Tag Archives: CB2

Distinct roles of neuronal and microglial CB2 cannabinoid receptors in the mouse hippocampus.

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“The effects of cannabinoids are primarily mediated by type-1 cannabinoid receptors in the brain and type-2 cannabinoid receptors (CB2Rs) in the peripheral immune system. However, recent evidence demonstrates that CB2Rs are also expressed in the brain and implicated in neuropsychiatric effects. Diverse types of cells in various regions in the brain express CB2Rs but the cellular loci of CB2Rs that induce specific behavioral effects have not been determined. To manipulate CB2R expression in specific types of cells in the dorsal hippocampus of adult mice, we used Cre-dependent overexpression and CRISPR-Cas9 genome editing techniques in combination with adeno-associated viruses and transgenic mice. Elevation and disruption of CB2R expression in microglia in the CA1 area increased and decreased, respectively, contextual fear memory. In CA1 pyramidal neurons, disruption of CB2R expression enhanced spatial working memory, whereas their overexpression reduced anxiety levels assessed as an increase in the exploration time in the central area of open field. Interneuronal CB2Rs were not involved in the modulation of cognitive or emotional behaviors tested in this study. The targeted manipulation of CB2R expression in pyramidal neurons and microglia suggests that CB2Rs in different types of cells in the mature hippocampus play distinct roles in the regulation of memory and anxiety.”

https://www.ncbi.nlm.nih.gov/pubmed/28888955

http://www.sciencedirect.com/science/article/pii/S0306452217306292

Cannabinoid Receptor 2 Modulates Neutrophil Recruitment in a Murine Model of Endotoxemia.

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“The endocannabinoid system consists of endogenous lipid mediators and cannabinoid receptors (CB) 1 and 2. It has previously been demonstrated that activation of the leukocyte-expressed CB2 has anti-inflammatory effects in vivo. Here, we report its role under baseline conditions and in a model of low-dose endotoxemia by comparing CB2 knockout to littermate control mice. CB2-deficient mice displayed significantly more neutrophils and fewer monocytes in the bone marrow under steady state. In initial validation experiments, administration of 1 mg/kg LPS to male C57BL/6J mice was shown to transiently upregulate systemic proinflammatory mediators (peaked at 2 hours) and mobilise bone marrow neutrophils and monocytes into circulation. In CB2 knockout mice, the level of the metalloproteinase MMP-9 was significantly elevated by 2 hours and we also observed augmented recruitment of neutrophils to the spleen in addition to increased levels of Ccl2, Ccl3, Cxcl10, and Il6. Collectively, our data show that the absence of CB2 receptor increases the levels of innate immune cell populations in the bone marrow under steady state. Furthermore, during an acute systemic inflammatory insult, we observe a highly reproducible and site-specific increase in neutrophil recruitment and proinflammatory chemokine expression in the spleen of CB2 knockout mice.”  https://www.ncbi.nlm.nih.gov/pubmed/28852269

“In summary, we found that the lack of this GPCR leads to enhanced retention of neutrophils and increased release of monocytes in the bone marrow under steady state. We highlight a critical role for CB2 in regulating neutrophil infiltration to the spleen during acute systemic inflammation. A potential mechanism for this effect is the increased secretion of MMP-9 and Ccl3/Cxcl10 expression in the spleens of CB2 knockout mice. Taken together, we propose a novel role for CB2 in suppressing neutrophil migration to lymphoid organs under inflammatory conditions which we believe warrants further investigation.” https://www.hindawi.com/journals/mi/2017/4315412/

Neuroprotective activity of cannabinoid receptor-2 against oxidative stress and apoptosis in rat pups having experimentally-induced congenital hypothyroidism.

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“In this study, it was aimed to show the cannabinoid receptor-2 (CB2) role, which is a part of neuroprotective endocannabinoidal system, against increasing nitric oxide synthetase (iNOS, eNOS) levels and the apoptotic activity (caspase-3, caspase-9 and DNA in situ fragmentation) within the postnatal critical period in pups of pregnant rats with artificially induced maternal thyroid hormone (TH) deficiency.

