Activation Of Cannabinoid Receptors Research Articles

Multiple cannabinoid signaling cascades powerfully suppress recurrent excitation in the hippocampus

Recurrent excitatory neural networks are unstable. In the hippocampus, excitatory mossy cells (MCs) receive strong excitatory inputs from dentate granule cells (GCs) and project back onto the proximal dendrites of GCs. By targeting the ipsi- and contralateral dentate gyrus (DG) along the dorsoventral axis of the hippocampus, MCs form an extensive recurrent excitatory circuit (GC-MC-GC) whose dysregulation can promote epilepsy. We recently reported that a physiologically relevant pattern of MC activity induces a robust form of presynaptic long-term potentiation (LTP) of MC-GC transmission which enhances GC output. Left unchecked, this LTP may interfere with DG-dependent learning, like pattern separation-which relies on sparse GC firing-and may even facilitate epileptic activity. Intriguingly, MC axons display uniquely high expression levels of type-1 cannabinoid receptors (CB1Rs), but their role at MC-GC synapses is poorly understood. Using rodent hippocampal slices, we report that constitutively active CB1Rs, presumably via βγ subunits, selectively inhibited MC inputs onto GCs but not MC inputs onto inhibitory interneurons or CB1R-sensitive inhibitory inputs onto GCs. Tonic CB1R activity also inhibited LTP and GC output. Furthermore, brief endocannabinoid release from GCs dampened MC-GC LTP in two mechanistically distinct ways: during induction via βγ signaling and before induction via αi/o signaling in a form of presynaptic metaplasticity. Lastly, a single in vivo exposure to exogenous cannabinoids was sufficient to induce this presynaptic metaplasticity. By dampening excitatory transmission and plasticity, tonic and phasic CB1R activity at MC axon terminals may preserve the sparse nature of the DG and protect against runaway excitation.

Putative Activation of the CB1 Cannabinoid Receptors Prevents Anxiety-Like Behavior, Oxidative Stress, and GABA Decrease in the Brain of Zebrafish Submitted to Acute Restraint Stress.

Anxiety disorder is a well-recognized condition observed in subjects submitted to acute stress. Although the brain mechanisms underlying this disorder remain unclear, the available evidence indicates that oxidative stress and GABAergic dysfunction mediate the generation of stress-induced anxiety. Cannabinoids are known to be efficient modulators of behavior, given that the activation of the cannabinoid receptors type-1 (CB1 receptors) induces anxiolytic-like effects in animal models. In the present study, we aimed to describe the effects of the stimulation of the CB1 receptors on anxiety-like behavior, oxidative stress, and the GABA content of the brains of zebrafish submitted to acute restraint stress (ARS). The animals submitted to the ARS protocol presented evident anxiety-like behavior with increased lipid peroxidation in the brain tissue. The evaluation of the levels of GABA in the zebrafish telencephalon presented decreased levels of GABA in the ARS group in comparison with the control. Treatment with ACEA, a specific CB1 receptor agonist, prevented ARS-induced anxiety-like behavior and oxidative stress in the zebrafish brain. ACEA treatment also prevented a decrease in GABA in the telencephalon of the animals submitted to the ARS protocol. Overall, these preclinical data strongly suggest that the CB1 receptors represent a potential target for the development of the treatment of anxiety disorders elicited by acute stress.

L-Theanine regulates glutamine metabolism and immune function by binding to cannabinoid receptor 1.

l-Theanine is a characteristic amino acid in tea with various effects including antioxidant and anti-inflammatory effects. Previously, most studies had reported that l-theanine regulates the immune function in vivo by inhibiting the expression of the inflammatory factors, but how l-theanine regulates the inflammatory factors' pathway is not known. In this study, we innovatively found the binding target of l-theanine in vivo-cannabinoid receptor 1, and demonstrated that l-theanine regulated the immune function and glutamine metabolism by competitively binding cannabinoid receptor 1. Mechanistically, l-theanine competitively binds cannabinoid receptor 1, leading to inhibition of cannabinoid receptor 1 activity, and regulates glutamine metabolism and immune function in normal and E44813-stressed rats. In normal rats, l-theanine inhibits ERK1/2 phosphorylation through Gβy by antagonizing cannabinoid receptor 1, thus affecting GS expression. From the point of view of immune signaling, after LTA antagonizes the activity of cannabinoid receptor 1, it relieves the inhibition of cannabinoid receptor 1 on COX-2 expression, downregulates Pdcd4 expression and NFκB, and ultimately enhances the expression of the anti-inflammatory factor IL-10. In E44813-stressed rats, l-theanine promotes the nuclear translocation of p-ERK1/2 by inhibiting the activity of cannabinoid receptor 1, and finally acts on GS. At the same time, it decreases the expression of the pro-inflammatory factor TNF-α and increases the expression of the anti-inflammatory factor IL-10 in stressed rats through the COX2-Pdcd4-NFκB-IL10 and TNFα pathways. In summary, these results demonstrate that l-theanine regulates glutamine metabolism and immune function by competitively binding to cannabinoid receptor 1.

