Nabilone increases choreatic movements in Huntington's disease

Medicinal Cannabis and Central Nervous System Disorders

Cannabinoids, including those found in cannabis, have shown promise as potential therapeutics for numerous health issues, including pathological pain and diseases that produce an impact on neurological processing and function. Thus, cannabis use for medicinal purposes has become accepted by a growing majority. However, clinical trials yielding satisfactory endpoints and unequivocal proof that medicinal cannabis should be considered a frontline therapeutic for most examined central nervous system indications remains largely elusive. Although cannabis contains over 100 + compounds, most preclinical and clinical research with well-controlled dosing and delivery methods utilize the various formulations of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), the two most abundant compounds in cannabis. These controlled dosing and delivery methods are in stark contrast to most clinical studies using whole plant cannabis products, as few clinical studies using whole plant cannabis profile the exact composition, including percentages of all compounds present within the studied product. This review will examine both preclinical and clinical evidence that supports or refutes the therapeutic utility of medicinal cannabis for the treatment of pathological pain, neurodegeneration, substance use disorders, as well as anxiety-related disorders. We will predominately focus on purified THC and CBD, as well as other compounds isolated from cannabis for the aforementioned reasons but will also include discussion over those studies where whole plant cannabis has been used. In this review we also consider the current challenges associated with the advancement of medicinal cannabis and its derived potential therapeutics into clinical applications.

Medicinal Cannabis and Central Nervous System Disorders

Cannabinoids, including those found in cannabis, have shown promise as potential therapeutics for numerous health issues, including pathological pain and diseases that produce an impact on neurological processing and function. Thus, cannabis use for medicinal purposes has become accepted by a growing majority. However, clinical trials yielding satisfactory endpoints and unequivocal proof that medicinal cannabis should be considered a frontline therapeutic for most examined central nervous system indications remains largely elusive. Although cannabis contains over 100 + compounds, most preclinical and clinical research with well-controlled dosing and delivery methods utilize the various formulations of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), the two most abundant compounds in cannabis. These controlled dosing and delivery methods are in stark contrast to most clinical studies using whole plant cannabis products, as few clinical studies using whole plant cannabis profile the exact composition, including percentages of all compounds present within the studied product. This review will examine both preclinical and clinical evidence that supports or refutes the therapeutic utility of medicinal cannabis for the treatment of pathological pain, neurodegeneration, substance use disorders, as well as anxiety-related disorders. We will predominately focus on purified THC and CBD, as well as other compounds isolated from cannabis for the aforementioned reasons but will also include discussion over those studies where whole plant cannabis has been used. In this review we also consider the current challenges associated with the advancement of medicinal cannabis and its derived potential therapeutics into clinical applications.

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

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.

Endocannabinoid system in neurodegenerative disorders

Most neurodegenerative disorders (NDDs) are characterized by cognitive impairment and other neurological defects. The definite cause of and pathways underlying the progression of these NDDs are not well-defined. Several mechanisms have been proposed to contribute to the development of NDDs. These mechanisms may proceed concurrently or successively, and they differ among cell types at different developmental stages in distinct brain regions. The endocannabinoid system, which involves cannabinoid receptors type 1 (CB1R) and type 2 (CB2R), endogenous cannabinoids and the enzymes that catabolize these compounds, has been shown to contribute to the development of NDDs in several animal models and human studies. In this review, we discuss the functions of the endocannabinoid system in NDDs and converse the therapeutic efficacy of targeting the endocannabinoid system to rescue NDDs.

Effects of a Sativex-Like Combination of Phytocannabinoids on Disease Progression in R6/2 Mice, an Experimental Model of Huntington's Disease

Several cannabinoids afforded neuroprotection in experimental models of Huntington’s disease (HD). We investigated whether a 1:1 combination of botanical extracts enriched in either ∆⁹-tetrahydrocannabinol (∆⁹-THC) or cannabidiol (CBD), which are the main constituents of the cannabis-based medicine Sativex^®, is beneficial in R6/2 mice (a transgenic model of HD), as it was previously shown to have positive effects in neurotoxin-based models of HD. We recorded the progression of neurological deficits and the extent of striatal deterioration, using behavioral, in vivo imaging, and biochemical methods in R6/2 mice and their corresponding wild-type mice. The mice were daily treated, starting at 4 weeks after birth, with a Sativex-like combination of phytocannabinoids (equivalent to 3 mg/kg weight of pure CBD + ∆⁹-THC) or vehicle. R6/2 mice exhibited the characteristic deterioration in rotarod performance that initiated at 6 weeks and progressed up to 10 weeks, and elevated clasping behavior reflecting dystonia. Treatment with the Sativex-like combination of phytocannabinoids did not recover rotarod performance, but markedly attenuated clasping behavior. The in vivo positron emission tomography (PET) analysis of R6/2 animals at 10 weeks revealed a reduced metabolic activity in the basal ganglia, which was partially attenuated by treatment with the Sativex-like combination of phytocannabinoids. Proton nuclear magnetic resonance spectroscopy (H⁺-MRS) analysis of the ex vivo striatum of R6/2 mice at 12 weeks revealed changes in various prognostic markers reflecting events typically found in HD patients and animal models, such as energy failure, mitochondrial dysfunction, and excitotoxicity. Some of these changes (taurine/creatine, taurine/N-acetylaspartate, and N-acetylaspartate/choline ratios) were completely reversed by treatment with the Sativex-like combination of phytocannabinoids. A Sativex-like combination of phytocannabinoids administered to R6/2 mice at the onset of motor symptoms produced certain benefits on the progression of striatal deterioration in these mice, which supports the interest of this cannabinoid-based medicine for the treatment of disease progression in HD patients.

