Pharmacological evaluation of new generation OXIZID synthetic cannabinoid receptor agonists.

Synthetic cannabinoid receptor agonists (SCRAs) remain one the largest classes of new psychoactive substances, and are increasingly associated with severe adverse effects and death compared to the phytocannabinoid Δ9-tetrahydrocannabinol (THC). In the attempt to circumvent the rapid emergence of novel SCRAs, several nations have implemented 'generic' legislations, or 'class-wide' bans based on common structural scaffolds. However, this has only encouraged the incorporation of new chemical entities, including distinct core and linker structures, for which there is a dearth of pharmacological data. The current study evaluated five emergent OXIZID SCRAs for affinity and functional activity at the cannabinoid CB1 receptor (CB1) in HEK 293 cells, as well as pharmacological equivalence with THC in drug discrimination in mice. All OXIZID compounds behaved as agonists in Gαi protein activation and ß-arrestin 2 translocation assays, possessing low micromolar affinity at CB1. All ligands also substituted for THC in drug discrimination, where potencies broadly correlated with in vitro activity, with the methylcyclohexane analogue BZO-CHMOXIZID being the most potent. Notably, MDA-19 (BZO-HEXOXIZID) exhibited partial efficacy in vitro, generating an activity profile most similar to that of THC, and partial substitution in vivo. Overall, the examined OXIZIDs were comparatively less potent and efficacious than previous generations of SCRAs. Further toxicological data will elucidate whether the moderate cannabimimetic activity for this series of SCRAs will translate to severe adverse health effects as seen with previous generations of SCRAs.

Activation of Cannabinoid Type 2 Receptor in Microglia Reduces Neuroinflammation through Inhibiting Aerobic Glycolysis to Relieve Hypertension.

BACKGROUND: Studies have shown that the chronic use of cannabis is associated with a decrease in blood pressure. Our previous studies prove that activating the cannabinoid type 2 (CB2) receptor in the brain can effectively reduce blood pressure in spontaneously hypertensive rats; however, the exact mechanism has not been clarified. The objective of this study is to demonstrate that activation of microglial CB2 receptors can effectively reduce the levels of TNF-α, IL-1ß, and IL-6 in the paraventricular nucleus (PVN) through inhibiting aerobic glycolysis, thereby relieving hypertension. METHODS: AngiotensinII (AngII) was administered to BV2 cells and C57 mice to induce hypertension and the release of proinflammatory cytokines. The mRNA and protein expression of the CB2 receptor, TNF-α, IL-1ß, IL-6, and the PFK and LDHa enzymes were detected using RT-qPCR and Western blotting. The Seahorse XF Energy Metabolism Analyzer was used to measure the oxidative phosphorylation and aerobic glycolysis metabolic pathways in BV2 cells. The long-term effects of injecting JWH133, a selective CB2 receptor agonist, intraperitoneally on blood pressure were ascertained. ELISA was used to measure norepinephrine and lactic acid levels while immunofluorescence labeling was used to locate the CB2 receptor and c-Fos. By injecting pAAV-F4/80-GFP-mir30shRNA (AAV2-r-CB2shRNA) into the lateral cerebral ventricle, the CB2 receptor in microglia was specifically knocked down. RESULTS: Activation of CB2 receptors by the agonist JWH133 suppressed TNF-α, IL-1ß, and IL-6 by inhibiting PFK and LDHa enzymes involved in glycolysis, as well as lactic acid accumulation, along with a reduction in glycoPER levels (marks of aerobic glycolysis) in AngII-treated BV2 cells. In AngII-treated mice, the administration of JWH133 specifically activated CB2 receptors on microglia, resulting in decreased expression levels of PFK, LDHa, TNF-α, IL-1ß, and IL-6, subsequently leading to a decrease in c-Fos protein expression within PVN neurons as well as reduced norepinephrine levels in plasma, ultimately contributing to blood pressure reduction. CONCLUSION: The results suggest that activation of the microglia CB2 receptor decreases the neuroinflammation to relieve hypertension; the underlying mechanism is related to inhibiting aerobic glycolysis of microglia.

