS-stimulated RAW264.7 cells were quantified by LC-MS/MS. Finally, effects on mRNA expression profiles were analysed using gene arrays followed by Ingenuity(®) Pathways Analysis. CB1 and CB2 receptors or PPARs were not involved in the effects of DHEA on NO release. NF-κB and IFN-β, key elements of the myeloid differentiation primary response protein D88 (MyD88)-dependent and MyD88-independent pathways were not decreased. By contrast, DHEA significantly reduced levels of several COX-2-derived eicosanoids. Gene expression analysis provided support for an effect on COX-2-mediated pathways. Our findings suggest that the anti-inflammatory effects of DHEA in macrophages predominantly take place via inhibition of eicosanoids produced through COX-2. This article is part of a themed section on Cannabinoids 2013 published in volume 171 issue 6. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.2014.171.issue-6/issuetoc.

Biphasic effects of Δ9-tetrahydrocannabinol on brain stimulation reward and motor activity

Δ(9)-tetrahydrocannabinol (Δ(9)-THC), the main psychoactive ingredient of marijuana, has led to equivocal results when tested with the intracranial self-stimulation (ICSS) procedure or the open-field test for motor activity, two behavioural models for evaluating the reward-facilitating and locomotor stimulating effects of drugs of abuse, respectively. Therefore, in the present study, the effects of high and low doses of Δ(9)-THC were compared in the ICSS procedure and the open-field test. Moreover, the involvement of CB(1) receptors in tentative Δ(9)-THC-induced effects was investigated by pre-treating the animals with the CB(1) receptor antagonist SR141716A (rimonabant). The results obtained show that low doses of Δ(9)-THC induce opposite effects from high doses of Δ(9)-THC. Specifically, 0.1 mg/kg Δ(9)-THC decreased ICSS thresholds and produced hyperactivity, whereas 1 mg/kg increased ICSS thresholds and produced hypoactivity. Both effects were reversed by pre-treatment with SR141716A, indicating the involvement of CB(1) receptors on these actions. Altogether, our results indicate that Δ(9)-THC can produce acute activating effects in locomotion that coincide with its reward-facilitating effects in the ICSS paradigm. The present findings provide further support that Δ(9)-THC induces behaviours typical of abuse and substantiate the notion that marijuana resembles other drugs of abuse.

The 2-arachidonoylglycerol effect on myosin light chain phosphorylation in human platelets

In human platelets the endocannabinoid 2-arachidonoylglycerol (2-AG) stimulates some important pathways leading to thromboxane B2 formation, calcium intracellular elevation, ATP secretion and actin polymerisation. The aim of the present study was to examine the 2-AG effect on myosin light chain (MLC) phosphorylation and to investigate the mechanisms involved. We demonstrated that 2-AG induced a rapid MLC phosphorylation, stimulating both the RhoA kinase (ROCK) and MLC kinase (MLCK) in a dose and time-dependent manner. In addition MLC phosphorylation was strengthened through the MLC phosphatase inhibition. MLC phosphatase inhibition was accomplished through the RhoA/ROCK and protein kinase C mediated phosphorylation of MLC phosphatase inhibiting subunits MYPT1 and CPI-17. The presence of CB1 receptor in human platelets and the involvement of CB1 receptor in MLC phosphorylation and MLC phosphatase inhibition was shown.

The cannabinoid CB2 receptor is necessary for nicotine-conditioned place preference, but not other behavioral effects of nicotine in mice

Whereas cannabinoid CB1 receptors have long been known to contribute to the rewarding effects and dependence liability of many drugs of abuse, recent studies have implicated the involvement of cannabinoid CB2 receptors. Here, we evaluated the role of CB2 receptors in the rewarding properties of nicotine, as assessed in the conditioned place preference (CPP) paradigm and mecamylamine-precipitated withdrawal in nicotine dependent mice. Using complementary pharmacological and genetic approaches, we investigated the involvement of CB2 receptors in nicotine- and cocaine-induced CPP in mice and mecamylamine-precipitated withdrawal in nicotine-dependent mice. We also determined whether deletion of CB2 receptors affects nicotine-induced hypothermia and hypoalgesia. Nicotine-induced (0.5mg/kg) CPP was completely blocked by selective CB2 antagonist, SR144528 (3mg/kg) in wild-type mice, and was absent in CB2 (-/-) mice. Conversely, the CB2 receptor agonist, O-1966 (1, 3, 5, 10, 20mg/kg) given in combination with a subthreshold dose of nicotine (0.1mg/kg) elicited a place preference. In contrast, O-1966 (20mg/kg) blocked cocaine (10mg/kg)-induced CPP in wild type mice, while CB2 (-/-) mice showed unaltered cocaine CPP. CB2 (+/+) and (-/-) nicotine-dependent mice showed almost identical precipitated withdrawal responses and deletion of CB2 receptor did not alter acute somatic effects of nicotine. Collectively, these results indicate that CB2 receptors are required for nicotine-induced CPP in the mouse, while it is not involved in nicotine withdrawal or acute effects of nicotine. Moreover, these results suggest that CB2 receptors play opposing roles in nicotine- and cocaine-induced CPP.