Marijuana Compounds: A Nonconventional Approach to Parkinson's Disease Therapy

Parkinson's disease (PD), a neurodegenerative disorder, is the second most common neurological illness in United States. Neurologically, it is characterized by the selective degeneration of a unique population of cells, the nigrostriatal dopamine neurons. The current treatment is symptomatic and mainly involves replacement of dopamine deficiency. This therapy improves only motor symptoms of Parkinson's disease and is associated with a number of adverse effects including dyskinesia. Therefore, there is unmet need for more comprehensive approach in the management of PD. Cannabis and related compounds have created significant research interest as a promising therapy in neurodegenerative and movement disorders. In this review we examine the potential benefits of medical marijuana and related compounds in the treatment of both motor and nonmotor symptoms as well as in slowing the progression of the disease. The potential for cannabis to enhance the quality of life of Parkinson's patients is explored.

From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Pharmacology

Apart from having been used and misused for at least four millennia for, among others, recreational and medicinal purposes, the cannabis plant and its most peculiar chemical components, the plant cannabinoids (phytocannabinoids), have the merit to have led humanity to discover one of the most intriguing and pleiotropic endogenous signaling systems, the endocannabinoid system (ECS). This review article aims to describe and critically discuss, in the most comprehensive possible manner, the multifaceted aspects of 1) the pharmacology and potential impact on mammalian physiology of all major phytocannabinoids, and not only of the most famous one Δ9-tetrahydrocannabinol, and 2) the adaptive pro-homeostatic physiological, or maladaptive pathological, roles of the ECS in mammalian cells, tissues, and organs. In doing so, we have respected the chronological order of the milestones of the millennial route from medicinal/recreational cannabis to the ECS and beyond, as it is now clear that some of the early steps in this long path, which were originally neglected, are becoming important again. The emerging picture is rather complex, but still supports the belief that more important discoveries on human physiology, and new therapies, might come in the future from new knowledge in this field.

Cannabis in the Treatment of Dystonia, Dyskinesias, and Tics

Cannabis has been used for many medicinal purposes, including management of spasms, dystonia, and dyskinesias, with variable success. Its use for tetanus was described in the second century BCE, but the literature continues to include more case reports and surveys of its beneficial effects in managing symptoms of hyperkinetic movement disorders than randomized controlled trials, making evidence-based recommendations difficult. This paper reviews clinical research using various formulations of cannabis (botanical products, oral preparations containing ∆(9)-tetrahydrocannabinol and/or cannabidiol) and currently available preparations in the USA (nabilone and dronabinol). This has been expanded from a recent systematic review of cannabis use in several neurologic conditions to include case reports and case series and results of anonymous surveys of patients using cannabis outside of medical settings, with the original evidence classifications marked for those papers that followed research protocols. Despite overlap in some patients, dyskinesias will be treated separately from dystonia and chorea; benefit was not established beyond individual patients for these conditions. Tics, usually due to Tourettes, did respond to cannabis preparations. Side effects reported in the trials will be reviewed but those due to recreational use, including the dystonia that can be secondary to synthetic marijuana preparations, are outside the scope of this paper.

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

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.

The therapeutic potential of cannabinoids for movement disorders

There is growing interest in the therapeutic potential of marijuana (cannabis) and cannabinoid-based chemicals within the medical community and, particularly, for neurological conditions. This interest is driven both by changes in the legal status of cannabis in many areas and increasing research into the roles of endocannabinoids within the central nervous system and their potential as symptomatic and/or neuroprotective therapies. We review basic science as well as preclinical and clinical studies on the therapeutic potential of cannabinoids specifically as it relates to movement disorders. The pharmacology of cannabis is complex, with over 60 neuroactive chemicals identified to date. The endocannabinoid system modulates neurotransmission involved in motor function, particularly within the basal ganglia. Preclinical research in animal models of several movement disorders have shown variable evidence for symptomatic benefits, but more consistently suggest potential neuroprotective effects in several animal models of Parkinson's (PD) and Huntington's disease (HD). Clinical observations and clinical trials of cannabinoid-based therapies suggests a possible benefit of cannabinoids for tics and probably no benefit for tremor in multiple sclerosis or dyskinesias or motor symptoms in PD. Data are insufficient to draw conclusions regarding HD, dystonia, or ataxia and nonexistent for myoclonus or RLS. Despite the widespread publicity about the medical benefits of cannabinoids, further preclinical and clinical research is needed to better characterize the pharmacological, physiological, and therapeutic effects of this class of drugs in movement disorders.

Neuroprotective properties of cannabigerol in Huntington's disease: studies in R6/2 mice and 3-nitropropionate-lesioned mice

Different plant-derived and synthetic cannabinoids have shown to be neuroprotective in experimental models of Huntington's disease (HD) through cannabinoid receptor-dependent and/or independent mechanisms. Herein, we studied the effects of cannabigerol (CBG), a nonpsychotropic phytocannabinoid, in 2 different in vivo models of HD. CBG was extremely active as neuroprotectant in mice intoxicated with 3-nitropropionate (3NP), improving motor deficits and preserving striatal neurons against 3NP toxicity. In addition, CBG attenuated the reactive microgliosis and the upregulation of proinflammatory markers induced by 3NP, and improved the levels of antioxidant defenses that were also significantly reduced by 3NP. We also investigated the neuroprotective properties of CBG in R6/2 mice. Treatment with this phytocannabinoid produced a much lower, but significant, recovery in the deteriorated rotarod performance typical of R6/2 mice. Using HD array analysis, we were able to identify a series of genes linked to this disease (e.g., symplekin, Sin3a, Rcor1, histone deacetylase 2, huntingtin-associated protein 1, δ subunit of the gamma-aminobutyric acid-A receptor (GABA-A), and hippocalcin), whose expression was altered in R6/2 mice but partially normalized by CBG treatment. We also observed a modest improvement in the gene expression for brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1), and peroxisome proliferator-activated receptor-γ (PPARγ), which is altered in these mice, as well as a small, but significant, reduction in the aggregation of mutant huntingtin in the striatal parenchyma in CBG-treated animals. In conclusion, our results open new research avenues for the use of CBG, alone or in combination with other phytocannabinoids or therapies, for the treatment of neurodegenerative diseases such as HD.

