Neuroprotection in oxidative stress-related neurodegenerative diseases: role of endocannabinoid system modulation.

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“Redox imbalance may lead to overproduction of reactive oxygen and nitrogen species (ROS/RNS) and subsequent oxidative tissue damage which is a critical event in the course of neurodegenerative diseases. It is still not fully elucidated, however, whether oxidative stress is the primary trigger or a consequence in process of neurodegeneration.

Recent Advances: Increasing evidence suggests that oxidative stress is involved in the propagation of neuronal injury and consequent inflammatory response, which in concert promote development of pathological alterations characteristic of most common neurodegenerative diseases.

Critical Issue: Accumulating recent evidence also suggests that there is an important interplay between the lipid endocannabinoid system (ECS; comprising of the main cannabinoid 1 and 2 receptors (CB1 and CB2), endocannabinoids and their synthetic and metabolizing enzymes) and various key inflammatory and redox-dependent processes.

FUTURE DIRECTIONS:

Targeting the ECS in order to modulate redox state-dependent cell death, and to decrease consequent or preceding inflammatory response holds therapeutic potential in multitude of oxidative stress-related acute or chronic neurodegenerative disorders from stroke and traumatic brain injury to Alzheimer`s and Parkinson`s diseases, and multiple sclerosis, just to name a few, which will be discussed in this overview.”

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Δ9-Tetrahydrocannabinol (THC) and AM 404 protect against cerebral ischaemia in gerbils through a mechanism involving cannabinoid and opioid receptors

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“It has been suggested that the endocannabinoid system elicits neuroprotection against excitotoxic brain damage.

In the present study the therapeutic potential of AM 404 on ischaemia-induced neuronal injury was investigated in vivo and compared with that of the classical cannabinoid receptor type 1 (CB1) agonist, Δ9-tetraydrocannabinol (THC), using a model of transient global cerebral ischaemia in the gerbil.

Our findings demonstrate that AM 404 and THC reduce neuronal damage caused by bilateral carotid occlusion in gerbils and that this protection is mediated through an interaction with CB1 and opioid receptors.

Endocannabinoids might form the basis for the development of new neuroprotective drugs useful for the treatment of stroke and other neurodegenerative pathologies.

There is some evidence from experiments with mice that increasing anandamide or 2-arachidonoyl glycerol content may lead to neuroprotection.

Collectively, our data demonstrate that AM 404 and THC protect against neuronal ischaemia-induced injury through a mechanism involving cannabinoid and opioid receptors but not vanilloid receptors.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2189998/

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Editorial: The CB2 Cannabinoid System: A New Strategy in Neurodegenerative Disorder and Neuroinflammation

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“The cannabinoid receptors subtype 2 (CB2R) are emerging as novel targets for the development of new therapeutic approaches and PET probes useful to early diagnose neuroinflammation as first step in several neurodegenerative disorders such as Alzheimer’s disease (AD) and Parkinson disease (PD).

This Research Topic is mainly focused on the involvment of CB2R in neurodegenerative disorders and on the usefulness of CB2R ligands in the therapy and early diagnosis of neuroinflammation as onset of neurodegeneration.

In the reviews of Aso and Ferrer and Cassano et al. an interesting and exaustive overview of the endogenous cannabinoid signaling and its role in neuroinflammation and neurogenesis is reported. The potential of CB2R as therapeutic target in AD is argued by several evidences derived by robust experimental models and the effects modulated by CB2R agonists on different pathways involved in the pathogenesis of AD are discussed; indeed, these ligands are able to reduce inflammation, Aβ production and deposition, tau protein hyper-phosphorylation and oxidative stress damage caused by Aβ peptides. CB2R agonists are also able to induce Aβ clearance leading to cognitive improvement in AD models.