Beta-Caryophyllene, a Cannabinoid Receptor Type 2 Selective Agonist, in Emotional and Cognitive Disorders.

Mental disorders account for one of the most prevalent categories of the burden of disease worldwide, with depression expected to be the largest contributor by 2030, closely followed by anxiety. The COVID-19 pandemic possibly exacerbated these challenges, especially amongst adolescents, who experienced isolation, disrupted routines, and limited healthcare access. Notably, the pandemic has been associated with long-term neurological effects known as "long-COVID", characterized by both cognitive and psychopathological symptoms. In general, psychiatric disorders, including those related to long-COVID, are supposed to be due to widespread inflammation leading to neuroinflammation. Recently, the endocannabinoid system (ECS) emerged as a potential target for addressing depression and anxiety pathophysiology. Specifically, natural or synthetic cannabinoids, able to selectively interact with cannabinoid type-2 receptor (CB2R), recently revealed new therapeutic potential in neuropsychiatric disorders with limited or absent psychotropic activity. Among the most promising natural CB2R ligands, the bicyclic sesquiterpene ß-caryophyllene (BCP) has emerged as an excellent anti-inflammatory and antioxidant therapeutic agent. This review underscores BCP's immunomodulatory and anti-inflammatory properties, highlighting its therapeutic potential for the management of depression and anxiety.

Cardiotoxic effects of common and emerging drugs: role of cannabinoid receptors.

Drug-induced cardiotoxicity has become one of the most common and detrimental health concerns, which causes significant loss to public health and drug resources. Cannabinoid receptors (CBRs) have recently achieved great attention for their vital roles in the regulation of heart health and disease, with mounting evidence linking CBRs with the pathogenesis and progression of drug-induced cardiotoxicity. This review aims to summarize fundamental characteristics of two well-documented CBRs (CB1R and CB2R) from aspects of molecular structure, signaling and their functions in cardiovascular physiology and pathophysiology. Moreover, we describe the roles of CB1R and CB2R in the occurrence of cardiotoxicity induced by common drugs such as antipsychotics, anti-cancer drugs, marijuana, and some emerging synthetic cannabinoids. We highlight the 'yin-yang' relationship between CB1R and CB2R in drug-induced cardiotoxicity and propose future perspectives for CBR-based translational medicine toward cardiotoxicity curation and clinical monitoring.

Novel pyrrole based CB2 agonists: New insights on CB2 receptor role in regulating neurotransmitters' tone.

The cannabinoid system is one of the most investigated neuromodulatory systems because of its involvement in multiple pathologies such as cancer, inflammation, and psychiatric diseases. Recently, the CB2 receptor has gained increased attention considering its crucial role in modulating neuroinflammation in several pathological conditions like neurodegenerative diseases. Here we describe the rational design of pyrrole-based analogues, which led to a potent and pharmacokinetically suitable CB2 full agonist particularly effective in improving cognitive functions in a scopolamine-induced amnesia murine model. Therefore, we extended our study by investigating the interconnection between CB2 activation and neurotransmission in this experimental paradigm. To this purpose, we performed a MALDI imaging analysis on mice brains, observing that the administration of our lead compound was able to revert the effect of scopolamine on different neurotransmitter tones, such as acetylcholine, serotonin, and GABA, shedding light on important networks not fully explored, so far.

Classical cannabinoid receptors as target in cancer-induced bone pain: a systematic review, meta-analysis and bioinformatics validation.

