The Endocannabinoid System and Oligodendrocytes in Health and Disease.

 Image result for frontiers in neuroscience“Cannabinoid-based interventions are being explored for central nervous system (CNS) pathologies such as neurodegeneration, demyelination, epilepsy, stroke, and trauma. As these disease states involve dysregulation of myelin integrity and/or remyelination, it is important to consider effects of the endocannabinoid system on oligodendrocytes and their precursors. In this review, we examine research reports on the effects of the endocannabinoid system (ECS) components on oligodendrocytes and their precursors, with a focus on therapeutic implications. Cannabinoid ligands and modulators of the endocannabinoid system promote cell signaling in oligodendrocyte precursor survival, proliferation, migration and differentiation, and mature oligodendrocyte survival and myelination. Agonist stimulation of oligodendrocyte precursor cells (OPCs) at both CB1 and CB2 receptors counter apoptotic processes via Akt/PI3K, and promote proliferation via Akt/mTOR and ERK pathways. CB1 receptors in radial glia promote proliferation and conversion to progenitors fated to become oligodendroglia, whereas CB2 receptors promote OPC migration in neonatal development. OPCs produce 2-arachidonoylglycerol (2-AG), stimulating cannabinoid receptor-mediated ERK pathways responsible for differentiation to arborized, myelin basic protein (MBP)-producing oligodendrocytes. In cell culture models of excitotoxicity, increased reactive oxygen species, and depolarization-dependent calcium influx, CB1 agonists improved viability of oligodendrocytes. In transient and permanent middle cerebral artery occlusion models of anoxic stroke, WIN55212-2 increased OPC proliferation and maturation to oligodendroglia, thereby reducing cerebral tissue damage. In several models of rodent encephalomyelitis, chronic treatment with cannabinoid agonists ameliorated the damage by promoting OPC survival and oligodendrocyte function. Pharmacotherapeutic strategies based upon ECS and oligodendrocyte production and survival should be considered.”

https://www.ncbi.nlm.nih.gov/pubmed/30416422

https://www.frontiersin.org/articles/10.3389/fnins.2018.00733/full

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Cannabigerol Action at Cannabinoid CB1 and CB2 Receptors and at CB1-CB2 Heteroreceptor Complexes.

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“Cannabigerol (CBG) is one of the major phytocannabinoids present in Cannabis sativa L. that is attracting pharmacological interest because it is non-psychotropic and is abundant in some industrial hemp varieties.

The aim of this work was to investigate in parallel the binding properties of CBG to cannabinoid CB1 (CB1R) and CB2 (CB2R) receptors and the effects of the compound on agonist activation of those receptors and of CB1-CB2 heteroreceptor complexes.

The results indicate that CBG is indeed effective as regulator of endocannabinoid signaling.”

https://www.ncbi.nlm.nih.gov/pubmed/29977202

https://www.frontiersin.org/articles/10.3389/fphar.2018.00632/full

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Bortezomib And Endocannabinoid/Endovanilloid System: A Synergism In Osteosarcoma.

Pharmacological Research

“Osteosarcoma is the most common primary malignant tumor of bone in children and adolescents.

Bortezomib (BTZ) is an approved anticancer drug, classified as a selective reversible inhibitor of the ubiquitin-dependent proteasome system, that leads to cancer cell cycle arrest and apoptosis reducing the invasion ability of Osteosarcoma cells in vitro. It also regulates the RANK/RANKL/OPG system, involved in the pathogenesis of bone tumors and in cell migration.

A side effect of BTZ is to induce painful sensory peripheral neuropathy which lead to cessation of therapy or dose reduction.

Recently BTZ has been evaluated in combination with Cannabinoids targeting CB1 receptor, demonstrating a promising synergic effect.

The Endocannabinoid/Endovanilloid (EC/EV) system includes two G protein-coupled receptors (CB1 and CB2), the Transient Potential Vanilloid 1 (TRPV1) channel and their endogenous ligands and enzymes.

CB1 and CB2 are expressed mainly in Central Nervous System and Immune Peripheral cells respectively. TRPV1 is also expressed in primary sensory neurons and is involved in pain modulation.

EC/EV system induces apoptosis, reduces invasion and cell proliferation in Osteosarcoma cell lines and is involved in bone metabolism.

We analyzed the effects of BTZ, alone and in combination with selective agonists at CB2 (JWH-133) and TRPV1 (RTX) receptors, in the Osteosarcoma cell line (HOS) on Apoptosis, Cell Cycle progression, migration and bone balance. We observed that the stimulation of CB2 and TRPV1 receptors increase the efficacy of BTZ in inducing apoptosis and reducing invasion, cell cycle progression and by modulating bone balance.

These data suggest the possibility to use BTZ, in combination with EC/EV agonists, in Osteosarcoma therapy reducing its dose and its side effects.”

https://www.ncbi.nlm.nih.gov/pubmed/30267762

https://www.sciencedirect.com/science/article/abs/pii/S1043661818310387

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Cannabidiol enhances morphine antinociception, diminishes NMDA-mediated seizures and reduces stroke damage via the sigma 1 receptor.

