Category Archives: Parkinson’s Disease

ENDOCANNABINOID SYSTEM: A multi-facet therapeutic target.

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“Cannabis sativa is also popularly known as marijuana. It is being cultivated and used by man for recreational and medicinal purposes from many centuries.

Study of cannabinoids was at bay for very long time and its therapeutic value could not be adequately harnessed due to its legal status as proscribed drug in most of the countries.

The research of drugs acting on endocannabinoid system has seen many ups and down in recent past. Presently, it is known that endocannabinoids has role in pathology of many disorders and they also serve “protective role” in many medical conditions.

Several diseases like emesis, pain, inflammation, multiple sclerosis, anorexia, epilepsy, glaucoma, schizophrenia, cardiovascular disorders, cancer, obesity, metabolic syndrome related diseases, Parkinson’s disease, Huntington’s disease, Alzheimer’s disease and Tourette’s syndrome could possibly be treated by drugs modulating endocannabinoid system.

Presently, cannabinoid receptor agonists like nabilone and dronabinol are used for reducing the chemotherapy induced vomiting. Sativex (cannabidiol and THC combination) is approved in the UK, Spain and New Zealand to treat spasticity due to multiple sclerosis. In US it is under investigation for cancer pain, another drug Epidiolex (cannabidiol) is also under investigation in US for childhood seizures. Rimonabant, CB1 receptor antagonist appeared as a promising anti-obesity drug during clinical trials but it also exhibited remarkable psychiatric side effect profile. Due to which the US Food and Drug Administration did not approve Rimonabant in US. It sale was also suspended across the EU in 2008.

Recent discontinuation of clinical trial related to FAAH inhibitor due to occurrence of serious adverse events in the participating subjects could be discouraging for the research fraternity. Despite of some mishaps in clinical trials related to drugs acting on endocannabinoid system, still lot of research is being carried out to explore and establish the therapeutic targets for both cannabinoid receptor agonists and antagonists.

One challenge is to develop drugs that target only cannabinoid receptors in a particular tissue and another is to invent drugs that acts selectively on cannabinoid receptors located outside the blood brain barrier. Besides this, development of the suitable dosage forms with maximum efficacy and minimum adverse effects is also warranted.

Another angle to be introspected for therapeutic abilities of this group of drugs is non-CB1 and non-CB2 receptor targets for cannabinoids.

In order to successfully exploit the therapeutic potential of endocannabinoid system, it is imperative to further characterize the endocannabinoid system in terms of identification of the exact cellular location of cannabinoid receptors and their role as “protective” and “disease inducing substance”, time-dependent changes in the expression of cannabinoid receptors.”

http://www.ncbi.nlm.nih.gov/pubmed/27086601

Targeting the cannabinoid CB2 receptor to attenuate the progression of motor deficits in LRRK2-transgenic mice.

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“Most of cases of Parkinson’s disease (PD) have a sporadic origin, with their causes mostly unknown, although overexposure to some environmental factors has been found to occur in some cases. Other forms of parkinsonism are the consequence of dominant or recessive mutations in specific genes, e.g. α-synuclein, parkin and, more recently, leucine-rich repeat kinase 2 (LRRK2), whose G2019S mutation represents the most prevalent form of late-onset, autosomal dominant familial PD.

A transgenic mouse model expressing the G2019S mutation of LRRK2 is already available and apparently may represent a valuable experimental model for investigating PD pathogenesis and novel treatments.

We designed a long-term study with these animals aimed at: (i) elucidating the changes experienced by the endocannabinoid signaling system in the basal ganglia during the progression of the disease in these mice, paying emphasis in the CB2 receptor, which has emerged as a promising target in PD, and (ii) evaluating the potential of compounds selectively activating this CB2 receptor, as disease-modifying agents in these mice.

Our results unequivocally demonstrate that LRRK2 transgenic mice develop motor impairment consisting of small anomalies in rotarod performance (presumably reflecting a deficit in motor coordination and dystonia) and a strong deficiency in the hanging-wire test (reflecting muscle weakness), rather than hypokinesia which was difficult to be demonstrated in the actimeter. These behavioral responses occurred in absence of any evidence of reactive gliosis and neuronal losses, as well as synaptic deterioration in the basal ganglia, except an apparent impairment in autophagy reflected by elevated LAMP-1 immunolabelling in the striatum and substantia nigra.

Furthermore, there were no changes in the status of the CB2 receptor, as well as in other elements of the endocannabinoid signaling, in the basal ganglia, but, paradoxically, the selective activation of this receptor partially reversed the deficits in the hanging-wire test of LRRK2 transgenic mice. This was accompanied by normalization in LAMP-1 immunolabelling in the basal ganglia, although it is possible that other CNS structures, remaining to be identified, are involved in the behavioral improvement.

