CB1 Inverse Agonist Research Articles

Cannabidiol Inhibits IgE-Mediated Mast Cell Degranulation and Anaphylaxis in Mice.

Cannabidiol (CBD), the most abundant non-psychoactive constituent of the plant Cannabis sativa, is known to possess immune modulatory properties. This study investigates the effects of CBD on mast cell degranulation in human and mouse primary mast cells and passive cutaneous anaphylaxis in mice. Mouse bone marrow-derived mast cells and human cord-blood derived mast cellsare generated. CBD suppressed antigen-stimulated mast cell degranulation in a concentration-dependent manner. Mechanistically, CBD inhibited both the phosphorylation of FcεRI downstream signaling molecules and calcium mobilization in mast cells, while exerting no effect on FcεRI expression and IgE binding to FcεRI. These suppressive effectsare preserved in the mast cells thatare depleted of type 1 (CB1) and type 2 (CB2) cannabinoid receptors, as well as in the presence of CB1 agonist, CB2 agonist, CB1 inverse agonist, and CB2 inverse agonist. CBD also inhibited the development of mast cells in a long-term culture. The intraperitoneal administration of CBD suppressed passive cutaneous anaphylaxis in mice as evidenced by a reduction in ear swelling and decrease in the number of degranulated mast cells. Based on these results, the administration of CBD is a new therapeutic intervention in mast cell-associated anaphylactic diseases.

Modulation of cannabinoid receptor‐2 alters brain clearance of human tau

AbstractBackgroundMultiple studies have demonstrated a strong neuroinflammatory response in the presence of Tau pathology, which is strongly associated with the clinical symptoms and cognitive decline found in Alzheimer’s disease (AD). The correlation between AD progression and tau pathologies, rather than Ab accumulation, suggests that targeting pathological tau may be a more effective therapeutic approach. Microglia have been implicated in tauopathies as they may contribute to tau phosphorylation and aggregation and the uptake and spread of seed‐competent tau to healthy neurons due to dysfunctional degradation. Cannabinoid type 2 receptors (CB2) are highly expressed in immune cells and upregulated in activated microglia under conditions of neurologic disease, such as AD. The pharmacological modulation of CB2 have demonstrated a reduction in inflammation and plaque deposition, suggesting a role of CB2 on the immune system to influence AD‐related pathologies and phenotypes. However, there are limited findings on the CB2 regulation of tau accumulation.MethodWe have generated organotypic brain slice cultures from CB2‐EGFP/f/f mice and transduced with rAAV‐P301L/S320F‐human tau, which previously has shown to accumulate total tau and develop insoluble tau species. Slices were treated with CB2‐selective compounds and evaluated for tau pathology and microglial phenotypes using real‐time imaging and biochemical analyses.ResultPrevious investigation in our lab of a synucleinopathy animal model revealed the capacity of CB2 signaling to alter the function of immune cells and reduce accumulation of phosphorylated human alpha‐synuclein. Furthermore, we have determined that treatment with a CB2 inverse agonist will increase phagocytosis of pHrodo E. coli bioparticles in microglia BV2 cultures stimulated by LPS. Our preliminary work in brain slices over‐expressing mutant human tau show a trend toward reduced ratio of phosphorylated tau (Ser202/Thr205) to total tau in the soluble protein fraction (p = 0.0549) in slices treated with CB2 inverse agonist SR144528 compared to vehicle. We are repeating the experiment and performing further evaluations in organotypic brain slice cultures from CB2‐KO mice.ConclusionThese studies will advance our understanding of the role of brain CB2 in pathologic tau removal and potentially highlight CB2 as a therapeutic target against tauopathies such as AD.

Systematic Modification of the Substitution Pattern of the 7-Hydroxy-5-oxopyrazolo[4,3-b]pyridine-6-carboxamide Scaffold Enabled the Discovery of New Ligands with High Affinity and Selectivity for the Cannabinoid Type 2 Receptor.

Selective ligands of the CB2 receptor are receiving considerable attention due to their potential as therapeutic agents for a variety of diseases. Recently, 7-hydroxy-5-oxopyrazolo[4,3-b]pyridine-6-carboxamide derivatives were shown to act at the CB2 receptor either as agonists or as inverse agonists/antagonists in vitro and to have anti-osteoarthritic activity in vivo. In this article, we report the synthesis, pharmacological profile, and molecular modeling of a series of twenty-three new 7-hydroxy-5-oxopyrazolo[4,3-b]pyridine-6-carboxamides with the aim of further developing this new class of selective CB2 ligands. In addition to these compounds, seven other analogs that had been previously synthesized were included in this study to better define the structure-activity relationship (SAR). Ten of the new compounds studied were found to be potent and selective ligands of the CB2 receptor, with Ki values ranging from 48.46 to 0.45 nM and CB1/CB2 selectivity indices (SI) ranging from >206 to >4739. In particular, compounds 54 and 55 were found to be high-affinity CB2 inverse agonists that were not active at all at the CB1 receptor, whereas 57 acted as an agonist. The functional activity profile of the compounds within this structural class depends mainly on the substitution pattern of the pyrazole ring.