On the Role of Central Type-1 Cannabinoid Receptor Gene Regulation in Food Intake and Eating Behaviors.

Different neuromodulatory systems are involved in long-term energy balance and body weight and, among these, evidence shows that the endocannabinoid system, in particular the activation of type-1 cannabinoid receptor, plays a key role. We here review current literature focusing on the role of the gene encoding type-1 cannabinoid receptors in the CNS and on the modulation of its expression by food intake and specific eating behaviors. We point out the importance to further investigate how environmental cues might have a role in the development of obesity as well as eating disorders through the transcriptional regulation of this gene in order to prevent or to treat these pathologies.

Kahweol, a natural diterpene from coffee, induces peripheral antinociception by endocannabinoid system activation.

Kahweol is a compound derived from coffee with reported antinociceptive effects. Based on the few reports that exist in the literature regarding the mechanisms involved in kahweol-induced peripheral antinociceptive action, this study proposed to investigate the contribution of the endocannabinoid system to the peripheral antinociception induced in rats by kahweol. Hyperalgesia was induced by intraplantar injection of prostaglandin E2(PGE2) and was measured with the paw pressure test. Kahweol and the drugs to test the cannabinoid system were administered locally into the right hind paw. The endocannabinoids were purified by open-bed chromatography on silica and measured by LC-MS. Kahweol (80 µg/paw) induced peripheral antinociception against PGE2-induced hyperalgesia. This effect was reversed by the intraplantar injection of the CB1 cannabinoid receptor antagonist AM251 (20, 40, and 80 μg/paw), but not by the CB2 cannabinoid receptor antagonist AM630 (100 μg/paw). Treatment with the endocannabinoid reuptake inhibitor VDM11 (2.5 μg/paw) intensified the peripheral antinociceptive effect induced by low-dose kahweol (40 μg/paw). The monoacylglycerol lipase (MAGL) inhibitor, JZL184 (4 μg/paw), and the dual MAGL/fatty acid amide hydrolase (FAAH) inhibitor, MAFP (0.5 μg/paw), potentiated the peripheral antinociceptive effect of low-dose kahweol. Furthermore, kahweol increased the levels of the endocannabinoid anandamide, but not of the other endocannabinoid 2-arachidonoylglycerol nor of anandamide-related N-acylethanolamines, in the plantar surface of the rat paw. Our results suggested that kahweol induced peripheral antinociception via anandamide release and activation of CB1 cannabinoid receptors and this compound could be used to develop new drugs for pain relief.

Cannabinoid Receptor Activation on Haematopoietic Cells and Enterocytes Protects against Colitis.

Cannabinoid receptor [CB] activation can attenuate inflammatory bowel disease [IBD] in experimental models and human cohorts. However, the roles of the microbiome, metabolome, and the respective contributions of haematopoietic and non-haematopoietic cells in the anti-colitic effects of cannabinoids have yet to be determined. Female C57BL/6 mice were treated with either cannabidiol [CBD], Δ 9-tetrahydrocannabinol [THC], a combination of CBD and THC, or vehicle, in several models of chemically induced colitis. Clinical parameters of colitis were assessed by colonoscopy, histology, flow cytometry, and detection of serum biomarkers; single-cell RNA sequencing and qRT-PCR were used to evaluate the effects of cannabinoids on enterocytes. Immune cell transfer from CB2 knockout mice was used to evaluate the contribution of haematopoietic and non-haematopoietic cells to colitis protection. We found that THC prevented colitis and that CBD, at the dose tested, provided little benefit to the amelioration of colitis, nor when added synergistically with THC. THC increased colonic barrier integrity by stimulating mucus and tight junction and antimicrobial peptide production, and these effects were specific to the large intestine. THC increased colonic Gram-negative bacteria, but the anti-colitic effects of THC were independent of the microbiome. THC acted both on immune cells via CB2 and on enterocytes, to attenuate colitis. Our findings demonstrate how cannabinoid receptor activation on both immune cells and colonocytes is critical to prevent colonic inflammation. These studies also suggest how cannabinoid receptor activation can be used as a preventive and therapeutic modality against colitis.

