Tag Archives: cannabinoid receptors

A peripherally restricted cannabinoid 1 receptor agonist as a novel analgesic in cancer-induced bone pain.

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“Many malignant cancers, including breast cancer, have a propensity to invade bones, leading to excruciating bone pain.

Opioids are the primary analgesics used to alleviate this cancer-induced bone pain (CIBP) but are associated with numerous severe side effects, including enhanced bone degradation, which significantly impairs patients’ quality of life.

In contrast, agonists activating only peripheral CB1 receptors (CB1Rs) have been shown to effectively alleviate multiple chronic pain conditions with limited side effects, yet no studies have evaluated their role(s) in CIBP.

Here, we demonstrate for the first time that a peripherally selective CB1R agonist can effectively suppress CIBP.

Overall, our studies demonstrate that CIBP can be effectively managed by using a peripherally restricted CB1R agonist, PrNMI, without inducing dose-limiting central side effects.

Thus, targeting peripheral CB1Rs could be an alternative therapeutic strategy for the treatment of CIBP.”

 https://www.ncbi.nlm.nih.gov/pubmed/29781960
https://insights.ovid.com/crossref?an=00006396-900000000-98957

Is Cannabidiol a Promising Substance for New Drug Development? A Review of its Potential Therapeutic Applications.

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Critical Reviews™ in Eukaryotic Gene Expression

“The pharmacological importance of cannabidiol (CBD) has been in study for several years.

CBD is the major nonpsychoactive constituent of plant Cannabis sativa and its administration is associated with reduced side effects.

Currently, CBD is undergoing a lot of research which suggests that it has no addictive effects, good safety profile and has exhibited powerful therapeutic potential in several vital areas.

It has wide spectrum of action because it acts through endocannabinoid receptors; CB1 and CB2 and it also acts on other receptors, such as GPR18, GPR55, GPR 119, 5HT1A, and TRPV2.

This indicates its therapeutic value for numerous medical conditions because of its neuroprotective and immunomodulatory properties.

Potential therapeutic applications of CBD include, analgesic, anti-inflammatory, anxiolytic, anti-arthritic, anti-depressant, anti-Alzheimer disease, anti-ischemic, neuroprotective, and anti-fibrotic.

More promising areas appear to include diabetes and cancer where CBD exhibits lesser side effects and more therapeutic benefits as compared to recent available medical therapies.

Hence, CBD is a promising substance for the development of new drug. However further research and clinical studies are required to explore its complete potential.”

 https://www.ncbi.nlm.nih.gov/pubmed/29773016
http://www.dl.begellhouse.com/journals/6dbf508d3b17c437,642ad759707fc517,35856ff546e47ff9.html

Larger Gray Matter Volume in the Basal Ganglia of Heavy Cannabis Users Detected by Voxel-Based Morphometry and Subcortical Volumetric Analysis.

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“Structural imaging studies of cannabis users have found evidence of both cortical and subcortical volume reductions, especially in cannabinoid receptor-rich regions such as the hippocampus and amygdala. However, the findings have not been consistent. In the present study, we examined a sample of adult heavy cannabis users without other substance abuse to determine whether long-term use is associated with brain structural changes, especially in the subcortical regions.

Method: We compared the gray matter volume of 14 long-term, heavy cannabis users with non-using controls. To provide robust findings, we conducted two separate studies using two different MRI techniques. Each study used the same sample of cannabis users and a different control group, respectively. Both control groups were independent of each other. First, whole-brain voxel-based morphometry (VBM) was used to compare the cannabis users against 28 matched controls (HC1 group). Second, a volumetric analysis of subcortical regions was performed to assess differences between the cannabis users and a sample of 100 matched controls (HC2 group) obtained from a local database of healthy volunteers.