To test the hypothesis that genetic and pharmacological modulation of the classical cannabinoid type 1 (CB1) and 2 (CB2) receptors attenuate cancer-induced bone pain, we searched Medline, Web of Science and Scopus for relevant skeletal and non-skeletal cancer studies from inception to July 28, 2022. We identified 29 animal and 35 human studies. In mice, a meta-analysis of pooled studies showed that treatment of osteolysis-bearing males with the endocannabinoids AEA and 2-AG (mean difference [MD] - 24.83, 95% confidence interval [95%CI] - 34.89, - 14.76, p < 0.00001) or the synthetic cannabinoid (CB) agonists ACPA, WIN55,212-2, CP55,940 (CB1/2-non-selective) and AM1241 (CB2-selective) (MD - 28.73, 95%CI - 45.43, - 12.02, p = 0.0008) are associated with significant reduction in paw withdrawal frequency. Consistently, the synthetic agonists AM1241 and JWH015 (CB2-selective) increased paw withdrawal threshold (MD 0.89, 95%CI 0.79, 0.99, p < 0.00001), and ACEA (CB1-selective), AM1241 and JWH015 (CB2-selective) reduced spontaneous flinches (MD - 4.85, 95%CI - 6.74, - 2.96, p < 0. 00001) in osteolysis-bearing male mice. In rats, significant increase in paw withdrawal threshold is associated with the administration of ACEA and WIN55,212-2 (CB1/2-non-selective), JWH015 and AM1241 (CB2-selective) in osteolysis-bearing females (MD 8.18, 95%CI 6.14, 10.21, p < 0.00001), and treatment with AM1241 (CB2-selective) increased paw withdrawal thermal latency in males (mean difference [MD]: 3.94, 95%CI 2.13, 5.75, p < 0.0001), confirming the analgesic capabilities of CB1/2 ligands in rodents. In human, treatment of cancer patients with medical cannabis (standardized MD - 0.19, 95%CI - 0.35, - 0.02, p = 0.03) and the plant-derived delta-9-THC (20 mg) (MD 3.29, CI 2.24, 4.33, p < 0.00001) or its synthetic derivative NIB (4 mg) (MD 2.55, 95%CI 1.58, 3.51, p < 0.00001) are associated with reduction in pain intensity. Bioinformatics validation of KEGG, GO and MPO pathway, function and process enrichment analysis of mouse, rat and human data revealed that CB1 and CB2 receptors are enriched in a cocktail of nociceptive and sensory perception, inflammatory, immune-modulatory, and cancer pathways. Thus, we cautiously conclude that pharmacological modulators of CB1/2 receptors show promise in the treatment of cancer-induced bone pain, however further assessment of their effects on bone pain in genetically engineered animal models and cancer patients is warranted.

Investigating selectivity and bias for G protein subtypes and ß-arrestins by synthetic cannabinoid receptor agonists at the cannabinoid CB1 receptor.

The cannabinoid CB1 receptor (CB1) is a G protein-coupled receptor (GPCR) with widespread expression in the central nervous system. This canonically G⍺i/o-coupled receptor mediates the effects of Δ9-tetrahydrocannabinol (THC) and synthetic cannabinoid receptor agonists (SCRAs). Recreational use of SCRAs is associated with serious adverse health effects, making pharmacological research into these compounds a priority. Several studies have hypothesised that signalling bias may explain the different toxicological profiles between SCRAs and THC. Previous studies have focused on bias between G protein activation measured by cyclic adenosine monophosphate (cAMP) inhibition and ß-arrestin translocation. In contrast, the current study characterises bias between G⍺ subtypes of the G⍺i/o family and ß-arrestins; this method facilitates a more accurate assessment of ligand bias by assessing signals that have not undergone major amplification. We have characterised G protein dissociation and translocation of ß-arrestin 1 and 2 using real-time BRET reporters. The responses produced by each SCRA across the G protein subtypes tested were consistent with the responses produced by the reference ligand AMB-FUBINACA. Ligand bias was probed by applying the operational analysis to determine biases within the G⍺i/o family, and between G protein subtypes and ß-arrestins. Overall, these results confirm SCRAs to be balanced, high-efficacy ligands compared to the low efficacy ligand THC, with only one SCRA, 4CN-MPP-BUT7IACA, demonstrating statistically significant bias in one pathway comparison (towards ß-arrestin 1 when compared with G⍺oA/oB). This suggests that the adverse effects caused by SCRAs are due to high potency and efficacy at CB1, rather than biased agonism.

