Category Archives: Endocannabinoid System

Crosstalk between endocannabinoid and immune systems: a potential dysregulation in depression?

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“The endocannabinoid (eCB) system, an endogenous lipid signaling system, appears to be dysregulated in depression. The role of endocannabinoids (eCBs) as potent immunomodulators, together with the accumulating support for a chronic low-grade inflammatory profile in depression, suggests a compelling hypothesis for a fundamental impairment in their intercommunication, in depression.

OBJECTIVE:

We aim to review previous literature on individual associations between the immune and eCB systems and depression. It will focus on peripheral and central mechanisms of crosstalk between the eCB and immune systems. A potential dysregulation in this crosstalk will be discussed in the context of depression.

RESULTS:

Investigations largely report a hypoactivity of the eCB system and increased inflammatory markers in individuals with depression. Findings depict a multifaceted communication whereby immunocompetent and eCB-related cells can both influence the suppression and enhancement of the other’s activity in both the periphery and central nervous system. A dysregulation of the eCB system, as seen in depression, appears to be associated with central and peripheral concentrations of inflammatory agents implicated in the pathophysiology of this illness.

CONCLUSION:

The eCB and immune systems have been individually associated with and implicated in pathogenic mechanisms of depression. Both systems tightly regulate the other’s activity. As such, a dysregulation in this crosstalk has potential to influence the onset and maintenance of this neuropsychiatric illness. However, few studies have investigated both systems and depression conjointly. This review highlights the demand to consider joint eCB-immune interactions in the pathoetiology of depression.”

http://www.ncbi.nlm.nih.gov/pubmed/26483037

Endocannabinoid signaling mediates oxytocin-driven social reward.

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Image result for Proc Natl Acad Sci U S A.

“Marijuana exerts profound effects on human social behavior, but the neural substrates underlying such effects are unknown. Here we report that social contact increases, whereas isolation decreases, the mobilization of the endogenous marijuana-like neurotransmitter, anandamide, in the mouse nucleus accumbens (NAc), a brain structure that regulates motivated behavior. The results indicate that anandamide-mediated signaling at CB1 receptors, driven by oxytocin, controls social reward. Deficits in this signaling mechanism may contribute to social impairment in autism spectrum disorders and might offer an avenue to treat these conditions.”  http://www.ncbi.nlm.nih.gov/pubmed/26504214

“In conclusion, our results illuminate a mechanism underlying the prosocial actions of oxytocin, and provide unexpected insights on possible neural substrates involved in the social facilitation caused by marijuana. Pharmacological modulation of oxytocin-driven anandamide signaling (by using, for example, FAAH inhibitors) might open new avenues to treat social impairment in autism spectrum disorders.”  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4653148/

Controlled downregulation of the cannabinoid CB1 receptor provides a promising approach for the treatment of obesity and obesity-derived type 2 diabetes.

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“Increased activity of the endocannabinoid system has emerged as a pathogenic factor in visceral obesity, which is a risk factor for type 2 diabetes mellitus (T2DM).

The endocannabinoid system is composed of at least two G-protein-coupled receptors (GPCRs), the cannabinoid receptor type 1 (CB1), and the cannabinoid receptor type 2 (CB2).

Downregulation of CB1 activity in rodents and humans has proven efficacious to reduce food intake, abdominal adiposity, fasting glucose levels, and cardiometabolic risk factors.

Unfortunately, downregulation of CB1 activity by universally active CB1 inverse agonists has been found to elicit psychiatric side effects, which led to the termination of using globally active CB1 inverse agonists to treat diet-induced obesity.

Interestingly, preclinical studies have shown that downregulation of CB1 activity by CB1 neutral antagonists or peripherally restricted CB1 inverse agonists provided similar anorectic effects and metabolic benefits without psychiatric side effects seen in globally active CB1 inverse agonists.

Furthermore, downregulation of CB1 activity may ease endoplasmic reticulum and mitochondrial stress which are contributors to obesity-induced insulin resistance and type 2 diabetes.

This suggests new approaches for cannabinoid-based therapy in the management of obesity and obesity-related metabolic disorders including type 2 diabetes.”

http://www.ncbi.nlm.nih.gov/pubmed/26498013

The Cannabinoid Receptor CB1 Interacts with the WAVE1 Complex and Plays a Role in Actin Dynamics and Structural Plasticity in Neurons.

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“The molecular composition of the cannabinoid type 1 (CB1) receptor complex beyond the classical G-protein signaling components is not known.

Using proteomics on mouse cortex in vivo, we pulled down proteins interacting with CB1 in neurons and show that the CB1 receptor assembles with multiple members of the WAVE1 complex and the RhoGTPase Rac1 and modulates their activity…

This study reports novel signaling mechanisms for cannabinoidergic modulation of the nervous system and demonstrates a previously unreported role for the WAVE1 complex in therapeutic applications of cannabinoids.”

http://www.ncbi.nlm.nih.gov/pubmed/26496209

Further Characterization of Hemopressin Peptide Fragments in the Opioid and Cannabinoid Systems.

