Cannabis, cannabinoid receptors, and endocannabinoid system: yesterday, today, and tomorrow

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“Cannabis sativa, is also popularly known as marijuana, has been cultivated and used for recreational and medicinal purposes for many centuries.

The main psychoactive content in cannabis is Δ9-tetrahydrocannabinol (THC). In addition to plant cannabis sativa, there are two classes of cannabinoids—the synthetic cannabinoids (e.g., WIN55212–2) and the endogenous cannabinoids (eCB), anandamide (ANA) and 2-arachidonoylglycerol (2-AG).

The biological effects of cannabinoids are mainly mediated by two members of the G-protein-coupled receptor family, cannabinoid receptors 1 (CB1R) and 2 (CB2R). The endocannabinoids, cannabinoid receptors, and the enzymes/proteins responsible for their biosynthesis, degradation, and re-updating constitute the endocannabinoid system.

In recent decades, the endocannabinoid system has attracted considerable attention as a potential therapeutic target in numerous physiological conditions, such as in energy balance, appetite stimulation, blood pressure, pain modulation, embryogenesis, nausea and vomiting control, memory, learning and immune response, as well as in pathological conditions such as Parkinson’s disease, Huntington’s disease, Alzheimer’s disease, and multiple sclerosis.

The major goal of this Special Issue is to discuss and evaluate the current progress in cannabis and cannabinoid research in order to increase our understanding about cannabinoid action and the underlying biological mechanisms and promote the development cannabinoid-based pharmacotherapies.

 Overall, the present special issue provides an overview and insight on pharmacological mechanisms and therapeutic potentials of cannabis, cannabinoid receptors, and eCB system. I believe that this special issue will promote further efforts to apply cannabinoid ligands as the therapeutic strategies for treating a variety of diseases.”

Cannabinoid Receptor as a potential therapeutic target for Parkinson’s Disease.

Brain Research Bulletin

“Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease, characterized by the loss of dopaminergic neurons from substantia nigra pars compacta of basal ganglia caused due to gene mutation, misfolded protein aggregation, reactive oxygen species generation and inflammatory stress. Degeneration of dopaminergic neurons results in muscle stiffness, uncoordinated body movements, sleep disturbance, fatigue, amnesia and impaired voice.

Currently, levodopa (L-DOPA) administration is the most widely used therapy for PD. But prolonged administration of L-DOPA is associated with the symptoms of dyskinesia.

However, emerging evidences suggest the role of cannabinoid receptors (CBRs) in curtailing the progression of PD by activating neuroprotective pathways. Hence, cannabinoid therapy could be a promising alternative to combat PD in future.

In the present review we have discussed the potential role of CBRs in attenuating the key mechanisms of PD and how the existing research gaps needs to be bridged in order to understand the molecular mechanism of CBRs in detail.”

https://www.ncbi.nlm.nih.gov/pubmed/30664919

https://www.sciencedirect.com/science/article/abs/pii/S0361923018306208?via%3Dihub

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

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“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/

Cannabis Therapeutics and the Future of Neurology.

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“Neurological therapeutics have been hampered by its inability to advance beyond symptomatic treatment of neurodegenerative disorders into the realm of actual palliation, arrest or reversal of the attendant pathological processes.

While cannabis-based medicines have demonstrated safety, efficacy and consistency sufficient for regulatory approval in spasticity in multiple sclerosis (MS), and in Dravet and Lennox-Gastaut Syndromes (LGS), many therapeutic challenges remain.

This review will examine the intriguing promise that recent discoveries regarding cannabis-based medicines offer to neurological therapeutics by incorporating the neutral phytocannabinoids tetrahydrocannabinol (THC), cannabidiol (CBD), their acidic precursors, tetrahydrocannabinolic acid (THCA) and cannabidiolic acid (CBDA), and cannabis terpenoids in the putative treatment of five syndromes, currently labeled recalcitrant to therapeutic success, and wherein improved pharmacological intervention is required: intractable epilepsy, brain tumors, Parkinson disease (PD), Alzheimer disease (AD) and traumatic brain injury (TBI)/chronic traumatic encephalopathy (CTE).