CB2 Cannabinoid Receptor as a Potential Target in Myocardial Infarction: Exploration of Molecular Pathogenesis and Therapeutic Strategies.

The lipid endocannabinoid system has recently emerged as a novel therapeutic target for several inflammatory and tissue-damaging diseases, including those affecting the cardiovascular system. The primary targets of cannabinoids are cannabinoid type 1 (CB1) and 2 (CB2) receptors. The CB2 receptor is expressed in the cardiomyocytes. While the pathological changes in the myocardium upregulate the CB2 receptor, genetic deletion of the receptor aggravates the changes. The CB2 receptor plays a crucial role in attenuating the advancement of myocardial infarction (MI)-associated pathological changes in the myocardium. Activation of CB2 receptors exerts cardioprotection in MI via numerous molecular pathways. For instance, delta-9-tetrahydrocannabinol attenuated the progression of MI via modulation of the CB2 receptor-dependent anti-inflammatory mechanisms, including suppression of pro-inflammatory cytokines like IL-6, TNF-α, and IL-1ß. Through similar mechanisms, natural and synthetic CB2 receptor ligands repair myocardial tissue damage. This review aims to offer an in-depth discussion on the ameliorative potential of CB2 receptors in myocardial injuries induced by a variety of pathogenic mechanisms. Further, the modulation of autophagy, TGF-ß/Smad3 signaling, MPTP opening, and ROS production are discussed. The molecular correlation of CB2 receptors with cardiac injury markers, such as troponin I, LDH1, and CK-MB, is explored. Special attention has been paid to novel insights into the potential therapeutic implications of CB2 receptor activation in MI.

Structure-Based Identification of Organoruthenium Compounds as Nanomolar Antagonists of Cannabinoid Receptors.

Metal complexes exhibit a diverse range of coordination geometries, representing novel privileged scaffolds with convenient click types of preparation inaccessible for typical carbon-centered organic compounds. Herein, we explored the opportunity to identify biologically active organometallic complexes by reverse docking of a rigid, minimum-size octahedral organoruthenium scaffold against thousands of protein-binding pockets. Interestingly, cannabinoid receptor type 1 (CB1) was identified based on the docking scores and the degree of overlap between the docked organoruthenium scaffold and the hydrophobic scaffold of the cocrystallized ligand. Further structure-based optimization led to the discovery of organoruthenium complexes with nanomolar binding affinities and high selectivity toward CB2. Our work indicates that octahedral organoruthenium scaffolds may be advantageous for targeting the large and hydrophobic binding pockets and that the reverse docking approach may facilitate the discovery of novel privileged scaffolds, such as organometallic complexes, for exploring chemical space in lead discovery.

The role of cannabinoid receptor 2 in bone remodeling during orthodontic tooth movement.

BACKGROUND: The purpose of this study is to explore the effects of CB2 on bone regulation during orthodontic tooth movement. METHODS: Thirty male mice were allocated into 2 groups (n = 15 in each group): wild type (WT) group and CB2 knockout (CB2-/-) group. Orthodontic tooth movement (OTM) was induced by applying a nickel-titanium coil spring between the maxillary first molar and the central incisors. There are three subgroups within the WT groups (0, 7 and 14 days) and the CB2-/- groups (0, 7 and 14 days). 0-day groups without force application. Tooth displacement, alveolar bone mass and alveolar bone volume were assessed by micro-CT on 0, 7 and 14 days, and the number of osteoclasts was quantified by tartrate-resistant acid phosphatase (TRAP) staining. Moreover, the expression levels of RANKL and OPG in the compression area were measured histomorphometrically. RESULTS: The WT group exhibited the typical pattern of OTM, characterized by narrowed periodontal space and bone resorption on the compression area. In contrast, the accelerated tooth displacement, increased osteoclast number (P < 0.0001) and bone resorption on the compression area in CB2-/- group. Additionally, the expression of RANKL was significantly upregulated, while OPG showed low levels in the compression area of the CB2 - / - group (P < 0.0001). CONCLUSIONS: CB2 modulated OTM and bone remodeling through regulating osteoclast activity and RANKL/OPG balance.

