Targeting CB1 and GPR55 Endocannabinoid Receptors as a Potential Neuroprotective Approach for Parkinson’s Disease.

 “Cannabinoid CB1 receptors (CB1R) and the GPR55 receptor are expressed in striatum and are potential targets in the therapy of Parkinson’s disease (PD), one of the most prevalent neurodegenerative diseases in developed countries.

The aim of this paper was to address the potential of ligands acting on those receptors to prevent the action of a neurotoxic agent, MPP+, that specifically affects neurons of the substantia nigra due to uptake via the dopamine DAT transporter.

These results show that neurons expressing heteromers are more resistant to cell death but question the real usefulness of CB1R, GPR55, and their heteromers as targets to afford PD-related neuroprotection.”

https://www.ncbi.nlm.nih.gov/pubmed/30687889

https://link.springer.com/article/10.1007%2Fs12035-019-1495-4

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Some Prospective Alternatives for Treating Pain: The Endocannabinoid System and Its Putative Receptors GPR18 and GPR55.

Image result for frontiers in pharmacology“Marijuana extracts (cannabinoids) have been used for several millennia for pain treatment.

Regarding the site of action, cannabinoids are highly promiscuous molecules, but only two cannabinoid receptors (CB1 and CB2) have been deeply studied and classified.

Thus, therapeutic actions, side effects and pharmacological targets for cannabinoids have been explained based on the pharmacology of cannabinoid CB1/CB2 receptors. However, the accumulation of confusing and sometimes contradictory results suggests the existence of other cannabinoid receptors.

Different orphan proteins (e.g., GPR18, GPR55, GPR119, etc.) have been proposed as putative cannabinoid receptors.

According to their expression, GPR18 and GPR55 could be involved in sensory transmission and pain integration.

This work summarized novel data supporting that, besides cannabinoid CB1 and CB2receptors, GPR18 and GPR55 may be useful for pain treatment.

Conclusion: There is evidence to support an antinociceptive role for GPR18 and GPR55.”

https://www.ncbi.nlm.nih.gov/pubmed/30670965

https://www.frontiersin.org/articles/10.3389/fphar.2018.01496/full

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Anti-neuroinflammatory effects of GPR55 antagonists in LPS-activated primary microglial cells.

Image result for jni journal of inflammation

“Neuroinflammation plays a vital role in Alzheimer’s disease and other neurodegenerative conditions.

The orphan G-protein-coupled receptor 55 (GPR55) has been reported to modulate inflammation and is expressed in immune cells such as monocytes and microglia.

Targeting GPR55 might be a new therapeutic option to treat neurodegenerative diseases with a neuroinflammatory background such as Alzheimer’s disease, Parkinson, and multiple sclerosis (MS).”

https://www.ncbi.nlm.nih.gov/pubmed/30453998

https://jneuroinflammation.biomedcentral.com/articles/10.1186/s12974-018-1362-7

“Pharmacological characterization of GPR55, a putative cannabinoid receptor.”  https://www.ncbi.nlm.nih.gov/pubmed/20298715

“Our findings also suggest that GPR55 may be a new pharmacological target for the following C. sativa constituents: Δ9-THCV, CBDV, CBGA, and CBGV. These Cannabis sativa constituents may represent novel therapeutics targeting GPR55.”  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249141/

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Activation of GPR55 induces neuroprotection of hippocampal neurogenesis and immune responses of neural stem cells following chronic, systemic inflammation.

Brain, Behavior, and Immunity

“New neurons are continuously produced by neural stem cells (NSCs) within the adult hippocampus. Numerous diseases, including major depressive disorder and HIV-1 associated neurocognitive disorder, are associated with decreased rates of adult neurogenesis. A hallmark of these conditions is a chronic release of neuroinflammatory mediators by activated resident glia.

Recent studies have shown a neuroprotective role on NSCs of cannabinoid receptor activation. Yet, little is known about the effects of GPR55, a candidate cannabinoid receptor, activation on reductions of neurogenesis in response to inflammatory insult.

In the present study, we examined NSCs exposed to IL-1β in vitro to assess inflammation-caused effects on NSC differentiation and the ability of GPR55 agonists to attenuate NSC injury.

Taken together, these results suggest a neuroprotective role of GPR55 activation on NSCs in vitro and in vivo and that GPR55 provides a novel therapeutic target against negative regulation of hippocampal neurogenesis by inflammatory insult.”

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GPR55 signalling promotes proliferation of pancreatic cancer cells and tumour growth in mice, and its inhibition increases effects of gemcitabine

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“The life expectancy for pancreatic cancer patients has seen no substantial changes in the last 40 years as very few and mostly just palliative treatments are available. As the five years survival rate remains around 5%, the identification of novel pharmacological targets and development of new therapeutic strategies are urgently needed.

Here we demonstrate that inhibition of the G protein-coupled receptor GPR55, using genetic and pharmacological approaches, reduces pancreatic cancer cell growth in vitro and in vivo and we propose that this may represent a novel strategy to inhibit pancreatic ductal adenocarcinoma (PDAC) progression.

