Category Archives: Endocannabinoid System

[The endocannabinoid system].

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Abstract

“The endocannabinoid system is a physiological system, which is responsible for the control of glucose and lipid-metabolism, as well as for the regulation of the body weight. The endocannabinoid receptors are distributed both in the central and peripher nervous system. Different studies provide evidence that an hyperactive endocannabinoid system is involved in the development of different cardiovascular risk factors. The pharmacological blockade of these cannabinoid receptors may represent a new approach for cardiometabolic risk management.”

http://www.ncbi.nlm.nih.gov/pubmed/18548817

Update on the endocannabinoid system as an anticancer target.

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“INTRODUCTION:

Recent studies have shown that the endocannabinoid system (ECS) could offer an attractive antitumor target. Numerous findings suggest the involvement of this system (constituted mainly by cannabinoid receptors, endogenous compounds and the enzymes for their synthesis and degradation) in cancer cell growth in vitro and in vivo.

AREAS COVERED:

This review covers literature from the past decade which highlights the potential of targeting the ECS for cancer treatment. In particular, the levels of endocannabinoids and the expression of their receptors in several types of cancer are discussed, along with the signaling pathways involved in the endocannabinoid antitumor effects. Furthermore, the beneficial and adverse effects of old and novel compounds in clinical use are discussed.

EXPERT OPINION:

One direction that should be pursued in antitumor therapy is to select compounds with reduced psychoactivity. This is known to be connected to the CB1 receptor; thus, targeting the CB2 receptor is a popular objective. CB1 receptors could be maintained as a target to design new compounds, and mixed CB1-CB2 ligands could be effective if they are able to not cross the BBB. Furthermore, targeting the ECS with agents that activate cannabinoid receptors or inhibitors of endogenous degrading systems such as fatty acid amide hydrolase inhibitors may have relevant therapeutic impact on tumor growth. Additional studies into the downstream consequences of endocannabinoid treatment are required and may illuminate other potential therapeutic targets.”  http://www.ncbi.nlm.nih.gov/pubmed/21244344

“Update on the endocannabinoid system as an anticancer target”  http://www.tandfonline.com/doi/abs/10.1517/14728222.2011.553606?journalCode=iett20

Cannabinoid receptor ligands as potential anticancer agents–high hopes for new therapies?

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“OBJECTIVES:

The endocannabinoid system is an endogenous lipid signalling network comprising arachidonic-acid-derived ligands, cannabinoid (CB) receptors, transporters and endocannabinoid degrading enzymes. The CB(1) receptor is predominantly expressed in neurons but is also co-expressed with the CB(2) receptor in peripheral tissues. In recent years, CB receptor ligands, including Delta(9)-tetrahydrocannabinol, have been proposed as potential anticancer agents.

KEY FINDINGS:

This review critically discusses the pharmacology of CB receptor activation as a novel therapeutic anticancer strategy in terms of ligand selectivity, tissue specificity and potency. Intriguingly, antitumour effects mediated by cannabinoids are not confined to inhibition of cancer cell proliferation; cannabinoids also reduce angiogenesis, cell migration and metastasis, inhibit carcinogenesis and attenuate inflammatory processes. In the last decade several new selective CB(1) and CB(2) receptor agents have been described, but most studies in the area of cancer research have used non-selective CB ligands. Moreover, many of these ligands exert prominent CB receptor-independent pharmacological effects, such as activation of the G-protein-coupled receptor GPR55, peroxisome proliferator-activated receptor gamma and the transient receptor potential vanilloid channels.

SUMMARY:

The role of the endocannabinoid system in tumourigenesis is still poorly understood and the molecular mechanisms of cannabinoid anticancer action need to be elucidated. The development of CB(2)-selective anticancer agents could be advantageous in light of the unwanted central effects exerted by CB(1) receptor ligands. Probably the most interesting question is whether cannabinoids could be useful in chemoprevention or in combination with established chemotherapeutic agents.”

http://www.ncbi.nlm.nih.gov/pubmed/19589225

Therapeutic potential of cannabinoid receptor ligands: current status.

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Abstract

“There are at least two types of cannabinoid receptors, CB1 also named CNR1 and CB2 also named CNR2, both coupled to G proteins. CB1 receptors exist primarily on central and peripheral neurons. CB2 receptors are present mainly on immune cells. Endogenous agonists for cannabinoid receptors (endocannabinoids) have also been discovered, the most important being arachidonoyl ethanolamide (anandamide), 2-arachidonoyl glycerol (2-AG), and 2-archidonyl glyceryl ether. Following their release, endocannabinoids are removed from the extracellular space and then degraded by intracellular enzymic hydrolysis. CB1/CB2 agonists are already used clinically as antiemetic or to stimulate appetite. Potential therapeutic uses of cannabinoid receptor agonists include the management of multiple sclerosis, spinal cord injury, pain, inflammatory disorders, glaucoma, bronchial asthma, vasodilatation that accompanies advanced cirrhosis, and cancer.”

http://www.ncbi.nlm.nih.gov/pubmed/16810344

Cannabinoids, Endocannabinoids, and Related Analogs in Inflammation.

