Category Archives: Endocannabinoid System

Goods and bads of endocannabinoid system as a therapeutic target: Lessons learned after 30 years

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Pharmacological Reviews: 75 (3)

“The cannabis derivative marijuana is the most widely used recreational drug in the Western world, that is consumed by an estimated 83 million individuals (~3% of the world population). In recent years, there has been a marked transformation in society regarding the risk perception of cannabis, driven by its legalization and medical use in many states in the USA and worldwide.

Compelling research evidence and the FDA cannabis-derived cannabidiol approval for severe childhood epilepsy have confirmed the large therapeutic potential of cannabidiol itself, Δ9-tetrahydrocannabinol (THC) and other plant-derived cannabinoids (phytocannabinoids). Of note, our body has a complex endocannabinoid system (ECS) – made of receptors, metabolic enzymes and transporters – that is also regulated by phytocannabinoids.

The first endocannabinoid to be discovered 30 years ago was anandamide (N-arachidonoyl-ethanolamine); since then, distinct elements of ECS have been the target of drug design programs aimed at curing (or at least slowing down) a number of human diseases, both in the central nervous system and at the periphery. Here, a critical review of our knowledge of the goods and bads of ECS as a therapeutic target are presented, in order to define the benefits of ECS-active phytocannabinoids and ECS-oriented synthetic drugs for human health.

Significance Statement The endocannabinoid system plays important roles everywhere in our body and is either involved in mediating key processes of central and peripheral diseases or represents a therapeutic target for treatment. Understanding structure, function, and pharmacology of the components of this complex system, and in particular of key receptors (like CB1R and CB2R) and metabolic enzymes (like FAAH and MAGL), will advance our understanding of endocannabinoid signaling and activity at molecular, cellular, and system levels providing new opportunities to treat patients.”

https://pubmed.ncbi.nlm.nih.gov/37164640/

https://pharmrev.aspetjournals.org/content/early/2023/05/09/pharmrev.122.000600

Impact of Cannabinoid Receptors in the Design of Therapeutic Agents against Human Ailments

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“The cannabinoid (CB) signalling cascade is widely located in the human body and is as-sociated with several pathophysiological processes. The endocannabinoid system comprises canna-binoid receptors CB1 and CB2, which belong to G-protein coupled receptors (GPCRs). CB1 recep-tors are primarily located on nerve terminals, prohibiting neurotransmitter release, whereas CB2 are present predominantly on immune cells, causing cytokine release. The activation of CB system con-tributes to the development of several diseases which might have lethal consequences, such as CNS disorders, cancer, obesity, and psychotic disorders on human health. Clinical evidence revealed that CB1 receptors are associated with CNS ailments such as Alzheimer’s disease, Huntington’s disease, and multiple sclerosis, whereas CB2 receptors are primarily connected with immune disorders, pain, inflammation, etc. Therefore, cannabinoid receptors have been proved to be promising targets in therapeutics and drug discovery. Experimental and clinical outcomes have disclosed the success sto-ry of CB antagonists, and several research groups have framed newer compounds with the binding potential to these receptors. In the presented review, we have summarized variously reported heter-ocycles with CB receptor agonistic/antagonistic properties against CNS disorders, cancer, obesity, and other complications. The structural activity relationship aspects have been keenly described along with enzymatic assay data. The specific outcomes of molecular docking studies have also been highlighted to get insights into the binding patterns of the molecules to CB receptors.”

https://pubmed.ncbi.nlm.nih.gov/37132103/

https://www.eurekaselect.com/article/131385

Phytocannabinoids as Potential Multitargeting Neuroprotectants in Alzheimer’s Disease

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“The Endocannabinoid System (ECS) is a well-studied system that influences a variety of physiological activities. It is evident that the ECS plays a significant role in metabolic activities and also has some neuroprotective properties.

In this review, we emphasize several plant-derived cannabinoids such as β-caryophyllene (BCP), Cannabichromene (CBC), Cannabigerol (CBG), Cannabidiol (CBD), and Cannabinol (CBN), which are known to have distinctive modulation abilities of ECS. In Alzheimer’s disease (AD), the activation of ECS may provide neuroprotection by modulating certain neuronal circuitry pathways through complex molecular cascades.

The present article also discusses the implications of cannabinoid receptors (CB1 and CB2) as well as cannabinoid enzymes (FAAH and MAGL) modulators in AD. Specifically, CBR1 or CB2R modulations result in reduced inflammatory cytokines such as IL-2 and IL-6, as well as a reduction in microglial activation, which contribute to an inflammatory response in neurons. Furthermore, naturally occurring cannabinoid metabolic enzymes (FAAH and MAGL) inhibit the NLRP3 inflammasome complex, which may offer significant neuroprotection.