Cannabinoids: new promising agents in the treatment of neurological diseases

Nowadays, Cannabis sativa is considered the most extensively used narcotic. Nevertheless, this fame obscures its traditional employ in native medicine of South Africa, South America, Turkey, Egypt and in many regions of Asia as a therapeutic drug. In fact, the use of compounds containing Cannabis and their introduction in clinical practice is still controversial and strongly limited by unavoidable psychotropic effects. So, overcoming these adverse effects represents the main open question on the utilization of cannabinoids as new drugs for treatment of several pathologies. To date, therapeutic use of cannabinoid extracts is prescribed in patients with glaucoma, in the control of chemotherapy-related vomiting and nausea, for appetite stimulation in patients with anorexia-cachexia syndrome by HIV, and for the treatment of multiple sclerosis symptoms. Recently, researcher efforts are aimed to employ the therapeutic potentials of Cannabis sativa in the modulation of cannabinoid receptor activity within the central nervous system, particularly for the treatment of neurodegenerative diseases, as well as psychiatric and non-psychiatric disorders. This review evaluates the most recent available data on cannabinoids utilization in experimental and clinical studies, and highlights their beneficial effects in the prevention of the main neurological diseases and for the clinical treatment of symptoms with them correlated.

Hyperglycemic chorea-ballism or acute exacerbation of Huntington's chorea? Huntington's disease unmasked by diabetic ketoacidosis in type 1 diabetes mellitus

CONTENT

Hyperglycemic chorea-ballism is predominantly observed in older type 2 diabetic patients, and it is rare in type 1 diabetes and diabetic ketoacidosis (DKA). Huntington's disease (HD) is one of several genetic syndromes associated with diabetes, although the reported prevalence of the association varies. There are few opportunities for most physicians to diagnose early-stage HD.

OBJECTIVE

We describe bilateral hyperglycemic chorea-ballism in a 40-yr-old female type 1 diabetes patient with DKA and HD.

SETTING

The study was conducted in a tertiary care referral hospital.

RESULTS

On admission, the patient exhibited severe involuntary movement of bilateral extremities with DKA, and hyperglycemic chorea-ballism was diagnosed. She recovered from chorea-ballism with admission of fluids and insulin, but mild choreatic movement persisted in the upper extremities. Brain magnetic resonance imaging and DNA analysis revealed HD. Although it has been considered that depletion of striatal γ-aminobutyric acid (GABA) content is rare in DKA, it is largely decreased in HD. Therefore, it is probable that hyperglycemic chorea-ballism or exacerbation of Huntington's chorea resulted from transient depletion of GABA.

CONCLUSION

The present case provides important insights on the role of GABA in hyperglycemic chorea-ballism and on the clinical issues associated with HD diagnosis.

Sativex-like combination of phytocannabinoids is neuroprotective in malonate-lesioned rats, an inflammatory model of Huntington's disease: role of CB1 and CB2 receptors

We have investigated whether a 1:1 combination of botanical extracts enriched in either Δ(9)-tetrahydrocannabinol (Δ(9)-THC) or cannabidiol (CBD), which are the main constituents of the cannabis-based medicine Sativex, is neuroprotective in Huntington's disease (HD), using an experimental model of this disease generated by unilateral lesions of the striatum with the mitochondrial complex II inhibitor malonate. This toxin damages striatal neurons by mechanisms that primarily involve apoptosis and microglial activation. We monitored the extent of this damage and the possible preservation of the striatal parenchyma by treatment with a Sativex-like combination of phytocannabinoids using different histological and biochemical markers. Results were as follows: (i) malonate increased the volume of edema measured by in vivo NMR imaging and the Sativex-like combination of phytocannabinoids partially reduced this increase; (ii) malonate reduced the number of Nissl-stained cells, while enhancing the number of degenerating cells stained with FluoroJade-B, and the Sativex-like combination of phytocannabinoids reversed both effects; (iii) malonate caused a strong glial activation (i.e., reactive microglia labeled with Iba-1, and astrogliosis labeled with GFAP) and the Sativex-like combination of phytocannabinoids attenuated both responses; and (iv) malonate increased the expression of inducible nitric oxide synthase and the neurotrophin IGF-1, and both responses were attenuated after the treatment with the Sativex-like combination of phytocannabinoids. We also wanted to establish whether targets within the endocannabinoid system (i.e., CB(1) and CB(2) receptors) are involved in the beneficial effects induced in this model by the Sativex-like combination of phytocannabinoids. This we did using selective antagonists for both receptor types (i.e., SR141716 and AM630) combined with the Sativex-like phytocannabinoid combination. Our results indicated that the effects of this combination are blocked by these antagonists and hence that they do result from an activation of both CB(1) and CB(2) receptors. In summary, this study provides preclinical evidence in support of a beneficial effect of the cannabis-based medicine Sativex as a neuroprotective agent capable of delaying signs of disease progression in a proinflammatory model of HD, which adds to previous data obtained in models priming oxidative mechanisms of striatal injury. However, the interest here is that, in contrast with these previous data, we have now obtained evidence that both CB(1) and CB(2) receptors appear to be involved in the effects produced by a Sativex-like phytocannabinoid combination, thus stressing the broad-spectrum properties of Sativex that may combine activity at the CB(1) and/or CB(2) receptors with cannabinoid receptor-independent actions.

