Cannabinoid receptor 2 agonist AM1241 alleviates epileptic seizures and epilepsy-associated depression via inhibiting neuroinflammation in a pilocarpine-induced chronic epilepsy mouse model.

Increasing evidence suggests that cannabinoid receptor 2 (CB2R) serves as a promising anti-inflammatory target. While inflammation is known to play crucial roles in the pathogenesis of epilepsy, the involvement of CB2R in epilepsy remains unclear. This study aimed to investigate the effects of a CB2R agonist, AM1241, on epileptic seizures and depressive-like behaviors in a mouse model of chronic epilepsy induced by pilocarpine. A chronic epilepsy mouse model was established by intraperitoneal administration of pilocarpine. The endogenous cannabinoid system (eCBs) in the hippocampus was examined after status epilepticus (SE). Animals were then treated with AM1241 and compared with a vehicle-treated control group. Additionally, the role of the AMPK/NLRP3 signaling pathway was explored using the selective AMPK inhibitor dorsomorphin. Following SE, CB2R expression increased significantly in hippocampal microglia. Administration of AM1241 significantly reduced seizure frequency, immobility time in the tail suspension test, and neuronal loss in the hippocampus. In addition, AM1241 treatment attenuated microglial activation, inhibited pro-inflammatory polarization of microglia, and suppressed NLRP3 inflammasome activation in the hippocampus after SE. Further, the therapeutic effects of AM1241 were abolished by the AMPK inhibitor dorsomorphin. Our findings suggest that CB2R agonist AM1241 may alleviate epileptic seizures and its associated depression by inhibiting neuroinflammation through the AMPK/NLRP3 signaling pathway. These results provide insight into a novel therapeutic approach for epilepsy.

A Comprehensive Exploration of the Multifaceted Neuroprotective Role of Cannabinoids in Alzheimer's Disease across a Decade of Research.

Alzheimer's disease (AD), a progressive neurodegenerative disorder, manifests through dysregulation of brain function and subsequent loss of bodily control, attributed to ß-amyloid plaque deposition and TAU protein hyperphosphorylation and aggregation, leading to neuronal death. Concurrently, similar cannabinoids to the ones derived from Cannabis sativa are present in the endocannabinoid system, acting through receptors CB1R and CB2R and other related receptors such as Trpv-1 and GPR-55, and are being extensively investigated for AD therapy. Given the limited efficacy and adverse effects of current available treatments, alternative approaches are crucial. Therefore, this review aims to identify effective natural and synthetic cannabinoids and elucidate their beneficial actions for AD treatment. PubMed and Scopus databases were queried (2014-2024) using keywords such as "Alzheimer's disease" and "cannabinoids". The majority of natural (Δ9-THC, CBD, AEA, etc.) and synthetic (JWH-133, WIN55,212-2, CP55-940, etc.) cannabinoids included showed promise in improving memory, cognition, and behavioral symptoms, potentially via pathways involving antioxidant effects of selective CB1R agonists (such as the BDNF/TrkB/Akt pathway) and immunomodulatory effects of selective CB2R agonists (TLR4/NF-κB p65 pathway). Combining anticholinesterase properties with a cannabinoid moiety may enhance therapeutic responses, addressing cholinergic deficits of AD brains. Thus, the positive outcomes of the vast majority of studies discussed support further advancing cannabinoids in clinical trials for AD treatment.

Foxq1 activates CB2R with oleamide to alleviate POCD.

Postoperative cognitive dysfunction (POCD) is a major concern, particularly among older adults. This study used social isolation (ISO) and multiomics analyses in aged mice to investigate potential mechanisms underlying POCD development. Aged mice were divided into two groups: ISO and paired housing (PH). Oleamide and the cannabinoid receptor type 2 (CB2R) antagonist AM630 were administered intraperitoneally, while Foxq1 adeno-associated viral (AAV) vector was injected directly into the hippocampus. Intramedullary tibial surgeries were subsequently performed to establish the POCD models. Behavioral tests comprising the Y-maze, open field test, and novel object recognition were conducted 2 days after surgery. Hippocampal and serum inflammatory cytokines were assessed. Following surgery, ISO mice demonstrated intensified cognitive impairments and escalated inflammatory markers. Integrative transcriptomic and metabolomic analysis revealed elevated oleamide concentrations in the hippocampus and serum of PH mice, with associative investigations indicating a close relationship between the Foxq1 gene and oleamide levels. While oleamide administration and Foxq1 gene overexpression substantially ameliorated postoperative cognitive performance and systemic inflammation in mice, CB2R antagonist AM630 impeded these enhancements. The Foxq1 gene and oleamide may be crucial in alleviating POCD. While potentially acting through CB2R-mediated pathways, these factors may modulate neuroinflammation and attenuate proinflammatory cytokine levels within the hippocampus, substantially improving cognitive performance postsurgery. This study lays the groundwork for future research into therapeutic approaches targeting the Foxq1-oleamide-CB2R axis, with the ultimate goal of preventing or mitigating POCD.

