Cannabinoids and neurodegenerative diseases.

“Although significant advances have taken place in recent years on our understanding of the molecular mechanisms of different neurodegenerative diseases, its translation into effective therapeutic treatments has not been as successful as could be expected. There is still a dramatic lack of curative treatments for the most frequent disorders and only symptomatic relief for many others. Under this perspective, the search for novel therapeutic approaches is demanding and significant attention and efforts have been directed to studying additional neurotransmission systems including the endocannabinoid system (ECS).

The neuroprotective properties of exogenous as well as endogenous cannabinoids have been known for years and the underlying molecular mechanisms have been recently unveiled. As discussed later, antioxidative, antiglutamatergic and antiinflammatory effects are now recognized as derived from cannabinoid action and are known to be of common interest for many neurodegenerative processes.

 Thus, these characteristics make cannabinoids attractive candidates for the development of novel therapeutic strategies.

 The present review will focus on the existing data regarding the possible usefulness of cannabinoid agents for the treatment of relevant neurological pathologies for our society such as Alzheimer’s disease, multiple sclerosis, Huntington’s disease and amyotrophic lateral sclerosis.”

http://www.ncbi.nlm.nih.gov/pubmed/19839933

Distribution patterns of cannabinoid CB1 receptors in the hippocampus of APPswe/PS1ΔE9 double transgenic mice.

Abstract

“Cannabinoids have neuroprotective effects that are exerted primarily through cannabinoid CB1 receptors in the brain. This study characterized CB1 receptor distribution in the double transgenic (dtg) APP(swe)/PS1(ΔE9) mouse model for Alzheimer’s disease. Immunohistochemical labeling of CB1 protein in non-transgenic mice revealed that CB1 was highly expressed in the hippocampus, with the greatest density of CB1 protein observed in the combined hippocampal subregions CA2 and CA3 (CA2/3). CB1 immunoreactivity in the CA1 and CA2/3 hippocampal regions was significantly decreased in the dtg APP(swe)/PS1(ΔE9) mice compared to non-transgenic littermates. Reduced CB1 expression in dtg APP(swe)/PS1(ΔE9) mice was associated with astroglial proliferation and elevated expression of the cytokines inducible nitric oxide synthase and tumor necrosis factor alpha. This finding suggests an anti-inflammatory effect of cannabinoids that is mediated by CB1 receptor, particularly in the CA2/3 region of the hippocampus. Furthermore, the study suggests a decreased CB1 receptor expression may result in diminished anti-inflammatory processes, exacerbating the neuropathology associated with Alzheimer’s disease.”

http://www.ncbi.nlm.nih.gov/pubmed/21192920

Functional autoradiography shows unaltered cannabinoid CB1 receptor signalling in hippocampus and cortex of APP/PS1 transgenic mice.

Abstract

“The cannabinoid CB1-receptor is among the most abundant G-protein-coupled receptors in the mammalian brain. Whereas post-mortem studies in Alzheimer´s disease (AD) brains compared to age-matched controls have reported decreased CB1-receptor binding but no change in their protein levels (immunoreactivity), decreased or increased CB1-receptor protein levels have been reported in APP/PS1 transgenic mice modelling AD. To complete the picture, the present study used functional autoradiography to assess CB1-receptor-dependent Gi protein activation in the hippocampus, entorhinal cortex and medial frontal cortex of 13- to14-month-old female APPswe/PS1dE9 transgenic and wild-type littermate control mice. The mouse brains were processed for [35S]GTPγS autoradiography so that brain sections were analysed in pairs of one transgenic and one control mouse brain. The autoradiography protocol was completed for each pair both in the absence and presence of dithiotreitol (DTT) to reveal possible redox-dependent alterations in CB1 receptor function. Five treatments were used: baseline, incubation with 10 μM GTPγS to assess non-specific binding, and CB1 receptor agonist CP55,940 in three concentrations. By and large we found no statistically significant differences between the APP/PS1 transgenic and control mice in CB1 receptor signalling. The only exception was a modest redox-dependent alteration in entorhinal cortical CB1 receptors between the genotypes. Thus, in accordance with the majority of earlier human AD findings, we did not find evidence for notable changes in the number of functional CB1 receptors in the common APPswe/PS1dE9 mouse model of AD.”

