Tag Archives: CB2

Activation of Cannabinoid Receptor 2 Attenuates Mechanical Allodynia and Neuroinflammatory Responses in a Chronic Post-Ischemic Pain Model of Complex Regional Pain Syndrome Type I in Rats.

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“Complex regional pain syndrome type 1 (CRPS-I) remains one of the most clinically challenging neuropathic pain syndromes and its mechanism has not been fully characterized.

Cannabinoid receptor 2 (CB2) has emerged as a promising target for treating different neuropathic pain syndromes.

In neuropathic pain models, activated microglia expressing CB2 receptors are seen in the spinal cord.

Chemokine fractalkine receptor (CX3CR1) plays a substantial role in microglial activation and neuroinflammation.

We hypothesized that CB2 agonist could modulate neuroinflammation and neuropathic pain in an ischemia model of CRPS by regulating CB2 and CX3CR1 signaling.

We used chronic post-ischemia pain (CPIP) as a model of CRPS-I. Rats in the CPIP group exhibited significant hyperemia and edema of the ischemic hindpaw and spontaneous pain behaviors (hindpaw shaking and licking).

Intraperitoneal administration of MDA7 (a selective CB2 agonist) attenuated mechanical allodynia induced by CPIP. MDA7 treatment was found to interfere with early events in the CRPS-I neuroinflammatory response by suppressing peripheral edema, spinal microglial activation and expression of CX3CR1 and CB2 receptors on the microglia in the spinal cord.

MDA7 also mitigated the loss of intraepidermal nerve fibers induced by CPIP. Neuroprotective effects of MDA7 were blocked by a CB2 antagonist, AM630.

Our findings suggest that MDA7, a novel CB2 agonist, may offer an innovative therapeutic approach for treating neuropathic symptoms and neuroinflammatory responses induced by CRPS-I in the setting of ischemia and reperfusion injury.”

https://www.ncbi.nlm.nih.gov/pubmed/27717112

Synthesis, Biodistribution and In vitro Evaluation of Brain Permeable High Affinity Type 2 Cannabinoid Receptor Agonists [11C]MA2 and [18F]MA3.

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“The type 2 cannabinoid receptor (CB2) is a member of the endocannabinoid system and is known for its important role in (neuro)inflammation.

A PET-imaging agent that allows in vivo visualization of CB2 expression may thus allow quantification of neuroinflammation.

In this paper, we report the synthesis, radiosynthesis, biodistribution and in vitro evaluation of a carbon-11 ([11C]MA2) and a fluorine-18 ([18F]MA3) labeled analog of a highly potent N-arylamide oxadiazole CB2 agonist (EC50 = 0.015 nM). MA2 and MA3 behaved as potent CB2 agonist (EC50: 3 nM and 0.1 nM, respectively) and their in vitro binding affinity for hCB2 was found to be 87 nM and 0.8 nM, respectively.

Also MA3 (substituted with a fluoro ethyl group) was found to have higher binding affinity and EC50 values when compared to the originally reported trifluoromethyl analog 12. [11C]MA2 and [18F]MA3 were successfully synthesized with good radiochemical yield, high radiochemical purity and high specific activity. In mice, both tracers were efficiently cleared from blood and all major organs by the hepatobiliary pathway and importantly these compounds showed high brain uptake.

In conclusion, [11C]MA2 and [18F]MA3 are shown to be high potent CB2 agonists with good brain uptake, these favorable characteristics makes them potential PET probes for in vivo imaging of brain CB2 receptors. However, in view of its higher affinity and selectivity, further detailed evaluation of MA3 as a PET tracer for CB2 is warranted.”

https://www.ncbi.nlm.nih.gov/pubmed/27713686

Targeting Cannabinoid CB2 Receptors in the Central Nervous System. Medicinal Chemistry Approaches with Focus on Neurodegenerative Disorders.

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“Endocannabinoids activate two types of specific G-protein-coupled receptors (GPCRs), namely cannabinoid CB1 and CB2. Contrary to the psychotropic actions of agonists of CB1 receptors, and serious side effects of the selective antagonists of this receptor, drugs acting on CB2 receptors appear as promising drugs to combat CNS diseases (Parkinson’s disease, Huntington’s chorea, cerebellar ataxia, amyotrohic lateral sclerosis). Differential localization of CB2 receptors in neural cell types and upregulation in neuroinflammation are keys to understand the therapeutic potential in inter alia diseases that imply progressive neurodegeneration. Medicinal chemistry approaches are now engaged to develop imaging tools to map receptors in the living human brain, to develop more efficacious agonists, and to investigate the possibility to develop allosteric modulators.”

 https://www.ncbi.nlm.nih.gov/pubmed/27679556

Δ9-Tetrahydrocannabinol Reverses TNFα-induced Increase in Airway Epithelial Cell Permeability through CB2 Receptors.

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“Despite pharmacological treatment, bronchial hyperresponsiveness continues to deteriorate as airway remodelling persists in airway inflammation.

Previous studies have demonstrated that the phytocannabinoid Δ9-tetrahydrocannabinol (THC) reverses bronchoconstriction with an anti-inflammatory action.

The aim of this study was to investigate the effects of THC on bronchial epithelial cell permeability after exposure to the pro-inflammatory cytokine, TNFα. Calu-3 bronchial epithelial cells were cultured at air-liquid interface.

These data indicate that THC prevents cytokine-induced increase in airway epithelial permeability through CB2 receptor activation.