Physical Exercise Improves the Neuronal Function in Ischemic Stroke Via Microglial CB2R/P2Y12 Signaling.

Physical exercise (PE) may be the single most important and accessible lifestyle habit throughout life, it inhibits the neuroinflammatory response and protects the brain against damage. As the innate cells in brain, microglia undergo morphological and functional changes to communicate with neurons protecting the neurons from injury. Herein, aiming at exploring the effects of PE on the communication between microglia-neuron during acute ischemic cerebral infarction, we carried out running wheel training before the conduction of transient middle cerebral artery occlusion (tMCAO) in C57BL/6 J and Cx3cr1-GFP mice. We found that microglial P2Y12 expression in the peri-infarct area was decreased, microglial dynamics and microglia-neuron communications were impaired, using in vivo two-photon imaging. PE up-regulated the microglial P2Y12 expression, increased the microglial dynamics, and promoted the contacts of microglia with neurons. As a result, PE inhibited neuronal Ca2+ overloads and protected against damage of the neuronal mitochondria in acute tMCAO. Mechanistically, PE increased the cannabinoid receptor 2 (CB2R) in microglia, promoted the phosphorylation of Nrf2 (NF-E2-related factor 2) at ser-344, increased the transcription factor level of Mafk, and up-regulated the level of P2Y12, whereby PE increased the levels of CB2R to promote microglia-neuron contacts to monitor and protect neuronal function.

Allosterism in the adenosine A2A and cannabinoid CB2 heteromer.

BACKGROUND AND PURPOSE: Allosterism is a regulatory mechanism for GPCRs that can be attained by ligand-binding or protein-protein interactions with another GPCR. We have studied the influence of the dimer interface on the allosteric properties of the A2A receptor and CB2 receptor heteromer. EXPERIMENTAL APPROACH: We have evaluated cAMP production, phosphorylation of signal-regulated kinases (pERK1/2), label-free dynamic mass redistribution, ß-arrestin 2 recruitment and bimolecular fluorescence complementation assays in the absence and presence of synthetic peptides that disrupt the formation of the heteromer. Molecular dynamic simulations provided converging evidence that the heteromeric interface influences the allosteric properties of the A2AR-CB2R heteromer. KEY RESULTS: Apo A2AR blocks agonist-induced signalling of CB2R. The disruptive peptides, with the amino acid sequence of transmembrane (TM) 6 of A2AR or CB2R, facilitate CB2R activation, suggesting that A2AR allosterically prevents the outward movement of TM 6 of CB2R for G protein binding. Significantly, binding of the selective antagonist SCH 58261 to A2AR also facilitated agonist-induced activation of CB2R. CONCLUSIONS AND IMPLICATIONS: It is proposed that the A2AR-CB2R heteromer contains distinct dimerization interfaces that govern its functional properties. The molecular interface between protomers of the A2AR-CB2R heteromer interconverted from TM 6 for apo or agonist-bound A2AR, blocking CB2R activation, to mainly the TM 1/7 interface for antagonist-bound A2AR, facilitating the independent opening of intracellular cavities for G protein binding. These novel results shed light on a different type of allosteric mechanism and extend the repertoire of GPCR heteromer signalling.

RG7774 (Vicasinabin), an orally bioavailable cannabinoid receptor 2 (CB2R) agonist, decreases retinal vascular permeability, leukocyte adhesion, and ocular inflammation in animal models.

