Cannabinoids and Cannabinoid Receptors: The Story So Far

 iScience journal (@iScience_CP) | Twitter“Like most modern molecular biology and natural product chemistry, understanding cannabinoid pharmacology centers around molecular interactions, in this case, between the cannabinoids and their putative targets, the G-protein coupled receptors (GPCRs) cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2). Understanding the complex structure and interplay between the partners in this molecular dance is required to understand the mechanism of action of synthetic, endogenous, and phytochemical cannabinoids. This review, with 91 references, surveys our understanding of the structural biology of the cannabinoids and their target receptors including both a critical comparison of the extant crystal structures and the computationally derived homology models, as well as an in-depth discussion about the binding modes of the major cannabinoids. The aim is to assist in situating structural biochemists, synthetic chemists, and molecular biologists who are new to the field of cannabis research.”

https://pubmed.ncbi.nlm.nih.gov/32629422/

https://www.cell.com/iscience/pdf/S2589-0042(20)30488-0.pdf?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2589004220304880%3Fshowall%3Dtrue

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Pharmacological Data of Cannabidiol- And Cannabigerol-Type Phytocannabinoids Acting on Cannabinoid CB 1, CB 2 and CB 1/CB 2 Heteromer Receptors

Pharmacological Research“Background: Recent approved medicines whose active principles are Δ9Tetrahidrocannabinol (Δ9-THC) and/or cannabidiol (CBD) open novel perspectives for other phytocannabinoids also present in Cannabis sativa L. varieties. Furthermore, solid data on the potential benefits of acidic and varinic phytocannabinoids in a variety of diseases are already available. Mode of action of cannabigerol (CBG), cannabidiolic acid (CBDA), cannabigerolic acid (CBGA), cannabidivarin (CBDV) and cannabigerivarin (CBGV) is, to the very least, partial.

Hypothesis/purpose: Cannabinoid CB1 or CB2 receptors, which belong to the G-protein-coupled receptor (GPCR) family, are important mediators of the action of those cannabinoids. Pure CBG, CBDA, CBGA, CBDV and CBGV from Cannabis sativa L. are differentially acting on CB1 or CB2 cannabinoid receptors.

Study design: Determination of the affinity of phytocannabinoids for cannabinoid receptors and functional assessment of effects promoted by these compounds when interacting with cannabinoid receptors.

Methods: A heterologous system expressing the human versions of CB1 and/or CB2 receptors was used. Binding to membranes was measured using radioligands and binding to living cells using a homogenous time resolved fluorescence resonance energy transfer (HTRF) assay. Four different functional outputs were assayed: determination of cAMP levels and of extracellular-signal-related-kinase phosphorylation, label-free dynamic mass redistribution (DMR) and ß-arrestin recruitment.

Results: Affinity of cannabinoids depend on the ligand of reference and may be different in membranes and in living cells. All tested phytocannabinoids have agonist-like behavior but behaved as inverse-agonists in the presence of selective receptor agonists. CBGV displayed enhanced potency in many of the functional outputs. However the most interesting result was a biased signaling that correlated with differential affinity, i.e. the overall results suggest that the binding mode of each ligand leads to specific receptor conformations underlying biased signaling outputs.

Conclusion: Results here reported and the recent elucidation of the three-dimensional structure of CB1 and CB2 receptors help understanding the mechanism of action that might be protective and the molecular drug-receptor interactions underlying biased signaling.”

https://pubmed.ncbi.nlm.nih.gov/32470563/

https://www.sciencedirect.com/science/article/abs/pii/S1043661820312482?via%3Dihub

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Can Hemp Help? Low-THC Cannabis and Non-THC Cannabinoids for the Treatment of Cancer.

cancers-logo“Cannabis has been used to relieve the symptoms of disease for thousands of years. However, social and political biases have limited effective interrogation of the potential benefits of cannabis and polarised public opinion.

Evidence is emerging for the therapeutic benefits of cannabis in the treatment of neurological and neurodegenerative diseases, with potential efficacy as an analgesic and antiemetic for the management of cancer-related pain and treatment-related nausea and vomiting, respectively.