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“Cannabidiol (CBD), the major non-psychotomimetic compound present in the Cannabis sativa plant, exhibits therapeutic potential for various human diseases, including chronic neurodegenerative diseases, such as Alzheimer’s and Parkinson’s, ischemic stroke, epilepsy and other convulsive syndromes, neuropsychiatric disorders, neuropathic allodynia and certain types of cancer.

CBD does not bind directly to endocannabinoid receptors 1 and 2, and despite research efforts, its specific targets remain to be fully identified. Notably, sigma 1 receptor (σ1R) antagonists inhibit glutamate N-methyl-D-aspartate acid receptor (NMDAR) activity and display positive effects on most of the aforesaid diseases. Thus, we investigated the effects of CBD on three animal models in which NMDAR overactivity plays a critical role: opioid analgesia attenuation, NMDA-induced convulsive syndrome and ischemic stroke.

In an in vitro assay, CBD disrupted the regulatory association of σ1R with the NR1 subunit of NMDAR, an effect shared by σ1R antagonists, such as BD1063 and progesterone, and prevented by σ1R agonists, such as 4-IBP, PPCC and PRE084. The in vivo administration of CBD or BD1063 enhanced morphine-evoked supraspinal antinociception, alleviated NMDA-induced convulsive syndrome, and reduced the infarct size caused by permanent unilateral middle cerebral artery occlusion.

These positive effects of CBD were reduced by the σ1R agonists PRE084 and PPCC, and absent in σ1R-/- mice. Thus, CBD displays antagonist-like activity toward σ1R to reduce the negative effects of NMDAR overactivity in the abovementioned experimental situations.”

https://www.ncbi.nlm.nih.gov/pubmed/30223868

https://molecularbrain.biomedcentral.com/articles/10.1186/s13041-018-0395-2

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Exploring the Ligand Efficacy of Cannabinoid Receptor 1 (CB1) using Molecular Dynamics Simulations.

Scientific Reports

“Cannabinoid receptor 1 (CB1) is a promising therapeutic target for a variety of disorders. Distinct efficacy profiles showed different therapeutic effects on CB1 dependent on three classes of ligands: agonists, antagonists, and inverse agonists. To discriminate the distinct efficacy profiles of the ligands, we carried out molecular dynamics (MD) simulations to identify the dynamic behaviors of inactive and active conformations of CB1 structures with the ligands. In addition, the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method was applied to analyze the binding free energy decompositions of the CB1-ligand complexes. With these two methods, we found the possibility that the three classes of ligands can be discriminated. Our findings shed light on the understanding of different efficacy profiles of ligands by analyzing the structural behaviors of intact CB1 structures and the binding energies of ligands, thereby yielding insights that are useful for the design of new potent CB1 drugs.”

https://www.ncbi.nlm.nih.gov/pubmed/30213978

https://www.nature.com/articles/s41598-018-31749-z

“Chemical structure of the partial agonist THC, antagonist THCV, and inverse agonist Taranabant.”

Figure 1

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Role of the endocannabinoid system in drug addiction.

Biochemical Pharmacology

“Drug addiction is a chronic relapsing disorder that produces a dramaticglobal health burden worldwide. Not effective treatment of drug addiction is currently available probably due to the difficulties to find an appropriate target to manage this complex disease raising the needs for further identification of novel therapeutic approaches.

The endocannabinoid system has been found to play a crucial role in the neurobiological substrate underlying drug addiction.

Endocannabinoids and cannabinoid receptors are widely expressed in the main areas of the mesocorticolimbic system that participate in the initiation and maintenance of drug consumption and in the development of compulsion and loss of behavioral control occurring during drug addiction.

The identification of the important role played by CB1 cannabinoid receptors in drug addiction encouraged the possible used of an early commercialized CB1 receptor antagonist for treating drug addiction.

However, the incidence of serious psychiatric adverse events leaded to the sudden withdrawal from the market of this CB1 antagonist and all the research programs developed by pharmaceutical companies to obtain new CB1 antagonists were stopped.

Currently, new research strategies are under development to target the endocannabinoid system for drug addiction avoiding these side effects, which include allosteric negative modulators of CB1 receptors and compounds targeting CB2 receptors.

Recent studies showing the potential role of CB2 receptors in the addictive properties of different drugs of abuse have open a promising research opportunity to develop novel possible therapeutic approaches.”

https://www.ncbi.nlm.nih.gov/pubmed/30217570

https://www.sciencedirect.com/science/article/abs/pii/S0006295218303952

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Cannabinoid 1 Receptor Signaling on Hippocampal GABAergic Neurons Influences Microglial Activity.

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“Microglia, the resident immune cells of the brain, play important roles in defending the brain against pathogens and supporting neuronal circuit plasticity. Chronic or excessive pro-inflammatory responses of microglia damage neurons, therefore their activity is tightly regulated.

