FAAH and MAGL inhibitors: therapeutic opportunities from regulating endocannabinoid levels.

Abstract

 “Apart from their widespread recreational abuse, the psychoactive preparations of the plant Cannabis sativa and its major psychotropic component, Delta9-tetrahydrocannabinol (THC), are also known for their medicinal properties. Following the identification of receptors for THC – the cannabinoid CB1 and CB2 receptors – in mammals, various pharmaceutical strategies have attempted to exploit the properties of the cannabinoid system while minimizing psychotropic side effects. The cloning of the cannabinoid CB1 and CB2 receptors enabled the discovery of the endogenous agonists of the receptors, the endocannabinoids, and eventually led to the identification of enzymes that catalyze endocannabinoid inactivation. Unlike exogenously administered THC and synthetic CB1 and CB2 agonists, the endocannabinoids that are produced endogenously following the onset of several pathologies may act in a site- and time-specific manner to minimize the consequences of such conditions. This observation has suggested the possibility of targeting endocannabinoid-degrading enzymes to prolong the precisely regulated pro-homeostatic action of endocannabinoids. Two major enzymes have been cloned and investigated thoroughly: fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). Inhibitors of these enzymes have demonstrated therapeutic benefit in animal models of several disorders, including neuropathic pain, anxiety and inflammatory bowel diseases, as well as against the proliferation and migration of cancer cells. This review describes the major biochemical properties of FAAH and MAGL, and the design and pharmacological properties of inhibitors of these enzymes.”

http://www.ncbi.nlm.nih.gov/pubmed/20047159

Therapeutic Potential of Monoacylglycerol Lipase Inhibitors.

Abstract

 “Marijuana and aspirin have been used for millennia to treat a wide range of maladies including pain and inflammation. Both cannabinoids, like marijuana, that exert anti-inflammatory action through stimulating cannabinoid receptors, and cyclooxygenase (COX) inhibitors, like aspirin, that suppress pro-inflammatory eicosanoid production have shown benefitial outcomes in mouse models of neurodegenerative diseases and cancer. Both cannabinoids and COX inhibitors, however, have untoward effects that discourage their chronic usage, including cognitive deficits and gastrointestinal toxicity, respectively. Recent studies have uncovered that the serine hydrolase monoacylglycerol lipase (MAGL) links the endocannabinoid and eicosanoid systems together through hydrolysis of the endocannabinoid 2-arachidonoylglycerol (2-AG) to provide the major arachidonic acid (AA) precursor pools for pro-inflammatory eicosanoid synthesis in specific tissues. Studies in recent years have shown that MAGL inhibitors elicit anti-nociceptive, anxiolytic, and anti-emetic responses and attenuate precipitated withdrawal symptoms in addiction paradigms through enhancing endocannabinoid signaling. MAGL inhibitors have also been shown to exert anti-inflammatory action in the brain and protect against neurodegeneration through lowering eicosanoid production. In cancer, MAGL inhibitors have been shown to have anti-cancer properties not only through modulating the endocannabinoid-eicosanoid network, but also by controlling fatty acid release for the synthesis of protumorigenic signaling lipids. Thus, MAGL serves as a critical node in simultaneously coordinating multiple lipid signaling pathways in both physiological and disease contexts. This review will discuss the diverse (patho)physiological roles of MAGL and the therapeutic potential of MAGL inhibitors in treating a vast array of complex human diseases.”

http://www.ncbi.nlm.nih.gov/pubmed/23142242

Monoacylglycerol Lipase Activity Is a Critical Modulator of the Tone and Integrity of the Endocannabinoid System

“Endocannabinoids are lipid molecules that serve as natural ligands for the cannabinoid receptors CB1 and CB2. They modulate a diverse set of physiological processes such as pain, cognition, appetite, and emotional states, and their levels and functions are tightly regulated by enzymatic biosynthesis and degradation. 2-Arachidonoylglycerol (2-AG) is the most abundant endocannabinoid in the brain and is believed to be hydrolyzed primarily by the serine hydrolase monoacylglycerol lipase (MAGL). Although 2-AG binds and activates cannabinoid receptors in vitro, when administered in vivo, it induces only transient cannabimimetic effects as a result of its rapid catabolism. Here we show using a mouse model with a targeted disruption of the MAGL gene that MAGL is the major modulator of 2-AG hydrolysis in vivo. Mice lacking MAGL exhibit dramatically reduced 2-AG hydrolase activity and highly elevated 2-AG levels in the nervous system. A lack of MAGL activity and subsequent long-term elevation of 2-AG levels lead to desensitization of brain CB1 receptors with a significant reduction of cannabimimetic effects of CB1 agonists. Also consistent with CB1 desensitization, MAGL-deficient mice do not show alterations in neuropathic and inflammatory pain sensitivity. These findings provide the first genetic in vivo evidence that MAGL is the major regulator of 2-AG levels and signaling and reveal a pivotal role for 2-AG in modulating CB1 receptor sensitization and endocannabinoid tone.”