In this review, we explored the multi-targeted neuroprotective properties of phytocannabinoids and their possible modulations, which could offer significant benefits in limiting AD.”

https://pubmed.ncbi.nlm.nih.gov/37132109/

https://www.eurekaselect.com/article/131371

Components of the Endocannabinoid System and Effects of Cannabinoids Against Bone Diseases: A Mini-Review

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Frontiers in Pharmacology welcomes new Field Chief Editor - Science & research news | Frontiers

“Background: The endocannabinoid system (ECS) is involved in multiple physiological processes, including appetite regulation, pain perception, motor function development, and immune response regulation. Cannabinoids have been approved for the clinical treatment of nausea and vomiting caused by cytostatic therapy or cancer chemotherapy, loss of appetite in HIV/AIDS-associated cachexia, refractory spasms induced by multiple sclerosis, chronic pain, and urinary incontinence. 

Methods: Check out the research on ECS and bone diseases in the past 20 years. 

Results: Many studies have demonstrated that endocannabinoids (eCBs) and cannabinoid receptors (CBRs) are expressed in bone and synovial tissues, playing important roles in bone metabolism. Preclinical studies using cannabis-based therapies in animal models have shown that cannabinoids (CBs) can alleviate the development of osteoarthritis (OA), prevent osteoporosis (OP), reduce cancer-induced osteolytic destruction, and improve fracture healing, highlighting the therapeutic potential of CBs for human bone diseases. 

Conclusions: The present review summarizes various components of the ECS in bone diseases and their potential as a therapeutic target.”

https://pubmed.ncbi.nlm.nih.gov/35126132/

https://www.frontiersin.org/articles/10.3389/fphar.2021.793750/full

Cannabinoid modulation of corticolimbic activation during extinction learning and fear renewal in adults with posttraumatic stress disorder

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Neurobiology of Learning and Memory

“Failure to successfully extinguish fear is a hallmark of trauma-related disorders, like posttraumatic stress disorder (PTSD). PTSD is also characterized by dysfunctional corticolimbic activation and connectivity.

The endocannabinoid system is a putative system to target for rescuing these behavioral and neural deficits. In healthy adults, acute, low-dose delta-9-tetrahydrocannabinol (THC) facilitates fear extinction and increases cortico-limbic activation and connectivity in response to threat.

The present study determines the effect of acute, low-dose THC on fear-related brain activation and connectivity during fear extinction in trauma-exposed adults with (PTSD = 19) and without PTSD [trauma-exposed controls (TEC) = 26] and non-trauma-exposed [healthy controls (HC) = 26]. We used a Pavlovian fear conditioning and extinction paradigm, where we measured concurrent functional magnetic resonance imaging (fMRI) and behavioral responses (i.e., skin conductance responding and expectancy ratings). Using a randomized, double-blind, placebo-controlled design, N = 71 subjects were randomized to receive placebo (PBO, n = 37) or THC (n = 34) prior to fear extinction learning.

During early extinction learning, individuals with PTSD given THC had greater vmPFC activation than their TEC counterparts. During a test of the return of fear (i.e., renewal), HC and individuals with PTSD given THC had greater vmPFC activation compared to TEC. Individuals with PTSD given THC also had greater amygdala activation compared to those given PBO. We found no effects of trauma group or THC on behavioral fear indices during extinction learning, recall, and fear renewal.

These data suggest that low dose, oral THC can affect neural indices of fear learning and memory in adults with trauma-exposure; this may be beneficial for future therapeutic interventions seeking to improve fear extinction learning and memory.”

https://pubmed.ncbi.nlm.nih.gov/37088409/

https://www.sciencedirect.com/science/article/abs/pii/S1074742723000394?via%3Dihub

SELECTED CANNABIS TERPENES SYNERGIZE WITH THC TO PRODUCE INCREASED CB1 RECEPTOR ACTIVATION

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Biochemical Pharmacology

“The cannabis plant exerts its pharmaceutical activity primarily by the binding of cannabinoids to two G protein-coupled cannabinoid receptors, CB1 and CB2. The role that cannabis terpenes play in this activation has been considered and debated repeatedly, based on only limited experimental results. In the current study we used a controlled in-vitro heterologous expression system to quantify the activation of CB1 receptors by sixteen cannabis terpenes individually, by tetrahydrocannabinol (THC) alone and by THC-terpenes mixtures. The results demonstrate that all terpenes, when tested individually, activate CB1 receptors, at about 10-50% of the activation by THC alone. The combination of some of these terpenes with THC significantly increases the activity of the CB1 receptor, compared to THC alone. In some cases, several fold. Importantly, this amplification is evident at terpene to THC ratios similar to those in the cannabis plant, which reflect very low terpene concentrations. For some terpenes, the activation obtained by THC- terpene mixtures is notably greater than the sum of the activations by the individual components, suggesting a synergistic effect. Our results strongly support a modulatory effect of some of the terpenes on the interaction between THC and the CB1 receptor. As the most effective terpenes are not necessarily the most abundant ones in the cannabis plant, reaching “whole plant” or “full spectrum” composition is not necessarily an advantage. For enhanced therapeutic effects, desired compositions are attainable by enriching extracts with selected terpenes. These compositions adjust the treatment for various desired medicinal and personal needs.”