Results: The VBM study revealed that, compared to the control group HC1, the cannabis users did not show cortical differences nor smaller volume in any subcortical structure but showed a cluster (p < 0.001) of larger GM volume in the basal ganglia, involving the caudate, putamen, pallidum, and nucleus accumbens, bilaterally. The subcortical volumetric analysis revealed that, compared to the control group HC2, the cannabis users showed significantly larger volumes in the putamen (p= 0.001) and pallidum (p = 0.0015). Subtle trends, only significant at the uncorrected level, were also found in the caudate (p = 0.05) and nucleus accumbens (p = 0.047).

Conclusions: This study does not support previous findings of hippocampal and/or amygdala structural changes in long-term, heavy cannabis users. It does, however, provide evidence of basal ganglia volume increases.”

 https://www.ncbi.nlm.nih.gov/pubmed/29773998
https://www.frontiersin.org/articles/10.3389/fpsyt.2018.00175/full

Endogenous systems involved in exercise-induced analgesia.

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“Exercise-induced analgesia is a phenomenon discussed worldwide. This effect began to be investigated in the early 1970s in healthy individuals and rodents during and after an acute or chronic session of running or swimming. Thereafter, studies found this effect was also induced by resistance exercises. Over the years, many studies have demonstrated the importance of exercise-induced analgesia in relieving pain caused by different conditions, such as fibromyalgia, low back pain, neuropathy, and osteoarthritis. This review aims to provide the reader with an in-depth description of the main endogenous systems, substances, neurotransmitters, receptors and enzymes that are thought to be involved in the analgesic effect induced by exercise. Many hypotheses have been proposed to elucidate the mechanisms responsible for exercise-induced analgesia. One of the most accepted hypotheses has been the activation of several endogenous systems described as analgesics. Studies have demonstrated that during and after exercise different endogenous systems are activated, which release substances or neurotransmitters, such as opioids, nitric oxide, serotonin, catecholamines and endocannabinoids, that may modulate the pain perception.”  https://www.ncbi.nlm.nih.gov/pubmed/29769416

http://www.jpp.krakow.pl/journal/archive/02_18/pdf/jpp.2018.1.01.pdf

“Exercise activates the endocannabinoid system.”  https://www.ncbi.nlm.nih.gov/pubmed/14625449

The endocannabinoid-alcohol crosstalk: recent advances on a bi-faceted target.

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“Increasing evidence focuses on the endocannabinoid system as a relevant player in the induction of aberrant synaptic plasticity and related addictive phenotype following chronic excessive alcohol drinking.

Besides, the endocannabinoid system is implicated in the pathogenesis of alcoholic liver disease.

Interestingly, whereas the involvement of CB1 cannabinoid receptors in alcohol rewarding properties is established, the central and peripheral action of CB2 cannabinoid signalling is still to be elucidated.

This review aims at giving the input to deepen knowledge on the role of the endocannabinoid system, highlighting the advancing evidence that suggests that CB1 and CB2 receptors may play opposite roles in the regulation of both the reinforcing properties of alcohol in the brain and the mechanisms responsible for cell injury and inflammation in the hepatic tissue.

The manipulation of the endocannabinoid system could represent a bi-faceted strategy to counteract alcohol-related dysfunction in central transmission and liver structural and functional disarrangement.”

https://www.ncbi.nlm.nih.gov/pubmed/29770478

https://onlinelibrary.wiley.com/doi/abs/10.1111/1440-1681.12967

Cannabinoid signalling in embryonic and adult neurogenesis: possible implications for psychiatric and neurological disorders.

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“Cannabinoid signalling modulates several aspects of brain function, including the generation and survival of neurons during embryonic and adult periods.

The present review intended to summarise evidence supporting a role for the endocannabinoid system on the control of neurogenesis and neurogenesis-dependent functions.

An understanding of the mechanisms by which cannabinoid signalling influences developmental and adult neurogenesis will help foster the development of new therapeutic strategies for neurodevelopmental, psychiatric and neurological disorders.”

https://www.ncbi.nlm.nih.gov/pubmed/29764526

https://www.cambridge.org/core/journals/acta-neuropsychiatrica/article/cannabinoid-signalling-in-embryonic-and-adult-neurogenesis-possible-implications-for-psychiatric-and-neurological-disorders/E9DE9116DC604D976C9C7B0D2D254674

Effects of CB2 and TRPV1 receptors’ stimulation in pediatric acute T-lymphoblastic leukemia

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“T-Acute Lymphoblastic Leukemia (T-ALL) is less frequent than B-ALL, but it has poorer outcome. For this reason new therapeutic approaches are needed to treat this malignancy.