OR03-2 Phase 1, Randomized, Controlled Trial of GFB-024, a Once-Monthly CB1 Inverse Agonist, in Healthy Overweight and Obese Participants and in Participants with Type 2 Diabetes Mellitus

Abstract Evidence from nonclinical studies suggests a role of cannabinoid-1 receptor (CB1) in the development of diabetic nephropathy (DN). Kidney CB1 expression is upregulated in podocytes and tubular cells in murine models of obesity and diabetes mellitus (DM). Inhibition by CB1 inverse agonists has been shown to ameliorate diabetes-induced albuminuria, inhibit kidney fibrosis and inflammation, and prevent podocyte dysfunction. Mouse models of DM have shown that genetic deletion of CB1 in podocytes or proximal tubular cells protects against glomerular and tubular dysfunction. GFB-024 is a recombinant humanized monoclonal antibody functioning as a CB1-specific inverse agonist. Pharmacodynamic studies demonstrated that GFB-024 protects human podocytes in vitro. Targeting the CB1 pathway with GFB-024 is a potentially novel approach to protecting podocytes from injury in patients with CB1-associated DN. In a phase 1, randomized, double-blind, placebo-controlled single ascending dose (SAD) trial, we evaluated the safety, tolerability, pharmacokinetics (PK), and immunogenicity of GFB-024 in up to 56 healthy overweight and obese (BMI 25–40 kg/m2) participants. A total of 38 subjects have completed 5 cohorts in the SAD, receiving single doses of 5 mg to 300 mg administered subcutaneously. GFB-024 was well tolerated, and there were no dose-limiting adverse effects. PK exposures achieved in the trial exceeded the estimated efficacious exposure, based on four different in vitro activity assays. Absorption was prolonged with flat exposure over the first 7 days, with a Tmax ranging from approximately 4-7 days. Elimination half-life was approximately 12-13 days, with exposures remaining in the estimated efficacious range at 28 days for all but the lowest dose tested. In summary, GFB-024 was safe and well tolerated following single doses of up to 300 mg. PK analysis demonstrated potentially efficacious exposure, a prolonged absorption phase, and elimination half-life compatible with once-monthly dosing. Presentation: Saturday, June 11, 2022 11:45 a.m. - 12:00 p.m.

Immune challenges upregulate the expression of cannabinoid receptors in cultured human odontoblasts and gingival fibroblasts.

Odontoblasts and gingival fibroblasts play essential roles in the physiological and pathological processes of dental tissue. Cannabinoid receptors (CB1 and CB2) are involved in analgesia by modulating the función of calcium channels that inhibit the synthesis of some neurotransmitters. A better understanding of the physiology of these receptors would provide the possibility of using them as therapeutic targets in controlling dental pain. The aim of this study was to evaluate the presence and activity of cannabinoid receptors in human odontoblast-like cells (OLC) and human gingival fibroblasts (HGF). CB1 and CB2 transcription was analyzed by real-time PCR, proteins were detected by immunofluorescence, and functional cannabinoid receptors were evaluated by measuring intracellular calcium concentration after stimulation with cannabidiol (CBD) and pre-treatment with a CB1 antagonist, a CB2 inverse agonist and a TRPV1 antagonist. Transcripts for CB1 and CB2 were found in both odontoblasts and gingival fibroblasts. Cannabidiol induced an increase in [Ca2+]i in both cells types, but surprisingly, pre-treatment with selective cannabinoid antagonists attenuated this effect, suggesting a functional communication between specific cannabinoid receptors and other CBD target receptors. In conclusion, human odontoblasts and gingival fibroblasts express functional CB1 and CB2 cannabinoid receptors, which could be modulated to improve the treatment of pain or dental sensitivity.

Treatment with Cannabidiol Results in an Antioxidant and Cardioprotective Effect in Several Pathophysiologies.

Cannabis sativa has chemically active compounds called cannabinoids, where Δ9- tetrahydrocannabinol (THC) and Cannabidiol (CBD) are the major ones responsible for the various pharmacological effects. The endocannabinoid system is an endogenous system considered a unique and widespread homeostatic physiological regulator. It is made up of type 1 (CB1) and type 2 (CB2) cannabinoid receptors. CBD, in turn, has a low affinity for CB1 and CB2 receptors, and regulates the effects arising from THC as a CB1 partial agonist, which are tachycardia, anxiety, and sedation. It also acts as a CB2 inverse agonist, resulting in anti-inflammatory effects. Furthermore, its anticonvulsant, neuroprotective, antipsychotic, antiemetic, anxiolytic, anticancer, and antioxidant effects seem to be linked to other discovered receptors such as GRP55, 5TH1a, TRPV I, TRPV II and the regulation of the intracellular concentration of Ca2+. Regarding oxidative stress, O2- can act as an oxidizing agent, being reduced to hydrogen peroxide (H2O2), or as a reducing agent, donating its extra electron to NO to form peroxynitrite (ONOO-). The ONOO- formed is capable of oxidizing proteins, lipids, and nucleic acids, causing several cell damages. In this sense, CBD can prevent cardiac oxidative damage in many conditions, such as hypertension, diabetes, or even through the cardiotoxic effects induced by chemotherapy, which makes it a potential target for future clinical use to minimize the deleterious effects of many pathophysiologies.