Prospects for cannabinoid therapies in basal ganglia disorders

Cannabinoids are promising medicines to slow down disease progression in neurodegenerative disorders including Parkinson's disease (PD) and Huntington's disease (HD), two of the most important disorders affecting the basal ganglia. Two pharmacological profiles have been proposed for cannabinoids being effective in these disorders. On the one hand, cannabinoids like Δ(9) -tetrahydrocannabinol or cannabidiol protect nigral or striatal neurons in experimental models of both disorders, in which oxidative injury is a prominent cytotoxic mechanism. This effect could be exerted, at least in part, through mechanisms independent of CB(1) and CB(2) receptors and involving the control of endogenous antioxidant defences. On the other hand, the activation of CB(2) receptors leads to a slower progression of neurodegeneration in both disorders. This effect would be exerted by limiting the toxicity of microglial cells for neurons and, in particular, by reducing the generation of proinflammatory factors. It is important to mention that CB(2) receptors have been identified in the healthy brain, mainly in glial elements and, to a lesser extent, in certain subpopulations of neurons, and that they are dramatically up-regulated in response to damaging stimuli, which supports the idea that the cannabinoid system behaves as an endogenous neuroprotective system. This CB(2) receptor up-regulation has been found in many neurodegenerative disorders including HD and PD, which supports the beneficial effects found for CB(2) receptor agonists in both disorders. In conclusion, the evidence reported so far supports that those cannabinoids having antioxidant properties and/or capability to activate CB(2) receptors may represent promising therapeutic agents in HD and PD, thus deserving a prompt clinical evaluation.

Loss of striatal type 1 cannabinoid receptors is a key pathogenic factor in Huntington's disease

Endocannabinoids act as neuromodulatory and neuroprotective cues by engaging type 1 cannabinoid receptors. These receptors are highly abundant in the basal ganglia and play a pivotal role in the control of motor behaviour. An early downregulation of type 1 cannabinoid receptors has been documented in the basal ganglia of patients with Huntington's disease and animal models. However, the pathophysiological impact of this loss of receptors in Huntington's disease is as yet unknown. Here, we generated a double-mutant mouse model that expresses human mutant huntingtin exon 1 in a type 1 cannabinoid receptor-null background, and found that receptor deletion aggravates the symptoms, neuropathology and molecular pathology of the disease. Moreover, pharmacological administration of the cannabinoid Δ(9)-tetrahydrocannabinol to mice expressing human mutant huntingtin exon 1 exerted a therapeutic effect and ameliorated those parameters. Experiments conducted in striatal cells show that the mutant huntingtin-dependent downregulation of the receptors involves the control of the type 1 cannabinoid receptor gene promoter by repressor element 1 silencing transcription factor and sensitizes cells to excitotoxic damage. We also provide in vitro and in vivo evidence that supports type 1 cannabinoid receptor control of striatal brain-derived neurotrophic factor expression and the decrease in brain-derived neurotrophic factor levels concomitant with type 1 cannabinoid receptor loss, which may contribute significantly to striatal damage in Huntington's disease. Altogether, these results support the notion that downregulation of type 1 cannabinoid receptors is a key pathogenic event in Huntington's disease, and suggest that activation of these receptors in patients with Huntington's disease may attenuate disease progression.

Cannabinoids and Dementia: A Review of Clinical and Preclinical Data

The endocannabinoid system has been shown to be associated with neurodegenerative diseases and dementia. We review the preclinical and clinical data on cannabinoids and four neurodegenerative diseases: Alzheimer’s disease (AD), Huntington’s disease (HD), Parkinson’s disease (PD) and vascular dementia (VD). Numerous studies have demonstrated an involvement of the cannabinoid system in neurotransmission, neuropathology and neurobiology of dementias. In addition, several candidate compounds have demonstrated efficacy in vitro. However, some of the substances produced inconclusive results in vivo. Therefore, only few trials have aimed to replicate the effects seen in animal studies in patients. Indeed, the literature on cannabinoid administration in patients is scarce. While preclinical findings suggest causal treatment strategies involving cannabinoids, clinical trials have only assessed the suitability of cannabinoid receptor agonists, antagonists and cannabidiol for the symptomatic treatment of dementia. Further research is needed, including in vivo models of dementia and human studies.

The therapeutic potential of G-protein coupled receptors in Huntington's disease

Huntington's disease is a late-onset autosomal dominant inherited neurodegenerative disease characterised by increased symptom severity over time and ultimately premature death. An expanded CAG repeat sequence in the huntingtin gene leads to a polyglutamine expansion in the expressed protein, resulting in complex dysfunctions including cellular excitotoxicity and transcriptional dysregulation. Symptoms include cognitive deficits, psychiatric changes and a movement disorder often referred to as Huntington's chorea, which involves characteristic involuntary dance-like writhing movements. Neuropathologically Huntington's disease is characterised by neuronal dysfunction and death in the striatum and cortex with an overall decrease in cerebral volume (Ho et al., 2001). Neuronal dysfunction begins prior to symptom presentation, and cells of particular vulnerability include the striatal medium spiny neurons. Huntington's is a devastating disease for patients and their families and there is currently no cure, or even an effective therapy for disease symptoms. G-protein coupled receptors are the most abundant receptor type in the central nervous system and are linked to complex downstream pathways, manipulation of which may have therapeutic application in many neurological diseases. This review will highlight the potential of G-protein coupled receptor drug targets as emerging therapies for Huntington's disease.