http://www.ncbi.nlm.nih.gov/pubmed/23244427

Nonpsychoactive Cannabidiol Prevents Prion Accumulation and Protects Neurons against Prion Toxicity

“Creutzfeldt–Jakob disease (CJD) in humans belongs to a group of fatal neurodegenerative disorders called transmissible spongiform encephalopathies (TSEs) or prion diseases. No therapeutic treatments against TSEs are currently available. The urgent need to find effective anti-prion therapies has been strengthened by the emergence of variant CJD (vCJD) caused by contaminated beef consumption …

Our results suggest that CBD may protect neurons against the multiple molecular and cellular factors involved in the different steps of the neurodegenerative process, which takes place during prion infection. When combined with its ability to target the brain and its lack of toxic side effects, CBD may represent a promising new anti-prion drug.

Overall, CBD is a promising therapeutic drug against the TSEs because it combines several crucial characteristics. It has a low toxicity and lack of psychotropic side effects as well as in vivo neuroprotective, anti-inflammatory, and anti-PrPres properties. Because CBD easily crosses the BBB, it also has the potential to be effective after prion infection has reached the CNS. Finally, prolonged treatments with CBD do not induce tolerance, a phenomenon frequently observed with THC. Additional investigations should be performed to define the optimal dose, route, frequency, and duration of the in vivo CBD treatment necessary to prevent TSE infection…”

http://www.jneurosci.org/content/27/36/9537.full

The marijuana component cannabidiol inhibits beta-amyloid-induced tau protein hyperphosphorylation through Wnt/beta-catenin pathway rescue in PC12 cells.

“Alzheimer’s disease (AD) is the most common age-related neurodegenerative disorder. A massive accumulation of beta-amyloid (Abeta) peptide aggregates has been proposed as pivotal event in AD. Abeta-induced toxicity is accompanied by a variegated combination of events including oxidative stress… Cannabidiol, a non-psychoactive marijuana component, has been recently proposed as an antioxidant neuroprotective agent in neurodegenerative diseases. Moreover, it has been shown to rescue PC12 cells from toxicity induced by Abeta peptide. Here, we report that cannabidiol inhibits hyperphosphorylation of tau protein in Abeta-stimulated PC12 neuronal cells, which is one of the most representative hallmarks in AD… These results provide new molecular insight regarding the neuroprotective effect of cannabidiol and suggest its possible role in the pharmacological management of AD, especially in view of its low toxicity in humans.”

http://www.ncbi.nlm.nih.gov/pubmed/16389547

 

Effects of cannabinoids on the immune system and central nervous system: therapeutic implications.

“Cannabinoids possess immunomodulatory activity, are neuroprotective in vivo and in vitro and can modify the production of inflammatory mediators… Cannabinoid-induced immunosuppression may have implications for the treatment of neurological disorders that are associated with excess immunological activity, such as multiple sclerosis and Alzheimer’s disease. There is anecdotal evidence that cannabis use improves the symptoms of multiple sclerosis, and studies with animal models are beginning to provide evidence for the mechanism of such effects. The development of nonpsychotropic cannabinoid analogues and modulators of the metabolism of endogenous cannabinoid ligands may lead to novel approaches to the treatment of neurodegenerative disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/18031185

An amyloid β42-dependent deficit in anandamide mobilization is associated with cognitive dysfunction in Alzheimer’s disease.

“The endocannabinoids and their attending cannabinoid (CB)(1) receptors have been implicated in the control of cognition, but their possible roles in dementias are still unclear.

 The results suggest that an Aβ(42)-dependent impairment in brain anandamide mobilization contributes to cognitive dysfunction in AD.”

http://www.ncbi.nlm.nih.gov/pubmed/21546126

Amyotrophic lateral sclerosis: delayed disease progression in mice by treatment with a cannabinoid.