392-P: Phase 1, Randomized, Controlled Trial of GFB-024, a Once-Monthly CB1 Inverse Agonist, in Healthy Overweight and Obese Participants and in Participants with Type 2 Diabetes Mellitus

Evidence from nonclinical studies suggests a role of cannabinoid-1 receptor (CB1) in the development of diabetic nephropathy (DN) . Kidney CB1 expression is upregulated in podocytes and tubular cells in murine models of obesity and diabetes mellitus (DM) . Inhibition by CB1 inverse agonists has been shown to ameliorate diabetes-induced albuminuria, inhibit kidney fibrosis and inflammation, and prevent podocyte dysfunction. Mouse models of DM have shown that genetic deletion of CB1 in podocytes or proximal tubular cells protects against glomerular and tubular dysfunction. GFB-024 is a recombinant humanized monoclonal antibody functioning as a CB1-specific inverse agonist that protects human podocytes in vitro. Targeting the CB1 pathway with GFB-024 is a potentially novel approach to protecting podocytes from injury in patients with CB1-associated DN. In a phase 1, randomized, double-blind, placebo-controlled single ascending dose (SAD) trial, we evaluated the safety, tolerability, pharmacokinetics (PK) , and immunogenicity of GFB-024 in 38 healthy overweight and obese (BMI 25 - 40 kg/m2) participants, receiving single doses of 5 mg to 300 mg administered subcutaneously. GFB-024 was well tolerated, and there were no dose-limiting adverse effects. PK exposures achieved in the trial exceeded the estimated efficacious exposure, based on in vitro activity assays. Absorption was prolonged with flat exposure over the first 7 days, with a Tmax ranging from approximately 4-7 days. Elimination half-life was approximately 12-13 days, with exposures remaining in the estimated efficacious range at 28 days for all but the lowest dose tested. In summary, GFB-024 was safe and well tolerated following single doses of up to 300 mg. PK analysis demonstrated potentially efficacious exposure, a prolonged absorption phase, and elimination half-life compatible with once-monthly dosing. Disclosure G.Gaich: Consultant; 89 bio, Inc., Employee; Goldfinch Bio, Inc. S.Bilic: Consultant; Goldfinch Bio, Inc. Y.Dagon: Employee; Goldfinch Bio, Inc. T.Gustafson: Employee; Goldfinch Bio, Inc., Janssen Pharmaceuticals, Inc. J.Lawler: Employee; Goldfinch Bio, Inc. L.Johnson: Employee; Goldfinch Bio, Inc. L.Rudolph-owen: Employee; Goldfinch Bio, Inc.

The Role of Cannabidiol (CBD) in a Cisplatin‐Induced Model of Chronic Neuropathic Pain

Cannabinoid‐based therapies offer a safer, non‐opioid alternative for the management of chronic pain. While most studies focus on the analgesic potential of the main psychoactive component of marijuana, Δ9‐tetrahydrocannabinol, fewer studies have investigated the role of the non‐psychoactive component, cannabidiol (CBD). CBD has been purported to have analgesic, anti‐inflammatory, anticonvulsant, and anxiolytic effects. In addition to having actions at both cannabinoid receptors (CB1 and CB2), CBD has been shown to interact with both the transient receptor potential vanilloid‐1 (TRPV1) and serotonergic (5‐HT) receptors. Clinically, CBD’s lack of psychoactivity and decreased abuse liability make it an appealing pharmacotherapeutic for the management of chronic pain. Therefore, the purpose of the current study was to determine whether CBD sex‐ or dose‐dependently reverses antinociception in an acute model of thermal pain and/or mechanical allodynia in a model of cisplatin‐induced chronic neuropathic pain. Furthermore, we observed the degree to which CB1, CB2, 5‐HT, and TRPV1 receptors may be mediating these anti‐allodynic responses. Male and female wild‐type mice were assessed for either the anti‐allodynic effects of 0, 1, 3, 10, and 30 mg/kg CBD in a cisplatin‐induced model of neuropathic pain or the antinociceptive effects of 0, 1, 3, 10, 30, and 100 mg/kg CBD in a model of acute thermal (tail‐flick) pain 60 minutes following CBD administration. To determine the relative contributions of each receptor subtype in mediating the anti‐allodynic effects of CBD, male and female mice were pretreated with either: vehicle, the CB1 inverse agonist SR141716A (10 mg/kg), the CB2 antagonist SR144528 (10 mg/kg), the TRPV1 antagonist capsazepine (10 mg/kg), or the 5‐HT2 antagonist methysergide (4 mg/kg) 30 minutes prior to treatment with CBD. Mice were assessed for the effects of the pretreatment alone and in combination with CBD. CBD at a dose of 3 mg/kg was able to partially reverse cisplatin‐induced allodynia in male and female mice, while doses of 10 and 30 mg/kg resulted in nearly complete reversal. Our preliminary findings showed that the anti‐allodynic effects of 30 mg/kg CBD were completely blocked following pretreatment with SR141716A and SR144528, and partially blocked by capsazepine in both male and female mice. Interestingly, pretreatment with methysergide partially attenuated the anti‐allodynic effects of CBD in females alone. In contrast, CBD (0‐100 mg/kg) failed to induce antinociception on the tail‐flick assay. CBD did induce mild hypothermia with males showing a greater degree of CBD‐mediated hypothermia than female mice. Taken together, these findings suggest that CBD may be a more effective treatment option for the management of chronic pain. This study highlights the therapeutic potential of CBD in a model of neuropathic pain and suggests that these effects may have clinical implications for the use of cannabinoids in chronic pain management.