Introduction: Preclinical studies suggest that cannabinoid receptor type 2 (CB2R) activation has a therapeutic effect in animal models on chronic inflammation and vascular permeability, which are key pathological features of diabetic retinopathy (DR). A novel CB2R agonist, triazolopyrimidine RG7774, was generated through lead optimization of a high-throughput screening hit. The aim of this study was to characterize the pharmacology, absorption, distribution, metabolism, elimination, and toxicity (ADMET) profile of RG7774, and to explore its potential for managing the key pathological features associated with retinal disease in rodents. Methods: The in vitro pharmacology of RG7774 was investigated for CB2R binding and receptor activation using recombinant human and mouse CB2R expression in Chinese hamster ovary cells, and endogenous CB2R expression in human Jurkat cells, and rat and mouse spleen cells. The ADMET profile was evaluated and the effects of RG7774 on retinal permeability, leukocyte adhesion, and choroidal neovascularization (CNV) were investigated in rodent models of retinal disease. Pharmacokinetic (PK) parameters and the exposure-response relationship were characterized in healthy animals and in animals with laser-induced CNV. Results: RG7774 was found to be a potent (EC50: 2.8 nM and Ki: 51.3 nM), selective, and full CB2R agonist with no signs of cannabinoid receptor type 1 (CB1R) binding or activation. The ligand showed a favorable ADMET profile and exhibited systemic and ocular exposure after oral delivery. Functional potency in vitro translated from recombinant to endogenous expression systems. In vivo, orally administered RG7774 reduced retinal permeability and leukocyte adhesion in rodents with lipopolysaccharide (LPS)-induced uveitis and streptozotocin (STZ)-induced DR, and reduced lesion areas in rats with laser-induced CNV with an ED50 of 0.32 mg/kg. Anatomically, RG7774 reduced the migration of retinal microglia to retinal lesions. Discussion: RG7774 is a novel, highly selective, and orally bioavailable CB2R agonist, with an acceptable systemic and ocular PK profile, and beneficial effects on retinal vascular permeability, leukocyte adhesion, and ocular inflammation in rodent animal models. Results support the development of RG7774 as a potential treatment for retinal diseases with similar pathophysiologies as addressed by the animal models.

Endocannabinoid Receptor 2 Function is Associated with Tumor-Associated Macrophage Accumulation and Increases in T Cell Number to Initiate a Potent Antitumor Response in a Syngeneic Murine Model of Glioblastoma.

Introduction: Glioblastoma patients have a highly immunosuppressive tumor microenvironment and systemic immunosuppression that comprise a major barrier to immune checkpoint therapy. Based on the production of endocannabinoids by glioblastomas, we explored involvement of endocannabinoid receptor 2 (CB2R), encoded by the CNR2 gene, which is predominantly expressed by immune cells, in glioblastoma-related immunosuppression. Materials & Methods: Bioinformatics of human glioblastoma databases was used to correlate enzymes involved in the synthesis and degradation of endocannabinoids, as well as CB2Rs, with patient overall survival. Intrastriatal administration of luciferase-expressing, murine GL261 glioblastoma cells was used to establish in in vivo glioblastoma model for characterization of tumor growth and intratumoral immune cell infiltration, as well as provide immune cells for in vitro co-culture experiments. Involvement of CB2Rs was determined by treatment with CB2R agonist (GW405833) or CB2R antagonist (AM630). ELISA, FACS, and immunocytochemistry were used to determine perforin, granzyme B, and surface marker levels. Results: Bioinformatics of human glioblastoma databases showed high expression of CB2R and elevated endocannabinoid production correlated with poorer prognosis, and involved immune-associated pathways. AM630treatment of GL261 glioblastoma-bearing mice induced a potent antitumor response, with survival plateauing at 50% on Day 40, when all control mice (median survival 28 days) and mice treated with GW405833 (median survival 21 days) had died. Luciferase tumor imaging revealed accelerated tumor growth by GW405833 treatment, but stable or regressing tumors in AM630-treated mice. Notably, in spleens, AM630 treatment caused an 83% decrease in monocytes/macrophages, and 1.8- and 1.6-fold increases in CD8+ and CD4+ cells, respectively. Within tumors, there was a corresponding decrease in tumor-associated macrophages (TAMs) and increase in CD8+ T cells. In vitro, lymphocytes from AM630-treated mice showed greater cytotoxic function (increased percentage of perforin- and granzyme B-positive CD8+ T cells). Discussion: These results suggest that inhibition of CB2R enhances both immunosuppressive TAM infiltration and systemic T-cell suppression through CB2R activation, and that inhibition of CB2Rs can potently counter both the immunosuppressive tumor microenvironment, as well as systemic immunosuppression in glioblastoma.

