>Sender: >To: >X-Original-Message-ID: <00ef01bf1759$b5956be0$9acf69cf@pacbell.net> >From: "Peter McWilliams" >Subject: Pain and marijuana >Date: Fri, 15 Oct 1999 15:07:45 -0700 >X-Mozilla-Status: 8001 >X-Mozilla-Status2: 00000000 > > >Subject: [evol-psych] Brain releases marijuana-like substance in >response to pain, study finds >Date: Tue, 12 Oct 1999 15:57:41 +0100 >From: "Ian Pitchford" >Reply-To: "Ian Pitchford" >Organization: http://www.human-nature.com/ >To: > >FOR RELEASE: 11 OCTOBER 1999 AT 17:00 ET US >Brown University >http://www.brown.edu/Administration/News_Bureau > >Brain releases marijuana-like substance in response to pain, study finds > >PROVIDENCE, R.I. - Pain triggers the brain's release of a naturally >produced cannabinoid, >a compound similar to the active ingredient in marijuana, according to a >new study by >Brown researchers that documented its release in the brain's pain >response system for the >first time. > >The cannabinoid known as anandamide produced analgesia - the absence of >a normal sense of >pain - in response to pain in anesthetized rats. The findings are >published in the Oct. 12 >issue of the Proceedings of the National Academy of Sciences (PNAS). > >Although the existence of non-opiate factors in the brain's pain >suppression system were >first noted 20 years ago, little was known about these substances. Brown >researchers were >able to measure the anandamide using a new type of mass spectrometry, >which is able to >detect minute amounts of a substance. > >Knowledge about a pain-modulatory system based on cannabinoids is >valuable for the future >treatment of pain, particularly in instances where opiates are >ineffective, according to >J. Michael Walker, psychology professor and lead researcher. > >"There are some types of pain that do not respond well to current >treatments," said >Walker. "The fact that you have different modulatory systems that are >effective for >different types of pain may offer hope." > >Drugs that inhibit the reuptake of anandamide by cells, or block its >degradation, may form >the basis of a modern pharmacotherapy for pain, he said. > >Researchers measured the levels of anandamide in the region of the brain >recognized for >its role in pain modulation - the periaqueductal gray (PAG). The PAG is >part of the brain >stem that connects the cerebral hemispheres with the spinal cord. It is >very similar in >animals and humans. > >Electrical stimulation of the PAG in anesthetized animal models was >accompanied by both >pain suppression and a marked increase in the release of anandamide. >Furthermore, >injections of formalin, a chemical irritant that induces prolonged pain, >profoundly >elevated the anandamide levels in the same location of the PAG in >anesthetized rats. >Although animals did not feel the pain, researchers were able to observe >pain modulation >because the brain responds in the same way. > >Researchers used atmospheric pressure-chemical ionization mass >spectrometry to measure the >molecular weight of anandamide. This multistep method permitted the >detection of the >extremely small amounts of the anandamide. They found the substance in a >different >location of the PAG than the location proven to play a part in the >release of natural >opiates. > >"One of the functions of chemical transmission in the brain is to modify >pain sensitivity, >and the brain uses the anandamide for this purpose," said Walker. "The >pain itself >triggers this reaction." > >The correlation between cannabinoids and pain suppression is not a >startling finding in >itself; cannabinoids have been used to treat pain for centuries. In >ancient China, hemp >extract was used as a surgical anesthetic, and archaeological finds in >Israel have >revealed its use against the pain of childbirth. > >Cannabis is still used to treat pain, despite its illegal status in most >parts of the >world. A report early this year by the National Academy of Sciences >Institute of Medicine >found that significant amounts of research - including research by >Walker and colleagues - >point to the potential to use marijuana derivatives in treating chronic >pain. > >However, more research needs to be done to determine whether there are >other naturally >produced cannabinoids released in the brain in addition to anandamide, >said Walker. > >Other researchers involved in the study were Susan M. Huang, Brown >graduate student; >Nicole M. Strangman, Brown graduate student; M. Clara Saûudo-Peûa, >assistant research >professor of psychology; and the late Brown University professor and >member of the Chinese >Academy of Sciences, Kang Tsou. The work was supported with funding from >the U.S. Public >Health Service and National Institutes of Health. In addition, Brown >University and the >National Institute on Drug Abuse financed the purchase of the mass >spectrometer used in >the experiments. > > >================================================================ > >This message is sent to you because you are subscribed to > the mailing list . >To unsubscribe, E-mail to: --------------------------------------------------------------------------------