Category Archives: Endocannabinoid System

[Role of cannabinoid receptors in renal diseases].

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“Chronic kidney disease remains a major challenge for public health systems and corresponds to the replacement of renal functional tissue by extracellular matrix proteins such as collagens and fibronectin. There is no efficient treatment to date for chronic kidney disease except nephroprotective strategies.

The cannabinoid system and more specifically the cannabinoid receptors 1 (CB1) and 2 (CB2) may represent a new therapeutic target in chronic kidney disease.

Experimental data obtained in models of diabetes and obesity suggested that CB1 blockade and CB2 stimulation may slow the development of diabetic nephropathy.

In human kidneys, CB1 expression is increased in various chronic nephropathies and correlates with renal function. Moreover, endogenous CB1 and CB2 ligands are greatly increased during renal fibrogenesis. A microarray analysis performed in an experimental model of renal fibrosis found that the gene encoding for the CB1 receptor was among the most upregulated genes. We also demonstrated that renal fibrogenesis could be reduced by CB1 inhibition and CB2 stimulation in an experimental model through a direct mechanism involving CB1 on myofibroblasts, which are the major effector cells during renal fibrosis.

Therefore, CB1 blockers may represent a novel therapeutic target in chronic kidney disease and diabetes.”

http://www.ncbi.nlm.nih.gov/pubmed/26968477

Cannabinoids inhibit insulin receptor signaling in pancreatic β-cells.

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“Optimal glucose homeostasis requires exquisitely precise adaptation of the number of insulin-secreting β-cells in the islets of Langerhans. Insulin itself positively regulates β-cell proliferation in an autocrine manner through the insulin receptor (IR) signaling pathway.

It is now coming to light that cannabinoid 1 receptor (CB1R) agonism/antagonism influences insulin action in insulin-sensitive tissues. However, the cells on which the CB1Rs are expressed and their function in islets have not been firmly established. We undertook the current study to investigate if intraislet endogenous cannabinoids (ECs) regulate β-cell proliferation and if they influence insulin action.

These findings provide direct evidence for a functional interaction between CB1R and IR signaling involved in the regulation of β-cell proliferation and will serve as a basis for developing new therapeutic interventions to enhance β-cell function and proliferation in diabetes.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3064093/

Exogenous hepatitis B virus envelope proteins induce endoplasmic reticulum stress: involvement of cannabinoid axis in liver cancer cells.

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“HBV represents the most common chronic viral infection and major cause of hepatocellular carcinoma (HCC), although its exact role in liver tumorigenesis is unclear. Massive storage of the small (SHBs), middle (MHBs) and large surface (LHBs) HBV envelope proteins leads to cell stress and sustained inflammatory responses. Cannabinoid (CB) system is involved in the pathogenesis of liver diseases, stimulating acute and chronic inflammation, liver damage and fibrogenesis; it triggers endoplasmic reticulum (ER) stress response. The aim of our work was to investigate the activation of ER stress pathway after ectopic HBV envelope proteins expression, in liver cancer cells, and the role exerted by CB receptors. PCR, immunofluorescence and western blotting showed that exogenous LHBs and MHBs induce a clear ER stress response in Huh-7 cells expressing CB1 receptor. Up-regulation of the chaperone BiP/GRP78 (Binding Immunoglobulin Protein/Glucose-Regulated Protein 78) and of the transcription factor CHOP/GADD153 (C/EBP Homologous Protein/Growth Arrest and DNA Damage inducible gene 153), phosphorylation of PERK (PKR-like ER Kinase) and eIF2α (Eukaryotic Initiation Factor 2α) and splicing of XBP1 (X-box binding protein 1) was observed. CB1-/- HepG2 cells did not show any ER stress activation. Inhibition of CB1 receptor counteracted BiP expression in transfected Huh-7 and in HBV+ PLC/PRF/5 cells; whereas no effect was observed in HBV- HLF cells. These results suggest that HBV envelope proteins are able to induce the ER stress pathway. CB1 expression is directly correlated with ER stress function. Further investigations are needed to clarify the involvement of cannabinoid in HCC progression after HBV infection.”

http://www.ncbi.nlm.nih.gov/pubmed/26967385

Endocannabinoids and Endocannabinoid-Related Mediators: Targets, Metabolism and Role In Neurological Disorders.