Specifically, we show that genetic ablation of Gpr55 in the KRASWT/G12D/TP53WT/R172H/Pdx1-Cre+/+ (KPC) mouse model of PDAC significantly prolonged survival.

Importantly, KPC mice treated with a combination of the GPR55 antagonist Cannabidiol (CBD) and gemcitabine (GEM, one of the most used drugs to treat PDAC), survived nearly three times longer compared to mice treated with vehicle or GEM alone.

Mechanistically, knockdown or pharmacologic inhibition of GPR55 reduced anchorage-dependent and independent growth, cell cycle progression, activation of mitogen-activated protein kinase (MAPK) signalling and protein levels of ribonucleotide reductases in PDAC cells. Consistent with this, genetic ablation of Gpr55 reduced proliferation of tumour cells, MAPK signalling and ribonucleotide reductase M1 levels in KPC mice.

Combination of CBD and GEM inhibited tumour cell proliferation in KPC mice and it opposed mechanisms involved in development of resistance to GEM in vitro and in vivo. Finally, we demonstrate that the tumour suppressor p53 regulates GPR55 protein expression through modulation of the microRNA miR34b-3p.

Our results demonstrate the important role played by GPR55 downstream of p53 in PDAC progression. Moreover our data indicate that combination of CBD and GEM, both currently approved for medical use, might be tested in clinical trials as a novel promising treatment to improve PDAC patients’ outcome.”

https://www.nature.com/articles/s41388-018-0390-1

“Cannabinoid improves survival rates of mice with pancreatic cancer”  https://medicalxpress.com/news/2018-07-cannabinoid-survival-mice-pancreatic-cancer.html

“Study: CBD From Marijuana Plus Chemotherapy Tripled Cancer Survival Rates In Mice” https://www.forbes.com/sites/daviddisalvo/2018/07/31/study-cbd-from-marijuana-plus-chemotherapy-triples-cancer-survival-rates-in-mice/#491942d44630

“Cannabis drug may help pancreatic-cancer patients live almost THREE TIMES longer, study finds” http://www.dailymail.co.uk/health/article-6007275/Cannabis-drug-help-pancreatic-cancer-patients-live-THREE-TIMES-longer-study-finds.html

“Substance in cannabis ‘could boost pancreatic cancer treatments’. Scientists say cannabidiol could extend patients’ lives by a matter of years”  https://www.theguardian.com/science/2018/jul/30/substance-in-cannabis-could-boost-pancreatic-cancer-treatments

“Cannabinoid mice trial holds hope for pancreatic cancer patients”  https://www.smh.com.au/national/cannabinoid-mice-trial-holds-hope-for-pancreatic-cancer-patients-20180731-p4zuls.html

“Medical cannabis extract could help pancreatic cancer patients live longer, early study suggests” https://www.independent.co.uk/news/health/pancreatic-cancer-medical-cannabis-cbd-oil-cannabidiol-chemotherapy-a8470406.html

“Cancer ‘remarkable’ treatment – cannabis CBD could improve survival rate by THREE times. CANCER symptoms could be prevented with a “remarkable” new treatment, which includes cannabis CBD, scientists have revealed. Pancreatic cancer survival rates could be improved by three times, by adding CBD into chemotherapy treatments, they said.” https://www.express.co.uk/life-style/health/996657/cancer-treatment-pancreatic-symptoms-cannabis-cbd

“Compound in cannabis could help pancreatic cancer patients live significantly longer” https://www.deccanchronicle.com/lifestyle/health-and-wellbeing/310718/compound-in-cannabis-could-help-pancreatic-cancer-patients-live-signif.html

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Chronic treatment with the phytocannabinoid Cannabidivarin (CBDV) rescues behavioural alterations and brain atrophy in a mouse model of Rett syndrome.

Neuropharmacology

“Rett syndrome (RTT) is a rare neurodevelopmental disorder, characterized by severe behavioural and physiological symptoms. RTT is caused by mutations in the MECP2 gene in about 95% of cases and to date no cure is available.

The endocannabinoid system modulates several physiological processes and behavioural responses that are impaired in RTT and its deregulation has been associated with neuropsychiatric disorders which have symptoms in common with RTT.

The present study evaluated the potential therapeutic efficacy for RTT of cannabidivarin (CBDV), a non-psychotropic phytocannabinoid from Cannabis sativa that presents antagonistic properties on the G protein-coupled receptor 55 (GPR55), the most recently identified cannabinoid receptor.

Present results demonstrate that systemic treatment with CBDV (2, 20, 100 mg/Kg ip for 14 days) rescues behavioural and brain alterations in MeCP2-308 male mice, a validated RTT model. The CBDV treatment restored the compromised general health status, the sociability and the brain weight in RTT mice. A partial restoration of motor coordination was also observed. Moreover, increased levels of GPR55 were found in RTT mouse hippocampus, suggesting this G protein-coupled receptor as new potential target for the treatment of this disorder.

Present findings highlight for the first time for RTT the translational relevance of CBDV, an innovative therapeutic agent that is under active investigation in the clinical setting.”