Dissecting the role of CB1 and CB2 receptors in cannabinoid reward versus aversion using transgenic CB1- and CB2-knockout mice

Cannabinoids produce both rewarding and aversive effects in humans and experimental animals. However, the mechanisms underlying these conflicting findings are unclear. Here we examined the potential involvement of CB1 and CB2 receptors in cannabinoid action using transgenic CB1-knockout (CB1-KO) and CB2-knockout (CB2-KO) mice. We found that Δ9-tetrahydrocannabinol (Δ9-THC) induced conditioned place preference at a low dose (1 mg/kg) in WT mice that was attenuated by deletion of the CB1 receptor. At 5 mg/kg, no subjective effects of Δ9-THC were detected in WT mice, but CB1-KO mice exhibited a trend towards place aversion and CB2-KO mice developed significant place preferences. This data suggests that activation of the CB1 receptor is rewarding, while CB2R activation is aversive. We then examined the nucleus accumbens (NAc) dopamine (DA) response to Δ9-THC using in vivo microdialysis. Unexpectedly, Δ9-THC produced a dose-dependent decrease in extracellular DA in WT mice, that was potentiated in CB1-KO mice. However, in CB2-KO mice Δ9-THC produced a dose-dependent increase in extracellular DA, suggesting that activation of the CB2R inhibits DA release in the NAc. In contrast, Δ9-THC, when administered systemically or locally into the NAc, failed to alter extracellular DA in rats. Lastly, we examined the locomotor response to Δ9-THC. Both CB1 and CB2 receptor mechanisms were shown to underlie Δ9-THC-induced hypolocomotion. These findings indicate that Δ9-THC's variable subjective effects reflect differential activation of cannabinoid receptors. Specifically, the opposing actions of CB1 and CB2 receptors regulate cannabis reward and aversion, with CB2-mediated effects predominant in mice.

New Insights Into Peptide Cannabinoids: Structure, Biosynthesis and Signaling

Classically, the endocannabinoid system (ECS) consists of endogenous lipids, of which the best known are anandamide (AEA) and 2 arachidonoylglycerol (2-AG), their enzyme machinery for synthesis and degradation and their specific receptors, cannabinoid receptor one (CB1) and cannabinoid receptor two (CB2). However, endocannabinoids also bind to other groups of receptors. Furthermore, another group of lipids are considered to be endocannabinoids, such as the fatty acid ethanolamides, the fatty acid primary amides and the monoacylglycerol related molecules. Recently, it has been shown that the hemopressin peptide family, derived from α and β chains of hemoglobins, is a new family of cannabinoids. Some studies indicate that hemopressin peptides are expressed in the central nervous system and peripheral tissues and act as ligands of these receptors, thus suggesting that they play a physiological role. In this review, we examine new evidence on lipid endocannabinoids, cannabinoid receptors and the modulation of their signaling pathways. We focus our discussion on the current knowledge of the pharmacological effects, the biosynthesis of the peptide cannabinoids and the new insights on the activation and modulation of cannabinoid receptors by these peptides. The novel peptide compounds derived from hemoglobin chains and their non-classical activation of cannabinoid receptors are only starting to be uncovered. It will be exciting to follow the ensuing discoveries, not only in reference to what is already known of the classical lipid endocannabinoids revealing more complex aspects of endocannabinoid system, but also as to its possibilities as a future therapeutic tool.

