Endocannabinoids and the Immune System in Health and Disease.

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“Endocannabinoids are bioactive lipids that have the potential to signal through cannabinoid receptors to modulate the functional activities of a variety of immune cells.

Their activation of these seven-transmembranal, G protein-coupled receptors sets in motion a series of signal transductional events that converge at the transcriptional level to regulate cell migration and the production of cytokines and chemokines.

There is a large body of data that supports a functional relevance for 2-arachidonoylglycerol (2-AG) as acting through the cannabinoid receptor type 2 (CB2R) to inhibit migratory activities for a diverse array of immune cell types.

However, unequivocal data that supports a functional linkage of anandamide (AEA) to a cannabinoid receptor in immune modulation remains to be obtained.

Endocannabinoids, as typical bioactive lipids, have a short half-life and appear to act in an autocrine and paracrine fashion.

Their immediate effective action on immune function may be at localized sites in the periphery and within the central nervous system.

It is speculated that endocannabinoids play an important role in maintaining the overall “fine-tuning” of the immune homeostatic balance within the host.”

http://www.ncbi.nlm.nih.gov/pubmed/26408161

Genetic Manipulation of the Endocannabinoid System.

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“The physiological and pathophysiological functions of the endocannabinoid system have been studied extensively using transgenic and targeted knockout mouse models.

The first gene deletions of the cannabinoid CB1 receptor were described in the late 1990s, soon followed by CB2 and FAAH mutations in early 2000.

These mouse models helped to elucidate the fundamental role of endocannabinoids as retrograde transmitters in the CNS and in the discovery of many unexpected endocannabinoid functions, for example, in the skin, bone and liver.

We now have knockout mouse models for almost every receptor and enzyme of the endocannabinoid system.

Conditional mutant mice were mostly developed for the CB1 receptor, which is widely expressed on many different neurons, astrocytes and microglia, as well as on many cells outside the CNS.

These mouse strains include “floxed” CB1 alleles and mice with a conditional re-expression of CB1. The availability of these mice made it possible to decipher the function of CB1 in specific neuronal circuits and cell populations or to discriminate between central and peripheral effects.

Many of the genetic mouse models were also used in combination with viral expression systems.

The purpose of this review is to provide a comprehensive overview of the existing genetic models and to summarize some of the most important discoveries that were made with these animals.”

http://www.ncbi.nlm.nih.gov/pubmed/26408160

Distribution of the Endocannabinoid System in the Central Nervous System.

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“The endocannabinoid system consists of endogenous cannabinoids (endocannabinoids), the enzymes that synthesize and degrade endocannabinoids, and the receptors that transduce the effects of endocannabinoids.

Much of what we know about the function of endocannabinoids comes from studies that combine localization of endocannabinoid system components with physiological or behavioral approaches.

This review will focus on the localization of the best-known components of the endocannabinoid system for which the strongest anatomical evidence exists.”

http://www.ncbi.nlm.nih.gov/pubmed/26408158

Biosynthesis and Fate of Endocannabinoids.

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“Since the discovery of the two cannabinoid receptors, CB1 and CB2, several molecules, commonly defined as endocannabinoids, able to bind to and functionally activate these receptors, have been discovered and characterized.

Although the general thought was that the endocannabinoids were mainly derivatives of the n-6 fatty acid arachidonic acid, recent data have shown that also derivatives (ethanolamides) of n-3 fatty acids may be classified as endocannabinoids.

Whether the n-3 endocannabinoids follow the same biosynthetic and metabolic routes of the n-6 endocannabinoids is not yet clear and so warrants further investigation.

In this review, we describe the primary biosynthetic and metabolic pathways for the two well-established endocannabinoids, anandamide and 2-arachidonoylglycerol.”

http://www.ncbi.nlm.nih.gov/pubmed/26408157

Endocannabinoids and Their Pharmacological Actions.

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“The endocannabinoid system consists of G protein-coupled cannabinoid CB1 and CB2 receptors, of endogenous compounds known as endocannabinoids that can target these receptors, of enzymes that catalyse endocannabinoid biosynthesis and metabolism, and of processes responsible for the cellular uptake of some endocannabinoids.

This review presents in vitro evidence that most or all of the following 13 compounds are probably orthosteric endocannabinoids since they have all been detected in mammalian tissues in one or more investigation, and all been found to bind to cannabinoid receptors, probably to an orthosteric site: anandamide, 2-arachidonoylglycerol, noladin ether, dihomo-γ-linolenoylethanolamide, virodhamine, oleamide, docosahexaenoylethanolamide, eicosapentaenoylethanolamide, sphingosine, docosatetraenoylethanolamide, N-arachidonoyldopamine, N-oleoyldopamine and haemopressin.