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Activation of GPR55 increases neural stem cell proliferation and promotes early adult hippocampal neurogenesis

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“The cannabinoid system exerts functional regulation of neural stem cell (NSC) proliferation and adult neurogenesis, yet not all effects of cannabinoid-like compounds seen can be attributed to the cannabinoid 1 receptor (CB1 R) or cannabinoid 2 receptor (CB2 R).

The recently de-orphaned GPR55 has been shown to be activated by numerous cannabinoid ligands suggesting that GPR55 is a third cannabinoid receptor.

Here we examined the role of GPR55 activation in NSC proliferation and early adult neurogenesis.

CONCLUSIONS AND IMPLICATIONS:

Together, these findings suggest GPR55 activation as a novel target and strategy to regulate NSC proliferation and adult neurogenesis.”

https://www.ncbi.nlm.nih.gov/pubmed/29888782

https://bpspubs.onlinelibrary.wiley.com/doi/abs/10.1111/bph.14387

“The orphan receptor GPR55 is a novel cannabinoid receptor”  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2095107/

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Localization of cannabinoid receptors CB1, CB2, GPR55, and PPARα in the canine gastrointestinal tract.

Histochemistry and Cell Biology

“The endocannabinoid system (ECS) is composed of cannabinoid receptors, their endogenous ligands, and the enzymes involved in endocannabinoid turnover.

Modulating the activity of the ECS may influence a variety of physiological and pathophysiological processes.

A growing body of evidence indicates that activation of cannabinoid receptors by endogenous, plant-derived, or synthetic cannabinoids may exert beneficial effects on gastrointestinal inflammation and visceral pain.

The present ex vivo study aimed to investigate immunohistochemically the distribution of cannabinoid receptors CB1, CB2, G protein-coupled receptor 55 (GPR55), and peroxisome proliferation activation receptor alpha (PPARα) in the canine gastrointestinal tract.

Cannabinoid receptors showed a wide distribution in the gastrointestinal tract of the dog.

Since cannabinoid receptors have a protective role in inflammatory bowel disease, the present research provides an anatomical basis supporting the therapeutic use of cannabinoid receptor agonists in relieving motility disorders and visceral hypersensitivity in canine acute or chronic enteropathies.”

https://www.ncbi.nlm.nih.gov/pubmed/29882158

https://link.springer.com/article/10.1007%2Fs00418-018-1684-7

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LH-21 and Abn-CBD improve β-cell function in isolated human and mouse islets through GPR55-dependent and -independent signalling.

Diabetes, Obesity and Metabolism

“CB1 and GPR55 are GPCRs expressed by islet β-cells. Pharmacological compounds have been used to investigate their function, but off-target effects of ligands have been reported.

This study examined the effects of Abn-CBD (GPR55 agonist) and LH-21 (CB1 antagonist) on human and mouse islet function, and islets from GPR55-/- mice were used to determine signalling via GPR55.

RESULTS:

Abn-CBD potentiated glucose-stimulated insulin secretion and elevated [Ca2+ ]i in human islets and islets from both GPR55+/+ and GPR55-/- mice. LH-21 also increased insulin secretion and [Ca2+ ]i in human islets and GPR55+/+ mouse islets, but concentrations of LH-21 up to 0.1 μM were ineffective in islets from GPR55-/- mice. Neither ligand affected basal insulin secretion or islet cAMP levels. Abn-CBD and LH-21 reduced cytokine-induced apoptosis in human islets and GPR55+/+ mouse islets, and these effects were suppressed following GPR55 deletion. They also increased β-cell proliferation: the effects of Abn-CBD were preserved in islets from GPR55-/- mice, while those of LH-21 were abolished. Abn-CBD and LH-21 increased AKT phosphorylation in mouse and human islets.

CONCLUSIONS:

This study demonstrated that Abn-CBD and LH-21 improve human and mouse islet β-cell function and viability. Use of islets from GPR55-/- mice suggests that designation of Abn-CBD and LH-21 as GPR55 agonist and CB1 antagonist, should be revised.”

https://www.ncbi.nlm.nih.gov/pubmed/29205751

http://onlinelibrary.wiley.com/doi/10.1111/dom.13180/abstract

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Review: The Role of Cannabinoids on Esophageal Function-What We Know Thus Far.

Mary Ann Liebert, Inc. publishers

“The endocannabinoid system (ECS) primarily consists of cannabinoid receptors (CBRs), endogenous ligands, and enzymes for endocannabinoid biosynthesis and inactivation. Although the presence of CBRs, both CB1 and CB2, as well as a third receptor (G-protein receptor 55 [GPR55]), has been established in the gastrointestinal (GI) tract, few studies have focused on the role of cannabinoids on esophageal function. To date, studies have shown their effect on GI motility, inflammation and immunity, intestinal and gastric acid secretion, nociception and emesis pathways, and appetite control. Given the varying and sometimes limited efficacy of current medical therapies for diseases of the esophagus, further understanding and investigation into the interplay of the ECS on esophageal health and disease may present new therapeutic modalities that may help advance current treatment options. In this brief review, the current understanding of the ECS role in various esophageal functions and disorders is presented.”

https://www.ncbi.nlm.nih.gov/pubmed/29098187

http://online.liebertpub.com/doi/10.1089/can.2017.0031

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