A pilot study using nabilone for symptomatic treatment in Huntington's disease

Pilot study of nabilone in Huntington's disease (HD). Double-blind, placebo-controlled, cross-over study of nabilone versus placebo. Primary outcome, Unified Huntington's Disease Rating Scale (UHDRS) total motor score. Secondary measures: UHDRS subsections for chorea, cognition and behavior, and neuropsychiatric inventory (NPI). 44 randomized patients received either nabilone (1 or 2 mg) followed by placebo (n = 22), or placebo followed by nabilone (n = 22). Recruiting was straightforward. Nabilone safe and well tolerated, no psychotic episodes. Assessment of either dose of nabilone versus placebo showed a treatment difference of 0.86 (95% CI: -1.8 to 3.52) for total motor score; 1.68 (95% CI: 0.44 to 2.92) for chorea; 3.57 (95% CI: -3.41 to 10.55) for UHDRS cognition; 4.01 (95% CI: -0.11 to 8.13) for UHDRS behavior, and 6.43 (95% CI: 0.2 to 12.66) for the NPI. Larger longer RCT of nabilone in HD is feasible and warranted.

The endocannabinoid system as a target for the treatment of motor dysfunction

There is evidence that cannabinoid-based medicines that are selective for different targets in the cannabinoid signalling system (e.g. receptors, inactivation mechanism, enzymes) might be beneficial in basal ganglia disorders, namely Parkinson's disease (PD) and Huntington's disease (HD). These benefits not only include the alleviation of specific motor symptoms [e.g. choreic movements with cannabinoid receptor type 1 (CB(1))/transient receptor potential vanilloid type 1 agonists in HD; bradykinesia with CB(1) antagonists and tremor with CB(1) agonists in PD], but also the delay of disease progression due to the neuroprotective properties demonstrated for cannabinoids (e.g. CB(1) agonists reduce excitotoxicity; CB(2) agonists limit the toxicity of reactive microglia; and antioxidant cannabinoids attenuate oxidative damage). In addition, extensive biochemical, anatomical, physiological and pharmacological studies have demonstrated that: (i) the different elements of the cannabinoid system are abundant in basal ganglia structures and they are affected by these disorders; (ii) the cannabinoid system plays a prominent role in basal ganglia function by modulating the neurotransmitters that operate in the basal ganglia circuits, both in healthy and pathological conditions; and (iii) the activation and/or inhibition of the cannabinoid system is associated with important motor responses that are maintained and even enhanced in conditions of malfunctioning and/or degeneration. In this article we will review the available data regarding the relationship between the cannabinoid system and basal ganglia activity, both in healthy and pathological conditions and will also try to identify future lines of research expected to increase current knowledge about the potential therapeutic benefits of targeting this system in PD, HD and other basal ganglia disorders.

The Toxicology of Cannabis and Cannabis Prohibition

The acute side effects caused by cannabis use are mainly related to psyche and cognition, and to circulation. Euphoria, anxiety, changes in sensory perception, impairment of memory and psychomotor performance are common effects after a dose is taken that exceeds an individually variable threshold. Cannabis consumption may increase heart rate and change blood pressure, which may have serious consequences in people with heart disease. Effects of chronic use may be induction of psychosis and development of dependency to the drug. Effects on cognitive abilities seem to be reversible after abstinence, except possibly in very heavy users. Cannabis exposure in utero may have negative consequences on brain development with subtle impairment of cognitive abilities in later life. Consequences of cannabis smoking may be similar to those of tobacco smoking and should be avoided. Use by young people has more detrimental effects than use by adults. There appear to be promising therapeutic uses of cannabis for a range of indications. Use of moderate doses in a therapeutic context is usually not associated with severe side effects. Current prohibition on cannabis use may also have harmful side effects for the individual and the society, while having little influence on prevalence of use. Harm is greatest for seriously ill people who may benefit from a treatment with cannabis. This makes it difficult to justify criminal penalties against patients.

A systematic review of the treatment studies in Huntington's disease since 1990

Huntington's disease (HD) is an autosomal dominant, inherited, neuropsychiatric disease that gives rise to progressive motor, cognitive and behavioural symptoms. Current drug therapy has no effect on the progression of disability, and the need for any pharmacological treatment should be carefully considered. Hyperkinesias and psychiatric symptoms may respond well to pharmacotherapy, but neuropsychological deficits and dementia remain untreatable. Pharmacological intervention in the treatment of the movement disorder of HD is aimed at restoring the balance of neurotransmitters in the basal ganglia. A surprising amount of current drug therapy of HD in clinical practice is based on studies published before 1990. The authors conducted a systematic review of pharmacological therapy in HD using the available papers that were published between 1990 and 2006.

The endocannabinoid system as an emerging target of pharmacotherapy

The recent identification of cannabinoid receptors and their endogenous lipid ligands has triggered an exponential growth of studies exploring the endocannabinoid system and its regulatory functions in health and disease. Such studies have been greatly facilitated by the introduction of selective cannabinoid receptor antagonists and inhibitors of endocannabinoid metabolism and transport, as well as mice deficient in cannabinoid receptors or the endocannabinoid-degrading enzyme fatty acid amidohydrolase. In the past decade, the endocannabinoid system has been implicated in a growing number of physiological functions, both in the central and peripheral nervous systems and in peripheral organs. More importantly, modulating the activity of the endocannabinoid system turned out to hold therapeutic promise in a wide range of disparate diseases and pathological conditions, ranging from mood and anxiety disorders, movement disorders such as Parkinson's and Huntington's disease, neuropathic pain, multiple sclerosis and spinal cord injury, to cancer, atherosclerosis, myocardial infarction, stroke, hypertension, glaucoma, obesity/metabolic syndrome, and osteoporosis, to name just a few. An impediment to the development of cannabinoid medications has been the socially unacceptable psychoactive properties of plant-derived or synthetic agonists, mediated by CB(1) receptors. However, this problem does not arise when the therapeutic aim is achieved by treatment with a CB(1) receptor antagonist, such as in obesity, and may also be absent when the action of endocannabinoids is enhanced indirectly through blocking their metabolism or transport. The use of selective CB(2) receptor agonists, which lack psychoactive properties, could represent another promising avenue for certain conditions. The abuse potential of plant-derived cannabinoids may also be limited through the use of preparations with controlled composition and the careful selection of dose and route of administration. The growing number of preclinical studies and clinical trials with compounds that modulate the endocannabinoid system will probably result in novel therapeutic approaches in a number of diseases for which current treatments do not fully address the patients' need. Here, we provide a comprehensive overview on the current state of knowledge of the endocannabinoid system as a target of pharmacotherapy.