Additive antinociceptive action of intrathecal anandamide reuptake inhibitor and morphine in the management of post-incisional pain in rats.

Spinal opioids have mixed efficacy and their adverse effects force treatment cessation of postoperative pain. Consequently, there is an ongoing search for new therapeutic strategies. Here, we evaluated the analgesic efficacy of intrathecal UCM707, an anandamide reuptake inhibitor, and morphine combination. Firstly, we assessed the effects of morphine (1, 5 and 10 µg), UCM707 (75 µg) and its combination in the hot plate. Then, morphine + UCM707 at sub-effective doses was evaluated in a rat post-incisional pain model. In addition, µ-, CB1r-, CB2r- and TRPV1-antagonists were pre-administered before the combination. Activation of µ-opioid and CB1r, and Cnr1, Cnr2, Oprm1 and TRPV1 expressions were evaluated in the lumbar sacra and periaqueductal grey by [35 S]-GTPγS binding autoradiography and qPCR studies. In the hot plate, morphine (1 µg) and UCM707 (75 µg) induced a more robust analgesic effect than each drug alone. Morphine plus UCM707 did not modify µ-opioid nor CB1 receptor function in the PAG or LS. Cnr1 and TRPV1 expression increased in the lumbar sacra (LS). Morphine plus UCM707 significantly reduced post-incisional pain at 1 and 4 days after surgery. Cnr1, Cnr2 and TRPV1 expressions increased in the LS. Blockade of µ-opioid receptor reduced combination effects on days 1 and 4. CB1r- and CB2r-antagonism reduced morphine + UCM707 effects on days 1 and 4, respectively. CB1r and TRPV1-antagonism improved their antinociceptive effects on day 4. These results revealed a synergistic/additive analgesic effect of UCM707 and morphine combination controlling postincisional pain. CB1r, CB2r and TRPV1 contribute differently as central sensitization occurs.

Potential of CBD Acting on Cannabinoid Receptors CB1 and CB2 in Ischemic Stroke.

Stroke is one of the leading causes of death. It not only affects adult people but also many children. It is estimated that, every year, 15 million people suffer a stroke worldwide. Among them, 5 million people die, while 5 million people are left permanently disabled. In this sense, the research to find new treatments should be accompanied with new therapies to combat neuronal death and to avoid developing cognitive impairment and dementia. Phytocannabinoids are among the compounds that have been used by mankind for the longest period of history. Their beneficial effects such as pain regulation or neuroprotection are widely known and make them possible therapeutic agents with high potential. These compounds bind cannabinoid receptors CB1 and CB2. Unfortunately, the psychoactive side effect has displaced them in the vast majority of areas. Thus, progress in the research and development of new compounds that show efficiency as neuroprotectors without this psychoactive effect is essential. On the one hand, these compounds could selectively bind the CB2 receptor that does not show psychoactive effects and, in glia, has opened new avenues in this field of research, shedding new light on the use of cannabinoid receptors as therapeutic targets to combat neurodegenerative diseases such as Alzheimer's, Parkinson's disease, or stroke. On the other hand, a new possibility lies in the formation of heteromers containing cannabinoid receptors. Heteromers are new functional units that show new properties compared to the individual protomers. Thus, they represent a new possibility that may offer the beneficial effects of cannabinoids devoid of the unwanted psychoactive effect. Nowadays, the approval of a mixture of CBD (cannabidiol) and Δ9-THC (tetrahydrocannabinol) to treat the neuropathic pain and spasticity in multiple sclerosis or purified cannabidiol to combat pediatric epilepsy have opened new therapeutic possibilities in the field of cannabinoids and returned these compounds to the front line of research to treat pathologies as relevant as stroke.

Pharmacological Evaluation of Cannabinoid Receptor Modulators Using GRABeCB2.0 Sensor.

Cannabinoid receptors CB1R and CB2R are G-protein coupled receptors acted upon by endocannabinoids (eCBs), namely 2-arachidonoylglycerol (2-AG) and N-arachidonoyl ethanolamine (AEA), with unique pharmacology and modulate disparate physiological processes. A genetically encoded GPCR activation-based sensor that was developed recently-GRABeCB2.0-has been shown to be capable of monitoring real-time changes in eCB levels in cultured cells and preclinical models. However, its responsiveness to exogenous synthetic cannabinoid agents, particularly antagonists and allosteric modulators, has not been extensively characterized. This current study expands upon the pharmacological characteristics of GRABeCB2.0 to enhance the understanding of fluorescent signal alterations in response to various functionally indiscriminate cannabinoid ligands. The results from this study could enhance the utility of the GRABeCB2.0 sensor for in vitro as well as in vivo studies of cannabinoid action and may aid in the development of novel ligands.