ß-Caryophyllene Inhibits Monoacylglycerol Lipase Activity and Increases 2-Arachidonoyl Glycerol Levels In Vivo: A New Mechanism of Endocannabinoid-Mediated Analgesia?

The mechanisms of ß-caryophyllene (BCP)-induced analgesia are not well studied. Here, we tested the efficacy of BCP in an acute postsurgical pain model and evaluated its effect on the endocannabinoid system. Rats were treated with vehicle and 10, 25, 50, and 75 mg/kg BCP. Paw withdrawal responses to mechanical stimuli were evaluated using an electronic von Frey anesthesiometer. Endocannabinoids, including 2-arachidonoylglycerol (2-AG), were also evaluated in plasma and tissues using high-performance liquid chromatography-tandem mass spectrometry. Monoacylglycerol lipase (MAGL) activity was evaluated in vitro as well as ex vivo. We observed a dose-dependent and time-dependent alleviation of hyperalgesia in incised paws up to 85% of the baseline value at 30 minutes after administration of BCP. We also observed dose-dependent increases in the 2-AG levels of about threefold after administration of BCP as compared with vehicle controls. Incubations of spinal cord tissue homogenates from BCP-treated rats with isotope-labeled 2-arachidonoylglycerol-d8 revealed a reduced formation of the isotope-labeled MAGL product 2-AG-d8 as compared with vehicle controls, indicating MAGL enzyme inhibition. In vitro MAGL enzyme activity assessment using 2-AG as the substrate revealed an IC50 of 15.8 µM for MAGL inhibition using BCP. These data showed that BCP inhibits MAGL activity in vitro and in vivo, causing 2-AG levels to rise. Since the endocannabinoid 2-AG is a CB1 and CB2 receptor agonist, we propose that 2-AG-mediated cannabinoid receptor activation contributes to BCP's mechanism of analgesia. SIGNIFICANCE STATEMENT: ß-Caryophyllene (BCP) consumption is relatively safe and is approved by the Food and Drug Administration as a flavoring agent, which can be used in cosmetic and food additives. BCP is a potent anti-inflammatory agent that showed substantial antihyperalgesic properties in this study of acute pain suggesting that BCP might be an alternative to opioids. This study shows an additive mechanism (monoacylglycerol lipase inhibition) by which BCP might indirectly alter CB1 and CB2 receptor activity and exhibit its pharmacological properties.

CB2 agonist mitigates cocaine-induced reinstatement of place preference and modulates the inflammatory response in mice.

Chronic exposure to cocaine is known to have profound effects on the brain, leading to the dysregulation of inflammatory signalling pathways, the activation of microglia, and the manifestation of cognitive and motivational behavioural impairments. The endocannabinoid system has emerged as a potential mediator of cocaine's deleterious effects. In this study, we sought to investigate the therapeutic potential of the cannabinoid CB2 receptor agonist, JWH-133, in mitigating cocaine-induced inflammation and associated motivational behavioural alterations in an in vivo model. Our research uncovered compelling evidence that JWH-133, a selective CB2 receptor agonist, exerts a significant dampening effect on the reinstatement of cocaine-induced conditioned place preference. This effect was accompanied by notable changes in the neurobiological landscape. Specifically, JWH-133 administration was found to upregulate Δ-FOSB expression in the nucleus accumbens (Nac), elevate CX3CL1 levels in both the ventral tegmental area and prefrontal cortex (PFC), and concurrently reduce IL-1ß expression in the PFC and NAc among cocaine-treated animals. These findings highlight the modulatory role of CB2 cannabinoid receptor activation in altering the reward-seeking behaviour induced by cocaine. Moreover, they shed light on the intricate interplay between the endocannabinoid system and cocaine-induced neurobiological changes, paving the way for potential therapeutic interventions targeting CB2 receptors in the context of cocaine addiction and associated behavioural deficits.