The Endocannabinoid/Endovanilloid (EC/EV) system has been proposed as possible target to treat several malignancies, including lymphoblastic diseases. The EC/EV system is composed of two G-Protein Coupled Receptors (CB1 and CB2), the Transient Potential Vanilloid 1 (TRPV1) channel, their endogenous and exogenous ligands and enzymes. CB1 is expressed mainly in central nervous system while CB2 predominantly on immune and peripheral cells, therefore we chose to selectively stimulate CB2 and TRPV1.

We treated T-ALL lymphoblasts derived from 4 patients and Jurkat cells with a selective agonist at CB2 receptor: JWH-133 [100 nM] and an agonist at TRPV1 calcium channel: RTX [5 uM] at 6, 12 and 24 hours. We analyzed the effect on apoptosis and Cell Cycle Progression by a cytofluorimetric assays and evaluated the expression level of several target genes (Caspase 3, Bax, Bcl-2, AKT, ERK, PTEN, Notch-1, CDK2, p53) involved in cell survival and apoptosis, by Real-Time PCR and Western Blotting.

We observed a pro-apoptotic, anti-proliferative effect of these compounds in both primary lymphoblasts obtained from patients with T-ALL and in Jurkat cell line. Our results show that both CB2 stimulation and TRPV1 activation, can increase the apoptosis in vitro, interfere with cell cycle progression and reduce cell proliferation, indicating that a new therapeutic approach to T-cell ALL might be possible by modulating CB2 and TRPV1 receptors.”

http://www.oncotarget.com/index.php?journal=oncotarget&page=article&op=view&path%5B%5D=25052

Δ9-Tetrahydrocannabinol induces endocannabinoid accumulation in mouse hepatocytes: antagonism by Fabp1 gene ablation.

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The Journal of Lipid Research “Phytocannabinoids, such as Δ9–tetrahydrocannabinol (THC), bind and activate cannabinoid (CB) receptors, thereby “piggy-backing” on the same pathway’s endogenous endocannabinoids (ECs).

The recent discovery that liver fatty acid binding protein-1 (FABP1) is the major cytosolic “chaperone” protein with high affinity for both Δ9-THC and ECs suggests that Δ9-THC may alter hepatic EC levels.

Therefore, the impact of Δ9-THC or EC treatment on the levels of endogenous ECs, such as N-arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG), was examined in cultured primary mouse hepatocytes from WT and Fabp1 gene-ablated (LKO) mice. Δ9-THC alone or 2-AG alone significantly increased AEA and especially 2-AG levels in WT hepatocytes. LKO alone markedly increased AEA and 2-AG levels. However, LKO blocked/diminished the ability of Δ9-THC to further increase both AEA and 2-AG. In contrast, LKO potentiated the ability of exogenous 2-AG to increase the hepatocyte level of AEA and 2-AG.

These and other data suggest that Δ9-THC increases hepatocyte EC levels, at least in part, by upregulating endogenous AEA and 2-AG levels.

This may arise from Δ9-THC competing with AEA and 2-AG binding to FABP1, thereby decreasing targeting of bound AEA and 2-AG to the degradative enzymes, fatty acid amide hydrolase and monoacylglyceride lipase, to decrease hydrolysis within hepatocytes.”

https://www.ncbi.nlm.nih.gov/pubmed/29414765

http://www.jlr.org/content/59/4/646

Cannabinoid 1 receptors are expressed in nociceptive primary sensory neurons.