The antitumor action of endocannabinoids in the tumor microenvironment of glioblastoma.

Approximately 80% of all malignant brain tumors are gliomas, which are primary brain tumors. The most prevalent subtype of glioma, glioblastoma multiforme (GBM), is also the most deadly. Chemotherapy, immunotherapy, surgery, and conventional pharmacotherapy are currently available therapeutic options for GBM; unfortunately, these approaches only prolong the patient's life by 5 years at most. Despite numerous intensive therapeutic options, GBM is considered incurable. Accumulating preclinical data indicate that overt antitumoral effects can be induced by pharmacologically activating endocannabinoid receptors on glioma cells by modifying important intracellular signaling cascades. The complex mechanism underlying the endocannabinoid receptor-evoked antitumoral activity in experimental models of glioma may inhibit the ability of cancer cells to invade, proliferate, and exhibit stem cell-like characteristics, along with altering other aspects of the complex tumor microenvironment. The exact biological function of the endocannabinoid system in the development and spread of gliomas, however, is remains unclear and appears to rely heavily on context. Previous studies have revealed that endocannabinoid receptors are present in the tumor microenvironment, suggesting that these receptors could be novel targets for the treatment of GBM. Additionally, endocannabinoids have demonstrated anticancer effects through signaling pathways linked to the classic features of cancer. Thus, the pharmacology of endocannabinoids in the glioblastoma microenvironment is the main topic of this review, which may promote the development of future GBM therapies.

Potential Therapeutic Targets to Modulate the Endocannabinoid System in Alzheimer's Disease.

Alzheimer's disease (AD), the most common neurodegenerative disease (NDD), is characterized by chronic neuronal cell death through progressive loss of cognitive function. Amyloid beta (Aß) deposition, neuroinflammation, oxidative stress, and hyperphosphorylated tau proteins are considered the hallmarks of AD pathology. Different therapeutic approaches approved by the Food and Drug Administration can only target a single altered pathway instead of various mechanisms that are involved in AD pathology, resulting in limited symptomatic relief and almost no effect in slowing down the disease progression. Growing evidence on modulating the components of the endocannabinoid system (ECS) proclaimed their neuroprotective effects by reducing neurochemical alterations and preventing cellular dysfunction. Recent studies on AD mouse models have reported that the inhibitors of the fatty acid amide hydrolase (FAAH) and monoacylglycerol (MAGL), hydrolytic enzymes for N-arachidonoyl ethanolamine (AEA) and 2-arachidonoylglycerol (2-AG), respectively, might be promising candidates as therapeutical intervention. The FAAH and MAGL inhibitors alone or in combination seem to produce neuroprotection by reversing cognitive deficits along with Aß-induced neuroinflammation, oxidative responses, and neuronal death, delaying AD progression. Their exact signaling mechanisms need to be elucidated for understanding the brain intrinsic repair mechanism. The aim of this review was to shed light on physiology and pathophysiology of AD and to summarize the experimental data on neuroprotective roles of FAAH and MAGL inhibitors. In this review, we have also included CB1R and CB2R modulators with their diverse roles to modulate ECS mediated responses such as anti-nociceptive, anxiolytic, and anti-inflammatory actions in AD. Future research would provide the directions in understanding the molecular mechanisms and development of new therapeutic interventions for the treatment of AD.

Quantitative Proteomics Reveal That CB2R Agonist JWH-133 Downregulates NF-κB Activation, Oxidative Stress, and Lysosomal Exocytosis from HIV-Infected Macrophages.