https://pubmed.ncbi.nlm.nih.gov/37084981/

https://www.sciencedirect.com/science/article/pii/S0006295223001399?via%3Dihub

Activation of CB1R alleviates central sensitization by regulating HCN2-pNR2B signaling in a chronic migraine rat model

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The Journal of Headache and Pain

“Background: Central sensitization has been widely accepted as an underlying pathophysiological mechanism of chronic migraine (CM), activation of cannabinoid type-1 receptor (CB1R) exerts antinociceptive effects by relieving central sensitization in many pain models. However, the role of CB1R in the central sensitization of CM is still unclear.

Methods: A CM model was established by infusing inflammatory soup (IS) into the dura of male Wistar rats for 7 days, and hyperalgesia was assessed by the mechanical and thermal thresholds. In the periaqueductal gray (PAG), the mRNA and protein levels of CB1R and hyperpolarization-activated cyclic nucleotide-gated cation channel 2 (HCN2) were measured by qRT-PCR and western blotting. After intraventricular injection of Noladin ether (NE) (a CB1R agonist), ZD 7288 (an HCN2 blocker), and AM 251 (a CB1R antagonist), the expression of tyrosine phosphorylation of N-methyl-D-aspartate receptor subtype 2B (pNR2B), calcium-calmodulin-dependent kinase II (CaMKII), and phosphorylated cAMP-responsive element binding protein (pCREB) was detected, and central sensitization was evaluated by the expression of calcitonin gene-related peptide (CGRP), c-Fos, and substance P (SP). Synaptic-associated protein (postsynaptic density protein 95 (PSD95) and synaptophysin (Syp)) and synaptic ultrastructure were detected to explore synaptic plasticity in central sensitization.

Results: We observed that the mRNA and protein levels of CB1R and HCN2 were both significantly increased in the PAG of CM rats. The application of NE or ZD 7288 ameliorated IS-induced hyperalgesia; repressed the pNR2B/CaMKII/pCREB pathway; reduced CGRP, c-Fos, SP, PSD95, and Syp expression; and inhibited synaptic transmission. Strikingly, the application of ZD 7288 relieved AM 251-evoked elevation of pNR2B, CGRP, and c-Fos expression.

Conclusions: These data reveal that activation of CB1R alleviates central sensitization by regulating HCN2-pNR2B signaling in CM rats. The activation of CB1R might have a positive influence on the prevention of CM by mitigating central sensitization.”

https://pubmed.ncbi.nlm.nih.gov/37085778/

https://thejournalofheadacheandpain.biomedcentral.com/articles/10.1186/s10194-023-01580-7

Endocannabinoid System: Chemical Characteristics and Biological Activity

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“The endocannabinoid system (eCB) has been studied to identify the molecular structures present in Cannabis sativa. eCB consists of cannabinoid receptors, endogenous ligands, and the associated enzymatic apparatus responsible for maintaining energy homeostasis and cognitive processes.

Several physiological effects of cannabinoids are exerted through interactions with various receptors, such as CB1 and CB2 receptors, vanilloid receptors, and the recently discovered G-protein-coupled receptors (GPR55, GPR3, GPR6, GPR12, and GPR19). Anandamide (AEA) and 2-arachidoylglycerol (2-AG), two small lipids derived from arachidonic acid, showed high-affinity binding to both CB1 and CB2 receptors.

eCB plays a critical role in chronic pain and mood disorders and has been extensively studied because of its wide therapeutic potential and because it is a promising target for the development of new drugs. Phytocannabinoids and synthetic cannabinoids have shown varied affinities for eCB and are relevant to the treatment of several neurological diseases.