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“Hemopressin, so-called because of its hypotensive effect, belongs to the derivatives of the hemoglobin α-chain. It was isolated from rat brain membrane homogenate by the use of catalytically inactive forms of endopeptidase 24.15 and neurolysin. Hemopressin has antihyperalgesic features that cannot be prevented by the opioid receptor antagonist, naloxone.

Here, we further confirm that hemopressins can modulate CB1 receptors and can have a slight modulatory effect on the opioid system.”

http://www.ncbi.nlm.nih.gov/pubmed/26465932

Type 1 cannabinoid receptor modulates water deprivation-induced homeostatic responses.

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“The present study investigated the type 1 cannabinoid receptor (CB1R) as a potential candidate to mediate the homeostatic responses triggered by 24 hours of water deprivation (WD), which constitutes primarily a hydroelectrolytic challenge and also significantly impacts energy homeostasis.

The present results demonstrated for the first time that CB1R mRNA expression is increased in the hypothalamus of WD rats. Furthermore, the administration of ACEA, a CB1R selective agonist, potentiated WD-induced dipsogenic effect, whereas AM251, a CB1R antagonist, attenuated not only water but also salt intake in response to WD. In parallel with the modulation of thirst and salt appetite, we confirmed that CB1Rs are essential for the development of appropriated neuroendocrine responses…

In conclusion, the present study demonstrated that CB1Rs participate in the homeostatic responses regulating fluid balance and energy homeostasis during WD.”

http://www.ncbi.nlm.nih.gov/pubmed/26468265

Training-Associated Emotional Arousal Shapes Endocannabinoid Modulation of Spatial Memory Retrieval in Rats.

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“Variations in environmental aversiveness influence emotional memory processes in rats. We have previously shown that cannabinoid effects on memory are dependent on the stress level at the time of training as well as on the aversiveness of the environmental context. Here, we investigated whether the hippocampal endocannabinoid system modulates memory retrieval depending on the training-associated arousal level…

The present findings indicate that the endocannabinoid 2-AG in the hippocampus plays a key role in the selective regulation of spatial memory retrieval of stressful experience, shedding light on the neurobiological mechanisms involved in the impact of stress effects on memory processing.

SIGNIFICANCE STATEMENT:

Endogenous cannabinoids play a central role in the modulation of memory for emotional events. Here we demonstrate that the endocannabinoid 2-arachidonoylglycerol in the hippocampus, a brain region crucially involved in the regulation of memory processes, selectively modulates spatial memory recall of stressful experiences. Thus, our findings provide evidence that the endocannabinoid 2-arachidonoylglycerol is a key player in mediating the impact of stress on memory retrieval.

These findings can pave the way to new potential therapeutic intervention for the treatment of neuropsychiatric disorders, such as post-traumatic stress disorder, where a previous exposure to traumatic events could alter the response to traumatic memory recall leading to mental illness.”

http://www.ncbi.nlm.nih.gov/pubmed/26468197

Human lung-resident macrophages express CB1 and CB2 receptors whose activation inhibits the release of angiogenic and lymphangiogenic factors.

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“Macrophages are pivotal effector cells in immune responses and tissue remodeling by producing a wide spectrum of mediators, including angiogenic and lymphangiogenic factors.

Activation of cannabinoid receptor types 1 and 2 has been suggested as a new strategy to modulate angiogenesis in vitro and in vivo.

We investigated whether human lung-resident macrophages express a complete endocannabinoid system by assessing their production of endocannabinoids and expression of cannabinoid receptors…

Activation of cannabinoid receptors on tissue-resident macrophages might be a novel strategy to modulate macrophage-assisted vascular remodeling in cancer and chronic inflammation.”

http://www.ncbi.nlm.nih.gov/pubmed/26467187

Evaluation of cannabinoid CB1 and CB2 receptors expression in mobile tongue squamous cell carcinoma: associations with clinicopathological parameters and patients’ survival.

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Tumor Biology

“Cannabinoid receptors (CB1R and CB2R) constitute essential members of the endocannabinoid system (ECS) which participates in many different functions indispensable to homeostatic regulation in several tissues, exerting also antitumorigenic effects. The present study aimed to assess the clinical significance of CB1R and CB2R protein expression in mobile tongue squamous cell carcinoma (SCC). The present study provides evidence that CB1R and CB2R may play a role in the pathophysiological aspects of the mobile tongue SCC and even each molecule may constitute a potential target for the development of novel anti-cancer drugs for this type of malignancy.” http://www.ncbi.nlm.nih.gov/pubmed/26459312

https://link.springer.com/article/10.1007%2Fs13277-015-4182-8

The skeletal endocannabinoid system: clinical and experimental insights.

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“Recently, there has been a rapidly growing interest in the role of cannabinoids in the regulation of skeletal remodeling and bone mass, addressed in basic, translational and clinical research.

Since the first publications in 2005, there are more than 1000 publications addressing the skeletal endocannabinoid system.

This review focuses on the roles of the endocannabinoid system in skeletal biology via the cannabinoid receptors CB1, CB2 and others.

Endocannabinoids play important roles in bone formation, bone resorption and skeletal growth, and are sometimes age, gender, species and strain dependent. Controversies in the literature and potential therapeutic approaches targeting the endocannabinoid system in skeletal disorders are also discussed.”

http://www.ncbi.nlm.nih.gov/pubmed/26457774