In addition, this review describes in vitro findings that suggest that the first eight of these compounds can activate CB1 and sometimes also CB2 receptors and that another two of these compounds are CB1 receptor antagonists (sphingosine) or antagonists/inverse agonists (haemopressin).

Evidence for the existence of at least three allosteric endocannabinoids is also presented. These endogenous compounds appear to target allosteric sites on cannabinoid receptors in vitro, either as negative allosteric modulators of the CB1 receptor (pepcan-12 and pregnenolone) or as positive allosteric modulators of this receptor (lipoxin A4) or of the CB2 receptor (pepcan-12).

Also discussed are current in vitro data that indicate the extent to which some established or putative orthosteric endocannabinoids seem to target non-cannabinoid receptors and ion channels, particularly at concentrations at which they have been found to interact with CB1 or CB2 receptors.”

http://www.ncbi.nlm.nih.gov/pubmed/26408156

Cannabinoid receptor activation in the basolateral amygdala blocks the effects of stress on the conditioning and extinction of inhibitory avoidance.

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“The endocannabinoid system has recently emerged as important in the regulation of extinction learning and in the regulation of the hypothalamic-pituitary-adrenal axis.

Here, we aimed to examine the involvement of the cannabinoid CB(1) receptor in the basolateral amygdala (BLA) in inhibitory avoidance (IA) conditioning and extinction and to test whether cannabinoid activation would reverse the effects of stress on these memory processes.

Together, our findings may support a wide therapeutic application for cannabinoids in the treatment of conditions associated with the inappropriate retention of aversive memories and stress-related disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/19741114

Cannabinoids prevent the development of behavioral and endocrine alterations in a rat model of intense stress.

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“Cannabinoids have recently emerged as a possible treatment of stress- and anxiety-related disorders such as post-traumatic stress disorder (PTSD).

Here, we examined whether cannabinoid receptor activation could prevent the effects of traumatic stress on the development of behavioral and neuroendocrine measures in a rat model of PTSD…

…cannabinoids could serve as a pharmacological treatment of stress- and trauma-related disorders.

…the results extend previous findings to another stress model and to a post-trauma treatment configuration that are more relevant to clinical context and add to the growing body of data pointing to a therapeutic potential of cannabinoids for treatment of PTSD.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3242307/

http://www.thctotalhealthcare.com/category/post-traumatic-stress-disorder-ptsd/

Cannabinoid receptor activation prevents the effects of chronic mild stress on emotional learning and LTP in a rat model of depression.

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“The endocannabinoid (eCB) system has recently emerged as a promising therapeutic target for the treatment of stress-related emotional disorders.

Recent data suggest that the eCB system could represent a new therapeutic target for the treatment of depression.

The findings suggest that enhancing cannabinoid signaling could represent a novel approach to the treatment of cognitive deficits that accompany stress-related depression.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3924526/

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

Cannabinoid type-1 receptor signaling in central serotonergic neurons regulates anxiety-like behavior and sociability.

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“The endocannabinoid (eCB) system possesses neuromodulatory functions by influencing the release of various neurotransmitters, including γ-aminobutyric acid (GABA) and glutamate. A functional interaction between eCBs and the serotonergic system has already been suggested.

Previously, we showed that cannabinoid type-1 (CB1) receptor mRNA and protein are localized in serotonergic neurons of the raphe nuclei, implying that the eCB system can modulate serotonergic functions.

In order to substantiate the physiological role of the CB1 receptor in serotonergic neurons of the raphe nuclei, we generated serotonergic 5-hydroxytryptamine (5-HT) neuron-specific CB 1 receptor-deficient mice, using the Cre/loxP system with a tamoxifen-inducible Cre recombinase under the control of the regulatory sequences of the tryptophan hydroxylase 2 gene (TPH2-CreER (T2)), thus, restricting the recombination to 5-HT neurons of the central nervous system (CNS).

Applying several different behavioral paradigms, we revealed that mice lacking the CB1 receptor in serotonergic neurons are more anxious and less sociable than control littermates. Thus, we were able to show that functional CB1 receptor signaling in central serotonergic neurons modulates distinct behaviors in mice.”

http://www.ncbi.nlm.nih.gov/pubmed/26388750

In vitro and non-invasive in vivo effects of the cannabinoid-1 receptor agonist AM841 on gastrointestinal motor function in the rat.

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“Cannabinoids have been traditionally used for the treatment of gastrointestinal (GI) symptoms, but the associated central effects, through cannabinoid-1 receptors (CB1R), constitute an important drawback. Our aims were to characterize the effects of the recently developed highly potent long-acting megagonist AM841 on GI motor function and to determine its central effects in rats…

The CB1R megagonist AM841 may potently depress GI motor function in the absence of central effects. This effect may be mediated peripherally and may be useful in the treatment of GI motility disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/26387676