In conclusion, considering that neuroinflammation has been widely reported as indicator and modulator of neurodegeneration, the reduction of the neuroinflammatory responses could be considered as a new therapeutic strategy in these diseases. Moreover, the selective CB2R overexpression on the activated-microglial cells provides also a highly specialized target useful to an early diagnosis of the neurodegenerative diseases.”

http://journal.frontiersin.org/article/10.3389/fnins.2017.00196/full

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Neurological aspects of medical use of cannabidiol.

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“Cannabidiol (CBD) is among the major secondary metabolites of Cannabis devoid of the delta-9-tetra-hydrocannabinol psychoactive effects. It is a resorcinol-based compound with a broad spectrum of potential therapeutic properties, including neuroprotective effects in numerous pathological conditions. CBD neuroprotection is due to its antioxidant and antiinflammatory activi-ties and the modulation of a large number of brain biological targets (receptors, channels) involved in the development and maintenance of neurodegenerative diseases.

OBJECTIVE:

Aim of the present review was to describe the state of art about the pre-clinical research, the potential use and, when existing, the clinical evidence related to CBD in the neurological field.

RESULTS:

Laboratory and clinical studies on the potential role of CBD in Parkinson’s disease (PD), Alzheimer’s disease (AD), multiple sclerosis (MS), Huntington’s disease (HD), amyotrophic lateral sclerosis ALS), cerebral ischemia, were examined.

CONCLUSIONS:

Pre-clinical evidence largely shows that CBD can produce beneficial effects in AD, PD and MS patients, but its employment for these disorders needs further confirmation from well designed clinical studies. CBD pre-clinical demonstration of antiepileptic activity is supported by recent clinical studies in human epileptic subjects resistant to standard antiepileptic drugs showing its potential use in children and young adults affected by refractory epilepsy. Evidence for use of CBD in PD is still not supported by sufficient data whereas only a few studies including a small number of patients are available.”

https://www.ncbi.nlm.nih.gov/pubmed/28412918

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Loss of Cannabinoid CB 1 Receptors Induces Cortical Migration Malformations and Increases Seizure Susceptibility.

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“Neuronal migration is a fundamental process of brain development, and its disruption underlies devastating neurodevelopmental disorders. The transcriptional programs governing this process are relatively well characterized. However, how environmental cues instruct neuronal migration remains poorly understood. Here, we demonstrate that the cannabinoid CB 1 receptor is strictly required for appropriate pyramidal neuron migration in the developing cortex. Acute silencing of the CB 1 receptor alters neuronal morphology and impairs radial migration. Consequently, CB 1 siRNA-electroporated mice display cortical malformations mimicking subcortical band heterotopias and increased seizure susceptibility in adulthood. Importantly, rescuing the CB 1 deficiency-induced radial migration arrest by knockdown of the GTPase protein RhoA restored the hyperexcitable neuronal network and seizure susceptibility. Our findings show that CB 1 receptor/RhoA signaling regulates pyramidal neuron migration, and that deficient CB 1 receptor signaling may contribute to cortical development malformations leading to refractory epilepsy independently of its canonical neuromodulatory role in the adult brain.”

https://www.ncbi.nlm.nih.gov/pubmed/28334226

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Neuroprotective effect of WIN55,212-2 against 3-nitropropionic acid-induced toxicity in the rat brain: involvement of CB1 and NMDA receptors.

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“The endocannabinoid system (ECS), and agonists acting on cannabinoid receptors (CBr), are known to regulate several physiological events in the brain, including modulatory actions on excitatory events probably through N-methyl-D-aspartate receptor (NMDAr) activity.

Actually, CBr agonists can be neuroprotective.

Our results demonstrate a protective role of WIN55,212-2 on the 3-NP-induced striatal neurotoxicity that could be partially related to the ECS stimulation and induction of NMDAr hypofunction, representing an effective therapeutic strategy at the experimental level for further studies.”

https://www.ncbi.nlm.nih.gov/pubmed/28337258

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

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“Several cannabinoids afforded in experimental models of Huntington’s disease (HD).

We investigated whether a 1:1 combination of botanical extracts enriched in either ∆⁸-tetrahydrocannabinol (∆⁸-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.

