Study Clarifies Brain Mechanisms of Cocaine's High

Apr 23, 2001, 01:00 ET from National Institute on Drug Abuse

    WASHINGTON, April 23 /PRNewswire Interactive News Release/ -- A team of
 researchers led by scientists from the National Institute on Drug Abuse's
 Intramural Research Program has made a major advance in understanding the
 molecular basis of how cocaine produces its characteristic high, suggesting
 new targets for developing anti-addiction medicines.  The findings, published
 in the April 24 issue of the Proceedings of the National Academy of Sciences,
 show that inactivating both the serotonin and dopamine transporters in the
 brains of mice dramatically reduces their experience of cocaine's rewarding,
 pleasurable effects.  It has been known for some time that cocaine use affects
 the brain's dopamine system, but also that manipulating dopamine does not
 fully control cocaine's effects.  Thus this study shows the critical
 importance of the serotonin system as well as the dopamine system in mediating
 cocaine's pleasurable effects.
     "Currently, there is no medication that effectively blocks the brain's
 reward response to cocaine or that substantially relieves cocaine addiction,"
 says NIDA director Dr. Alan I. Leshner.  "The finding that serotonin as well
 as dopamine plays a critical role in the development of cocaine addiction
 suggests a new biological target and approaches for developing such
 medications."
     Dr. George Uhl, head of the NIDA research team, explains that his team
 studied genetically altered mice that were missing one or both copies of the
 dopamine transporter (DAT) and serotonin transporter (SERT) genes.  They found
 that mice with even a single DAT gene copy and no SERT copies still
 experienced reward/reinforcement following cocaine administration.  However,
 cocaine-induced reward/reinforcement behavior was totally blocked in mice with
 no DAT gene and either half-normal or absent SERT.
     Dr. Uhl says, "These results demonstrate the dependence of cocaine reward
 on both DAT and SERT blockade.  They define for the first time the brain
 molecular targets necessary for cocaine reward.  They suggest that drugs
 acting on both dopamine and serotonin brain systems might be needed to
 effectively combat cocaine addiction."
 
     The National Institute on Drug Abuse is a component of the National
 Institutes of Health, U.S. Department of Health and Human Services.  NIDA
 supports more than 85 percent of the world's research on the health aspects of
 drug abuse and addiction.  The Institute carries out a large variety of
 programs to ensure the rapid dissemination of research information and its
 implementation in policy and practice.  Fact sheets on the health effects of
 drugs of abuse and other topics can be ordered free of charge in English and
 Spanish through NIDA Infofax at 1-888-NIH-NIDA (644-6432) or 1-888-TTY-NIDA
 (889-6432) for the deaf.  These fact sheets and further information on NIDA
 research and other activities can be found on the NIDA home page at
 http://www.drugabuse.gov .
 
                     MAKE YOUR OPINION COUNT -  Click Here
                http://tbutton.prnewswire.com/prn/11690X82731537
 
 

SOURCE National Institute on Drug Abuse
    WASHINGTON, April 23 /PRNewswire Interactive News Release/ -- A team of
 researchers led by scientists from the National Institute on Drug Abuse's
 Intramural Research Program has made a major advance in understanding the
 molecular basis of how cocaine produces its characteristic high, suggesting
 new targets for developing anti-addiction medicines.  The findings, published
 in the April 24 issue of the Proceedings of the National Academy of Sciences,
 show that inactivating both the serotonin and dopamine transporters in the
 brains of mice dramatically reduces their experience of cocaine's rewarding,
 pleasurable effects.  It has been known for some time that cocaine use affects
 the brain's dopamine system, but also that manipulating dopamine does not
 fully control cocaine's effects.  Thus this study shows the critical
 importance of the serotonin system as well as the dopamine system in mediating
 cocaine's pleasurable effects.
     "Currently, there is no medication that effectively blocks the brain's
 reward response to cocaine or that substantially relieves cocaine addiction,"
 says NIDA director Dr. Alan I. Leshner.  "The finding that serotonin as well
 as dopamine plays a critical role in the development of cocaine addiction
 suggests a new biological target and approaches for developing such
 medications."
     Dr. George Uhl, head of the NIDA research team, explains that his team
 studied genetically altered mice that were missing one or both copies of the
 dopamine transporter (DAT) and serotonin transporter (SERT) genes.  They found
 that mice with even a single DAT gene copy and no SERT copies still
 experienced reward/reinforcement following cocaine administration.  However,
 cocaine-induced reward/reinforcement behavior was totally blocked in mice with
 no DAT gene and either half-normal or absent SERT.
     Dr. Uhl says, "These results demonstrate the dependence of cocaine reward
 on both DAT and SERT blockade.  They define for the first time the brain
 molecular targets necessary for cocaine reward.  They suggest that drugs
 acting on both dopamine and serotonin brain systems might be needed to
 effectively combat cocaine addiction."
 
     The National Institute on Drug Abuse is a component of the National
 Institutes of Health, U.S. Department of Health and Human Services.  NIDA
 supports more than 85 percent of the world's research on the health aspects of
 drug abuse and addiction.  The Institute carries out a large variety of
 programs to ensure the rapid dissemination of research information and its
 implementation in policy and practice.  Fact sheets on the health effects of
 drugs of abuse and other topics can be ordered free of charge in English and
 Spanish through NIDA Infofax at 1-888-NIH-NIDA (644-6432) or 1-888-TTY-NIDA
 (889-6432) for the deaf.  These fact sheets and further information on NIDA
 research and other activities can be found on the NIDA home page at
 http://www.drugabuse.gov .
 
                     MAKE YOUR OPINION COUNT -  Click Here
                http://tbutton.prnewswire.com/prn/11690X82731537
 
 SOURCE  National Institute on Drug Abuse