Effects of cannabinoid and vanilloid receptor antagonists on nicotine induced relaxation response enhancement in rabbit corpus cavernosum.

Objective(s):Endocannabinoids and nicotine regulate the neurotransmitter release in different central and peripheral synapses. Various studies in the literature demonstrate the interaction between endocannabinoid and nicotinic systems, especially in the central nervous system. The interaction between nicotinic and endocannabinoid systems was investigated in this study. We aimed to show the effects of cannabinoid and vanilloid receptor antagonists on nicotine-induced relaxation response increases in rabbit corpus cavernosum.Materials and Methods:From a total of seven male albino rabbits, three or four equal strips were cut from each corpus cavernosum and inserted in isolated organ baths. Tissues were contracted with phenylephrine (3×10−5 M). After contraction reached a plateau, strips were stimulated with EFS, and with the stabilization of EFS relaxation responses, 10-4 M of nicotine was administered to tissues. After that, in order to investigate the effects of AM251 (CB1 antagonist), AM630 (CB2 inverse agonist) or capsazepine (a vanilloid receptor antagonist) were given to different tissues, after the resting period.Results:Nicotine (10−4 M) increased the EFS-induced relaxation responses (14.60%±2.94%, P<0.05). AM630 decreased the enhancement of nicotine-induced EFS relaxation responses (nicotine 10-4 M enhancement: 17.16%±3.19%; nicotine 10-4 M enhancement in the presence of AM630 10-6 M: 4.44%±3.43% P<0.05; n=6), whereas effects of AM251 and capsazepine were not significant. Conclusion:In the present study, nicotine increased the amplitudes of EFS-induced relaxation responses probably via nicotinic acetylcholine receptors located on the nitrergic nerves of the corpus cavernosum. We showed the role of cannabinoid-like endo-ligands in nicotine-induced enhancement via CB2 receptors but not CB1 and VR1 receptors.

Raloxifene, a cannabinoid type-2 receptor inverse agonist, mitigates visual deficits and pathology and modulates microglia after ocular blast

Visual deficits after ocular blast injury (OBI) are common, but pharmacological approaches to improve long-term outcomes have not been identified. Blast forces frequently damage the retina and optic nerves, and work on experimental animals has shown the pro-inflammatory actions of microglia can further exacerbate such injuries. Cannabinoid type-2 receptor (CB2) inverse agonists specifically target activated microglia, biasing them away from the harmful pro-inflammatory M1 state toward the helpful reparative M2 state. We previously found that treating mice with CB2 inverse agonists after traumatic brain injury, produced by either focal cranial air blast or dorsal cranial impact, greatly attenuated the visual deficits and pathology that otherwise resulted. Here we examined the consequences of single and repeat OBI and the benefit provided by raloxifene, an FDA-approved estrogen receptor drug that possesses noteworthy CB2 inverse agonism. After single OBI, although the amplitudes of the A- and B-waves of the electroretinogram and pupil light response appeared to be normal, the mice showed hints of deficits in contrast sensitivity and visual acuity, a trend toward optic nerve axon loss, and significantly increased light aversion, which were reversed by 2 weeks of daily treatment with raloxifene. Mice subjected to repeat OBI (5 blasts spaced 1 min apart), exhibited more severe visual deficits, including decreases in contrast sensitivity, visual acuity, the amplitudes of the A- and B-waves of the electroretinogram, light aversion, and resting pupil diameter (i.e. hyperconstriction), accompanied by the loss of photoreceptor cells and optic nerve axons, nearly all of which were mitigated by raloxifene. Interestingly, optic nerve axon abundance was strongly correlated with contrast sensitivity and visual acuity across all groups of experimental mice in the repeat OBI study, suggesting optic nerve axon loss with repeat OBI and its attenuation with raloxifene are associated with the extent of these two deficits while photoreceptor abundance was highly correlated with A-wave amplitude and resting pupil size, suggesting a prominent role for photoreceptors in these two deficits. Quantitative PCR (qPCR) showed levels of M1-type microglial markers (e.g. iNOS, IL1β, TNFα, and CD32) in retina, optic nerve, and thalamus were increased 3 days after repeat OBI. With raloxifene treatment, the overall expression of M1 markers was more similar to that in sham mice. Raloxifene treatment was also associated with the elevation of IL10 transcripts in all three tissues compared to repeat OBI alone, but the results for the three other M2 microglial markers we examined were more varied. Taken together, the qPCR results suggest that raloxifene benefit for visual function and pathology was associated with a lessening of the pro-inflammatory actions of microglia. The benefit we find for raloxifene following OBI provides a strong basis for phase-2 efficacy testing in human clinical trials for treating ocular injury.

