Scripps research team defines new painkilling chemical pathwayNovember 24, 2008Discovery could lead to new pain treatments Marijuana kills pain by activating a set of proteins known as cannabinoid receptors, which can also regulate appetite, inflammation, and memory. The body also has chemicals known as endocannabinoids that naturally activate these same receptors, namely N-arachidonoyl ethanolamine (AEA) and 2-arachidonoylglycerol (2-AG). These natural components of the cannabinoid system remain the focus of intense efforts to develop new treatments not only for chronic pain, but also for obesity, anxiety, and depression. However, until the new paper, specific methods to study 2-AG signaling have been lacking. AEA's activity has been well understood for years. In past research, Cravatt and his team identified an enzyme called fatty acid amide hydrolase, or FAAH, that breaks down AEA, effectively reducing its pain killing activity. A number of compounds are now in clinical development that target and breakdown FAAH, allowing AEA to build up, reducing pain. However, FAAH does not control 2-AG metabolism in vivo, and therefore, the potential biological functions and therapeutic potential of this second endocannabinoid have remained largely unknown. Teasing out 2-AG's specific impacts have proven challenging. Comparable to FAAH, an enzyme called monoacylglycerol lipase (MAGL) breaks down 2-AG. But, despite numerous attempts, no group had been able to develop a chemical that inhibits MAGL specifically. "The tools-selective and efficacious MAGL inhibitors-just weren't there, " says Jonathan Long, a graduate student of the Scripps Research Kellogg School of Science and Technology who is a member of the Cravatt lab and a first author of the new paper. But now, a MAGL-specific inhibitor is finally available, thanks to the lab's new work. Key to this success was Activity-Based Protein Profiling, a unique chemical technique the group devised and has used fruitfully in other inhibitor hunts. This system enables the rapid engineering and testing of chemical compounds against many members of enzyme families, in hope of finding effective and selective inhibitors. For this project, the group developed about 200 compounds and found that one was a highly effective block for MAGL. The scientists dubbed the compound JZL184, named after Long's initials and the order in the series of potential inhibitors tested. JZL184 effectively blocks only MAGL among more than 40 related brain enzymes, which opened the door for the first definitive study of 2-AG's activity. A New View of 2-AG Unlike increased AEA, which causes only reduced pain sensation, the team found that MAGL inhibition using JZL184, and the resulting increase in 2-AG concentration, not only reduced pain in mice, but also induced other effects associated with the cannabinoid receptors, namely hypothermia and decreased movement. "This really does suggest a sort of segregation of labor, if you will," says Cravatt of the differential effects of elevating AEA versus 2-AG as part of the overall function of the cannabinoid system. "That, I think, is a truly unique result." While treatments based on inhibiting FAAH show great promise for controlling pain, manipulating MAGL levels could also be a boon for treatment development, especially if 2-AG's other effects, such as hypothermia, can be managed. "There are so many different types of pain," Cravatt says, "that it's possible some types could be more effectively treated with one treatment than another." Scripps Research Institute |
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| Related Cannabinoid Current Events and Cannabinoid News Articles Impact of cannabis on bones changes with age, study finds Scientists investigating the effects of cannabis on bone health have found that its impact varies dramatically with age. Marijuana use linked to increased risk of testicular cancer Frequent and/or long-term marijuana use may significantly increase a man's risk of developing the most aggressive type of testicular cancer, according to a study by researchers at Fred Hutchinson Cancer Research Center. The study results were published online Feb. 9 in the journal Cancer. New cannabis-like drugs could block pain without affecting brain, says study A new type of drug could alleviate pain in a similar way to cannabis without affecting the brain, according to a new study published in the journal Pain on Monday 15 September. Milestone for cannabinoid MS study The CUPID (Cannabinoid Use in Progressive Inflammatory brain Disease) study at the Peninsula Medical School in Plymouth has reached an important milestone with the news that the full cohort of 493 people with multiple sclerosis (MS) has been recruited to the study. Schizophrenia linked to dysfunction in molecular brain pathway activated by marijuana Alterations in a molecular brain pathway activated by marijuana may contribute to the cognitive symptoms of schizophrenia, according to a report in the July issue of Archives of General Psychiatry, one of the JAMA/Archives journals. Opioids and cannabinoids influence mobility of spermatozoids A PhD thesis from the University of the Basque Country has concluded that there are opioid and cannabinoid receptors in human sperm and that these influence the mobility of spermatozoid. Medicines derived from cannabis: a review of adverse events Researchers at the McGill University Health Centre (MUHC), McGill University and the University of British Columbia (UBC) determined that medical use of cannabinoids do not cause an increase in serious adverse events, but are associated with an increase in some non-serious adverse events. New Mount Sinai research tracks effects of addictive drugs on brain Mount Sinai researchers may have unlocked the key to better understanding the effect addictive drugs have on the human brain. U of Minnesota researcher discovers the starting point of sun-induced skin cancer According to a new study from the University of Minnesota, the earliest event in the development of sun-induced skin cancer may have been identified. Study finds possible connection between marijuana abuse and stroke or heart attacks Long-term harmful effects of marijuana (MJ) include risk for heart attacks and strokes in addition to impaired learning and memory. The active chemical in MJ called delta-9-tetrahyrdocannabinol (THC) is believed to exert these effects by binding to cannabinoid (CB) receptors located on several cell types in various organs. More Cannabinoid Current Events and Cannabinoid News Articles |
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