This review provides a description of eCB components and discusses how phytocannabinoids and other exogenous compounds may regulate the eCB balance. Furthermore, we show the hypo- or hyperfunctionality of eCB in the body and how eCB is related to chronic pain and mood disorders, even with integrative and complementary health practices (ICHP) harmonizing the eCB.”

https://pubmed.ncbi.nlm.nih.gov/37017445/

“The roles of cannabinoid receptors and their agonists in multiple conditions have been addressed in this review. Since research with derivatives of Cannabis has started and the biological functions of isolated compounds in experimental and human diseases have shown promising outcomes, it is evident that selective ligands of specific Cannabis receptors could induce beneficial outcomes, depending on the clinical condition. More research on the biological function of each Cannabis derivative should be encouraged.”

https://www.mdpi.com/1424-8247/16/2/148

Cannabidiol reduces LPS-induced nociception via endocannabinoid system activation

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“Bacterial infections are often accompanied by fever and generalized muscle pain. However, the treatment of pain with an infectious etiology has been overlooked. Thus, we investigated the impact of cannabidiol (CBD) in bacterial lipopolysaccharide (LPS)-induced nociception.

Male Swiss mice received intrathecal (i.t.) LPS injection, and the nociceptive threshold was measured by the von Frey filaments test. Spinal involvement of the cannabinoid CB2 receptor, toll-like receptor 4 (TLR4), microglia and astrocytes were evaluated by i.t. administration of their respectively antagonists or inhibitors. Western blot, immunofluorescence, ELISA and liquid chromatography-mass spectrometry were used to assess Cannabinoid CB2 receptors and TLR4 spinal expression, proinflammatory cytokines and endocannabinoid levels. CBD was administered intraperitoneally at 10 mg/kg.

The pharmacological assay demonstrated TLR4 participation in LPS-induced nociception. In addition, spinal TLR4 expression and proinflammatory cytokine levels were increased in this process.

CBD treatment prevented LPS-induced nociception and TLR4 expression.

AM630 reversed antinociception and reduced CBD-induced endocannabinoids upregulation. Increased spinal expression of the cannabinoid CB2 receptor was also found in animals receiving LPS, which was accompanied by reduced TLR4 expression in CBD-treated mice.

Taken together, our findings indicated that CBD is a potential treatment strategy to control LPS-induced pain by attenuating TLR4 activation via the endocannabinoid system.”

https://pubmed.ncbi.nlm.nih.gov/37076976/

https://onlinelibrary.wiley.com/doi/10.1111/bcpt.13876

The Effects of Endogenous Cannabinoids on the Mammalian Respiratory System: A Scoping Review of Cyclooxygenase-Dependent Pathways

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“Introduction: The endogenous cannabinoid (endocannabinoid) system is an emerging target for the treatment of chronic inflammatory disease with the potential to advance treatment for many respiratory illnesses. The varied effects of endocannabinoids across tissue types makes it imperative that we explore their physiologic impact within unique tissue targets. The aim of this scoping review is to explore the impact of endocannabinoid activity on eicosanoid production as a measure of human airway inflammation. 

Methods: A scoping literature review was conducted according to PRISMA-ScR (Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews) guidelines. Search strategies using MeSH terms related to cannabinoids, eicosanoids, cyclooxygenase (COX), and the respiratory system were used to query Medline, Embase, Cochrane, CINAHL, Web of Science, and Biosis Previews in December 2021. Only studies that investigated the relationship between endocannabinoids and the eicosanoid system in mammalian respiratory tissue after 1992 were included. 

Results: Sixteen studies were incorporated in the final qualitative review. Endocannabinoid activation increases COX-2 expression, potentially through ceramide-dependent or p38 and p42/44 Mitogen-Activated Protein Kinase pathways and is associated with a concentration-dependent increase in prostaglandin (PG)E2. Inhibitors of endocannabinoid hydrolysis found either an increase or no change in levels of PGE2 and PGD2 and decreased levels of leukotriene (LT)B4, PGI2, and thromboxane A2 (TXA2). Endocannabinoids increase bronchial epithelial cell permeability and have vasorelaxant effects in human pulmonary arteries and cause contraction of bronchi and decreased gas trapping in guinea pigs. Inhibitors of endocannabinoid hydrolysis were found to have anti-inflammatory effects on pulmonary tissue and are primarily mediated by COX-2 and activation of eicosanoid receptors. Direct agonism of endocannabinoid receptors appears to play a minor role. 

Conclusion: The endocannabinoid system has diverse effects on the mammalian airway. While endocannabinoid-derived PGs can have anti-inflammatory effects, endocannabinoids also produce proinflammatory conditions, such as increased epithelial permeability and bronchial contraction. These conflicting findings suggest that endocannabinoids produce a variety of effects depending on their local metabolism and receptor agonism. Elucidation of the complex interplay between the endocannabinoid and eicosanoid pathways is key to leveraging the endocannabinoid system as a potential therapeutic target for human airway disease.”

https://pubmed.ncbi.nlm.nih.gov/37074668/

https://www.liebertpub.com/doi/10.1089/can.2022.0277