In summary, our data support the interest of the CB2 receptor as a potential pharmacological target in LRRK2 transgenic mice, although the neuronal substrates underlying these benefits might be not completely related to the basal ganglia and to the presumed parkinsonian features of these mice.”  http://www.ncbi.nlm.nih.gov/pubmed/27063942

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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“Parkinson’s disease (PD) is characterized by the degeneration of nigrostriatal dopamine neurons.

The endocannabinoid system consists of cannabinoid receptors, their ligands and enzymes for the synthesis and degradation of cannabinoids.

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.

In summary, we demonstrated that activation of the CB2 receptor inhibits BBB damage, the expression of iNOS and proinflammatory cytokines/chemokines in activated microglia, the infiltration of T cells and astroglial expression of MPO, resulting in the survival of dopamine neurons in vivo in the MPTP mouse model of PD.

Therefore, it is likely that targeting the CB2 receptor may have therapeutic value in the treatment of aspects of PD related to neuroinflammation.”

http://www.nature.com/emm/journal/v48/n1/full/emm2015100a.html

The neuroprotection of cannabidiol against MPP+-induced toxicity in PC12 cells involves trkA receptors, upregulation of axonal and synaptic proteins, neuritogenesis, and might be relevant to Parkinson’s disease.

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“Cannabidiol (CBD) is a non-psychoactive constituent of Cannabis sativa with potential to treat neurodegenerative diseases.

Its neuroprotection has been mainly associated with anti-inflammatory and antioxidant events; however, other mechanisms might be involved.

We investigated the involvement of neuritogenesis, NGF receptors (trkA), NGF, and neuronal proteins in the mechanism of neuroprotection of CBD against MPP+ toxicity in PC12 cells…

This is the first study to report the involvement of neuronal proteins and trkA in the neuroprotection of CBD.

Our findings suggest that CBD has a neurorestorative potential independent of NGF that might contribute to its neuroprotection against MPP+, a neurotoxin relevant to Parkinson’s disease.”

http://www.ncbi.nlm.nih.gov/pubmed/26556726

Endocannabinoids and Neurodegenerative Disorders: Parkinson’s Disease, Huntington’s Chorea, Alzheimer’s Disease, and Others.

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“This review focuses on the role of the endocannabinoid signaling system in controlling neuronal survival, an extremely important issue to be considered when developing new therapies for neurodegenerative disorders.

First, we will describe the cellular and molecular mechanisms, and the signaling pathways, underlying these neuroprotective properties, including the control of glutamate homeostasis, calcium influx, the toxicity of reactive oxygen species, glial activation and other inflammatory events; and the induction of autophagy.

We will then concentrate on the preclinical studies and the few clinical trials that have been carried out targeting endocannabinoid signaling in three important chronic progressive neurodegenerative disorders (Parkinson’s disease, Huntington’s chorea, and Alzheimer’s disease), as well as in other less well-studied disorders.

We will end by offering some ideas and proposals for future research that should be carried out to optimize endocannabinoid-based treatments for these disorders.

Such studies will strengthen the possibility that these therapies will be investigated in the clinical scenario and licensed for their use in specific disorders.”

Increasing levels of the endocannabinoid 2-AG is neuroprotective in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson’s disease.

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“Parkinson’s disease (PD) is a common chronic neurodegenerative disorder, usually of idiopathic origin. Symptoms including tremor, bradykinesia, rigidity and postural instability are caused by the progressive loss of dopaminergic neurons in the nigrostriatal region of the brain.

Symptomatic therapies are available but no treatment slows or prevents the loss of neurons.

Neuroinflammation has been implicated in its pathogenesis.

To this end, the present study utilises the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin to reproduce the pattern of cell death evident in PD patients.

Herein, the role of a potential regulator of an immune response, the endocannabinoid system (ECS), is investigated.

The most prevalent endocannabinoid, 2-arachidonoylglycerol (2-AG) (3 and 5mg/kg), was added exogenously and its enzymatic degradation inhibited to provide protection against MPTP-induced cell death.

Furthermore, the addition of DFU (25mg/kg), a selective inhibitor of inflammatory mediator cyclooxygenase-2 (COX-2), potentiated these effects.

Levels of 2-AG were shown to be upregulated in a time- and region-specific manner following MPTP administration, indicating that the ECS represents a natural defence mechanism against inflammation, potentiation of which could provide therapeutic benefits.

The results expand the current understanding of the role that this signalling system has and its potential influence in PD.”

Cannabinoids in Neurodegenerative Disorders and Stroke/Brain Trauma: From Preclinical Models to Clinical Applications.