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“The endocannabinoid system (ECS) is composed of two G protein-coupled receptors (GPCRs), the cannabinoid CB1 and CB2 receptors, and the two main endogenous lipid ligands of such receptors (also known as the “endocannabinoids”), anandamide and 2-arachidonoyl-glycerol. The ECS is a pleiotropic signalling systems involved in all aspects of mammalian physiology and pathology, and for this reason it represents a potential target for the design and development of new therapeutic drugs. However, the endocannabinoids as well as some of their congeners also interact with a much wider range of receptors, including members of the Transient Receptor Potential (TRP) channels, Peroxisome Proliferator-Activated Receptors (PPARs), and other GPCRs. Indeed, following the discovery of the endocannabinoids, endocannabinoid-related lipid mediators, which often share the same metabolic pathways of the endocannabinoids, have also been identified or rediscovered. In this review article, we discuss the role of endocannabinoids and related lipids during physiological functions, as well as their involvement is some of the most common neurological disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/26965148

Cannabis in Pain Treatment: Clinical & Research Considerations.

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“Cannabinoids show promise as therapeutic agents, particularly as analgesics, but their development and clinical use has been complicated by recognition of their botanical source, cannabis, as a substance of misuse. While research into endogenous cannabinoid systems and potential cannabinoid pharmaceuticals is slowly increasing, there has been intense societal interest in making herbal (plant) cannabis available for medicinal use; 23 U.S. States and all Canadian provinces currently permit use in some clinical contexts. Whether or not individual professionals support the clinical use of herbal cannabis, all clinicians will encounter patients who elect to use it and therefore need to be prepared to advise them on cannabis-related clinical issues despite limited evidence to guide care. Expanded research on cannabis is needed both to better determine the individual and public health effects of increasing use of herbal cannabis and to advance understanding of the pharmaceutical potential of cannabinoids as medications. This paper reviews clinical, research and policy issues related to herbal cannabis in order to support clinicians in thoughtfully advising and caring for patients who use cannabis and it examines obstacles and opportunities to expand research on the health effects of herbal cannabis and cannabinoids.

PERSPECTIVE:

Herbal cannabis is increasingly available for clinical use in the U.S despite continuing controversies over its efficacy and safety. This paper explores important considerations in the use of plant Cannabis to better prepare clinicians to care for patients who use it and to identify needed directions for research.”

http://www.ncbi.nlm.nih.gov/pubmed/26961090

Dynamic of expression and localization of cannabinoid-degrading enzymes FAAH and MGLL in relation to CB1 during meiotic maturation of human oocytes.

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“The endogenous cannabinoid system has been characterized in some female reproductive organs but little is known about the expression and localization pattern of cannabinoid-degrading enzymes in relation to the CB1 cannabinoid receptor in human oocytes. In this study, we focus on the investigation of the presence and differential distribution of fatty acid amide hydrolase (FAAH) and monoglyceride lipase (MGLL) in relation to CB1 during the maturation of human oocytes. We used a total of 290 human oocytes not suitable for in vitro fertilization/intracytoplasmic sperm injection (ICSI): germinal-vesicle (GV) and metaphase-I (MI) stages and metaphase-II (MII) oocytes that had not developed into an embryo after ICSI.Cannabinoid-degrading enzymes and the cannabinoid CB1 receptor were present in human oocytes. Specifically, FAAH was detected in the periphery of the oocyte from the GV to MI stage and co-localized with CB1. Later, by the MII stage, FAAH was spread within the oocyte, whereas MGLL immunostaining was homogeneous across the oocyte at all stages of maturation and only overlapped with CB1 at the GV stage. This coordinated redistribution of cannabinoid system proteins suggests a role for this system in the maturation of the female gamete.”

http://www.ncbi.nlm.nih.gov/pubmed/26948343

Cannabinoid receptors are involved in the protective effect of a novel curcumin derivative C66 against CCl4-induced liver fibrosis.