In conclusion, apoptosis was triggered via oxidative stress in hypothyroid pups. Accordingly, neuroprotective activity of CB2 receptors were motivated spontaneously to resist to CNS lesions during the first 3 weeks of postnatal period.”

https://www.ncbi.nlm.nih.gov/pubmed/28799288

Cannabinoid receptor 2-63 RR variant is independently associated with severe necroinflammation in HIV/HCV coinfected patients.

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“This is the first study to analyze the impact of the rs35761398 variant of the CNR2 gene leading to the substitution of GLN (Q) of codon 63 of the cannabinoid receptor 2 (CB2) with ARG (R) on the clinical presentation of chronic hepatitis in HIV/HCV coinfected patients.

This study shows interesting interplay between the CB2-RR variant and liver necroinflammation in chronic hepatitis patients with HIV/HCV coinfection, an observation of clinical value that coincides with the interest in the use of the CB2 agonists and antagonists in clinical practice emerging from the literature.”

 https://www.ncbi.nlm.nih.gov/pubmed/28759568
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0181890

Alleviation of Neuropathology by Inhibition of Monoacylglycerol Lipase in APP Transgenic Mice Lacking CB2 Receptors.

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Molecular Neurobiology

“Inhibition of monoacylglycerol lipase (MAGL), the primary enzyme that hydrolyzes the endocannabinoid 2-arachidonoylglycerol (2-AG) in the brain, produces profound anti-inflammatory and neuroprotective effects and improves synaptic and cognitive functions in animal models of Alzheimer’s disease (AD). However, the molecular mechanisms underlying the beneficial effects produced by inhibition of 2-AG metabolism are still not clear.

The cannabinoid receptor type 2 (CB2R) has been thought to be a therapeutic target for AD. Here, we provide evidence, however, that CB2R does not play a role in ameliorating AD neuropathology produced by inactivation of MAGL in 5XFAD APP transgenic mice, an animal model of AD.

Our results suggest that CB2R is not required in ameliorating neuropathology and preventing cognitive decline by inhibition of 2-AG metabolism in AD model animals.”

 https://www.ncbi.nlm.nih.gov/pubmed/28733897
https://link.springer.com/article/10.1007%2Fs12035-017-0689-x

AM1241 alleviates MPTP-induced Parkinson’s disease and promotes the regeneration of DA neurons in PD mice.

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“The main pathological feature of Parkinson’s disease (PD) is the loss of dopaminergic neurons in the substantia nigra. In this study, we investigated the role of cannabinoid receptor 2 (CB2R) agonist AM1241 on 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neurotoxicity in a mouse model of PD. Upon treatment with AM1241, the decreased CB2R level in the PD mouse brain was reversed and the behavior score markedly elevated, accompanied with a dose-dependent increase of dopamine and serotonin. In addition, western blot assay and immunostaining results suggested that AM1241 significantly activated PI3K/Akt/MEK phosphorylation and increased the expression of Parkin and PINK1, both in the substantia nigra and hippocampus. The mRNA expression analysis further demonstrated that AM1241 increased expression of the CB2R and activated Parkin/PINK1 signaling pathways. Furthermore, the increased number of TH-positive cells in the substantia nigra indicated that AM1241 regenerated DA neurons in PD mice, and could therefore be a potential candidate for PD treatment. The clear co-localization of CB2R and DA neurons suggested that AM1241 targeted CB2R, thus also identifying a novel target for PD treatment. In conclusion, the selective CB2 agonist AM1241 has a significant therapeutic effect on PD mice and resulted in regeneration of DA neurons following MPTP-induced neurotoxicity. The possible mechanisms underlying the neurogenesis effect of AM1241 might be the induction of CB2R expression and an increase in phosphorylation of the PI3K/AKT signaling pathway.”

 https://www.ncbi.nlm.nih.gov/pubmed/28733540
http://www.impactjournals.com/oncotarget/index.php?journal=oncotarget&page=article&op=view&path[]=18871&path[]=60558

Antiallodynic effect of β-caryophyllene on paclitaxel-induced peripheral neuropathy in mice.