The role of cannabinoid receptor 2 in microglial clearance of human tau.

It is well accepted that neuroinflammation is a key component in the pathobiology of Alzheimer's disease (AD). Multiple studies have demonstrated a strong neuroinflammatory response in the presence of Tau pathology, which is strongly associated with the clinical symptoms and cognitive decline found in AD patients. The correlation between AD progression and tau pathologies, rather than Ab accumulation, suggests that targeting pathological tau may be a more effective therapeutic approach. Microglia have been implicated in tauopathies as they may contribute to tau phosphorylation and aggregation and the uptake and spread of seed-competent tau to healthy neurons due to dysfunctional degradation. Cannabinoid type 2 receptors (CB2) are highly expressed in immune cells and upregulated in activated microglia under conditions of neurologic disease, such as AD. Moreover, the pharmacological modulation of CB2 using CB2-selective compounds have demonstrated a reduction in inflammation and plaque deposition, suggesting a role of CB2 on the immune system to influence AD-related pathologies and phenotypes. However, there are limited findings on the CB2 regulation of tau accumulation. Brain slice cultures will be generated from CB2-EGFP knock-in mice and transduced with virus-mediated tau previously shown to accumulate total tau and develop insoluble tau species. Brain slices will be evaluated for tau pathology and microglial phenotypes using real-time imaging and biochemical analyses. Previous investigation in our lab of a synucleinopathy animal model revealed the capacity of CB2 to alter the function of immune cells and reduce accumulation of toxic human alpha-synuclein. Furthermore, we have determined that treatment with a CB2 inverse agonist will increase phagocytosis of pHrodo E. coli bioparticles in microglia BV2 cultures stimulated by LPS. We are currently working with brain slice cultures to evaluate how CB2 alters the behavior of microglia including phagocytosis and clearance of human tau. These studies will advance our understanding of the role of CB2 in the microglial contribution to pathologic tau removal and potentially highlight CB2 as a therapeutic target against tauopathies such as AD.

Raloxifene Modulates Microglia and Rescues Visual Deficits and Pathology After Impact Traumatic Brain Injury.

Mild traumatic brain injury (TBI) involves widespread axonal injury and activation of microglia, which initiates secondary processes that worsen the TBI outcome. The upregulation of cannabinoid type-2 receptors (CB2) when microglia become activated allows CB2-binding drugs to selectively target microglia. CB2 inverse agonists modulate activated microglia by shifting them away from the harmful pro-inflammatory M1 state toward the helpful reparative M2 state and thus can stem secondary injury cascades. We previously found that treatment with the CB2 inverse agonist SMM-189 after mild TBI in mice produced by focal cranial blast rescues visual deficits and the optic nerve axon loss that would otherwise result. We have further shown that raloxifene, which is Food and Drug Administration (FDA)-approved as an estrogen receptor modulator to treat osteoporosis, but also possesses CB2 inverse agonism, yields similar benefit in this TBI model through its modulation of microglia. As many different traumatic events produce TBI in humans, it is widely acknowledged that diverse animal models must be used in evaluating possible therapies. Here we examine the consequences of TBI created by blunt impact to the mouse head for visual function and associated pathologies and assess raloxifene benefit. We found that mice subjected to impact TBI exhibited decreases in contrast sensitivity and the B-wave of the electroretinogram, increases in light aversion and resting pupil diameter, and optic nerve axon loss, which were rescued by daily injection of raloxifene at 5 or 10 mg/ml for 2 weeks. Raloxifene treatment was associated with reduced M1 activation and/or enhanced M2 activation in retina, optic nerve, and optic tract after impact TBI. Our results suggest that the higher raloxifene dose, in particular, may be therapeutic for the optic nerve by enhancing the phagocytosis of axonal debris that would otherwise promote inflammation, thereby salvaging less damaged axons. Our current work, together with our prior studies, shows that microglial activation drives secondary injury processes after both impact and cranial blast TBI and raloxifene mitigates microglial activation and visual system injury in both cases. The results thus provide a strong basis for phase 2 human clinical trials evaluating raloxifene as a TBI therapy.