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 Neuroscience

“Expression of cannabinoid 1 (CB1) and vanilloid 1 (VR1) receptor proteins was studied in adult, cultured rat dorsal root ganglion neurons. Immunostaining of CB1 receptors alone produced labelling in 57+/-2% of the cultured dorsal root ganglion neurons (n=3 cultures). The area of the labelled cells was between 200 and 800 microm(2) with an average of 527+/-68 microm(2). VR1 immunolabelling revealed immunopositivity in 42+/-6% of the total population of dorsal root ganglion neurons. Cells showing VR1-like immunopositivity had an area between 200 and 600 microm(2). The mean area of the VR1-like immunopositive neurons was 376+/-61 microm(2). Double immunostaining with antisera raised against the CB1 and VR1 receptor proteins, showed a high degree of co-expression between CB1 and VR1 receptors. An average of 82+/-3% of the CB1-like immunopositive cells also showed VR1-like immunoreactivity (n=3 cultures) while 98+/-2% of the VR1-like immunolabelled neurons showed CB1 receptor-like immunostaining (n=3 cultures). Our data suggests that nociceptive primary sensory neurons co-express CB1 and VR1 receptors to a very high degree. We propose that this may provide an anatomical basis for a powerful combination of VR1 mediated excitation and CB1-mediated inhibition of nociceptive responses at central and peripheral terminals of nociceptive primary afferents.”

https://www.ncbi.nlm.nih.gov/pubmed/11036202

https://www.sciencedirect.com/science/article/abs/pii/S0306452200003894

Possible mechanisms of cannabinoid-induced antinociception in the spinal cord.

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European Journal of Pharmacology

“Anandamide is an endogenous ligand at both the inhibitory cannabinoid CB(1) receptor and the excitatory vanilloid receptor 1 (VR1). The CB(1) receptor and vanilloid VR1 receptor are expressed in about 50% and 40% of dorsal root ganglion neurons, respectively. While all vanilloid VR1 receptor-expressing cells belong to the calcitonin gene-related peptide-containing and isolectin B4-binding sub-populations of nociceptive primary sensory neurons, about 80% of the cannabinoid CB(1) receptor-expressing cells belong to those sub-populations. Furthermore, all vanilloid VR1 receptor-expressing cells co-express the cannabinoid CB(1) receptor.

In agreement with these findings, neonatal capsaicin treatment that induces degeneration of capsaicin-sensitive, vanilloid VR1 receptor-expressing, thin, unmyelinated, nociceptive primary afferent fibres significantly reduced the cannabinoid CB(1) receptor immunostaining in the superficial spinal dorsal horn.

Synthetic cannabinoid CB(1) receptor agonists, which do not have affinity at the vanilloid VR1 receptor, and low concentrations of anandamide both reduce the frequency of miniature excitatory postsynaptic currents and electrical stimulation-evoked or capsaicin-induced excitatory postsynaptic currents in substantia gelatinosa cells in the spinal cord without any effect on their amplitude. These effects are blocked by selective cannabinoid CB(1) receptor antagonists. Furthermore, the paired-pulse ratio is increased while the postsynaptic response of substantia gelatinosa neurons induced by alpha-amino-3-hydroxy-5-methylisoxasole-propionic acid (AMPA) in the presence of tetrodotoxin is unchanged following cannabinoid CB(1) receptor activation.

These results strongly suggest that the cannabinoid CB(1) receptor is expressed presynaptically and that the activation of these receptors by synthetic cannabinoid CB(1) receptor agonists or low concentration of anandamide results in inhibition of transmitter release from nociceptive primary sensory neurons. High concentrations of anandamide, on the other hand, increase the frequency of miniature excitatory postsynaptic currents recorded from substantia gelatinosa neurons. This increase is blocked by ruthenium red, suggesting that this effect is mediated through the vanilloid VR1 receptor.

Thus, anandamide at high concentrations can activate the VR1 and produce an opposite, excitatory effect to its inhibitory action produced at low concentrations through cannabinoid CB(1) receptor activation. This “dual”, concentration-dependent effect of anandamide could be an important presynaptic modulatory mechanism in the spinal nociceptive system.”

https://www.ncbi.nlm.nih.gov/pubmed/11698030

https://www.sciencedirect.com/science/article/pii/S0014299901013097?via%3Dihub