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.”

https://www.ncbi.nlm.nih.gov/pubmed/28333097

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Cell-Autonomous Excitation of Midbrain Dopamine Neurons by Endocannabinoid-Dependent Lipid Signaling.

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“The major endocannabinoid in the mammalian brain is the bioactive lipid 2-arachidonoylglycerol (2-AG). The best-known effects of 2-AG are mediated by G-protein-coupled cannabinoid receptors. In principle, 2-AG could modify neuronal excitability by acting directly on ion channels, but such mechanisms are poorly understood.

Using a preparation of dissociated mouse midbrain dopamine neurons to isolate effects on intrinsic excitability, we found that 100 nM 2-AG accelerated pacemaking and steepened the frequency-current relationship for burst-like firing. In voltage-clamp experiments, 2-AG reduced A-type potassium current (IA) through a cannabinoid receptor-independent mechanism mimicked by arachidonic acid, which has no activity on cannabinoid receptors. Activation of orexin, neurotensin, and metabotropic glutamate Gq/11-linked receptors mimicked the effects of exogenous 2-AG and their actions were prevented by inhibiting the 2-AG-synthesizing enzyme diacylglycerol lipase α.

The results show that 2-AG and related lipid signaling molecules can directly tune neuronal excitability in a cell-autonomous manner by modulating IA.”

https://www.ncbi.nlm.nih.gov/pubmed/28262417

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Inflammatory Regulation by Driving Microglial M2 Polarization: Neuroprotective Effects of Cannabinoid Receptor-2 Activation in Intracerebral Hemorrhage.

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“The cannabinoid receptor-2 (CB2R) was initially thought to be the “peripheral cannabinoid receptor.” Recent studies, however, have documented CB2R expression in the brain in both glial and neuronal cells, and increasing evidence suggests an important role for CB2R in the central nervous system inflammatory response.

Intracerebral hemorrhage (ICH), which occurs when a diseased cerebral vessel ruptures, accounts for 10-15% of all strokes. Although surgical techniques have significantly advanced in the past two decades, ICH continues to have a high mortality rate.

The aim of this study was to investigate the therapeutic effects of CB2R stimulation in acute phase after experimental ICH in rats and its related mechanisms.

These findings demonstrated that CB2R stimulation significantly protected the brain damage and suppressed neuroinflammation by promoting the acquisition of microglial M2 phenotype in acute stage after ICH.

Taken together, this study provided mechanism insight into neuroprotective effects by CB2R stimulation after ICH.”

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Cannabidiol Prevents Cerebral Infarction Via a Serotonergic 5-Hydroxytryptamine1A Receptor–Dependent Mechanism

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“Cannabis contains ≈80 different cannabinoids, including the psychoactive component Δ9-tetrahydrocannabinol, and nonpsychoactive components, which include cannabidiol, cannabinol, and cannabigerol.

In those components, cannabidiol, a nonpsychoactive constituent of cannabis, was found to be an anticonvulsant in animal models of epilepsy and in humans with epilepsy. Moreover, cannabidiol has been shown to have antispasmodic, anxiolytic, antinausea, and antirheumatoid arthritic properties. In addition, cannabidiol has been shown to be protective against global and focal ischemic injury.

Cannabidiol has been reported to be a neuroprotectant, but the neuroprotective mechanism of cannabidiol remains unclear. We studied the neuroprotective mechanism of cannabidiol in 4-hour middle cerebral artery (MCA) occlusion mice.

Cannabidiol significantly reduced the infarct volume induced by MCA occlusion in a bell-shaped curve. Similarly, abnormal cannabidiol but not anandamide or methanandamide reduced the infarct volume.

Cannabidiol and abnormal cannabidiol reduced the infarct volume.

These results suggested that the neuroprotective effect of cannabidiol may be related to the increase in CBF through the serotonergic 5-HT1A receptor.”

http://stroke.ahajournals.org/content/36/5/1071

http://www.thctotalhealthcare.com/category/stroke-2/

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