“In summary, we provide data showing that MAGL is a critical modulator of 2-AG levels and functions and that the endocannabinoid system adapts to long-term elevation of 2-AG levels by down-regulating CB1 receptor density and signaling. Moreover, our gain of function in vivo model of 2-AG signaling sheds light on the physiological and pathophysiological consequences of long-term inhibition of MAGL, a pharmacological target with therapeutic potential for neurologic and metabolic diseases.”

http://molpharm.aspetjournals.org/content/78/6/996.long

Fatty acid amide hydrolase: a potential target for next generation therapeutics.

Abstract

“Endocannabinoids are amides, esters and ethers of long chain polyunsaturated fatty acids, which act as new lipid mediators. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol are the main endogenous agonists of cannabinoid receptors, able to mimic several pharmacological effects of Delta(9)-tetrahydrocannabinol, the active principle of Cannabis sativa preparations like hashish and marijuana. The activity of AEA at its receptors is limited by cellular uptake through a specific membrane transporter, followed by intracellular degradation by a fatty acid amide hydrolase (FAAH). Growing evidence demonstrates that FAAH is the critical regulator of the endogenous levels of AEA, suggesting that it may serve as an attractive therapeutic target for the treatment of human disorders. In particular, FAAH inhibitors may be next generation therapeutic drugs of potential value for the treatment of pathologies in the central nervous system and in the periphery. Here, the potential applications of these inhibitors for human disease will be reviewed, with an emphasis on the properties of hydro(pero)xy-anandamides. In fact, these oxygenated derivatives of AEA are the most powerful inhibitors of FAAH of natural origin as yet discovered. In addition, new insights into the promoter region of FAAH gene will be presented, and the therapeutic potential of mimetics of transcription factors of this gene in the management of human infertility will be discussed.”

http://www.ncbi.nlm.nih.gov/pubmed/16472164

Fatty acid amide hydrolase: a gate-keeper of the endocannabinoid system.

Abstract

“The family of endocannabinoids contains several polyunsaturated fatty acid amides such as anandamide (AEA), but also esters such as 2-arachidonoylglycerol (2-AG). These compounds are the main endogenous agonists of cannabinoid receptors, able to mimic several pharmacological effects of Delta9-tetrahydrocannabinol (Delta9-THC), the active principle of Cannabis sativa preparations like hashish and marijuana. The activity of AEA at its receptors is limited by cellular uptake, through a putative membrane transporter, followed by intracellular degradation by fatty acid amide hydrolase (FAAH). Growing evidence demonstrates that FAAH is the critical regulator of the endogenous levels of AEA, suggesting that it may serve as an attractive therapeutic target for the treatment of human disorders. In particular, FAAH inhibitors may be next generation therapeutics of potential value for the treatment of pathologies of the central nervous system, and of peripheral tissues. Investigations into the structure and function of FAAH, its biological and therapeutic implications, as well as a description of different families of FAAH inhibitors, are the topic of this chapter.”

http://www.ncbi.nlm.nih.gov/pubmed/18751909

New insights into endocannabinoid degradation and its therapeutic potential.

Abstract

“Endocannabinoids are amides, esters and ethers of long chain polyunsaturated fatty acids, which act as new lipidic mediators. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol (2-AG) are the main endogenous agonists of cannabinoid receptors, able to mimic several pharmacological effects of (-)-Delta9-tetrahydrocannabinol (THC), the active principle of Cannabis sativa preparations like hashish and marijuana. The activity of AEA and 2-AG at their receptors is limited by cellular uptake through an anandamide membrane transporter (AMT), followed by intracellular degradation. A fatty acid amide hydrolase (FAAH) is the main AEA hydrolase, whereas a monoacylglycerol lipase (MAGL) is critical in degrading 2-AG. Here, we will review growing evidence that demonstrates that these hydrolases are pivotal regulators of the endogenous levels of AEA and 2-AG in vivo, overall suggesting that specific inhibitors of AMT, FAAH or MAGL may serve as attractive therapeutic targets for the treatment of human disorders. Recently, the N-acylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD), which synthesizes AEA from N-arachidonoylphosphatidylethanolamine (NArPE), and the diacylglycerol lipase (DAGL), which generates 2-AG from diacylglycerol (DAG) substrates, have been characterized. The role of these synthetic routes in maintaining the endocannabinoid tone in vivo will be discussed. Finally, the effects of inhibitors of endocannabinoid degradation in animal models of human disease will be reviewed, with an emphasis on their ongoing applications in anxiety, cancer and neurodegenerative disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/16515464

Therapeutic potential of endocannabinoid-hydrolysing enzyme inhibitors.

