Cocaine: How addiction developsAugust 22, 2008Permanent drug seeking and relapse after renewed drug administration are typical behavioral patterns of addiction. Molecular changes at the connection points in the brain's reward center are directly responsible for this. This finding was published by a research team from the Institute of Mental Health (ZI) in Mannheim, the German Cancer Research Center (DKFZ) in Heidelberg and the University of Geneva, Switzerland, in the latest issue of Neuron. The results provide researchers with new approaches in the medical treatment of drug addiction. Addiction leaves detectable traces in the brain: In particular regions of the central nervous system, which produce the messenger substance dopamine, the drug cocaine causes molecular restructuring processes at the synapses, the points of connection between two neurons. As a reaction to the drug, protein subunits are exchanged in specific receptor complexes. As a result, the modified synapse becomes able to transmit nervous signals with enhanced strength - a phenomenon that has been termed 'drug-induced synaptic plasticity'. Researchers have suspected for many years that drug-induced synaptic plasticity plays a crucial role in addiction development. However, this hypothesis has not yet been proven experimentally. Using genetic engineering, researchers headed by Professor Dr. Günther Schütz at the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) have now been able to selectively switch off those protein components in dopamine-producing neurons that are integrated into the receptor complexes under the influence of cocaine. Jointly with the team of Professor Dr. Rainer Spanagel at the Central Institute of Mental Health (Zentralinstitut für Seelische Gesundheit, ZI) in Mannheim and the research group of Professor Dr. Christian Lüscher at Geneva University, the Heidelberg researchers studied the changes in physiology and behavior of the genetically modified animals.
The scientists performed standardized tests to measure addictive behavior in the animals. At first sight, both the genetically modified and the control animals displayed the usual behavior under the influence of cocaine. Forced to increase their agility, the lab animals covered significantly greater running distances and preferentially frequented those places where they had been conditioned to be regularly administered the drug. If normal mice do not find drugs at the familiar places over a longer period of time, their addictive behavior and preference for the cocaine-associated places subside. However, this is not true for animals whose receptor subunit GluR1 has been switched off: These mice invariably frequent the places where they expect to find the drug, i.e., their addictive behavior persists. Mice whose NR1 protein has been switched off have surprised scientists with a different conspicuous behavior. If control animals withdrawn from cocaine are readministered the drug after some time, addictive behavior and drug seeking are reactivated. In contrast, NR1 deficient animals proved to be resistant to relapsing into the addiction. "It is fascinating to observe how individual proteins can determine addictive behavioral patterns," says Günther Schütz, and his colleague Rainer Spanagel adds: "In addition, our results open up whole new prospects for treating addiction. Thus, blocking the NR1 receptor might protect from relapsing into addiction. Selective activation of GluR1 would even contribute to 'extinguishing' the addiction." Helmholtz Association of German Research Centres | |||||||||||||||||||||
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Related Cocaine Current Events and Cocaine News Articles Hope for treating relapse to methamphetamine abuse A new study at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory suggests that vigabatrin (a.k.a. gamma vinyl-GABA, or GVG) blocks drug-seeking behavior in animals previously trained to associate methamphetamine with a particular environment. Stem Cells from Monkey Teeth Can Stimulate Growth and Generation of Brain Cells Researchers at the Yerkes National Primate Research Center, Emory University, have discovered dental pulp stem cells can stimulate growth and generation of several types of neural cells. Findings from this study, available in the October issue of the journal Stem Cells, suggest dental pulp stem cells show promise for use in cell therapy and regenerative medicine, particularly therapies associated with the central nervous system. Extended-treatment with combination medication for opioid-addicted youths shows benefit Adolescents addicted to opioids who received continuing treatment with the combination medication buprenorphine-naloxone had lower rates of testing positive or reporting use of opioids compared to youths who went through a short-term detoxification program using the same medication, according to a study in the November 5 issue of JAMA. Singing to females makes male birds' brains happy The melodious singing of birds has been long appreciated by humans, and has often been thought to reflect a particularly positive emotional state of the singer. Adolescent insomnia linked to depression and substance abuse during adolescence and young adulthood A study in the Oct. 1 issue of the journal Sleep shows that adolescent insomnia symptoms are associated with depression, suicide ideation and attempts, and the use of alcohol, cannabis and other drugs such as cocaine. Caffeine experts at Johns Hopkins call for warning labels for energy drinks Johns Hopkins scientists who have spent decades researching the effects of caffeine report that a slew of caffeinated energy drinks now on the market should carry prominent labels that note caffeine doses and warn of potential health risks for consumers. College freshmen: pain killers and stimulants less risky than cocaine; more risky than marijuana First year college students believe that occasional nonmedical use of prescription pain killers and stimulants is less risky than cocaine, but more risky than marijuana or consuming five or more alcoholic beverages every weekend. New evidence on addiction to medicines Diazepam has effect on nerve cells in the brain reward system Addictions to medicines and drugs are thought to develop over a relatively long period of time. The process involves both structural and functional changes in brain nerve cells that are still poorly understood. Addiction treatment proves successful in animal weight loss study Vigabatrin, a medication proposed as a potential treatment for drug addiction by scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory, also leads to rapid weight loss and reduced food intake according to a new animal study from the same research group. Cocaine-induced synaptic plasticity linked to persistent addictive behaviors The persistent nature of addiction is its most devastating feature. Understanding the mechanism underlying this phenomenon is the key for designing efficient therapy. Two separate studies published by Cell Press is the August 14 issue of the journal Neuron identify specific cocaine-induced changes in dopamine (DA) neurons that play a pivotal role in behaviors associated with drug addiction. More Cocaine Current Events and Cocaine News Articles |
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