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“This review covers reports published in the last 5 years on the anti-inflammatory activities of all classes of cannabinoids, including phytocannabinoids such as tetrahydrocannabinol and cannabidiol, synthetic analogs such as ajulemic acid and nabilone, the endogenous cannabinoids anandamide and related compounds, namely, the elmiric acids, and finally, noncannabinoid components of Cannabis that show anti-inflammatory action. It is intended to be an update on the topic of the involvement of cannabinoids in the process of inflammation. A possible mechanism for these actions is suggested involving increased production of eicosanoids that promote the resolution of inflammation. This differentiates these cannabinoids from cyclooxygenase-2 inhibitors that suppress the synthesis of eicosanoids that promote the induction of the inflammatory process.”

 

“INTRODUCTION

This review is intended to be an update on the topic of the involvement of cannabinoids in the process of inflammation. Other reviews cover certain aspects of this subject and the reader is referred to them for a discussion of earlier reports. In this review are reports published in the last 5 years on the activities of all classes of cannabinoids, including the endogenous cannabinoids such as anandamide, related compounds such as the elmiric acids (EMAs), and noncannabinoid components of Cannabis that show anti-inflammatory action. An interesting recently published example of the latter one is caryophyllene, an abundant component of Cannabis oil that shows anti-inflammatory activity and has high affinity for cannabinoid receptor 2 (CB2; 5).”

 

“Phytocannabinoids: Tetrahydrocannabinol and Cannabidiol”

 

“PLANT PREPARATIONS AND NONCANNABINOID CONSTITUENTS OF CANNABIS”

“Cannabis sativa is a complex botanical, and it is not unlikely that the therapeutic benefits of marijuana are due to some of the more than 60 cannabinoids and 200–250 noncannabinoid constituents of the plant. One noncannabinoid, the geranylated flavone cannflavin A (Fig. 5), is 30 times more potent than aspirin as an inhibitor of prostaglandin E2 . These potentially important findings have been overlooked, as most attention in marijuana research has been directed to the analgesic effects of the plant and to mechanisms of psychoactivity. A further example that this line of inquiry has remained dormant is a series of overlooked observations, which demonstrate potent anti-inflammatory actions of a crude marijuana extract and of the nonpsychoactive Cannabis constituents, CBD, cannabinol, and cannabichromene in the carrageenan paw edema model of acute inflammation in rats. Volatile oil products of the plant also have biological activity. Thus, pyrolysis products may add to the therapeutic properties of smoked marijuana. Several of the most abundant cannabinoid and noncannabinoid constituents of C. sativa are nonpsychoactive.”

“Flavonoids are ubiquitous plant phenolic compounds that consist of two aromatic rings linked by a three carbon bridge. They are attracting interest because of their antioxidant, antitumor, anti-inflammatory, and antimicrobial activities. The flavone luteolin, a constituent of C. sativa, is also found in spices and in vegetables such as celery and green pepper. When added to peripheral blood mononuclear cells in vitro, luteolin suppresses production of the inflammatory cytokines TNFα, IL-1b, and IL-6, actions that relate to a selective reduction in numbers of monocytes. Perhaps more importantly, luteolin inhibits growth of Plasmodium falciparum in vitro and protects against induction of colon cancer in mice.”

“CONCLUSIONS

Possibly the very earliest literature reference on Cannabis describes its use as an anti-inflammatory agent. The Chinese emperor Shen-nung (ca. 2000 B.C.), in a work called Pen-ts’ao Ching, noted many of the effects of Cannabis in humans. Among other properties, it was claimed that cannabis “undoes rheumatism”, suggesting possible anti-inflammatory effects. The reports described in this review of the current literature provide support for the claims made by the ancient Chinese healers. These more recent publications include relief from chronic neuropathic pain, fibromyalgia, rheumatoid arthritis, and postoperative pain. In addition, a large body of preclinical data on all classes of cannabinoids, including the endogenous examples, point to a variety of therapeutic targets for cannabinoids and important roles for the endocannabinoids in the physiology of inflammation.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2664885/

Endocannabinoid overactivity and intestinal inflammation

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Abstract

“Cannabinoid receptors of type 1 and 2 (CB1 and CB2), endogenous ligands that activate them (endocannabinoids), and mechanisms for endocannabinoid biosynthesis and inactivation have been identified in the gastrointestinal system. Activation of CB1 receptors by endocannabinoids produces relaxation of the lower oesophageal sphincter and inhibition of gastric acid secretion, intestinal motility, and fluid stimulated secretion. However, stimulation of cannabinoid receptors impacts on gastrointestinal functions in several other ways. Recent data indicate that the endocannabinoid system in the small intestine and colon becomes over stimulated during inflammation in both animal models and human inflammatory disorders. The pathological significance of this “endocannabinoid overactivity” and its possible exploitation for therapeutic purposes are discussed here.”