Current basic science and clinical investigations support the safety and efficacy of such interventions in treatment of these currently intractable conditions, that in some cases share pathological processes, and the plausibility of interventions that harness endocannabinoid mechanisms, whether mediated via direct activity on CB1 and CB2 (tetrahydrocannabinol, THC, caryophyllene), peroxisome proliferator-activated receptor-gamma (PPARγ; THCA), 5-HT1A (CBD, CBDA) or even nutritional approaches utilizing prebiotics and probiotics.

The inherent polypharmaceutical properties of cannabis botanicals offer distinct advantages over the current single-target pharmaceutical model and portend to revolutionize neurological treatment into a new reality of effective interventional and even preventative treatment.”

https://www.ncbi.nlm.nih.gov/pubmed/30405366

https://www.frontiersin.org/articles/10.3389/fnint.2018.00051/full

Molecular Imaging of the Cannabinoid System in Idiopathic Parkinson’s Disease.

International Review of Neurobiology

“The endocannabinoid system is a modulator of neurotransmitter release and is involved in several physiological functions. Hence, it has been increasingly studied as a potential pharmacologic target of Parkinson’s disease.

Several preclinical and clinical studies evidenced a substantial rearrangement of the endocannabinoid system in the basal ganglia circuit following dopamine depletion. The endocannabinoid system has been additionally implicated in the regulation of neuroinflammation and neuroprotection through the activation of CB2 receptors, suggesting a potential target for disease modifying therapies in Parkinson’s disease.

In this chapter, current pharmacological and physiological knowledge on the role of the endocannabinoid system will be reviewed, focusing on preclinical studies animal models and clinical studies in patients with idiopathic Parkinson’s disease. The main strategies for imaging the brain cannabinoid system will be summarized to finally focus on in vivo imaging of patients with Parkinson’s disease.”

https://www.ncbi.nlm.nih.gov/pubmed/30314601

https://www.sciencedirect.com/science/article/pii/S0074774218300692?via%3Dihub

Translational Investigation of the Therapeutic Potential of Cannabidiol (CBD): Toward a New Age.

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“Among the many cannabinoids in the cannabis plant, cannabidiol (CBD) is a compound that does not produce the typical subjective effects of marijuana.

The aim of the present review is to describe the main advances in the development of the experimental and clinical use of cannabidiol CBD in neuropsychiatry.

CBD was shown to have anxiolytic, antipsychotic and neuroprotective properties. In addition, basic and clinical investigations on the effects of CBD have been carried out in the context of many other health conditions, including its potential use in epilepsy, substance abuse and dependence, schizophrenia, social phobia, post-traumatic stress, depression, bipolar disorder, sleep disorders, and Parkinson.

CBD is an useful and promising molecule that may help patients with a number of clinical conditions. Controlled clinical trials with different neuropsychiatric populations that are currently under investigation should bring important answers in the near future and support the translation of research findings to clinical settings.”

https://www.ncbi.nlm.nih.gov/pubmed/30298064

https://www.frontiersin.org/articles/10.3389/fimmu.2018.02009/full

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

Antiapoptotic effects of cannabidiol in an experimental model of cognitive decline induced by brain iron overload.

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“Iron accumulation in the brain has been recognized as a common feature of both normal aging and neurodegenerative diseases. Cognitive dysfunction has been associated to iron excess in brain regions in humans. We have previously described that iron overload leads to severe memory deficits, including spatial, recognition, and emotional memory impairments in adult rats.

In the present study we investigated the effects of neonatal iron overload on proteins involved in apoptotic pathways, such as Caspase 8, Caspase 9, Caspase 3, Cytochrome c, APAF1, and PARP in the hippocampus of adult rats, in an attempt to establish a causative role of iron excess on cell death in the nervous system, leading to memory dysfunction.

Cannabidiol (CBD), the main non-psychotropic component of Cannabis sativa, was examined as a potential drug to reverse iron-induced effects on the parameters analyzed.

These results suggest that iron can trigger cell death pathways by inducing intrinsic apoptotic proteins. The reversal of iron-induced effects by CBD indicates that it has neuroprotective potential through its anti-apoptotic action.”