An increasing number of preclinical studies have established that ∆9-THC can inhibit the growth and proliferation of cancerous cells through the modulation of cannabinoid receptors (CB1R and CB2R), but clinical confirmation remains lacking.

In parallel, the anti-cancer properties of non-THC cannabinoids, such as cannabidiol (CBD), are linked to the modulation of non-CB1R/CB2R G-protein-coupled receptors, neurotransmitter receptors, and ligand-regulated transcription factors, which together modulate oncogenic signalling and redox homeostasis.

Additional evidence has also demonstrated the anti-inflammatory properties of cannabinoids, and this may prove relevant in the context of peritumoural oedema and the tumour immune microenvironment. This review aims to document the emerging mechanisms of anti-cancer actions of non-THC cannabinoids.”

https://www.ncbi.nlm.nih.gov/pubmed/32340151

https://www.mdpi.com/2072-6694/12/4/1033

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Terpenoids, Cannabimimetic Ligands, beyond the Cannabis Plant.

molecules-logo “Medicinal use of Cannabis sativa L. has an extensive history and it was essential in the discovery of phytocannabinoids, including the Cannabis major psychoactive compound-Δ9-tetrahydrocannabinol (Δ9-THC)-as well as the G-protein-coupled cannabinoid receptors (CBR), named cannabinoid receptor type-1 (CB1R) and cannabinoid receptor type-2 (CB2R), both part of the now known endocannabinoid system (ECS).

Cannabinoids is a vast term that defines several compounds that have been characterized in three categories: (i) endogenous, (ii) synthetic, and (iii) phytocannabinoids, and are able to modulate the CBR and ECS. Particularly, phytocannabinoids are natural terpenoids or phenolic compounds derived from Cannabis sativa.

However, these terpenoids and phenolic compounds can also be derived from other plants (non-cannabinoids) and still induce cannabinoid-like properties. Cannabimimetic ligands, beyond the Cannabis plant, can act as CBR agonists or antagonists, or ECS enzyme inhibitors, besides being able of playing a role in immune-mediated inflammatory and infectious diseases, neuroinflammatory, neurological, and neurodegenerative diseases, as well as in cancer, and autoimmunity by itself.

In this review, we summarize and critically highlight past, present, and future progress on the understanding of the role of cannabinoid-like molecules, mainly terpenes, as prospective therapeutics for different pathological conditions.”

https://www.ncbi.nlm.nih.gov/pubmed/32235333

https://www.mdpi.com/1420-3049/25/7/1567

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The role of the cannabinoid system in opioid analgesia and tolerance.

“Opioid receptor agonist drugs, such as morphine, are very effective for treating chronic and severe pain; but, tolerance can develop with long-term use. Although there is a lot of information about the pathophysiological mechanisms of opioid tolerance, it is still not fully clarified. Suggested mechanisms for opioid tolerance include opioid receptor desensitisation, reduction of sensitivity G-proteins, activation of mitogen-activated protein kinase (MAPK), altered intracellular signaling pathway including nitric oxide, and activation of mammalian target of rapamycin (mTOR).

One way to reduce opioid tolerance and increase the analgesic potential is to use low doses. Combination of cannabinoids with opioids has been shown to manifest reduce the opioid dose. Experimental studies revealed an interaction of the endocannabinoid system and opioid antinociception.

Cannabinoid and opioid receptor systems use common pathways in the formation of analgesic effect and demonstrate their activity via G protein coupled receptors (GPCR). Cannabinoid drugs modulate opioid analgesic activity at a number of distinct levels within the cell, ranging from direct receptor associations, to post-receptor interactions through shared signal transduction pathways.

This review summarizes the data indicating that with combining cannabinoids and opioids drugs may be able to produce long-term analgesic effects, while preventing the opioid analgesic tolerance.”

https://www.ncbi.nlm.nih.gov/pubmed/32167427

http://www.eurekaselect.com/180186/article

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Role of cannabis in inflammatory bowel diseases.