Sex differences in cocaine-associated memory: The interplay between CB1, mGluR5, and estradiol

We know surprisingly little about the sex differences in the neurobiology of cocaine addiction, except females are more susceptible to the rewarding effects of cocaine than their male counterparts. Only a handful of recent studies have examined the neurobiology of cocaine-induced conditioned place preference (CPP) memory among female rodents. We contribute to this emerging line of research by documenting sex differences in cocaine-associated memory and illustrating the underlying signaling pathways in five experiments. Rimonabant (Rim), a cannabinoid CB1 antagonist and inverse agonist, exerted a facilitating effect for low-dose cocaine and an impairing effect for high-dose cocaine CPP memory in male mice, as in our previous study, but not in female mice. Nor did we observe the effect exist among CB1 knockout male mice, which indicated that the CB1 receptors played a mediating role. We also found that the metabotropic glutamate receptor 5 (mGluR5) was located in the same signaling pathway as CB1 in male mice. To clarify the mechanisms behind the sex differences, we used ovariectomized (OVX) female mice with estradiol benzoate (EB) replacement. In the OVX female mice, we showed that Rim-alone and EB-alone, but not Rim-and-EB-combined, facilitated the low-dose cocaine CPP memory. Moreover, 4-hydroxytamoxifen (4-OHT), an estrogen receptor (ER) antagonist, blocked Rim's and EB's facilitating effect. Finally, 2-methyl-6-(phenylethynyl)pyridine (MPEP), an mGluR5 antagonist, partially blocked EB’s facilitating effect. In sum, we identified sex-specific effects of Rim on cocaine-induced CPP memory and the respective signaling pathways: mGluR5-CB1 for male mice and ER-mGluR5-CB1 for female mice. These findings may have merits for the development of sex-specific treatment for cocaine addiction.

Short and long-term neuroprotective effects of cannabidiol after neonatal peripheral nerve axotomy

Neonatal rat sciatic nerve crush mimics obstetric axonotmesis, leading to extensive loss of motor and sensory neurons. The present study aimed to investigate the neuroprotective potential of cannabidiol (CBD) and the role of cannabinoid receptors after sciatic nerve crush in neonatal rats. For that, two-day-old Wistar rats were used, organized into the following experimental groups: sciatic nerve crush plus CBD treatment (CBD), crush plus vehicle treatment (VE), crush + CBD + AM251 treatment (AM251 – CB1 inverse agonist), crush + CBD + AM630 treatment (AM630 – CB2 antagonist). Spinal motoneuron survival was evaluated by Nissl staining of the lumbar spinal cord, 5- and 56-days following injury. CBD treatment enhanced neuronal survival by ~54 % both 5 days and 8 weeks after injury. However, AM251 and AM630 treatment decreased neuronal rescue by 30 % when compared to the CBD group, suggesting that CBD acts partially through such pathways. However, in the long term, only the CB1 blockade reverted CBD positive results. Synaptic preservation was evaluated by anti-synaptophysin immunolabeling. Five days after the lesion, CBD treatment preserved ~35 % of synapses in the ventral horn, and such effect was partially reversed by CB1 inactivation. Additionally, CBD treatment reduced astroglial reaction both at 5 days (39 %, compared to VE) and 8 weeks (31 %, compared to VE) after lesion. The microglial response was acutely reduced by 62 % after CBD treatment. Overall, the results herein show that CBD is neuroprotective, increasing neuronal survival and reducing glial reaction after neonatal axotomy. Such effects require CB1 and CB2 receptors to be effective, in turn influencing neuroprotection, glial reactivity, and functional recovery.

Pharmacological inhibition of the primary endocannabinoid producing enzyme, DGL-α, induces autism spectrum disorder-like and co-morbid phenotypes in adult C57BL/J mice.

Accumulating evidence links dysfunction in the endocannabinoid system (ECS) with the pathology of neurodevelopmental disorders, particularly autism spectrum disorder (ASD). Variants in ECS genes CNR1 and DAGLA are associated with neurological phenotypes in humans. The endocannabinoids (eCBs), 2-AG and AEA, which act at the primary cannabinoid receptor (CB1), mediate behaviors relevant to neurodevelopmental disorders. The overlap between these eCBs is poorly understood. Most ECS studies have focused on stress responses, anxiety, and epilepsy, however, its role in social behavior and communication has only recently come under investigation. This represents a critical gap in our understanding of the ECS and its relationship to ASD. Furthermore, the increasing prevalence of ASD and a lack of therapeutics emphasize a crucial need for novel therapeutic targets. To this aim, we used an inhibitor of the eCB producing enzyme DGL-α, DO34, and the CB1 inverse agonist, rimonabant, to evaluate the role of the primary eCB, 2-AG, in ASD. Adult male C57BL/6J mice were used in a series of behavioral paradigms which assessed social behavior, social communication, repetitive behaviors, anxiety and locomotor activity. DO34 and rimonabant increased anxiety-like behavior, while only DO34 induced hyperactivity, social deficits, and repetitive self-grooming behavior. These data indicate that reduced 2-AG bioavailability, or CB1 inhibition, each induce unique respective behavioral phenotypes relevant to neurodevelopmental disorders, particularly ASD. This suggests fundamental differences in CB1 signaling via 2-AG and the CB1 receptor itself, particularly for social behaviors, and that 2-AG signaling may represent a target for the development of novel therapeutics. LAY SUMMARY: Endocannabinoids play a critical role in the developing nervous system. Alterations in the endocannabinoid system are linked to neurodevelopmental disorders. Studies suggest these variants may play a critical role in the core symptoms of autism spectrum disorder. In this study, pharmacological inhibition of the primary endocannabinoid producing enzyme, DGL-α, induced a constellation of deficits in behavioral domains associated with autism.