Discovery of a CB2 and 5-HT1A receptor dual agonist for the treatment of depression and anxiety.

Cannabinoid CB2R agonists have gained considerable attention as potential novel therapies for psychiatric disorders due to their non-psychoactive nature, in contrast to CB1R agonists. In this study, we employed molecular docking to design and synthesize 23 derivatives of cannabidiol (CBD) with the aim of discovering potent CB2R agonists rather than CB2R antagonists or inverse agonists. Structure-activity relationship (SAR) investigations highlighted the critical importance of the amide group at the C-3' site and the cycloalkyl group at the C-4' site for CB2R activation. Interestingly, three CBD derivatives, namely 2o, 6g, and 6h, exhibited substantial partial agonistic activity towards the CB2 receptor, in contrast to the inverse agonistic property of CBD. Among these, 2o acted as a CB2R and 5-HT1AR dual agonist, albeit with some undesired antagonist activity for CB1R. It demonstrated significant CB2R partial agonism while maintaining a level of 5-HT1AR agonistic and CB1R antagonistic activity similar to CBD. Pharmacokinetic experiments confirmed that 2o possesses favorable pharmacokinetic properties. Behavioral studies further revealed that 2o elicits significant antidepressant-like and anxiolytic-like effects while maintaining a good safety profile.

Cannabinoid CB2 receptors and hypersensitivity to methamphetamine: Vulnerability to schizophrenia.

The human cannabinoid receptor 2 (CB2R) gene CNR2 has been associated with schizophrenia development. Inbred mice treated with the CB2R inverse agonist AM630 and challenged with methamphetamine (MAP) showed reduced prepulse inhibition (%PPI) response and locomotor hyperactivity, both behavioral measures in rodents that correlate with psychosis. Mice lacking CB2R on striatal dopaminergic neurons exhibit a hyperdopaminergic tone and a hyperactivity phenotype. Hyperdopaminergia plays a role in the etiology of schizophrenia. This study aimed to determine the direct role of CB2R, heterozygous Cnr2 gene knockout (Het) mice treated with MAP to induce behavioral sensitivity mimicking a schizophrenia-like human phenotype. Additionally, the study aims to explore the unique modulation of dopamine activity by neuronal CB2R. Conditional knockout DAT-Cnr2-/- mice were evaluated in response to MAP treatments for this purpose. Sensorimotor gating deficits in DAT-Cnr2-/- mice were also evaluated. Het mice developed reverse tolerance (RT) to MAP-enhanced locomotor activity, and RT reduced the %PPI compared to wild-type (WT) mice. DAT-Cnr2-/- mice showed an increased sensitivity to stereotypical behavior induced by MAP and developed RT to MAP. DAT-Cnr2-/- mice exhibit a reduction in %PPI and alter social interaction, another core symptom of schizophrenia. These results demonstrate that there is an interaction between neuronal CB2R and MAP treatment, which increases the risk of schizophrenia-like behavior in this mouse model. This finding provides evidence for further studies targeting CB2R as a potential schizophrenia therapy.

Activation of the cannabinoid type 2 (CB2) receptor improves cardiac contractile performance in fish, Brycon amazonicus.

In addition to their well-known classical effects, cannabinoid CB1 and CB2 receptors have also been involvement in both deleterious and protective actions on the heart under various pathological conditions. While the potential therapeutic applications of the endocannabinoid system in the context of cardiovascular function are indeed a viable prospect, significant debate exists within the literature regarding whether CB1, CB2, or a combination of both receptors exert a favorable influence on cardiac function. Hence, the aim of this study was to investigate the effects of CB1 + CB2 or CB2 agonists on cardiac excitation-contraction (E-C) coupling, utilizing fish (Brycon amazonicus) as an experimental model. The CB2 agonist elicited marked positive inotropic and lusitropic responses in isolated ventricular myocardium, induced cyclic adenosine 3',5'-monophosphate (cAMP) production, and upregulated critical Ca2+ handling proteins, such as sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) and Na+/Ca2+ exchanger (NCX). Our current study demonstrated, for the first time, that CB2 receptor activation-induced effects improved the efficiency of Ca2+ cycling, excitation-contraction coupling (E-C coupling), and cardiac performance in under physiological conditions. Hence, CB2 receptors could be considered a potential therapeutic target for modulating cardiac contractile dysfunctions.