Endocannabinoids regulate cerebellar GABAergic transmission in a synapse type‐dependent manner

Endocannabinoids (eCBs) act as ubiquitous modulators of synaptic transmission via the activation of cannabinoid receptors (CBRs). Cerebellar Purkinje cells (PCs) make strong inhibitory synaptic contacts not only with neurons in the deep cerebellar nuclei (DCN) but also with Lugaro cells and globular cells, whose cell bodies are located underneath the PC layer. However, little is known about the modulatory actions of eCBs on GABA release from PC axon terminals. Here, we examined the effects of eCBs on the GABAergic transmission at PC-globular cell synapses and PC-large DCN neuron synapses electrophysiologically using mouse cerebellar slices. We showed that the types 1 and 2 CBR agonist WIN55212 did not affect either spontaneous or miniature inhibitory postsynaptic currents (IPSCs) in globular cells under control conditions and in a state of enhanced synaptic activity. By contrast, another Gi/o protein-coupled receptor agonist, baclofen, significantly reduced the miniature IPSC frequency in globular cells. WIN55212 had no effects on IPSCs in large DCN neurons. A type 2 CBR agonist, HU308, also had no effects on IPSCs in either globular cells or large DCN neurons. Moreover, the PCs' target neurons did not elicit depolarization-induced suppression of inhibition. These results suggest the lack of a functional role of CBRs at PCs' axon terminals. This is in sharp contrast to the fact that PCs receive abundant excitatory and inhibitory inputs that are under eCB-mediated presynaptic inhibitory modulation. The actions of eCBs are selective to distinct synapses and possibly contribute to information processes and rigorous signal transmission in the cerebellum.

Cannabinoid CB1 receptor mediates METH-induced electrophysiological and morphological alterations in cerebellum Purkinje cells.

Our previous studies on cannabinoid type1 receptor (CB1R) activation on Methamphetamine (METH)-induced neurodegeneration and locomotion impairments in male rats suggest an interaction between CB1Rs and METH. However, the role of these receptors in METH-neurotoxicity has not been fully identified. Therefore, the purpose of the present study is to investigate the involvement of CB1Rs in these effects. We conducted an electrophysiological study to evaluate functional interactions between METH and CB1Rs using whole-cell patch current clamp recording. Furthermore, we designed the Nissl staining protocol to assess the effect of METH on the basic cerebellar Purkinje cell structure. Our findings revealed that METH significantly increased the action potential half-width, spontaneous interspike intervals, first spike latency, and decreased the rebound action potential and spontaneous firing frequency. Using CB1R agonist and antagonist, our results showed a significant interaction with some of the electrophysiological alterations induced by METH. Further, Nissl staining revealed that the exposure to the combination of METH and SR141716A resulted in the necrotic cell death. Results of the current study raises the possibility that METH consumption profoundly affect the intrinsic membrane properties of cerebellar Purkinje neurons and cannabinoid system manipulations may counteract some of these effects. In summary, our findings provide further insights into the modulatory role of the endocannabinoid system in METH-induced neurologic changes, which can be used in the development of potential therapeutic interventions for METH dependence.

Biased agonism at the cannabinoid receptors – Evidence from synthetic cannabinoid receptor agonists

The type 1 and type 2 cannabinoid receptors are G protein-coupled receptors implicated in a variety of physiological processes and diseases. Synthetic cannabinoid receptor agonists (SCRAs) were originally developed to explore the therapeutic benefits of cannabinoid receptor activation, although more recently, these compounds have been diverted to the recreational drug market and are increasingly associated with incidences of toxicity. A prominent concept in contemporary pharmacology is functional selectivity or biased agonism, which describes the ability of ligands to elicit differential activation of signalling pathways through stabilisation of distinct receptor conformations. Biased agonists may maximise drug effectiveness by reducing on-target adverse effects if they are mediated by signalling pathways distinct from those that drive the therapeutic effects. For the cannabinoid receptors, it remains unclear as to which signalling pathways mediate desirable and adverse effects. However, given their structural diversity and potential to induce a plethora of signalling effects, SCRAs provide the most promising prospect for detecting and studying bias at the cannabinoid receptors. This review summarises the emerging evidence of SCRA bias at the cannabinoid receptors.

Cannabinoid-2 Agonism with AM2301 Mitigates Morphine-Induced Respiratory Depression.

Introduction: An escalating number of fatalities resulting from accidental opioid overdoses typically attributed to respiratory depression continue to define the opioid epidemic. Opioid respiratory depression results from a decrease in reflexive inspiration within the preBötzinger complex in the brainstem. Objective: Cannabinoid receptor agonism is reported to enhance opioid analgesia, yet whether cannabinoids enhance or inhibit opioid-induced respiratory depression is unknown. Methods: Studies herein sought to define the roles of cannabinoid-1 receptor (CB1R) and cannabinoid-2 receptor (CB2R) on respiratory depression using selective agonists alone and in combination with morphine in male mice. Results: Using whole body plethysmography, the nonselective CB1R and CB2R agonist (Δ9-tetrahydrocannabinol) and the CB1R synthetic cannabinoid, AM356, induced respiratory depression, whereas the well-published selective CB2 agonist, JWH 133, and the novel CB2 agonist (AM2301) did not. Moreover, a selective CB2R agonist (AM2301) significantly attenuated morphine sulfate-induced respiratory depression. Conclusion: Notably, findings suggest that attenuation of opioid-induced respiratory depression relies on CB2R activation, supporting selective CB2R agonism as an opioid adjunct therapy.