COX-2 Inhibition Antagonizes Intra-Accumbens 2-Arachidonoylglycerol-Mediated Reduction in Ethanol Self-Administration in Rats.

Ethanol (EtOH) self-administration is particularly sensitive to the modulation of CB1 signaling in the nucleus accumbens (NAc) shell, and EtOH consumption increases extracellular levels of the endogenous cannabinoid CB1 receptor agonist 2-arachidonoyl glycerol (2-AG) in this brain region. Stimulation of CB1 receptor with agonists increases EtOH consumption, suggesting that EtOH-induced increases in 2-AG might sustain motivation for EtOH intake. In order to further explore this hypothesis, we analyzed the alterations in operant EtOH self-administration induced by intra-NAc shell infusions of 2-AG itself, the CB1 inverse agonist SR141716A, the 2-AG clearance inhibitor URB602, anandamide, and the cyclooxygenase-2 (COX-2) inhibitor nimesulide. Surprisingly, self-administration of 10% EtOH was dose-dependently reduced by either intra-NAc shell SR141716A or 2-AG infusions. Similar effects were found by intra-NAc shell infusions of URB602, suggesting again a role for accumbal 2-AG on the modulation of EtOH intake. Intra-NAc shell anandamide did not alter EtOH self-administration, pointing to a specific role for 2-AG in the modulation of EtOH self-administration. Finally, the inhibitory effect of intra-NAc shell 2-AG on EtOH intake was significantly reversed by pretreatment with nimesulide, suggesting that oxidative metabolites of 2-AG might mediate these inhibitory effects on operant self-administration. We propose that 2-AG signaling in the NAc exerts an inhibitory influence on EtOH consumption through a non-CB1 receptor mechanism involving the COX-2 pathway.

Targeting the Endocannabinoid CB1 Receptor to Treat Body Weight Disorders: A Preclinical and Clinical Review of the Therapeutic Potential of Past and Present CB1 Drugs.

Obesity rates are increasing worldwide and there is a need for novel therapeutic treatment options. The endocannabinoid system has been linked to homeostatic processes, including metabolism, food intake, and the regulation of body weight. Rimonabant, an inverse agonist for the cannabinoid CB1 receptor, was effective at producing weight loss in obese subjects. However, due to adverse psychiatric side effects, rimonabant was removed from the market. More recently, we reported an inverse relationship between cannabis use and BMI, which has now been duplicated by several groups. As those results may appear contradictory, we review here preclinical and clinical studies that have studied the impact on body weight of various cannabinoid CB1 drugs. Notably, we will review the impact of CB1 inverse agonists, agonists, partial agonists, and neutral antagonists. Those findings clearly point out the cannabinoid CB1 as a potential effective target for the treatment of obesity. Recent preclinical studies suggest that ligands targeting the CB1 may retain the therapeutic potential of rimonabant without the negative side effect profile. Such approaches should be tested in clinical trials for validation.

Cannabinoid CB2 receptors mediate the anxiolytic-like effects of monoacylglycerol lipase inhibition in a rat model of predator-induced fear