Abstract

“Effective treatment for amyotrophic lateral sclerosis (ALS) remains elusive. Two of the primary hypotheses underlying motor neuron vulnerability are susceptibility to excitotoxicity and oxidative damage. There is rapidly emerging evidence that the cannabinoid receptor system has the potential to reduce both excitotoxic and oxidative cell damage. Here we report that treatment with Delta(9)-tetrahydrocannabinol (Delta(9)-THC) was effective if administered either before or after onset of signs in the ALS mouse model (hSOD(G93A) transgenic mice). Administration at the onset of tremors delayed motor impairment and prolonged survival in Delta(9)-THC treated mice when compared to vehicle controls. In addition, we present an improved method for the analysis of disease progression in the ALS mouse model. This logistic model provides an estimate of the age at which muscle endurance has declined by 50% with much greater accuracy than could be attained for any other measure of decline. In vitro, Delta(9)-THC was extremely effective at reducing oxidative damage in spinal cord cultures. Additionally, Delta(9)-THC is anti-excitotoxic in vitro. These cellular mechanisms may underlie the presumed neuroprotective effect in ALS. As Delta(9)-THC is well tolerated, it and other cannabinoids may prove to be novel therapeutic targets for the treatment of ALS.”

http://www.ncbi.nlm.nih.gov/pubmed/15204022

Increasing cannabinoid levels by pharmacological and genetic manipulation delay disease progression in SOD1 mice.

“Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by the selective loss of motoneurons in the spinal cord, brain stem, and motor cortex. However, despite intensive research, an effective treatment for this disease remains elusive. In this study we show that treatment of postsymptomatic, 90-day-old SOD1G93A mice with a synthetic cannabinoid, WIN55,212-2, significantly delays disease progression…

Increasing evidence suggests that cannabinoids might have therapeutic potential in neurodegenerative conditions. In a variety of in vivo and in vitro models, cannabinoids exert neuroprotective effects under excitotoxic, ischemic, and inflammatory conditions. This combination of neuroprotective actions might be particularly relevant to ALS and suggests that cannabinoids might have a greater impact on disease progression than the established therapy that targets excitotoxicity alone.

… the neuroprotective effects observed following pharmacological and genetic augmentation of cannabinoid levels are not necessarily mediated by the CB1 receptor, and indeed inhibition of the CB1 receptor might actually be neuroprotective. Therefore, in contrast to previous studies that have suggested that cannabinoids exert neuroprotection via the CB1 receptor, the present results suggest that activation of CB2 receptors might underlie the beneficial effects of cannabinoids at least in SOD1G93A mice .”

Together these results show that cannabinoids have significant neuroprotective effects in this model of ALS and suggest that these beneficial effects may be mediated by non-CB1 receptor mechanisms.”

http://www.fasebj.org/content/20/7/1003.long

The CB2 cannabinoid agonist AM-1241 prolongs survival in a transgenic mouse model of amyotrophic lateral sclerosis when initiated at symptom onset.

“Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive motor neuron loss, paralysis and death within 2-5 years of diagnosis. Currently, no effective pharmacological agents exist for the treatment of this devastating disease. Neuroinflammation may accelerate the progression of ALS. Cannabinoids produce anti-inflammatory actions via cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2), and delay the progression of neuroinflammatory diseases…

 …treatment with non-selective cannabinoid partial agonists prior to, or upon, symptom appearance minimally delays disease onset and prolongs survival through undefined mechanisms…

…Δ9-Tetrahydrocannabinol (Δ9-THC) is the main psychoactive constituent in the plant Cannabis sativa (marijuana) and produces its effects by activation of cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2) cannabinoid receptors. CB1 receptors are expressed throughout the CNS, while CB2 receptors are expressed predominantly in immune cells and non-neuronal tissues. Therapeutic agents which modulate the cann-abinoid system are effective in treating a wide variety of disorders characterized by inflammation. More specifically, drugs which activate CB2 receptors successfully improve the symptoms of several inflammatory diseases…

More importantly, daily injections of the selective CB2 agonist AM-1241, initiated at symptom onset, increase the survival interval after disease onset by 56%. Therefore, CB2 agonists may slow motor neuron degeneration and preserve motor function, and represent a novel therapeutic modality for treatment of ALS.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819701/