The Interplay between Cancer Biology and the Endocannabinoid System-Significance for Cancer Risk, Prognosis and Response to Treatment.

Simple SummaryThis review analyses the complex involvement of the various components of the endocannabinoid system (ECS) in the susceptibility to cancer, prognosis, and response to treatment, focusing on its relationship with cancer biology in selected solid cancers (breast, gastrointestinal, gynaecological, prostate cancer, thoracic, thyroid, central nervous system (CNS) tumours, and melanoma). The same ECS component can exert both protective and pathogenic effects in different tumour subtypes, which are often pathologically driven by different biological factors. Although an attractive target in cancer, the use of components in anti-cancer treatment is still interlinked with many legal and ethical issues that need to be considered. The legislation which outlines the permissive boundaries of their therapeutic use in oncology is still unable to follow the current scientific burden of evidence, but the number of ongoing clinical trials might tip the scale forward in the near future.The various components of the endocannabinoid system (ECS), such as the cannabinoid receptors (CBRs), cannabinoid ligands, and the signalling network behind it, are implicated in several tumour-related states, both as favourable and unfavourable factors. This review analyses the ECS’s complex involvement in the susceptibility to cancer, prognosis, and response to treatment, focusing on its relationship with cancer biology in selected solid cancers (breast, gastrointestinal, gynaecological, prostate cancer, thoracic, thyroid, CNS tumours, and melanoma). Changes in the expression and activation of CBRs, as well as their ability to form distinct functional heteromers affect the cell’s tumourigenic potential and their signalling properties, leading to pharmacologically different outcomes. Thus, the same ECS component can exert both protective and pathogenic effects in different tumour subtypes, which are often pathologically driven by different biological factors. The use of endogenous and exogenous cannabinoids as anti-cancer agents, and the range of effects they might induce (cell death, regulation of angiogenesis, and invasion or anticancer immunity), depend in great deal on the tumour type and the specific ECS component that they target. Although an attractive target, the use of ECS components in anti-cancer treatment is still interlinked with many legal and ethical issues that need to be considered.

URB597 Prevents the Short-Term Excitotoxic Cell Damage in Rat Cortical Slices: Role of Cannabinoid 1 Receptors.

Endocannabinoid-based therapies constitute an emerging tool for the potential treatment of neurodegenerative disorders, requiring characterization at the experimental level. The effects of URB597, an inhibitor of the fatty acid amide hydrolase (FAAH), were tested against the quinolinic acid (QUIN)-induced early toxic effects in rat cortical slices, and compared with those effects exerted by the endocannabinoid anandamide (AEA). URB597 prevented the QUIN-induced loss of mitochondrial function/cell viability and lipid peroxidation, while reduced necrosis, and to a lesser extent, apoptosis. The protective effects of URB597 were mediated by activation of cannabinoid receptor 1 (CB1r), as evidenced by their inhibition by the selective CB1r antagonist AM281. Similar effects were observed when testing AEA against QUIN toxicity. Our findings demonstrate the neuroprotective properties of URB597 during the early stages of excitotoxic damage to cortical tissue, suggesting that these properties are mediated by FAAH inhibition, and might be linked to the protective effects of AEA, or the combination of endocannabinoids.

The sequel to COVID-19: the antithesis to life

The sequel to COVID-19: the antithesis to life

Cannabidiol and Oxygen-Ozone Combination Induce Cytotoxicity in Human Pancreatic Ductal Adenocarcinoma Cell Lines