Pharmacological and genetic studies revealed that cannabinoid type 1 (CB1) receptor activity influences microglial activity, although microglial CB1 receptor expression is very low and activity-dependent. The CB1 receptor is mainly expressed on neurons in the central nervous system (CNS)-with an especially high level on GABAergic interneurons.

Here, we determined whether CB1 signaling on this neuronal cell type plays a role in regulating microglial activity.

Our result suggests that CB1 receptor agonists can modulate microglial activity indirectly, through CB1 receptors on GABAergic neurons.

Altogether, we demonstrated that GABAergic neurons, despite their relatively low density in the hippocampus, have a specific role in the regulation of microglial activity and cannabinoid signaling plays an important role in this arrangement.”

https://www.ncbi.nlm.nih.gov/pubmed/30210289

https://www.frontiersin.org/articles/10.3389/fnmol.2018.00295/full

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Cannabis sativa: A comprehensive ethnopharmacological review of a medicinal plant with a long history.

Journal of Ethnopharmacology

“Cannabis sativa L. (C. sativa) is an annual dioecious plant, which shares its origins with the inception of the first agricultural human societies in Asia. Over the course of time different parts of the plant have been utilized for therapeutic and recreational purposes, for instance, extraction of healing oils from seed, or the use of inflorescences for their psychoactive effects. The key psychoactive constituent in C. sativa is called Δ-9-tetrahydrocannabinol (D9-THC). The endocannabinoid system seems to be phylogenetically ancient, as it was present in the most primitive vertebrates with a neuronal network. N-arachidonoylethanolamine (AEA) and 2-arachidonoyl glycerol (2-AG) are the main endocannabinoids ligands present in the animal kingdom, and the main endocannabinoid receptors are cannabinoid type-1 (CB1) receptor and cannabinoid type-2 (CB2) receptor.

AIM OF THE STUDY:

The review aims to provide a critical and comprehensive evaluation, from the ancient times to our days, of the ethnological, botanical, chemical and pharmacological aspects of C. sativa, with a vision for promoting further pharmaceutical research to explore its complete potential as a therapeutic agent.

RESULTS AND CONCLUSIONS:

A detailed comparative analysis of the available resources for C. sativa confirmed its origin and traditional spiritual, household and therapeutic uses and most importantly its popularity as a recreational drug. The result of several studies suggested a deeper involvement of phytocannabinoids (the key compounds in C. sativa) in several others central and peripheral pathophysiological mechanisms such as food intake, inflammation, pain, colitis, sleep disorders, neurological and psychiatric illness. However, despite their numerous medicinal benefits, they are still considered as a menace to the society and banned throughout the world, except for few countries. We believe that this review will help lay the foundation for promoting exhaustive pharmacological and pharmaceutical studies in order to better understand the clinical relevance and applications of non-psychoactive cannabinoids in the prevention and treatment of life-threatening diseases and help to improve the legal status of C. sativa.”

https://www.ncbi.nlm.nih.gov/pubmed/30205181

https://www.sciencedirect.com/science/article/pii/S0378874118316611?via%3Dihub

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Cellular localization and regulation of receptors and enzymes of the endocannabinoid system in intestinal and systemic inflammation.

“Surveys suggest that Cannabis provides benefit for people with inflammatory bowel disease.

However, mechanisms underlying beneficial effects are not clear. We performed in situ hybridization RNAscope® combined with immunohistochemistry to show cell-specific distribution and regulation of cannabinoid receptor 1 and 2 (CB1, CB2), G protein-coupled receptor 55 (GPR55), and monoacylglycerol lipase (MGL) mRNA in immune cells using murine models of intestinal and systemic inflammation.

In summary, our study reveals changes in gene expression of members of the endocannabinoid system in situ attesting particularly GPR55 and MGL a distinct cellular role in the regulation of the immune response to intestinal and systemic inflammation.”

https://www.ncbi.nlm.nih.gov/pubmed/30196316

https://link.springer.com/article/10.1007%2Fs00418-018-1719-0

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The Endocannabinoid/Cannabinoid Receptor 2 System Protects Against Cisplatin-Induced Hearing Loss.

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“Previous studies have demonstrated the presence of cannabinoid 2 receptor (CB2R) in the rat cochlea which was induced by cisplatin. In an organ of Corti-derived cell culture model, it was also shown that an agonist of the CB2R protected these cells against cisplatin-induced apoptosis.

In the current study, we determined the distribution of CB2R in the mouse and rat cochleae and examined whether these receptors provide protection against cisplatin-induced hearing loss.

These data unmask a protective role of the cochlear endocannabinoid/CB2R system which appears tonically active under normal conditions to preserve normal hearing. However, an exogenous agonist is needed to boost the activity of endocannabinoid/CB2R system for protection against a more traumatic cochlear insult, as observed with cisplatin administration.”

https://www.ncbi.nlm.nih.gov/pubmed/30186120

https://www.frontiersin.org/articles/10.3389/fncel.2018.00271/full

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