[The endogenous cannabinoid system. Therapeutic implications for neurologic and psychiatric disorders]

For about 5,000 years, cannabis has been used as a therapeutic agent. There has been growing interest in the medical use of cannabinoids. This is based on the discovery that cannabinoids act with specific receptors (CB1 and CB2). CB1 receptors are located in specific brain areas (e.g. cerebellum, basal ganglia, and hippocampus) and CB2 receptors on cells of the immune system. Endogenous ligands of the cannabinoid receptors were also discovered (e.g. anandamids). Many physiologic processes are modulated by the two subtypes of cannabinoid receptor: motor functions, memory, appetite, and pain. These innovative neurobiologic/pharmacologic findings could possibly lead to the use of synthetic and natural cannabinoids as therapeutic agents in various areas. Until now, cannabinoids were used as antiemetic agents in chemotherapy-induced emesis and in patients with HIV-wasting syndrome. Evidence suggests that cannabinoids may prove useful in some other diseases, e.g. movement disorders such as Gilles de la Tourette's syndrome, multiple sclerosis, and pain. These new findings also explain the acute adverse effects following cannabis use.

Arvanil, a hybrid endocannabinoid and vanilloid compound, behaves as an antihyperkinetic agent in a rat model of Huntington's disease

The present study was designed to examine whether arvanil (N-arachidonoyl-vanillyl-amide), an endocannabinoid/vanilloid structural "hybrid", might provide symptom relief in the rat model of Huntington's disease (HD) generated by bilateral intrastriatal application of 3-nitropropionic acid (3-NP), where previous evidence suggests that hybrid cannabinoid/vanilloid compounds might be effective. As expected, arvanil did reduce ambulation, stereotypic activity, and number of hole entries, and increased the inactivity, in control rats. It was also active in 3-NP-lesioned rats, where, despite its lowering effects on stereotypic activity and number of hole entries, arvanil reduced the hyperkinesia (increased ambulation) typical of these rats, and also increased the inactivity, these two effects being more moderate than those found in control rats. Arvanil caused its antihyperkinetic effects in 3-NP-lesioned rats presumably by enhancing excitatory transmission at the globus pallidus, since it increased glutamate content in this region. This contrasts with its effects in control rats where arvanil enhanced GABA transmission at the globus pallidus. In summary, arvanil does alleviate hyperkinesia typical of HD, although it also affects locomotion in normal rats. Nevertheless, considering the lack of efficacious pharmacological treatments in this basal ganglia disorder, our findings might provide the basis for the development of more specific drugs against HD.

Cannabinoid control of motor function at the basal ganglia

Classic and novel data strengthen the idea of a prominent role for the endocannabinoid signaling system in the control of movement. This finding is supported by three-fold evidence: (1) the abundance of the cannabinoid CB1 receptor subtype, but also of CB2 and vanilloid VR1 receptors, as well as of endocannabinoids in the basal ganglia and the cerebellum, the areas that control movement; (2) the demonstration of a powerful action, mostly of an inhibitory nature, of plant-derived, synthetic, and endogenous cannabinoids on motor activity, exerted by modulating the activity of various classic neurotransmitters; and (3) the occurrence of marked changes in endocannabinoid transmission in the basal ganglia of humans affected by several motor disorders, an event corroborated in animal models of these neurological diseases. This three-fold evidence has provided support to the idea that cannabinoid-based compounds, which act at key steps of the endocannabinoid transmission [receptors, transporter, fatty acid amide hydrolase (FAAH)], might be of interest because of their potential ability to alleviate motor symptoms and/or provide neuroprotection in a variety of neurological pathologies directly affecting basal ganglia structures, such as Parkinson's disease and Huntington's chorea, or indirectly, such as multiple sclerosis and Alzheimer's disease. The present chapter will review the knowledge on this issue, trying to establish future lines for research into the therapeutic potential of the endocannabinoid system in motor disorders.

Cannabis et récepteurs cannabinoïdes : de la physiopathologie aux possibilités thérapeutiques

BACKGROUND

Although cannabis has been used as a medicine for several centuries, the therapeutic properties of cannabis preparations (essentially haschich and marijuana) make them far most popular as a recreational drugs.

STATE OF THE ART

Scientific studies on the effects of cannabis were advanced considerably by the identification in 1964 of cannabinoid D9-tetrahydrocannadinol (THC), recognized as the major active constituent of cannabis. Cloning of the centrally located CB1 receptor in 1990 and the identification of the first endogenous ligand of the CB1 receptor, anandamide, in 1992 further advanced our knowledge.

PERSPECTIVE AND CONCLUSIONS

Progress has incited further research on the biochemistry and pharmacology of the cannabinoids in numerous diseases of the central nervous system. In the laboratory animal, cannabinoids have demonstrated potential in motion disorders, demyelinizing disease, epilepsy, and as anti-tumor and neuroprotector agents. Several clinical studies are currently in progress, but therapeutic use of cannabinoids in humans couls be hindered by undesirable effects, particularly psychotropic effects. CB1 receptor antagonists also have interesting therapeutic potential.