Neuroprotection and Beyond: The Central Role of CB1 and CB2 Receptors in Stroke Recovery.

The endocannabinoid system, with its intricate presence in numerous cells, tissues, and organs, offers a compelling avenue for therapeutic interventions. Central to this system are the cannabinoid receptors 1 and 2 (CB1R and CB2R), whose ubiquity can introduce complexities in targeted treatments due to their wide-ranging physiological influence. Injuries to the central nervous system (CNS), including strokes and traumatic brain injuries, induce localized pro-inflammatory immune responses, termed neuroinflammation. Research has shown that compensatory immunodepression usually follows, and these mechanisms might influence immunity, potentially affecting infection risks in patients. As traditional preventive treatments like antibiotics face challenges, the exploration of immunomodulatory therapies offers a promising alternative. This review delves into the potential neuroprotective roles of the cannabinoid receptors: CB1R's involvement in mitigating excitotoxicity and CB2R's dual role in promoting cell survival and anti-inflammatory responses. However, the potential of cannabinoids to reduce neuroinflammation must be weighed against the risk of exacerbating immunodepression. Though the endocannabinoid system promises numerous therapeutic benefits, understanding its multifaceted signaling mechanisms and outcomes remains a challenge.

Role of the CB2 Cannabinoid Receptor in the Regulation of Food Intake: A Systematic Review.

The CB2 cannabinoid receptor has been found in brain areas that are part of the reward system and has been shown to play a role in food intake regulation. Herein, we conducted a systematic review of studies assessing the role of the CB2 receptor in food intake regulation. Records from the PubMed, Scopus, and EBSCO databases were screened, resulting in 13 studies that were used in the present systematic review, following the PRISMA guidelines. A risk of bias assessment was carried out using the tool of the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE). The studies analyzed used two main strategies: (1) the intraperitoneal or intracerebroventricular administration of a CB2 agonist/antagonist; and (2) depletion of CB2 receptors via knockout in mice. Both strategies are useful in identifying the role of the CB2 receptor in food intake in standard and palatable diets. The conclusions derived from animal models showed that CB2 receptors are necessary for modulating food intake and mediating energy balance.

Investigating the Effects of Exogenous and Endogenous 2-Arachidonoylglycerol on Retinal CB1 Cannabinoid Receptors and Reactive Microglia in Naive and Diseased Retina.

The endocannabinoid system (ECS) is a new target for the development of retinal disease therapeutics, whose pathophysiology involves neurodegeneration and neuroinflammation. The endocannabinoid 2-arachidonoylglycerol (2-AG) affects neurons and microglia by activating CB1/CB2 cannabinoid receptors (Rs). The aim of this study was to investigate the effects of 2-AG on the CB1R expression/downregulation and retinal neurons/reactive microglia, when administered repeatedly (4 d), in three different paradigms. These involved the 2-AG exogenous administration (a) intraperitoneally (i.p.) and (b) topically and (c) by enhancing the 2-AG endogenous levels via the inhibition (AM11920, i.p.) of its metabolic enzymes (MAGL/ABHD6). Sprague Dawley rats were treated as mentioned above in the presence or absence of CB1/CB2R antagonists and the excitatory amino acid, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Immunohistochemistry, Western blot and a 2-AG level analyses were performed. The 2-AG repeated treatment (i.p.) induced the CB1R downregulation, abolishing its neuroprotective actions. However, 2-AG attenuated the AMPA-induced activation of microglia via the CB2R, as concurred by the AM630 antagonist effect. Topically administered 2-AG was efficacious as a neuroprotectant/antiapoptotic and anti-inflammatory agent. AM11920 increased the 2-AG levels providing neuroprotection against excitotoxicity and reduced microglial activation without affecting the CB1R expression. Our findings show that 2-AG, in the three paradigms studied, displays differential pharmacological profiles in terms of the downregulation of the CB1R and neuroprotection. All treatments, however, attenuated the activation of microglia via the CB2R activation, supporting the anti-inflammatory role of 2-AG in the retina.