Abstract

“The specific protein target of delta9-tetrahydrocannabinol (delta9-THC), the main active ingredient of Cannabis sativa L., was characterized from rat brain nearly 20 years ago, and several endogenous compounds and proteins comprising the endocannabinoid (eCB) system have since been discovered. It has become evident that the eCB system consists of at least two cannabinoid receptors (i.e. the CB1 and CB2 receptors), in addition to their endogenous ligands (the eCBs) and several enzymes involved in the biosynthesis and catabolism of the eCBs. The two well-established eCBs, N-arachidonoylethanolamide (AEA) and 2-arachidonoylglycerol (2-AG), are produced by neurons on demand, act near their sites of synthesis and are effectively metabolized by fatty acid amide hydrolase (FAAH) and monoglyceride lipase (MGL), respectively. Inhibitors specifically targeting these enzymes could offer novel therapeutic approaches (e.g. for the treatment of pain and movement disorders). This MiniReview summarizes the literature concerning the potential therapeutic potential of FAAH and MGL inhibitors.”

http://www.ncbi.nlm.nih.gov/pubmed/17910610

Discovery and development of endocannabinoid-hydrolyzing enzyme inhibitors.

Abstract

“Fatty acid amide hydrolase (FAAH) and monoglyceride lipase (MGL) are hydrolytic enzymes which degrade the endogenous cannabinoids (endocannabinoids) N-arachidonoylethanolamine (anandamide, AEA) and 2-arachidonoylglycerol (2-AG), respectively. Endocannabinoids are an important class of lipid messenger molecules that are produced on demand in response to elevated intracellular calcium levels. They recognize and activate the cannabinoid CB(1) and CB(2) receptors, the molecular targets for Delta(9)-tetrahydrocannabinol (Delta(9)-THC) in marijuana evoking several beneficial therapeutic effects. However, in vivo the cannabimimetic effects of AEA and 2-AG remain weak owing to their rapid inactivation by FAAH and MGL, respectively. The inactivation of FAAH and MGL by specific enzyme inhibitors increases the levels of AEA and 2-AG, respectively, producing therapeutic effects such as pain relief and depression of anxiety.”

http://www.ncbi.nlm.nih.gov/pubmed/20370710

Cannabinoid 2 receptor induction by IL-12 and its potential as a therapeutic target for the treatment of anaplastic thyroid carcinoma.

“Anaplastic thyroid carcinoma is the most aggressive type of thyroid malignancies…”

 “These data suggest that CB2 overexpression may contribute to the regression of human anaplastic thyroid tumor… Given that cannabinoids have shown antitumor effects in many types of cancer models, CB2 may be a viable therapeutic target for the treatment of anaplastic thyroid carcinoma.”

http://www.ncbi.nlm.nih.gov/pubmed/18197164

Endogenous cannabinoids and neutrophil chemotaxis.

Abstract

  “Neutrophils are the earliest inflammatory cell to infiltrate tissue, playing an important role in early phagocytosis. Under pathological conditions, pro-inflammatory actions of neutrophils contribute to the development of various inflammatory diseases. G(i) protein-coupled cell-surface receptors are an essential component of pro-migratory responses in leukocytes; however, few investigations regarding inhibitors of cell migration have been reported. Kurihara et al. (2006) and McHugh et al. (2008) have revealed that certain endogenous cannabinoids and lipids are potent inhibitors of induced human neutrophil migration. McHugh et al. implicate a novel SR141716A-sensitive pharmacological target distinct from cannabinoid CB(1) and CB(2) receptors, which is antagonized by N-arachidonoyl-l-serine; and that the CB(2) receptor exerts negative co-operativity upon this receptor. Kurihara et al. demonstrate that fMLP-induced RhoA activity is decreased following endocannabinoid pretreatment, disrupting the front/rear polarization necessary for neutrophils to engage in chemotaxis.

The therapeutic potential of exploiting endocannabinoids as neutrophilic chemorepellants is plain to see.”

http://www.ncbi.nlm.nih.gov/pubmed/19647118