[Therapeutic use of cannabinoids in neurology]

This review gives insight into the potential therapeutical role of cannabinoids in neurology. Preclinical data are presented which could give a rationale for the clinical use of cannabinoids in the fields of multiple sclerosis, spasticity, epilepsy, movement disorders, and neuroprotection after traumatic head injury or ischemic stroke. Besides, clinical data (case reports, open-label and randomised controlled studies) dealing with the therapeutical use of cannabinoids in these fields are reported and discussed. At present, clinical data are insufficient to recommend the use of cannabinoids in any neurological disease as standard therapy. Several questions still have to be answered (which cannabinoid? which way of administration? stimulation of endogenous cannabinoids? separation between desired and undesired effects?), and controlled studies are still needed to clarify the potential therapeutical role of cannabinoids in neurology.

Pharmacokinetics and pharmacodynamics of cannabinoids

Delta(9)-Tetrahydrocannabinol (THC) is the main source of the pharmacological effects caused by the consumption of cannabis, both the marijuana-like action and the medicinal benefits of the plant. However, its acid metabolite THC-COOH, the non-psychotropic cannabidiol (CBD), several cannabinoid analogues and newly discovered modulators of the endogenous cannabinoid system are also promising candidates for clinical research and therapeutic uses. Cannabinoids exert many effects through activation of G-protein-coupled cannabinoid receptors in the brain and peripheral tissues. Additionally, there is evidence for non-receptor-dependent mechanisms. Natural cannabis products and single cannabinoids are usually inhaled or taken orally; the rectal route, sublingual administration, transdermal delivery, eye drops and aerosols have only been used in a few studies and are of little relevance in practice today. The pharmacokinetics of THC vary as a function of its route of administration. Pulmonary assimilation of inhaled THC causes a maximum plasma concentration within minutes, psychotropic effects start within seconds to a few minutes, reach a maximum after 15-30 minutes, and taper off within 2-3 hours. Following oral ingestion, psychotropic effects set in with a delay of 30-90 minutes, reach their maximum after 2-3 hours and last for about 4-12 hours, depending on dose and specific effect. At doses exceeding the psychotropic threshold, ingestion of cannabis usually causes enhanced well-being and relaxation with an intensification of ordinary sensory experiences. The most important acute adverse effects caused by overdosing are anxiety and panic attacks, and with regard to somatic effects increased heart rate and changes in blood pressure. Regular use of cannabis may lead to dependency and to a mild withdrawal syndrome. The existence and the intensity of possible long-term adverse effects on psyche and cognition, immune system, fertility and pregnancy remain controversial. They are reported to be low in humans and do not preclude legitimate therapeutic use of cannabis-based drugs. Properties of cannabis that might be of therapeutic use include analgesia, muscle relaxation, immunosuppression, sedation, improvement of mood, stimulation of appetite, antiemesis, lowering of intraocular pressure, bronchodilation, neuroprotection and induction of apoptosis in cancer cells.

Compounds acting at the endocannabinoid and/or endovanilloid systems reduce hyperkinesia in a rat model of Huntington's disease

We have recently reported that the administration of AM404, an inhibitor of the endocannabinoid re-uptake process, which also has affinity for the vanilloid VR1 receptors, is able to reduce hyperkinesia, and causes recovery from neurochemical deficits, in a rat model of Huntington's disease (HD) generated by bilateral intrastriatal injections of 3-nitropropionic acid (3NP). In the present study, we wanted to explore the mechanism(s) by which AM404 produces its antihyperkinetic effect in 3NP-lesioned rats by employing several experimental approaches. First, we tried to block the effects of AM404 with selective antagonists for the CB1 or VR1 receptors, i.e. SR141716A and capsazepine, respectively. We found that the reduction caused by AM404 of the increased ambulation exhibited by 3NP-lesioned rats in the open-field test was reversed when the animals had been pre-treated with capsazepine but not with SR141716A, thus suggesting a major role of VR1 receptors in the antihyperkinetic effects of AM404. However, despite the lack of behavioral effects of the CB1 receptor antagonist, the pretreatment with this compound abolished the recovery of neurochemical [gamma-aminobutyric acid (GABA) and dopamine] deficits in the caudate- putamen caused by AM404, as also did capsazepine. In a second group of studies, we wanted to explore the potential antihyperkinetic effects of various compounds which, compared to AM404, exhibit more selectivity for either the endovanilloid or the endocannabinoid systems. First, we tested VDM11 or AM374, two selective inhibitors or the endocannabinoid re-uptake or hydrolysis, respectively. Both compounds were mostly unable to reduce hyperkinesia in 3NP-lesioned rats, although VDM11 produced a certain motor depression, and AM374 exhibited a trend to stimulate ambulation, in control rats. We also tested the effects of selective direct agonists for VR1 (capsaicin) or CB1 (CP55,940) receptors. Capsaicin exhibited a strong antihyperkinetic activity and, moreover, was able to attenuate the reductions in dopamine and GABA transmission provoked by the 3NP lesion, whereas CP55,940 had also antihyperkinetic activity but was unable to cause recovery of either dopamine or GABA deficits in the basal ganglia. In summary, our data indicate a major role for VR1 receptors, as compared to CB1 receptors, in the antihyperkinetic effects and the recovery of neurochemical deficits caused in 3NP-lesioned rats by compounds that activate both CB1 and VR1 receptors, either directly or via manipulation of the levels of endogenous agonists.