 

“The endocannabinoid system of the gastrointestinal tract includes not only cannabinoid receptors but also endogenous agonists of these receptors, as well as mechanisms for their biosynthesis and inactivation”

 

“The main psychotropic constituent of the plant Cannabis sativa and marijuana, Δ9‐tetrahydrocannabinol, exerts its pharmacological effects by activating two G protein coupled cannabinoid receptors.1These are the CB1 receptor, present in central and peripheral nerves (including the human enteric nervous system), and the CB2 receptor, expressed abundantly in immune cells. In rodents, CB1 receptor immunoreactivity has been detected in discrete nuclei of the dorsovagal complex (involved in emesis), and in efferents from the vagal ganglia and in enteric (myenteric and submucosal) nerve terminals where they inhibit excitatory (mainly cholinergic) neurotransmission. In vivo pharmacological studies have shown that activation of CB1 receptors reduces emesis, produces inhibition of gastric acid secretion8 and relaxation of the lower oesophageal sphincter (two effects that might be beneficial in the treatment of gastro‐oesophageal reflux disease), and inhibits intestinal motility and secretion. Consistent with immunohistochemical data showing that CB2 receptors are particularly evident in colonic tissues from patients with inflammatory bowel diseases (IBD), evidence suggests that CB2 inhibits intestinal motility during certain pathological states.1″

 

“…endocannabinoids convey protection from enteric hypersecretory states (for example, cholera toxin induced diarrhoea), which is in agreement with anecdotal reports from folk medicine on the use of Cannabis sativa in the treatment of diarrhoea.“

 

“Overactivity of the endocannabinoid system is becoming a well established concept in human intestinal conditions with an inflammatory component”

   

“The inhibitory effects of cannabinoids on intestinal inflammation, as well as on intestinal motility and secretory diarrhoea, observed in preclinical studies, increase the potential for their use in the treatment of IBD”

  

“There is great potential for the development of new therapeutic agents against intestinal inflammation from the endocannabinoid system”

 

“Conclusions: new therapies for the treatment of IBD from the endocannabinoid system”

 

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1856409/

Targeting the endocannabinoid system: to enhance or reduce?

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Abstract

“As our understanding of the endocannabinoids improves, so does the awareness of their complexity. During pathological states, the levels of these mediators in tissues change, and their effects vary from those of protective endogenous compounds to those of dysregulated signals. These observations led to the discovery of compounds that either prolong the lifespan of endocannabinoids or tone down their action for the potential future treatment of pain, affective and neurodegenerative disorders, gastrointestinal inflammation, obesity and metabolic dysfunctions, cardiovascular conditions and liver diseases. When moving to the clinic, however, the pleiotropic nature of endocannabinoid functions will require careful judgement in the choice of patients and stage of the disorder for treatment.”

http://www.ncbi.nlm.nih.gov/pubmed/18446159

Cannabinoids in intestinal inflammation and cancer.

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Abstract

“Emerging evidence suggests that cannabinoids may exert beneficial effects in intestinal inflammation and cancer. Adaptive changes of the endocannabinoid system have been observed in intestinal biopsies from patients with inflammatory bowel disease and colon cancer. Studies on epithelial cells have shown that cannabinoids exert antiproliferative, antimetastatic and apoptotic effects as well as reducing cytokine release and promoting wound healing. In vivo, cannabinoids – via direct or indirect activation of CB(1) and/or CB(2) receptors – exert protective effects in well-established models of intestinal inflammation and colon cancer. Pharmacological elevation of endocannabinoid levels may be a promising strategy to counteract intestinal inflammation and colon cancer.”

http://www.ncbi.nlm.nih.gov/pubmed/19442536

The role of cannabinoid system on immune modulation: therapeutic implications on CNS inflammation.

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Abstract

“There is a growing amount of evidence suggesting that cannabinoids may be neuroprotective in CNS inflammatory conditions. Advances in the understanding of the physiology and pharmacology of the cannabinoid system have increased the interest of cannabinoids as potential therapeutic targets. Cannabinoid receptors and their endogenous ligands, the endocannabinoids, have been detected in cells of the immune system, as well as in brain glial cells. In the present review it is summarized the effects of cannabinoids on immune reactivity and on the regulation of neuroinflammatory processes associated with brain disorders with special attention to chronic inflammatory demyelinating diseases such as multiple sclerosis.”

http://www.ncbi.nlm.nih.gov/pubmed/16026313

Cannabinoids and the immune system: potential for the treatment of inflammatory diseases?

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Abstract

“Since the discovery of the cannabinoid receptors and their endogenous ligands, significant advances have been made in studying the physiological function of the endocannabinoid system. The presence of cannabinoid receptors on cells of the immune system and anecdotal and historical evidence suggesting that cannabis use has potent immuno-modulatory effects, has led to research directed at understanding the function and role of these receptors within the context of immunological cellular function. Studies from chronic cannabis smokers have provided much of the evidence for immunomodulatory effects of cannabis in humans, and animal and in vitro studies of immune cells such as T cells and macrophages have also provided important evidence. Cannabinoids can modulate both the function and secretion of cytokines from immune cells. Therefore, cannabinoids may be considered for treatment of inflammatory disease. This review article will highlight recent research on cannabinoids and how they interact with the immune system and also their potential use as therapeutic agents for a number of inflammatory disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/16023222