Tag Archives: endocannabinoid system

The endocannabinoid system: a general view and latest additions

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Abstract

“After the discovery, in the early 1990s, of specific G-protein-coupled receptors for marijuana’s psychoactive principle Delta(9)-tetrahydrocannabinol, the cannabinoid receptors, and of their endogenous agonists, the endocannabinoids, a decade of investigations has greatly enlarged our understanding of this altogether new signalling system. Yet, while the finding of the endocannabinoids resulted in a new effort to reveal the mechanisms regulating their levels in the brain and peripheral organs under physiological and pathological conditions, more endogenous substances with a similar action, and more molecular targets for the previously discovered endogenous ligands, anandamide and 2-arachidonoylglycerol, or for some of their metabolites, were being proposed. As the scenario becomes subsequently more complicated, and the experimental tasks to be accomplished correspondingly more numerous, we briefly review in this article the latest ‘additions’ to the endocannabinoid system together with earlier breakthroughs that have contributed to our present knowledge of the biochemistry and pharmacology of the endocannabinoids.”

Introduction

“The discovery in the early 1990s of specific membrane receptors of marijuana’s psychoactive component (-)-Δ9-tetrahydrocannabinol (THC) opened the way to the revelation of a whole endogenous signaling system now known as the endocannabinoid system. Apart from the cannabinoid CB1 and CB2 receptors (Pertwee, 1997), this system comprises also their endogenous ligands (the endocannabinoids) and the proteins for their synthesis and inactivation, as well as other molecular targets for the endocannabinoids. However, as new findings on the regulation of the levels and action of the endocannabinoids, and new data on their possible physiological and pathological role, are reported every day in the literature, it is easy to understand that the story of the endocannabinoid system is far from set. For example, while until the end of the 20th century only two endocannabinoids, anandamide (N-arachidonoyl-ethanolamine, AEA) and 2-arachidonoyl-glycerol (2-AG) had been discovered (Devane et al., 1992; Mechoulam et al., 1995; Sugiura et al., 1995), in just a couple of years, three more candidates to the role of cannabinoid receptor agonists have been proposed: 2-arachidonyl-glyceryl ether (noladin, 2-AGE), O-arachidonoyl-ethanolamine (virhodamine) and N-arachidonoyl-dopamine (NADA) (Bisogno et al., 2000; Huang et al., 2002; Porter et al., 2002). These findings not only suggest that the endocannabinoid family is larger than initially thought but also enlarge our view on the possible molecular mechanisms for the biosynthesis, action and inactivation of these lipid mediators. This brief article aims at giving a picture as much updated as possible on the ‘old’ and ‘new’ components of the endocannabinoid system, while highlighting the latest and most important findings in this field.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1574255/

 

The endocannabinoid system: its general strategy of action, tools for its pharmacological manipulation and potential therapeutic exploitation.

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Abstract

“The endocannabinoid signalling system includes: (1) at least two G-protein-coupled receptors, known as the cannabinoid CB(1) and CB(2) receptors and discovered following studies on the mechanism of action of Delta(9)-tetrahydrocannabinol, the major psychoactive principle of the hemp plant Cannabis sativa; (2) the endogenous agonists at these receptors, known as endocannabinoids, of which anandamide and 2-arachidonoylglycerol are the best known; and (3) proteins and enzymes for the regulation of endocannabinoid levels and action at receptors. The endocannabinoid system is quite widespread in mammalian tissues and cells and appears to play a pro-homeostatic role by being activated following transient or chronic perturbation of homeostasis, and by regulating in a local way the levels and action of other chemical signals. Compounds that selectively manipulate the action and levels of endocannabinoids at their targets have been and are being developed, and represent templates for potential new therapeutic drugs.”

http://www.ncbi.nlm.nih.gov/pubmed/19559360

An introduction to the endocannabinoid system: from the early to the latest concepts

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Abstract

“A rather complex and pleiotropic endogenous signalling system was discovered in the late 1990s, starting from studies on the mechanism of action of Delta(9)-tetrahydrocannabinol, the major psychoactive principle of the hemp plant Cannabis sativa. This system includes: (1) at least two G-protein-coupled receptors, known as the cannabinoid CB(1) and CB(2) receptors; (2) the endogenous agonists at these receptors, known as endocannabinoids, of which anandamide and 2-arachidonoylglycerol are the best known; and (3) proteins and enzymes for the regulation of endocannabinoid levels and action at receptors. The number of the members of this endocannabinoid signalling system seems to be ever increasing as new non-CB(1) non-CB(2) receptors for endocannabinoids, endocannabinoid-related molecules with little activity at CB(1) and CB(2) receptors, and new enzymes for endocannabinoid biosynthesis and degradation are being identified every year. The complexity of the endocannabinoid system and of its physiological and pathological function is outlined in this introductory chapter, for a better understanding of the subsequent chapters in this special issue.”

http://www.ncbi.nlm.nih.gov/pubmed/19285257

The endocannabinoid system: physiology and pharmacology.

