Category Archives: Endocannabinoid System

Expression and Function of the Endocannabinoid System in the Retina and the Visual Brain.

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“Endocannabinoids are important retrograde modulators of synaptic transmission throughout the nervous system.

Cannabinoid receptors are seven transmembrane G-protein coupled receptors favoring Gi/o protein. They are known to play an important role in various processes, including metabolic regulation, craving, pain, anxiety, and immune function.

In the last decade, there has been a growing interest for endocannabinoids in the retina and their role in visual processing.

The purpose of this review is to characterize the expression and physiological functions of the endocannabinoid system in the visual system, from the retina to the primary visual cortex, with a main interest regarding the retina, which is the best-described area in this system so far.

It will show that the endocannabinoid system is widely present in the retina, mostly in the through pathway where it can modulate neurotransmitter release and ion channel activity, although some evidence also indicates possible mechanisms via amacrine, horizontal, and Müller cells.

The presence of multiple endocannabinoid ligands, synthesizing and catabolizing enzymes, and receptors highlights various pharmacological targets for novel therapeutic application to retinal diseases.”

http://www.ncbi.nlm.nih.gov/pubmed/26839718

The molecular mechanism and effect of cannabinoid-2 receptor agonist on the blood-spinal cord barrier permeability induced by ischemia-reperfusion injury.

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“Previous studies have shown that modulation of the receptor-mediated endocannabinoid system during ischemia injury can induce potent neuroprotective effects.

However, little is known about whether cannabinoid-2 (CB2) receptor agonist would produce a protective effect on blood-spinal cord barrier (BSCB) during ischemia.

Taken together, all of these results suggested that JWH-015 might regulate the BSCB permeability and this effect could be related to paracellular and transcellular pathway.

And pharmacological CB2R ligands offer a new strategy for BSCB protection during ischemic injury.”

http://www.ncbi.nlm.nih.gov/pubmed/26835555

Cannabinoids for pediatric epilepsy? Up in smoke or real science?

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“Public interest in the use of “medical marijuana” for the treatment of childhood epilepsy has burgeoned in the last few years. This has occurred in parallel with a growing interest in “medical marijuana” in general. Physicians and pediatricians must balance their patients’ desire for immediate access to these products with the tenets of evidence-based medicine. This review discusses the biochemistry of cannabis products (the phytocannabinoids) setting this in the context of the endogenous endocannabinoid system. The differing and potentially modulating effects of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are reviewed. The evidence-base supporting or not the use of cannabis products for the treatment of neurological disease and specifically epilepsy is explored. The potential for adverse effects and particularly of neurotoxicity is addressed. Finally, public health and sociocultural implications are touched upon. Specific recommendations for interested physicians are provided including advocacy for patients and for a change in the “scheduling” of cannabis in order to better foster much-needed high-quality scientific research in this important area.”

http://www.ncbi.nlm.nih.gov/pubmed/26835389

Regulation of Stem Cells by the Endocannabinoid System

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“The endocannabinoids, endogenous lipid mediators of related chemical structure to the prototype exogenous cannabinoid Δ9-THC found in marijuana, have emerged as important mediators that regulate central and peripheral neural functions as well as immune responses.

Endogenous and exogenous cannabinoid ligands bind to cannabinoid receptors: the predominant central cannabinoid receptor type 1 (CB1) and the peripheral cannabinoid receptor type 2 (CB2). CB1 and CB2 are members of the G-protein coupled receptor family.

Cannabinoids were shown to modulate the immune system and to affect the migration of blood cells, such as T-cells, monocytes and myeloid leukemia cells, through CB receptors.

Recent data indicate the potential role of cannabinoid ligands and receptors in the regulation of hematopoiesis and hematopoietic stem cell (HSC) migration and trafficking.

These studies may lead to clinical applications of cannabinoid-based compounds as new HSC-mobilizer agents for therapeutic intervention in bone marrow failure.”

http://link.springer.com/chapter/10.1007/978-94-007-2993-3_30

Cannabinoid receptor signaling in progenitor/stem cell proliferation and differentiation.

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“Cannabinoids, the active components of cannabis (Cannabis sativa) extracts, have attracted the attention of human civilizations for centuries, much earlier than the discovery and characterization of their substrate of action, the endocannabinoid system (ECS).

The latter is an ensemble of endogenous lipids, their receptors [in particular type-1 (CB1) and type-2 (CB2) cannabinoid receptors] and metabolic enzymes.

Cannabinoid signaling regulates cell proliferation, differentiation and survival, with different outcomes depending on the molecular targets and cellular context involved.

Cannabinoid receptors are expressed and functional from the very early developmental stages, when they regulate embryonic and trophoblast stem cell survival and differentiation, and thus may affect the formation of manifold adult specialized tissues derived from the three different germ layers (ectoderm, mesoderm and endoderm).