Dual allosteric and orthosteric pharmacology of synthetic analog cannabidiol-dimethylheptyl, but not cannabidiol, on the cannabinoid CB2 receptor.

Cannabinoid CB2 receptor (CB2R) is a class A G protein-coupled receptor (GPCR) involved in a broad spectrum of physiological processes and pathological conditions. For that reason, targeting CB2R might provide therapeutic opportunities in neurodegenerative disorders, neuropathic pain, inflammatory diseases, and cancer. The main components from Cannabis sativa, such as Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD), have been therapeutically exploited and synthetically-derived analogs have been generated. One example is cannabidiol-dimethylheptyl (CBD-DMH), which exhibits anti-inflammatory effects. Nevertheless, its pharmacological mechanism of action is not yet fully understood and is hypothesized for multiple targets, including CB2R. The aim of this study was to further investigate the molecular pharmacology of CBD-DMH on CB2R while CBD was taken along as control. These compounds were screened in equilibrium and kinetic radioligand binding studies and various functional assays, including G protein activation, inhibition of cAMP production and ß-arrestin-2 recruitment. In dissociation studies, CBD-DMH allosterically modulated the radioligand binding. Furthermore, CBD-DMH negatively modulated the G protein activation of reference agonists CP55,940, AEA and 2-AG, but not the agonist-induced ß-arrestin-2 recruitment. Nevertheless, CBD-DMH also displayed competitive binding to CB2R and partial agonism on G protein activation, inhibition of cAMP production and ß-arrestin-2 recruitment. CBD did not exhibit such allosteric behavior and only very weakly bound CB2R without activation. This study shows a dual binding mode of CBD-DMH, but not CBD, to CB2R with the suggestion of two different binding sites. Altogether, it encourages further research into this dual mechanism which might provide a new class of molecules targeting CB2R.

Activation of cannabinoid receptors 2 alleviates myocardial damage in cecal ligation and puncture-induced sepsis by inhibiting pyroptosis.

BACKGROUND: It has been reported that cannabinoid receptors 2 (CB2 receptors) play an important role in the pathophysiological process of sepsis, which may also be associated with the regulation of pyroptosis, an inflammatory programmed cell death. The present study aimed to investigate the protective effect of CB2 receptors on myocardial damage in a model of septic mice by inhibiting pyroptosis. METHODS: The C57BL/6 mice underwent cecal ligation and puncture (CLP) to induce sepsis. All mice were randomly divided into the sham, CLP, or CLP+HU308 group. Blood and heart tissue samples were collected 12 h after surgery. Hematoxylin and eosin staining was used for analyzing histopathological results. Creatine kinase isoenzymes (CK-MB) and IL-1ß were measured using ELISA, while lactate dehydrogenase (LDH) level was determined using photoelectric colorimetry. The expression levels of CB2 receptors and pyroptosis-associated proteins (NLRP3, caspase-1, and GSDMD) were measured using western blotting. The location and distribution of CB2 receptors and caspase-1 in myocardial tissues were assessed by immunofluorescence. TUNEL staining was used to quantify the number of dead cells in myocardial tissues. RESULTS: The CLP procedure increased CB2 receptor expression in mice. CB2 receptors were located in myocardial macrophages. Activating CB2 receptors decreased the levels of myocardial damage mediator LDH, CK-MB, and inflammatory cytokine IL-1ß. The results also showed that CLP increased the pyroptosis in myocardial tissues, while CB2 agonist HU308 inhibited pyroptosis by decreasing the level of NLRP3 and activating caspase-1 and GSDMD. CONCLUSIONS: CB2 receptor activation has a protective effect on the myocardium of mice with sepsis by inhibiting pyroptosis.