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Abstract

“The endogenous cannabinoid system is an ubiquitous lipid signalling system that appeared early in evolution and which has important regulatory functions throughout the body in all vertebrates. The main endocannabinoids (endogenous cannabis-like substances) are small molecules derived from arachidonic acid, anandamide (arachidonoylethanolamide) and 2-arachidonoylglycerol. They bind to a family of G-protein-coupled receptors, of which the cannabinoid CB(1) receptor is densely distributed in areas of the brain related to motor control, cognition, emotional responses, motivated behaviour and homeostasis. Outside the brain, the endocannabinoid system is one of the crucial modulators of the autonomic nervous system, the immune system and microcirculation. Endocannabinoids are released upon demand from lipid precursors in a receptor-dependent manner and serve as retrograde signalling messengers in GABAergic and glutamatergic synapses, as well as modulators of postsynaptic transmission, interacting with other neurotransmitters, including dopamine. Endocannabinoids are transported into cells by a specific uptake system and degraded by two well-characterized enzymes, the fatty acid amide hydrolase and the monoacylglycerol lipase. Recent pharmacological advances have led to the synthesis of cannabinoid receptor agonists and antagonists, anandamide uptake blockers and potent, selective inhibitors of endocannabinoid degradation. These new tools have enabled the study of the physiological roles played by the endocannabinoids and have opened up new strategies in the treatment of pain, obesity, neurological diseases including multiple sclerosis, emotional disturbances such as anxiety and other psychiatric disorders including drug addiction. Recent advances have specifically linked the endogenous cannabinoid system to alcoholism, and cannabinoid receptor antagonism now emerges as a promising therapeutic alternative for alcohol dependence and relapse.”

CONCLUSION

“Since the discovery of anandamide, the increasing information on the physiological roles played by the endogenous cannabinoid system and its contribution to pathology have led to this signalling system becoming more important in neurobiology. The intense pharmacological research based on this information has yielded, in a very short time, potent, selective drugs targeting the endogenous cannabinoid system that have opened up new avenues for the understanding and treatment of major diseases including cancer, pain, neurodegeneration, anxiety and addiction. This is a very promising starting point for a new age that takes over from the ancient use of Cannabis as a medicine. Now is the time for clinical trials aimed at evaluating the efficacy of cannabinoid drugs in disorders lacking effective therapeutic approaches, such as alcoholism.”

http://alcalc.oxfordjournals.org/content/40/1/2.long

The endocannabinoid system and its therapeutic exploitation

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Abstract

“The term ‘endocannabinoid’ – originally coined in the mid-1990s after the discovery of membrane receptors for the psychoactive principle in Cannabis, Delta9-tetrahydrocannabinol and their endogenous ligands – now indicates a whole signalling system that comprises cannabinoid receptors, endogenous ligands and enzymes for ligand biosynthesis and inactivation. This system seems to be involved in an ever-increasing number of pathological conditions. With novel products already being aimed at the pharmaceutical market little more than a decade since the discovery of cannabinoid receptors, the endocannabinoid system seems to hold even more promise for the future development of therapeutic drugs. We explore the conditions under which the potential of targeting the endocannabinoid system might be realized in the years to come.”

http://www.ncbi.nlm.nih.gov/pubmed/15340387

The endocannabinoid system: a drug discovery perspective.

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Abstract

“The endocannabinoids are lipid messengers that engage the same cell surface receptors targeted by delta9-tetrahydrocannabinol, the active component of marijuana. They are produced by cells in the brain and other tissues and combine with two subtypes of G protein-coupled cannabinoid receptors, CB1 and CB2. Their ability to modulate a variety of pathophysiological processes, including appetite, pain and mood, provides unique opportunities for drug discovery. Three such opportunities are discussed here: reduction of body weight through blockade of CB1 receptors, alleviation of pain through activation of extracerebral cannabinoid receptors, and modulation of pain and anxiety through inhibition of endocannabinoid degradation.”

http://www.ncbi.nlm.nih.gov/pubmed/16044662

[The endocannabinoid system as a target for the development of new drugs for cancer therapy].

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“Studies on the main bioactive components of Cannabis sativa, the cannabinoids, and particularly delta 9-tetrahydrocannabinol (THC), led to the discovery of a new endogenous signalling system that controls several physiological and pathological conditions: the endocannabinoid system. This comprises the cannabinoid receptors, their endogenous agonists–the endocannabinoids–and proteins for endocannabinoid biosynthesis and inactivation.

Recently, evidence has accumulated indicating that stimulation of cannabinoid receptors by either THC or the endocannabinoids influence the intracellular events controlling the proliferation and apoptosis of numerous types of cancer cells, thereby leading to anti-tumour effects both in vitro and in vivo.