HIV-associated neurocognitive disorders (HAND) affect 15-55% of HIV-positive patients and effective therapies are unavailable. HIV-infected monocyte-derived macrophages (MDM) invade the brain of these individuals, promoting neurotoxicity. We demonstrated an increased expression of cathepsin B (CATB), a lysosomal protease, in monocytes and post-mortem brain tissues of women with HAND. Increased CATB release from HIV-infected MDM leads to neurotoxicity, and their secretion is associated with NF-κB activation, oxidative stress, and lysosomal exocytosis. Cannabinoid receptor 2 (CB2R) agonist, JWH-133, decreases HIV-1 replication, CATB secretion, and neurotoxicity from HIV-infected MDM, but the mechanisms are not entirely understood. We hypothesized that HIV-1 infection upregulates the expression of proteins associated with oxidative stress and that a CB2R agonist could reverse these effects. MDM were isolated from healthy women donors (n = 3), infected with HIV-1ADA, and treated with JWH-133. After 13 days post-infection, cell lysates were labeled by Tandem Mass Tag (TMT) and analyzed by LC/MS/MS quantitative proteomics bioinformatics. While HIV-1 infection upregulated CATB, NF-κB signaling, Nrf2-mediated oxidative stress response, and lysosomal exocytosis, JWH-133 treatment downregulated the expression of the proteins involved in these pathways. Our results suggest that JWH-133 is a potential alternative therapy against HIV-induced neurotoxicity and warrant in vivo studies to test its potential against HAND.

Electrophysiological Phenotypes of Hippocampal Synaptic and Network Functions in Cannabinoid Receptor 2 Knockout Mice.

Background: The cannabinoid receptor 2 (CB2R), a cannabinoid receptor primarily expressed in immune cells, has been found in the brain, particularly in the hippocampus, where it plays crucial roles in modulating various neural functions, including synaptic plasticity, neuroprotection, neurogenesis, anxiety and stress responses, and neuroinflammation. Despite this growing understanding, the intricate electrophysiological characteristics of hippocampal neurons in CB2R knockout (CB2R KO) mice remain elusive. Aim and Methods: This study aimed to comprehensively assess the electrophysiological traits of hippocampal synaptic and network functions in CB2R KO mice. The focus was on aspects such as synaptic transmission, short- and long-term synaptic plasticity, and neural network synchrony (theta oscillations). Results: Our findings unveiled multiple functional traits in these CB2R KO mice, notably elevated synaptic transmission in hippocampal CA1 neurons, decreased both synaptic short-term plasticity (paired-pulse facilitation) and long-term potentiation (LTP), and impaired neural network synchronization. Conclusion: In essence, this study yields insightful revelations about the influence of CB2Rs on hippocampal neural functions. By illuminating the electrophysiological modifications in CB2R KO mice, our research enriches the comprehension of CB2R involvement in hippocampal function. Such insights could hold implications for advancing our understanding of the neural mechanisms under the influence of CB2Rs within the brain.

Novel Dual-Acting Hybrids Targeting Type-2 Cannabinoid Receptors and Cholinesterase Activity Show Neuroprotective Effects In Vitro and Amelioration of Cognitive Impairment In Vivo.

Alzheimer's disease (AD) is a neurodegenerative form of dementia characterized by the loss of synapses and a progressive decline in cognitive abilities. Among current treatments for AD, acetylcholinesterase (AChE) inhibitors have efficacy limited to symptom relief, with significant side effects and poor compliance. Pharmacological agents that modulate the activity of type-2 cannabinoid receptors (CB2R) of the endocannabinoid system by activating or blocking them have also been shown to be effective against neuroinflammation. Herein, we describe the design, synthesis, and pharmacological effects in vitro and in vivo of dual-acting compounds that inhibit AChE and butyrylcholinesterase (BChE) and target CB2R. Within the investigated series, compound 4g proved to be the most promising. It achieved IC50 values in the low micromolar to submicromolar range against both human cholinesterase isoforms while antagonizing CB2R with Ki of 31 nM. Interestingly, 4g showed neuroprotective effects on the SH-SY5Y cell line thanks to its ability to prevent oxidative stress-induced cell toxicity and reverse scopolamine-induced amnesia in the Y-maze forced alternation test in vivo.

Cannabinoid type 2 receptors play a crucial role in social defeat-induced depression.