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“Liver fibrosis is one of the major causes of morbidity and mortality worldwide and lacks efficient therapy. Recent studies suggest the curcumin protects liver from fibrosis. However, curcumin itself is in low bioavailable concentration when administered orally, and the protective mechanism remains poorly understood. The current study aimed to investigate whether a more stable derivative of curcumin, C66, protects against CCl4-inudced liver fibrosis and examine the underlying mechanism involving cannabinoid receptor (CB receptor). At a dose lower than curcumin itself, C66 displayed a superior anti-fibrotic effect. C66 significantly reduced collagen deposition, pro-inflammatory cytokine expression, and liver enzyme activities. Mechanistic study revealed that C66 treatment decreased CCl4-induced cannabinoid receptor 1 (CB1 receptor) expression and increased cannabinoidreceptor 2 (CB2 receptor) expression, along with an inhibition of JNK/NF-κB-mediated inflammatory signaling. In conclusion, this curcumin derivative attenuates liver fibrosis likely involving a CB/JNK/NF-κB-mediated pathway.”

http://www.ncbi.nlm.nih.gov/pubmed/26945822

Nutritional n-3 PUFA Deficiency Abolishes Endocannabinoid Gating of Hippocampal Long-Term Potentiation.

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“Maternal n-3 polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid, is critical during perinatal brain development. How early postnatal n-3 PUFA deficiency impacts on hippocampal synaptic plasticity is mostly unknown. Here we compared activity-dependent plasticity at excitatory and inhibitory synapses in the CA1 region of the hippocampus in weaned pups whose mothers were fed with an n-3 PUFA-balanced or n-3 PUFA-deficient diet. Normally, endogenous cannabinoids (eCB) produced by the post-synapse dually control network activity by mediating the long-term depression of inhibitory inputs (iLTD) and positively gating NMDAR-dependent long-term potentiation (LTP) of excitatory inputs. We found that both iLTD and LTP were impaired in n-3 PUFA-deficient mice. Pharmacological dissection of the underlying mechanism revealed that impairment of NMDAR-dependent LTP was causally linked to and attributable to the ablation of eCB-mediated iLTD and associated to disinhibitory gating of excitatory synapses. The data shed new light on how n-3 PUFAs shape synaptic activity in the hippocampus and provide a new synaptic substrate to the cognitive impairments associated with perinatal n-3 deficiency.”

http://www.ncbi.nlm.nih.gov/pubmed/26946127

An Increase in the Omega-6/Omega-3 Fatty Acid Ratio Increases the Risk for Obesity.

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“In the past three decades, total fat and saturated fat intake as a percentage of total calories has continuously decreased in Western diets, while the intake of omega-6 fatty acid increased and the omega-3 fatty acid decreased, resulting in a large increase in the omega-6/omega-3 ratio from 1:1 during evolution to 20:1 today or even higher.

This change in the composition of fatty acids parallels a significant increase in the prevalence of overweight and obesity.

Experimental studies have suggested that omega-6 and omega-3 fatty acids elicit divergent effects on body fat gain through mechanisms of adipogenesis, browning of adipose tissue, lipid homeostasis, brain-gut-adipose tissue axis, and most importantly systemic inflammation.

Prospective studies clearly show an increase in the risk of obesity as the level of omega-6 fatty acids and the omega-6/omega-3 ratio increase in red blood cell (RBC) membrane phospholipids, whereas high omega-3 RBC membrane phospholipids decrease the risk of obesity.

Recent studies in humans show that in addition to absolute amounts of omega-6 and omega-3 fatty acid intake, the omega-6/omega-3 ratio plays an important role in increasing the development of obesity via both AA eicosanoid metabolites and hyperactivity of the cannabinoid system, which can be reversed with increased intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

A balanced omega-6/omega-3 ratio is important for health and in the prevention and management of obesity.”

http://www.ncbi.nlm.nih.gov/pubmed/26950145

Effects of cannabinoid receptor activation by CP55,940 on normal bladder function and irritation-induced bladder overactivity in non-awake anaesthetised rats.

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“CP55,940 is a synthetic analogue of tetrahydrocannabidiol, which is a psychoactive ingredient of the Cannabis plant.

This study was designed to evaluate the effects of CP55,940 on normal bladder function in vivo and examine whether it suppresses urinary frequency induced by nociceptive stimuli in the bladder.

CP55,940 decreases bladder activity and urinary frequency induced by nociceptive stimuli, probably by suppression of bladder afferent activity. Effects of CP55,940 were abolished by both CBR antagonists. This data implicates a role for the endocannabinoid system in bladder mechanoafferent function in rats. In addition, our results show that CP55,940 reverses urinary frequency exemplified in an overactive bladder model, suggesting it could be an effective treatment for patients with lower urinary tract symptoms.”

http://www.ncbi.nlm.nih.gov/pubmed/26942594