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“Painful peripheral neuropathy is a common side effect of paclitaxel (PTX). The use of analgesics is an important component for management of PTX-induced peripheral neuropathy (PINP). However, currently employed analgesics have several side effects and are poorly effective.

β-caryophyllene (BCP), a dietary selective CB2 agonist, has shown analgesic effect in neuropathic pain models, but its role in chemotherapy-induced neuropathic pain has not yet been investigated. Herein, we used the mouse model of PINP to show the therapeutic effects of BCP in this neuropathy.

Our findings show that BCP effectively attenuated PINP, possibly through CB2-activation in the CNS and posterior inhibition of p38 MAPK/NF-κB activation and cytokine release. Taken together, our results suggest that BCP could be used to attenuate the establishment and/or treat PINP.”  https://www.ncbi.nlm.nih.gov/pubmed/28729222

http://www.sciencedirect.com/science/article/pii/S0028390817303465

“β-caryophyllene (BCP) is a common constitute of the essential oils of numerous spice, food plants and major component in Cannabis.”  http://www.ncbi.nlm.nih.gov/pubmed/23138934

Amidoalkylindoles as Potent and Selective Cannabinoid Type 2 Receptor Agonists with In Vivo Efficacy in a Mouse Model of Multiple Sclerosis.

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Journal of Medicinal Chemistry

“Selective CB2 agonists represent an attractive therapeutic strategy for the treatment of a variety of diseases without psychiatric side effects mediated by the CB1 receptor.

We carried out a rational optimization of a black market designer drug SDB-001 that led to the identification of potent and selective CB2 agonists. A 7-methoxy or 7-methylthio substitution at the 3-amidoalkylindoles resulted in potent CB2 antagonists (27 or 28, IC50 = 16-28 nM). Replacement of the amidoalkyls from 3-position to the 2-position of the indole ring dramatically increased the agonist selectivity on the CB2 over CB1 receptor. Particularly, compound 57 displayed a potent agonist activity on the CB2 receptor (EC50 = 114-142 nM) without observable agonist or antagonist activity on the CB1 receptor.

Furthermore, 57 significantly alleviated the clinical symptoms and protected the murine central nervous system from immune damage in an experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis.”

https://www.ncbi.nlm.nih.gov/pubmed/28726401
http://pubs.acs.org/doi/abs/10.1021/acs.jmedchem.7b00724

Activation of cannabinoid receptor type 2 attenuates surgery-induced cognitive impairment in mice through anti-inflammatory activity.

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“Neuroinflammation plays a major role in postoperative cognitive dysfunction (POCD).

Accumulated evidence indicates that cannabinoid receptor type 2 (CB2R) can mediate anti-inflammatory and immunomodulatory effects in part by controlling microglial activity.

These findings indicate that CB2R may modulate the neuroinflammatory and cognitive impairment in a mouse model of orthopedic surgery, and the activation of CB2R may effectively ameliorate the hippocampal-dependent memory loss of mice in the early postoperative stage.”

https://www.ncbi.nlm.nih.gov/pubmed/28724382

https://jneuroinflammation.biomedcentral.com/articles/10.1186/s12974-017-0913-7

Deletion of Type-2 Cannabinoid Receptor Induces Alzheimer’s Disease-Like Tau Pathology and Memory Impairment Through AMPK/GSK3β Pathway.

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Molecular Neurobiology

“Although several studies have shown that type-2 cannabinoid receptor (CB2R) is involved in Alzheimer’s disease (AD) pathology, the effects of CB2R on AD-like tau abnormal phosphorylation and its underlying mechanism remain unclear.

Herein, we employed the CB2R-/- mice as the animal model to explore roles of CB2R in regulating tau phosphorylation and brain function.

Taken together, our study indicated that deletion of CB2R induces behavior damage and AD-like pathological alternation via AMPK/GSK3β pathway. These findings proved that CB2R/AMPK/GSK3β pathway can be a promising new drug target for AD.”

 https://www.ncbi.nlm.nih.gov/pubmed/28717968
https://link.springer.com/article/10.1007%2Fs12035-017-0676-2