BACKGROUND: The endocannabinoid system plays a crucial role in regulating mood, but the specific involvement of cannabinoid receptor type 2 (CB2R) in depression remains poorly understood. Similarly, the mechanisms by which electroacupuncture (EA) provides therapeutic benefits for depression are not clearly defined. This research aims to explore the function of CB2R in depression and examine if the therapeutic effects of EA are associated with the hippocampal CB2R system. METHODS: Mice experiencing social defeat stress (SDS) were used to model depression and anxiety behaviors. We quantified hippocampal CB2R and N-arachidonoylethanolamide (AEA) levels. The efficacy of a CB2R agonist, JWH133, in mitigating SDS-induced behaviors was evaluated. Additionally, EA's impact on CB2R and AEA was assessed, along with the influence of CB2R antagonist AM630 on EA's antidepressant effects. RESULTS: SDS led to depressive and anxiety-like behaviors, with corresponding decreases in hippocampal CB2R and AEA. Treatment with JWH133 ameliorated these behaviors. EA treatment resulted in increased CB2R and AEA levels, while AM630 blocked these antidepressant effects. LIMITATIONS: The study mainly focused on the SDS model, which may not entirely reflect other depression models. Besides, further investigation is needed to understand the precise mechanisms by which CB2R and AEA contribute to EA's effects. CONCLUSIONS: The study suggests hippocampal downregulation of CB2R and AEA contributes to depression. Upregulation of CB2R and AEA in response to EA suggests their involvement in EA's antidepressant effects. These findings provide insights into the role of the hippocampal CB2R system in depression and the potential mechanisms underlying EA's therapeutic effects.

The progress of small molecules against cannabinoid 2 receptor (CB2R).

The two subtypes of cannabinoid receptors (CBR), namely CB1R and CB2R, belong to the G protein-coupled receptor (GPCR) superfamily and are confirmed as potential therapeutic targets for a variety of diseases such as inflammation, neuropathic pain, and immune-related disorders. Since CB1R is mainly distributed in the central nervous system (CNS), it could produce severe psychiatric adverse reactions and addiction. In contrast, CB2R are predominantly distributed in the peripheral immune system with minimal CNS-related side effects. Therefore, more attention has been devoted to the discovery of CB2R ligands. In view of the favorable profile of CB2R, many high-binding affinity and selectivity CB2R ligands have been developed recently. This paper reviews recent research progress on CB2R ligands, including endogenous CB2R ligands, natural compounds, and novel small molecules, in order to provide a reference for subsequent CB2R ligand development.

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.

A Robust and Efficient FRET-Based Assay for Cannabinoid Receptor Ligands Discovery.

The identification of new modulators for Cannabinoid Receptors (CBRs) has garnered significant attention in drug discovery over recent years, owing to their manifold pathophysiological implications. In the context of hit identification, the availability of robust and sensitive high-throughput screening assays is essential to enhance the likelihood of success. In this study, we present the development and validation of a Tag-lite® binding assay designed for screening hCB1/hCB2 binding, employing a dual fluorescent ligand, CELT-335. Representative ligands for CBRs, exhibiting diverse affinity and functional profiles, were utilized as reference compounds to validate the robustness and efficiency of the newly developed Tag-lite® binding assay protocol. The homogeneous format, coupled with the sensitivity and optimal performance of the fluorescent ligand CELT-335, establishes this assay as a viable and reliable method for screening in hit and lead identification campaigns.

Activation of CB2R by synthetic CB2R agonist, PM289, improves brain endothelial barrier properties, decreases inflammatory response and enhances endothelial repair.

The Cannabinoid 2 Receptor (CB2R) has been found to provide immunological modulation in different cell types. More recently, detection of CB2R in the cerebral endothelium suggests a possible role in the resolution of inflammation at the level of the blood-brain-barrier (BBB). Here, the notion that CB2R upregulation in brain endothelial cells could be exploited to promote vascular protection and BBB integrity was evaluated. Targeting and activation of CB2R was accomplished by a novel and highly specific chromenopyrazole based CB2R agonist, PM289. This study demonstrates that CB2R upregulation is induced as early as 8 h in the cortical vasculature in an experimental mouse model of TBI. Unlike CB2R, CB1R was marginally detected and not significantly induced. In the human brain endothelial cell line, hCMEC/D3 cells, similar induction of CB2R was observed upon stimulation with TNFα. Analysis of transendothelial electrical resistance shows that PM289 markedly prevented the barrier-leakiness induced by TNFα. The BBB is also responsible for maintaining an immunological barrier. The five-fold increase in ICAM1 expression in stimulated endothelial cells was significantly diminished due to CB2R activation. Utilizing wounding assays, results showed that wound repair could be accomplished in nearly half the time when the novel CB2R agonist is present compared to the untreated control. Lastly, mechanistically, the effects of CB2R may be explained by the observed inhibition of the p65 NFκB subunit. Overall, these studies support the notion that targeting and activating CB2R in the brain vasculature could aid in BBB and vascular protection in the context of neuroinflammation.