Simple SummaryPancreatic cancer (PC) is related to lifestyle risks, chronic inflammation, and germline mutations. Surgical resection and adjuvant chemotherapy are the main therapeutic strategies but are less effective in patients with high-grade tumors. Oxygen-ozone (O2/O3) therapy is an emerging alternative tool for the treatment of several clinical disorders. The advantages of using cannabinoids have been evaluated in several human cancers. Regarding PC, activation of cannabinoid receptors was found to induce PC cell apoptosis without affecting the normal pancreas cells. Herein, we evaluate the anticancer effect of cannabidiol (CBD) and O2/O3, alone or in combination, on two human pancreatic ductal adenocarcinoma (PDAC) cell lines, PANC-1 and MiaPaCa-2, examining expression profiles of 92 pancreatic adenocarcinoma associated genes, cytotoxicity, migration properties, and cell death. Finally, we assess the combination effects with gemcitabine and paclitaxel. Summarizing, for the first time the antitumoral effect of combined therapy with CBD and oxygen-ozone therapy in PDAC is evidenced.Pancreatic cancer (PC) is related to lifestyle risks, chronic inflammation, and germline mutations in BRCA1/2, ATM, MLH1, TP53, or CDKN2A. Surgical resection and adjuvant chemotherapy are the main therapeutic strategies but are less effective in patients with high-grade tumors. Oxygen-ozone (O2/O3) therapy is an emerging alternative tool for the treatment of several clinical disorders. O2/O3 therapy has been found to ameliorate mechanisms promoting chronic pain and inflammation, including hypoxia, inflammatory mediators, and infection. The advantages of using cannabinoids have been evaluated in vitro and in vivo models of several human cancers. Regarding PDAC, activation of cannabinoid receptors was found to induce pancreatic cancer cell apoptosis without affecting the normal pancreas cells. In a murine model of PDAC, a combination of cannabidiol (CBD) and gemcitabine increased survival length by nearly three times. Herein, we evaluate the anticancer effect of CBD and O2/O3, alone or in combination, on two human PDAC cell lines, PANC-1 and MiaPaCa-2, examining expression profiles of 92 pancreatic adenocarcinoma associated genes, cytotoxicity, migration properties, and cell death. Finally, we assess the combination effects with gemcitabine and paclitaxel. Summarizing, for the first time the antitumoral effect of combined therapy with CBD and oxygen-ozone therapy in PDAC is evidenced.

A cannabinoid type 2 (CB2) receptor agonist augments NOS-dependent responses of cerebral arterioles during type 1 diabetes

While activation of cannabinoid (CB2) receptors has been shown to be neuroprotective, no studies have examined whether this neuroprotection is directed at cerebral arterioles and no studies have examined whether activation of CB2 receptors can rescue cerebrovascular dysfunction during a chronic disease state such as type 1 diabetes (T1D). Our goal was to test the hypothesis that administration of a CB2 agonist (JWH-133) would improve impaired endothelial (eNOS)- and neuronal (nNOS)-dependent dilation of cerebral arterioles during T1D. In vivo diameter of cerebral arterioles in nondiabetic and T1D rats was measured in response to an eNOS-dependent agonist (adenosine 5′-diphosphate; ADP), an nNOS-dependent agonist (N-methyl-d-aspartate; NMDA), and an NOS-independent agonist (nitroglycerin) before and 1 h following JWH-133 (1 mg/kg IP). Dilation of cerebral arterioles to ADP and NMDA was greater in nondiabetic than in T1D rats. Treatment with JWH-133 increased responses of cerebral arterioles to ADP and NMDA in both nondiabetic and T1D rats. Responses of cerebral arterioles to nitroglycerin were similar between nondiabetic and T1D rats, and JWH-133 did not influence responses to nitroglycerin in either group. The restoration in responses to the agonists by JWH-133 could be inhibited by treatment with a specific inhibitor of CB2 receptors (AM-630; 3 mg/kg IP). Thus, activation of CB2 receptors can potentiate reactivity of cerebral arterioles during physiologic and pathophysiologic states. We speculate that treatment with CB2 receptor agonists may have potential therapeutic benefits for the treatment of cerebral vascular diseases via a mechanism that can increase cerebral blood flow.