Image result for Ann Gastroenterol“For many centuries, cannabis (marijuana) has been used for both recreational and medicinal purposes. Currently, there are about 192 million cannabis users worldwide, constituting approximately 3.9% of the global population. Cannabis comprises more than 70 aromatic hydrocarbon compounds known as cannabinoids. Endogenous circulating cannabinoids, or endocannabinoids, such as anandamide and 2-arachidonoyl-glycerol, their metabolizing enzymes (fatty acid amide hydrolase and monoacylglycerol lipase) and 2 G-protein coupled cannabinoid receptors, CB1 and CB2, together represent the endocannabinoid system and are present throughout the human body. In the gastrointestinal (GI) tract, the activated endocannabinoid system reduces gut motility, intestinal secretion and epithelial permeability, and induces inflammatory leukocyte recruitment and immune modulation through the cannabinoid receptors present in the enteric nervous and immune systems. Because of the effects of cannabinoids on the GI tract, attempts have been made to investigate their medicinal properties, particularly for GI disorders such as pancreatitis, hepatitis, and inflammatory bowel diseases (IBD). The effects of cannabis on IBD have been elucidated in several small observational and placebo-controlled studies, but with varied results. The small sample size and short follow-up duration in these studies make it difficult to show the clear benefits of cannabis in IBD. However, cannabis is now being considered as a potential drug for inflammatory GI conditions, particularly IBD, because of its spreading legalization in the United States and other countries and the growing trend in its use. More high-quality controlled studies are warranted to elucidate the mechanism and benefits of cannabis use as a possible option in IBD management.”

https://www.ncbi.nlm.nih.gov/pubmed/32127734

http://www.annalsgastro.gr/files/journals/1/earlyview/2020/ev-02-2020-03-AG4866-0452.pdf

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Localization of cannabinoid and cannabinoid related receptors in the cat gastrointestinal tract.

Image result for Histochem Cell Biol journal “A growing body of literature indicates that activation of cannabinoid receptors may exert beneficial effects on gastrointestinal inflammation and visceral hypersensitivity.

The present study aimed to immunohistochemically investigate the distribution of the canonical cannabinoid receptors CB1 (CB1R) and CB2 (CB2R) and the putative cannabinoid receptors G protein-coupled receptor 55 (GPR55), nuclear peroxisome proliferator-activated receptor alpha (PPARα), transient receptor potential ankyrin 1 (TRPA1), and serotonin receptor 5-HT1a 5-HT1aR) in tissue samples of the gastrointestinal tract of the cat.

CB1R-immunoreactivity (CB1R-IR) was observed in gastric epithelial cells, intestinal enteroendocrine cells (EECs) and goblet cells, lamina propria mast cells (MCs), and enteric neurons. CB2R-IR was expressed by EECs, enterocytes, and macrophages. GPR55-IR was expressed by EECs, macrophages, immunocytes, and MP neurons. PPARα-IR was expressed by immunocytes, smooth muscle cells, and enteroglial cells. TRPA1-IR was expressed by enteric neurons and intestinal goblet cells. 5-HT1a receptor-IR was expressed by gastrointestinal epithelial cells and gastric smooth muscle cells.

Cannabinoid receptors showed a wide distribution in the feline gastrointestinal tract layers. Although not yet confirmed/supported by functional evidences, the present research might represent an anatomical substrate potentially useful to support, in feline species, the therapeutic use of cannabinoids during gastrointestinal inflammatory diseases.”

https://www.ncbi.nlm.nih.gov/pubmed/32095931

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The proposed mechanisms of action of CBD in epilepsy.