This evidence is reviewed here and suggests that future anti-cancer therapy might be developed from our knowledge of how the endocannabinoid system controls the growth and metastasis of malignant cells.”

http://www.ncbi.nlm.nih.gov/pubmed/12723496

Endocannabinoid system modulation in cancer biology and therapy.

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“The discovery of the endocannabinoid system and the recognition of its potential impact in a plethora of pathological conditions, led to the development of therapeutic agents related to either the stimulation or antagonism of CB1 and CB2 cannabinoid receptors, the majority of which are actually tested in preclinical studies for the pharmacotherapy of several diseases. Endocannabinoid-related agents have been reported to affect multiple signaling pathways and biological processes involved in the development of cancer, displaying an interesting anti-proliferative, pro-apoptotic, anti-angiogenic and anti-metastatic activity both in vitro and in vivo in several models of cancer. Emerging evidence suggests that agonists of cannabinoid receptors, which share the useful property to discern between tumor cells and their non-transformed counterparts, could represent novel tumor-selective tools to treat cancer in addition to their already exploited use as palliative drugs to treat chemotherapy-induced nausea, pain and anorexia/weight loss in cancer patients. The aim of this review is to evidence and update the recent emerging knowledge about the role of the endocannabinoid system in cancer biology and the potentiality of its modulation in cancer therapy.”  http://www.ncbi.nlm.nih.gov/pubmed/19559362

http://www.sciencedirect.com/science/article/pii/S1043661809000863

Cannabinoid receptor systems: therapeutic targets for tumour intervention

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Abstract

“The past decade has witnessed a rapid expansion of our understanding of the biological roles of cannabinoids and their cognate receptors. It is now certain that Delta9-tetrahydrocannabinol, the principle psychoactive component of the Cannabis sativa plant, binds and activates membrane receptors of the 7-transmembrane domain, G-protein-coupled superfamily. Several putative endocannabinoids have since been identified, including anandamide, 2-arachidonyl glycerol and noladin ether. Synthesis of numerous cannabinomimetics has also greatly expanded the repertoire of cannabinoid receptor ligands with the pharmacodynamic properties of agonists, antagonists and inverse agonists. Collectively, these ligands have proven to be powerful tools both for the molecular characterisation of cannabinoid receptors and the delineation of their intrinsic signalling pathways. Much of our understanding of the signalling mechanisms activated by cannabinoids is derived from studies of receptors expressed by tumour cells; hence, this review provides a succinct summary of the molecular pharmacology of cannabinoid receptors and their roles in tumour cell biology. Moreover, there is now a genuine expectation that the manipulation of cannabinoid receptor systems may have therapeutic potential for a diverse range of human diseases. Thus, this review also summarises the demonstrated antitumour actions of cannabinoids and indicates possible avenues for the future development of cannabinoids as antitumour agents.”

http://www.ncbi.nlm.nih.gov/pubmed/14640910

Changes in the Endocannabinoid System May Give Insight into new and Effective Treatments for Cancer

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“The endocannabinoid system comprises specific cannabinoid receptors such as Cb1 and Cb2, the endogenous ligands (anandamide and 2-arachidonyl glycerol among others) and the proteins responsible for their synthesis and degradation. This system has become the focus of research in recent years because of its potential therapeutic value several disease states. The following review describes our current knowledge of the changes that occur in the endocannabinoid system during carcinogenesis and then focuses on the effects of anandamide on various aspects of the carcinogenic process such as growth, migration, and angiogenesis in tumors from various origins.

Marijuana and its derivatives have been used in medicine for centuries, however, it was not until the isolation of the psychoactive component of Cannabis sativa (Δ9-tetrahydrocannabinol; Δ9-THC) and the subsequent discovery of the endogenous cannabinoid signaling system that research into the therapeutic value of this system reemerged. Ongoing research is determining that regulation of the endocannabinoid system may be effective in the treatment of pain (Calignano et al., 1998; Manzanares et al., 1999), glaucoma (Voth and Schwartz, 1997), and neurodegenerative disorders such as Parkinson’s disease (Piomelli et al., 2000) and multiple sclerosis (Baker et al., 2000). In addition, cannabinoids might be effective anti-tumoral agents because of their ability to inhibit the growth of various types of cancer cell lines in culture (De Petrocellis et al., 1998; Ruiz et al., 1999; Sanchez et al., 1998, 2001) and in laboratory animals (Galve-Roperh et al., 2000).

In conclusion, the endocannabinoid system exerts a myriad of effects on tumor cell growth, progression, angiogenesis, and migration. With a notable few exceptions, targeting the endocannabinoid system with agents that activate cannabinoid receptors or increase the endogenous levels of AEA may prove to have therapeutic benefit in the treatment of various cancers. Further studies into the downstream consequences of AEA treatment are required and may illuminate other potential therapeutic targets.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2791688/