In the ectoderm-derived nervous system, both CB1 and CB2 receptors are present in neural progenitor/stem cells and control their self-renewal, proliferation and differentiation. CB1 and CB2 show opposite patterns of expression, the former increasing and the latter decreasing along neuronal differentiation.

Recently, endocannabinoid (eCB) signaling has also been shown to regulate proliferation and differentiation of mesoderm-derived hematopoietic and mesenchymal stem cells, with a key role in determining the formation of several cell types in peripheral tissues, including blood cells, adipocytes, osteoblasts/osteoclasts and epithelial cells.

Here, we will review these new findings, which unveil the involvement of eCB signaling in the regulation of progenitor/stem cell fate in the nervous system and in the periphery.

The developmental regulation of cannabinoid receptor expression and cellular/subcellular localization, together with their role in progenitor/stem cell biology, may have important implications in human health and disease.”

http://www.ncbi.nlm.nih.gov/pubmed/24076098

CB2 cannabinoid receptors promote mouse neural stem cell proliferation.

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“Neurospheres are clonal cellular aggregates of neural stem/precursor cells that grow in culture as free-floating clusters. Activation of CB1 cannabinoid receptors, which are expressed by these cells, promotes proliferation.

In the present study we investigated the expression of CB2 cannabinoid receptors and the effect of exogenous cannabinoids on neural stem/precursor cell proliferation.

Neurospheres containing nestin-positive and sn-1 diacylglycerol lipase alpha-positive cells expressed both CB1 and CB2 receptors, which were maintained through several passages…

Together, our results suggest that cannabinoids stimulate proliferation of neural stem/precursor cells acting on both CB1 and CB2 cannabinoid receptors through a phosphoinositide-3 kinase/Akt pathway.”

http://www.ncbi.nlm.nih.gov/pubmed/17328768

Cannabinoid receptor 2 and its agonists mediate hematopoiesis and hematopoietic stem and progenitor cell mobilization.

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“Endocannabinoids are arachidonic acid derivatives and part of a novel bioactive lipid signaling system, along with their G-coupled cannabinoid receptors (CB₁ and CB₂) and the enzymes involved in their biosynthesis and degradation.

However, their roles in hematopoiesis and hematopoietic stem and progenitor cell (HSPC) functions are not well characterized. Here, we show that bone marrow stromal cells express endocannabinoids (anandamide and 2-arachidonylglycerol), whereas CB₂ receptors are expressed in human and murine HSPCs.

On ligand stimulation with CB₂ agonists, CB₂ receptors induced chemotaxis, migration, and enhanced colony formation of bone marrow cells, which were mediated via ERK, PI3-kinase, and Gαi-Rac1 pathways.

Taken together, these results demonstrate that the endocannabinoid system is involved in hematopoiesis and that CB₂/CB₂ agonist axis mediates repopulation of hematopoiesis and mobilization of HSPCs.

Thus, CB₂ agonists may be therapeutically applied in clinical conditions, such as bone marrow transplantation.”

http://www.ncbi.nlm.nih.gov/pubmed/21063029

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

CB2 Cannabinoid Receptor Knockout in Mice Impairs Contextual Long-Term Memory and Enhances Spatial Working Memory.

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“Neurocognitive effects of cannabinoids have been extensively studied with a focus on CB1 cannabinoid receptors because CB1 receptors have been considered the major cannabinoid receptor in the nervous system. However, recent discoveries of CB2 cannabinoid receptors in the brain demand accurate determination of whether and how CB2 receptors are involved in the cognitive effects of cannabinoids.

CB2 cannabinoid receptors are primarily involved in immune functions, but also implicated in psychiatric disorders such as schizophrenia and depression. Here, we examined the effects of CB2 receptor knockout in mice on memory to determine the roles of CB2 receptors in modulating cognitive function.

Our results suggest that CB2 cannabinoid receptors play diverse roles in regulating memory depending on memory types and/or brain areas.”

http://www.ncbi.nlm.nih.gov/pubmed/26819779

Clinical/Therapeutic Approaches for Cannabinoid Ligands in Central and Peripheral Nervous System Diseases: Mini Review.

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“Cannabinoids, the components of Cannabis sativa Linnaeus, interact with CB1 and CB2 receptors, which are located both in the central nervous system and in the periphery and thus may exert a widespread biological activity in the body.

The main medicinal properties of cannabinoids include analgesic, anti-inflammatory, antitumor, appetite stimulation, antiemesis, and muscle relaxation effects.

This mini review aims to explore existing clinical trials that investigated the use of cannabinoids in diseases affecting the nervous system.

There is evidence that cannabinoid-based drugs may effectively control some symptoms associated with nervous system dysfunction, especially various types of pain and neurologic disorders, although studies are limited.

The efficacy of cannabinoid drugs in the treatment of nervous system diseases should be verified in future large-scale randomized clinical trials.”

http://www.ncbi.nlm.nih.gov/pubmed/26818043