This highlights that THC, or other cannabinoid receptor ligands, could be beneficial in the prevention of inflammation-induced changes in airway epithelial cell permeability, an important feature of airways diseases.”

http://www.ncbi.nlm.nih.gov/pubmed/27641813

Activation of Cannabinoid Receptor Type II by AM1241 Ameliorates Myocardial Fibrosis via Nrf2-Mediated Inhibition of TGF-β1/Smad3 Pathway in Myocardial Infarction Mice.

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“Myocardial interstitial fibrosis is a major histologic landmark resulting in cardiac dysfunction after myocardial infarction (MI).

Activation of cannabinoid receptor type II (CB2 receptor) have been demonstrated to reduce fibrosis in hepatic cirrhotic rat.

In this study, we aimed to investigate the effects of a CB2 receptor selective agonist AM1241 on myocardial fibrosis post MI in mice.

CONCLUSION:

CB2 receptor agonist AM1241 alleviated myocardial interstitial fibrosis via Nrf2 -mediated down-regulation of TGF-β1/Smad3 pathway, which suggested that CB2 receptor activation might represent a promising target for retarding cardiac fibrosis after MI.”

http://www.ncbi.nlm.nih.gov/pubmed/27614871

Activation of Cannabinoid Receptor 2 Ameliorates DSS-Induced Colitis through Inhibiting NLRP3 Inflammasome in Macrophages.

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“Activation of cannabinoid receptor 2 (CB2R) ameliorates inflammation, but the underlying mechanism remains unclear.

In the present study, we examined whether activation of CB2R could suppress the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome.

We conclude that activation of CB2R ameliorates DSS-induced colitis through enhancing autophagy that may inhibit NLRP3 inflammasome activation in macrophages.”

http://www.ncbi.nlm.nih.gov/pubmed/27611972

Selective modulator of cannabinoid receptor type 2 (CB2) against biochemical alterations and brain damage in chronic cerebral hypoperfusion induced vascular dementia.

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“Vascular dementia is the second most common cause of cognitive decline in aged people but the effectual therapeutic target is still missing.

Chronic cerebral hypoperfusion (CCH) has been widely found in vascular dementia (VaD) patients. CCH is thought to link with neurodegenerative disorders and their subsequent cognitive impairment.

The present study has been framed to investigate the role of selective agonist of CB2 receptor (1-phenylisatin) in CCH induced VaD.

These results indicate that 2VO induced CCH in rats, which was attenuated with the treatment of 1-phenylisatin.

Hence, it may be suggested that modulation in cannabinoid receptor may provide benefits in CCH as cognitive impairment and VaD.

Therefore, pharmacological positive modulation of CB2 receptors may be a potential research target for alleviation of VaD.”

http://www.ncbi.nlm.nih.gov/pubmed/27599483

Selective modulator of cannabinoid receptor type 2 reduces memory impairment and infarct size during cerebral hypoperfusion and vascular dementia.

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“Vascular dementia is the highly devastating neurodegenerative disorder after Alzheimer’s disease (AD) and mainly found in aged people but the effectual therapeutic target is still not there.

Chronic cerebral hypoperfusion (CCH) has been broadly found in vascular dementia (VaD) patients. CCH is thought to link with neurodegenerative disorders and their subsequent cognitive deteriorate on.

This study has been framed to examine the role of a selective agonist of cannabinoid receptor type 2(CB2); 1-phenylisatin in CCH induced VaD.

These results indicate that 2VO induced CCH in rats, which was attenuated with the treatment of 1-phenylisatin.

Hence, it may be suggested that modulation of cannabinoid receptor may provide benefits in CCH as cognitive impairment and VaD.

Therefore, selective agonists of CB2 receptors may be a potential research target for the alleviation of VaD.”

http://www.ncbi.nlm.nih.gov/pubmed/27586843

Cannabinoid 2 receptor is a novel anti-inflammatory target in experimental proliferative vitreoretinopathy.

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“Proliferative vitreoretinopathy (PVR) can develop after ocular trauma or inflammation and is a common complication of surgery to correct retinal detachment.

Currently, there are no pharmacological treatments for PVR.

Cannabinoids acting at cannabinoid 2 receptor (CB2R) can decrease inflammation and fibrosis.

The objective of this study was to examine the anti-inflammatory actions of CB2R as a candidate novel therapeutic target in experimental PVR.

In conclusion, our results indicate that intervention at early stage PVR with CB2R agonists reduces ocular inflammation and disease severity.

CB2R may represent a therapeutic target to prevent PVR progression and vision loss.”

http://www.ncbi.nlm.nih.gov/pubmed/27569993

CB2 receptor activation prevents glial-derived neurotoxic mediator production, BBB leakage and peripheral immune cell infiltration and rescues dopamine neurons in the MPTP model of Parkinson’s disease.

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“The cannabinoid (CB2) receptor type 2 has been proposed to prevent the degeneration of dopamine neurons in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice.

Our results suggest that targeting the cannabinoid system may be beneficial for the treatment of neurodegenerative diseases, such as PD, that are associated with glial activation, BBB disruption and peripheral immune cell infiltration.”

http://www.ncbi.nlm.nih.gov/pubmed/27534533

“The cannabinoid type two receptors (CB2), an important component of the endocannabinoid system, have recently emerged as neuromodulators and therapeutic targets for neurodegenerative diseases including Parkinson’s disease (PD).” http://www.ncbi.nlm.nih.gov/pubmed/27531971