The cannabinoid CB2 receptor agonist LY2828360 synergizes with morphine to suppress neuropathic nociception and attenuates morphine reward and physical dependence

The opioid crisis has underscored the urgent need to identify safe and effective therapeutic strategies to overcome opioid-induced liabilities. We recently reported that LY2828360, a slowly signaling G protein-biased cannabinoid CB2 receptor agonist, suppresses neuropathic nociception and attenuates the development of tolerance to the opioid analgesic morphine in paclitaxel-treated mice. Whether beneficial effects of LY2828360 are dependent upon the presence of a pathological pain state are unknown and its impact on unwanted opioid-induced side-effects have never been investigated. Here, we asked whether LY2828360 would produce synergistic anti-allodynic effects with morphine in a paclitaxel model of chemotherapy-induced neuropathic pain and characterized its impact on opioid-induced reward and other unwanted side-effects associated with chronic opioid administration. Isobolographic analysis revealed that combinations of LY2828360 and morphine produced synergistic anti-allodynic effects in suppressing paclitaxel-induced mechanical allodynia. In wildtype (WT) mice, LY2828360 blocked morphine-induced reward in a conditioned place preference assay without producing reward or aversion when administered alone. The LY2828360-induced attenuation of morphine-induced reward was absent in CB2 knockout (CB2KO) mice. In the absence of a neuropathic pain state, LY2828360 partially attenuated naloxone-precipitated opioid withdrawal in morphine-dependent WT mice, and this withdrawal was itself markedly exacerbated in CB2KO mice. Moreover, LY2828360 did not reliably alter morphine-induced slowing of colonic transit or attenuate tolerance to morphine antinociceptive efficacy in the hot plate test of acute nociception. Our results suggest that cannabinoid CB2 receptor activation enhances the therapeutic properties of opioids while attenuating unwanted side-effects such as reward and dependence that occur with sustained opioid treatment.

Δ9-Tetrahydrocannabinol Prevents Mortality from Acute Respiratory Distress Syndrome through the Induction of Apoptosis in Immune Cells, Leading to Cytokine Storm Suppression

Acute Respiratory Distress Syndrome (ARDS) causes up to 40% mortality in humans and is difficult to treat. ARDS is also one of the major triggers of mortality associated with coronavirus-induced disease (COVID-19). We used a mouse model of ARDS induced by Staphylococcal enterotoxin B (SEB), which triggers 100% mortality, to investigate the mechanisms through which Δ9-tetrahydrocannabinol (THC) attenuates ARDS. SEB was used to trigger ARDS in C3H mice. These mice were treated with THC and analyzed for survival, ARDS, cytokine storm, and metabolome. Additionally, cells isolated from the lungs were used to perform single-cell RNA sequencing and transcriptome analysis. A database analysis of human COVID-19 patients was also performed to compare the signaling pathways with SEB-mediated ARDS. The treatment of SEB-mediated ARDS mice with THC led to a 100% survival, decreased lung inflammation, and the suppression of cytokine storm. This was associated with immune cell apoptosis involving the mitochondrial pathway, as suggested by single-cell RNA sequencing. A transcriptomic analysis of immune cells from the lungs revealed an increase in mitochondrial respiratory chain enzymes following THC treatment. In addition, metabolomic analysis revealed elevated serum concentrations of amino acids, lysine, n-acetyl methionine, carnitine, and propionyl L-carnitine in THC-treated mice. THC caused the downregulation of miR-185, which correlated with an increase in the pro-apoptotic gene targets. Interestingly, the gene expression datasets from the bronchoalveolar lavage fluid (BALF) of human COVID-19 patients showed some similarities between cytokine and apoptotic genes with SEB-induced ARDS. Collectively, this study suggests that the activation of cannabinoid receptors may serve as a therapeutic modality to treat ARDS associated with COVID-19.

Activation of Cannabinoid Receptor 2 Prevents Colitis-Associated Colon Cancer through Myeloid Cell De-activation Upstream of IL-22 Production.

SummaryIntestinal disequilibrium leads to inflammatory bowel disease (IBD), and chronic inflammation predisposes to oncogenesis. Antigen-presenting dendritic cells (DCs) and macrophages can tip the equilibrium toward tolerance or pathology. Here we show that delta-9-tetrahydrocannabinol (THC) attenuates colitis-associated colon cancer and colitis induced by anti-CD40. Working through cannabinoid receptor 2 (CB2), THC increases CD103 expression on DCs and macrophages and upregulates TGF-β1 to increase T regulatory cells (Tregs). THC-induced Tregs are necessary to remedy systemic IFNγ and TNFα caused by anti-CD40, but CB2-mediated suppression of APCs by THC quenches pathogenic release of IL-22 and IL-17A in the colon. By examining tissues from multiple sites, we confirmed that THC affects DCs, especially in mucosal barrier sites in the colon and lungs, to reduce DC CD86. Using models of colitis and systemic inflammation we show that THC, through CB2, is a potent suppressor of aberrant immune responses by provoking coordination between APCs and Tregs.