The endogenous cannabinoid system and the basal ganglia. biochemical, pharmacological, and therapeutic aspects

New data strengthen the idea of a prominent role for endocannabinoids in the modulation of a wide variety of neurobiological functions. Among these, one of the most important is the control of movement. This finding is supported by 3 lines of evidence: (1) the demonstration of a powerful action, mostly inhibitory in nature, of synthetic and plant-derived cannabinoids and, more recently, of endocannabinoids on motor activity; (2) the presence of the cannabinoid CB(1) receptor subtype and the recent description of endocannabinoids in the basal ganglia and the cerebellum, the areas that control movement; and (3) the fact that CB(1) receptor binding was altered in the basal ganglia of humans affected by several neurological diseases and also of rodents with experimentally induced motor disorders. Based on this evidence, it has been suggested that new synthetic compounds that act at key steps of endocannabinoid activity (i.e., more-stable analogs of endocannabinoids, inhibitors of endocannabinoid reuptake or metabolism, antagonists of CB(1) receptors) might be of interest for their potential use as therapeutic agents in a variety of pathologies affecting extrapyramidal structures, such as Parkinson's and Huntington's diseases. Currently, only a few data exist in the literature studying such relationships in humans, but an increasing number of journal articles are revealing the importance of this new neuromodulatory system and arguing in favour of the funding of more extensive research in this field. The present article will review the current knowledge of this neuromodulatory system, trying to establish the future lines for research on the therapeutic potential of the endocannabinoid system in motor disorders.

Endocannabinoids and basal ganglia functionality

In recent years, our knowledge on the cannabinoid pharmacology has shown a significant rise in terms of both quantity (more compounds and more targets) and quality (more selective compounds). This allows to consider cannabinoids and related compounds as a promising new line of research for therapeutic treatment of a variety of conditions, such as brain injury, chronic pain, glaucoma, asthma, cancer and AIDS-associated effects and other pathologies. Motor disorders are another promising field for the therapeutic application of cannabinoid-related compounds, since the control of movement is one of the more relevant physiological roles of the endocannabinoid transmission in the brain. There are two pathologies, Parkinson's disease and Huntington's chorea, which are particularly interesting from a clinical point of view due to the direct relationship of endocannabinoids and their receptors with neurons that degenerate in those disorders. However, other neurological pathologies, such as Alzheimer's disease or multiple sclerosis, which are not motor disorders in origin, but present a strong alteration in the control of movement, have also been a subject of interesting research for a cannabinoid therapy. This review will summarize our current knowledge on the role of these endogenous substances in the control of movement and, in particular, on the possible therapeutic usefulness of these compounds in the treatment of motor pathologies.

The role of cannabinoids in neurodegenerative diseases

An understanding of the actions of Cannabis (Marijuana) has evolved from folklore to science over the previous hundred years. This progression was spurred by the discovery of an endogenous cannabinoid system consisting of two receptors and two endogenous ligands. This system appears to be intricately involved in normal physiology, specifically in the control of movement, formation of memories and appetite control. As we are developing an increased understanding of the physiological role of endocannabinoids it is becoming clear that they may be involved in the pathology of several neurological diseases. Furthermore an array of potential therapeutic targets is being determined--including specific cannabinoid agonists and antagonists as well as compounds that interrupt the synthesis, uptake or metabolism of the endocannabinoids. This article reviews the recent progress in understanding the contribution of endocannabinoids to the pathology and therapy of Huntington's disease. Parkinson's disease, schizophrenia and tremor.

Cannabinoids in clinical practice

Cannabis has a potential for clinical use often obscured by unreliable and purely anecdotal reports. The most important natural cannabinoid is the psychoactive tetrahydrocannabinol (delta9-THC); others include cannabidiol (CBD) and cannabigerol (CBG). Not all the observed effects can be ascribed to THC, and the other constituents may also modulate its action; for example CBD reduces anxiety induced by THC. A standardised extract of the herb may be therefore be more beneficial in practice and clinical trial protocols have been drawn up to assess this. The mechanism of action is still not fully understood, although cannabinoid receptors have been cloned and natural ligands identified. Cannabis is frequently used by patients with multiple sclerosis (MS) for muscle spasm and pain, and in an experimental model of MS low doses of cannabinoids alleviated tremor. Most of the controlled studies have been carried out with THC rather than cannabis herb and so do not mimic the usual clincal situation. Small clinical studies have confirmed the usefulness of THC as an analgesic; CBD and CBG also have analgesic and antiinflammatory effects, indicating that there is scope for developing drugs which do not have the psychoactive properties of THC. Patients taking the synthetic derivative nabilone for neurogenic pain actually preferred cannabis herb and reported that it relieved not only pain but the associated depression and anxiety. Cannabinoids are effective in chemotherapy-induced emesis and nabilone has been licensed for this use for several years. Currently, the synthetic cannabinoid HU211 is undergoing trials as a protective agent after brain trauma. Anecdotal reports of cannabis use include case studies in migraine and Tourette's syndrome, and as a treatment for asthma and glaucoma. Apart from the smoking aspect, the safety profile of cannabis is fairly good. However, adverse reactions include panic or anxiety attacks, which are worse in the elderly and in women, and less likely in children. Although psychosis has been cited as a consequence of cannabis use, an examination of psychiatric hospital admissions found no evidence of this, however, it may exacerbate existing symptoms. The relatively slow elimination from the body of the cannabinoids has safety implications for cognitive tasks, especially driving and operating machinery; although driving impairment with cannabis is only moderate, there is a significant interaction with alcohol. Natural materials are highly variable and multiple components need to be standardised to ensure reproducible effects. Pure natural and synthetic compounds do not have these disadvantages but may not have the overall therapeutic effect of the herb.