Image result for epileptic disorders journal“Highly purified cannabidiol (CBD) (approved as Epidiolex® in the United States and as EPIDYOLEX from the EU agency) has demonstrated efficacy with an acceptable safety profile in patients with Lennox-Gastaut or Dravet syndrome in four randomized controlled trials. While the mechanism of action of CBD underlying the reduction of seizures in humans is unknown, CBD possesses affinity for multiple targets, across a range of target classes, resulting in functional modulation of neuronal excitability, relevant to the pathophysiology of many disease types, including epilepsy. Here we present the pharmacological data supporting the role of three such targets, namely Transient receptor potential vanilloid-1 (TRPV1), the orphan G protein-coupled receptor-55 (GPR55) and the equilibrative nucleoside transporter 1 (ENT-1).”

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Targeting GPCRs Against Cardiotoxicity Induced by Anticancer Treatments.

Image result for frontiers in cardiovascular medicine“Novel anticancer medicines, including targeted therapies and immune checkpoint inhibitors, have greatly improved the management of cancers. However, both conventional and new anticancer treatments induce cardiac adverse effects, which remain a critical issue in clinic.

Cardiotoxicity induced by anti-cancer treatments compromise vasospastic and thromboembolic ischemia, dysrhythmia, hypertension, myocarditis, and cardiac dysfunction that can result in heart failure. Importantly, none of the strategies to prevent cardiotoxicity from anticancer therapies is completely safe and satisfactory.

Certain clinically used cardioprotective drugs can even contribute to cancer induction. Since G protein coupled receptors (GPCRs) are target of forty percent of clinically used drugs, here we discuss the newly identified cardioprotective agents that bind GPCRs of adrenalin, adenosine, melatonin, ghrelin, galanin, apelin, prokineticin and cannabidiol.

We hope to provoke further drug development studies considering these GPCRs as potential targets to be translated to treatment of human heart failure induced by anticancer drugs.”

https://www.ncbi.nlm.nih.gov/pubmed/32039239

https://www.frontiersin.org/articles/10.3389/fcvm.2019.00194/full

“Cannabidiol Protects against Doxorubicin-Induced Cardiomyopathy by Modulating Mitochondrial Function and Biogenesis.”  https://www.ncbi.nlm.nih.gov/pubmed/25569804

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Cannabinoid Signaling in Glioma Cells.

 “Cannabinoids are a group of structurally heterogeneous but pharmacologically related compounds, including plant-derived cannabinoids, synthetic substances and endogenous cannabinoids, such as anandamide and 2-arachidonoylglycerol.

Cannabinoids elicit a wide range of central and peripheral effects mostly mediated through cannabinoid receptors. There are two types of specific Gi/o-protein-coupled receptors cloned so far, called CB1 and CB2, although an existence of additional cannabinoid-binding receptors has been suggested. CB1 and CB2 differ in their predicted amino acid sequence, tissue distribution, physiological role and signaling mechanisms.

Significant alterations of a balance in the cannabinoid system between the levels of endogenous ligands and their receptors occur during malignant transformation in various types of cancer, including gliomas.

Cannabinoids exert anti-proliferative action in tumor cells.

Induction of cell death by cannabinoid treatment relies on the generation of a pro-apoptotic sphingolipid ceramide and disruption of signaling pathways crucial for regulation of cellular proliferation, differentiation or apoptosis. Increased ceramide levels lead also to ER-stress and autophagy in drug-treated glioblastoma cells.

Beyond blocking of tumor cells proliferation cannabinoids inhibit invasiveness, angiogenesis and the stem cell-like properties of glioma cells, showing profound activity in the complex tumor microenvironment. Advances in translational research on cannabinoid signaling led to clinical investigations on the use of cannabinoids in treatments of glioblastomas.”

https://www.ncbi.nlm.nih.gov/pubmed/32034716

https://link.springer.com/chapter/10.1007%2F978-3-030-30651-9_11

“Cannabinoids exert anti-proliferative action in tumor cells.” https://www.ncbi.nlm.nih.gov/pubmed/22879071

“A glioma is a primary brain tumor that originates from the supportive cells of the brain, called glial cells.” http://neurosurgery.ucla.edu/body.cfm?id=159

“Remarkably, cannabinoids kill glioma cells selectively and can protect non-transformed glial cells from death.” http://www.ncbi.nlm.nih.gov/pubmed/15275820

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