The endocannabinoid system is a key regulator of the response to psychological stress. Inhibitors of monoacylglycerol lipase (MGL), the enzyme that deactivates the endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG), exert anxiolytic-like effects in rodent models via 2-AG-dependent activation of CB1 cannabinoid receptors. In the present study, we examined whether the MGL inhibitor JZL184 might modulate persistent predator-induced fear in rats, a model that captures features of human post-traumatic stress disorder. Exposure to 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), a volatile chemical that is innately aversive to some rodent species, produced in male rats a long-lasting anxiety-like state that was measured 7 days later in the elevated plus maze test. Systemic administration of JZL184 [4, 8 and 16 mg/kg, intraperitoneal (IP)] 4 h before testing caused dose-dependent inhibition of MGL activity and elevation of 2-AG content in brain tissue. Concomitantly, the inhibitor suppressed TMT-induced fear behaviors with a median effective dose (ED50) of 4 mg/kg. A similar behavioral response was observed with another MGL inhibitor, KML29 (4 and 16 mg/kg, IP). Surprisingly, the effect of JZL184 was prevented by co-administration of the CB2 inverse agonist AM630 (5 mg/kg, IP), but not the CB1 inverse agonist rimonabant (1 mg/kg, IP). Supporting mediation of the response by CB2 receptors, the CB2 agonist JWH133 (0.3, 1 and 3 mg/kg, IP) also produced anxiolytic-like effects in TMT-stressed rats, which were suppressed by AM630. Notably, (i) JWH133 was behaviorally ineffective in animals that had no prior experience with TMT; and (ii) CB2 mRNA levels in rat prefrontal cortex were elevated 7 days after exposure to the aversive odorant. The results suggest that JZL184 attenuates the behavioral consequences of predator stress through a mechanism that requires 2-AG-mediated activation of CB2 receptors, whose transcription may be induced by the stress itself.

Anxiolytic Effects of Cannabinoid Receptor Agonists in the Zebrafish Species, Danio rerio

As of July 2019, 34 states in the U.S. have legalized medical marijuana and an additional 12 have legalized “low THC, high cannabidiol (CBD)” substances (Hanson &amp; Garcia, 2019). While acute cannabis use has been associated with decreased anxiety levels, users have also experienced adverse side effects including increased anxiety, panic reactions, and psychotic symptoms (Hall &amp; Degenhardt, 2009). Plant‐derived pharmacological agents, like cannabis, can vary in quality and composition (and thus efficacy) due to a variety of environmental factors (Atanasov et. al. 2015). In order to use cannabinoids to treat anxiety safely, a synthetic cannabinoid that can produce consistent therapeutic (anxiolytic) effects without producing psychoactive effects is necessary. Zebrafish are an increasingly popular model organism used due to their high sensitivity to chemicals as absorbed through their gills and quantifiable behavioral phenotypes (Stewart 2014). Humans and zebrafish have comparable endocannabinoid pathways that each contain CB1 and CB2 receptors (Krug and Clark 2015). When observed in a Novel Dive Tank, anxiety levels in zebrafish can be quantified. Like humans, male and female zebrafish differ in hormonal composition and therefore respond to treatments differently. In this study, male and female zebrafish were treated with CB receptor agonists anandamide and WIN 55,212‐2 and CB2 inverse agonist JTE‐907 in order to model the how the endocannabinoid system influences anxiety. The reduced amount of time spent in the upper zone by the JTE + Anandamide treated fish, combined with the increased time classified as highly mobile, suggests that JTE‐907 had an anxiogenic effect. Significant anxiolytic effects were observed the WIN treatment group, particularly in male treated fish. These results suggest that male treated fish are more receptive to the anxiolytic effects of a non‐selective CB agonist such as WIN 55, 212. Future research with a water‐soluble CB1 inverse agonist could provide insight into the differing roles of CB1 and CB2 receptors in cannabis‐based treatments.

Multi-Target Effects of the Cannabinoid CP55940 on Familial Alzheimer's Disease PSEN1 E280A Cholinergic-Like Neurons: Role of CB1 Receptor.

Background:Alzheimer’s disease (AD) is characterized by structural damage, death, and functional disruption of cholinergic neurons (ChNs) as a result of intracellular amyloid-β (Aβ) aggregation, extracellular neuritic plaques, and hyperphosphorylation of protein tau (p-Tau) overtime.Objective:To evaluate the effect of the synthetic cannabinoid CP55940 (CP) on PSEN1 E280A cholinergic-like nerve cells (PSEN1 ChLNs)—a natural model of familial AD.Methods:Wild type (WT) and PSEN1 ChLNs were exposed to CP (1μM) only or in the presence of the CB1 and CB2 receptors (CB1Rs, CB2Rs) inverse agonist SR141716 (1μM) and SR144528 (1μM) respectively, for 24 h. Untreated or treated neurons were assessed for biochemical and functional analysis.Results:CP in the presence of both inverse agonists (hereafter SR) almost completely inhibits the aggregation of intracellular sAβPPβf and p-Tau, increases ΔΨm, decreases oxidation of DJ-1Cys106-SH residue, and blocks the activation of c-Jun, p53, PUMA, and caspase-3 independently of CB1Rs signaling in mutant ChLNs. CP also inhibits the generation of reactive oxygen species partially dependent on CB1Rs. Although CP reduced extracellular Aβ42, it was unable to reverse the Ca2+ influx dysregulation as a response to acetylcholine stimuli in mutant ChLNs. Exposure to anti-Aβ antibody 6E10 (1:300) in the absence or presence of SR plus CP completely recovered transient [Ca2+]i signal as a response to acetylcholine in mutant ChLNs.Conclusion:Taken together our findings suggest that the combination of cannabinoids, CB1Rs inverse agonists, and anti-Aβ antibodies might be a promising therapeutic approach for the treatment of familial AD.