“In summary, we have shown that iron treatment in the neonatal period disrupts the apoptotic intrinsic pathway. This finding may place iron excess as a central component in neurodegenerative processes since many neurodegenerative disorders are accompanied by iron accumulation in brain regions. Moreover, indiscriminate iron supplementation to toddlers and infants, modeled here by iron overload in the neonatal period, has been considered a potential environmental risk factor for the development of neurodegenerative disorders later in life. Our findings also strongly suggest that CBD has neuroprotective effects, at least in part by blocking iron-induced apoptosis even at later stages, following iron overload, which puts CBD as a potential therapeutic agent in the treatment of neurodegenerative diseases.”

A Brief Background on Cannabis: From Plant to Medical Indications.

 Ingenta Connect

“Cannabis has been used as a medicinal plant for thousands of years.

As a result of centuries of breeding and selection, there are now over 700 varieties of cannabis that contain hundreds of compounds, including cannabinoids and terpenes.

Cannabinoids are fatty compounds that are the main biological active constituents of cannabis. Terpenes are volatile compounds that occur in many plants and have distinct odors.

Cannabinoids exert their effect on the body by binding to receptors, specifically cannabinoid receptors types 1 and 2. These receptors, together with endogenous cannabinoids and the systems for synthesis, transport, and degradation, are called the Endocannabinoid System.

The two most prevalent and commonly known cannabinoids in the cannabis plant are delta-9-tetrahydrocannabinol (THC) and cannabidiol.

The speed, strength, and type of effects of cannabis vary based on the route of administration. THC is rapidly distributed through the body to fatty tissues like the brain and is metabolized by the cytochrome P450 system to 11-hydroxy-THC, which is also psychoactive.

Cannabis and cannabinoids have been indicated for several medical conditions.

There is evidence of efficacy in the symptomatic treatment of nausea and vomiting, pain, insomnia, post-traumatic stress disorder, anxiety, loss of appetite, Tourette’s syndrome, and epilepsy. Cannabis has also been associated with treatment for glaucoma, Huntington’s Disease, Parkinson’s Disease, and dystonia, but there is not good evidence to support its efficacy. Side effects of cannabis include psychosis and anxiety, which can be severe.

Here, we provided a summary of the history of cannabis, its pharmacology, and its medical uses.”

https://www.ncbi.nlm.nih.gov/pubmed/30139415

Cannabinoid pharmacology/therapeutics in chronic degenerative disorders affecting the central nervous system.

 Biochemical Pharmacology “The endocannabinoid system (ECS) exerts a modulatory effect of important functions such as neurotransmission, glial activation, oxidative stress, or protein homeostasis.

Dysregulation of these cellular processes is a common neuropathological hallmark in aging and in neurodegenerative diseases of the central nervous system (CNS). The broad spectrum of actions of cannabinoids allows targeting different aspects of these multifactorial diseases.

In this review, we examine the therapeutic potential of the ECS for the treatment of chronic neurodegenerative diseases of the CNS focusing on Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and amyotrophic lateral sclerosis.

First, we describe the localization of the molecular components of the ECS and how they are altered under neurodegenerative conditions, either contributing to or protecting cells from degeneration.

Second, we address recent advances in the modulation of the ECS using experimental models through different strategies including the direct targeting of cannabinoid receptors with agonists or antagonists, increasing the endocannabinoid tone by the inhibition of endocannabinoid hydrolysis, and activation of cannabinoid receptor-independent effects.

Preclinical evidence indicates that cannabinoid pharmacology is complex but supports the therapeutic potential of targeting the ECS.

Third, we review the clinical evidence and discuss the future perspectives on how to bridge human and animal studies to develop cannabinoid-based therapies for each neurodegenerative disorder.

Finally, we summarize the most relevant opportunities of cannabinoid pharmacology related to each disease and the multiple unexplored pathways in cannabinoid pharmacology that could be useful for the treatment of neurodegenerative diseases.”

https://www.ncbi.nlm.nih.gov/pubmed/30121249

https://www.sciencedirect.com/science/article/abs/pii/S000629521830337X