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“Cannabinoids form a singular family of plant-derived compounds (phytocannabinoids), endogenous signaling lipids (endocannabinoids), and synthetic derivatives with multiple biological effects and therapeutic applications in the central and peripheral nervous systems.

One of these properties is the regulation of neuronal homeostasis and survival, which is the result of the combination of a myriad of effects addressed to preserve, rescue, repair, and/or replace neurons, and also glial cells against multiple insults that may potentially damage these cells.

These effects are facilitated by the location of specific targets for the action of these compounds (e.g., cannabinoid type 1 and 2 receptors, endocannabinoid inactivating enzymes, and nonendocannabinoid targets) in key cellular substrates (e.g., neurons, glial cells, and neural progenitor cells).

This potential is promising for acute and chronic neurodegenerative pathological conditions. In this review, we will collect all experimental evidence, mainly obtained at the preclinical level, supporting that different cannabinoid compounds may be neuroprotective in adult and neonatal ischemia, brain trauma, Alzheimer’s disease, Parkinson’s disease, Huntington’s chorea, and amyotrophic lateral sclerosis.

This increasing experimental evidence demands a prompt clinical validation of cannabinoid-based medicines for the treatment of all these disorders, which, at present, lack efficacious treatments for delaying/arresting disease progression…”

http://www.ncbi.nlm.nih.gov/pubmed/26260390

Cannabinoids and Tremor Induced by Motor-related Disorders: Friend or Foe?

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“Tremor arises from an involuntary, rhythmic muscle contraction/relaxation cycle and is a common disabling symptom of many motor-related diseases such as Parkinson disease, multiple sclerosis, Huntington disease, and forms of ataxia.

In the wake of anecdotal, largely uncontrolled, observations claiming the amelioration of some symptoms among cannabis smokers, and the high density of cannabinoid receptors in the areas responsible for motor function, including basal ganglia and cerebellum, many researchers have pursued the question of whether cannabinoid-based compounds could be used therapeutically to alleviate tremor associated with central nervous system diseases.

In this review, we focus on possible effects of cannabinoid-based medicines, in particular on Parkinsonian and multiple sclerosis-related tremors and the common probable molecular mechanisms. While, at present, inconclusive results have been obtained, future investigations should extend preclinical studies with different cannabinoids to controlled clinical trials to determine potential benefits in tremor.”

http://www.ncbi.nlm.nih.gov/pubmed/26152606

The endocannabinoid system as a target for the treatment of neurodegenerative disease.

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“The Cannabis sativa plant has been exploited for medicinal, agricultural and spiritual purposes in diverse cultures over thousands of years.

Cannabis has been used recreationally for its psychotropic properties, while effects such as stimulation of appetite, analgesia and anti-emesis have lead to the medicinal application of cannabis.

Indeed, reports of medicinal efficacy of cannabis can been traced back as far as 2700 BC, and even at that time reports also suggested a neuroprotective effect of the cultivar.

…alterations in the endocannabinoid system have been extensively investigated in a range of neurodegenerative disorders.

In this review we examine the evidence implicating the endocannabinoid system in the cause, symptomatology or treatment of neurodegenerative disease. We examine data from human patients and compare and contrast this with evidence from animal models of these diseases. On the basis of this evidence we discuss the likely efficacy of endocannabinoid-based therapies in each disease context.

There has been anecdotal and preliminary scientific evidence of cannabis affording symptomatic relief in diverse neurodegenerative disorders. These include multiple sclerosis, Huntington’s, Parkinson’s and Alzheimer’s diseases, and amyotrophic lateral sclerosis.

This evidence implied that hypofunction or dysregulation of the endocannabinoid system may be responsible for some of the symptomatology of these diseases.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2931550/

Differential upregulation of the cannabinoid CB2 receptor in neurotoxic and inflammation-driven rat models of Parkinson’s disease.

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“The cannabinoid CB2 receptor has recently emerged as a potential anti-inflammatory target to break the self-sustaining cycle of neuroinflammation and neurodegeneration that is associated with neurodegenerative diseases.

…the aim of this study was to investigate and compare the changes that occur in the endocannabinoid system in neurotoxic and inflammation-driven models of Parkinson’s disease.

…this study has shown that the endocannabinoid system is dysregulated in animal models of Parkinson’s disease, and has also revealed significant differences in the level of dysregulation between the models themselves.

This study indicates that targeting the CB2 receptor may represent a viable target for anti-inflammatory disease modification in Parkinson’s disease.”

 http://www.ncbi.nlm.nih.gov/pubmed/25895887

http://www.thctotalhealthcare.com/category/parkinsons-disease/