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 Science News and Science Current Events Tag Cloud This tag cloud is a visual representation of term frequencies of random science news topics with common terms grouped together and emphasized by their display size. Amyloid-beta Cancer Survivors Narcolepsy Color Vision HPV Inflammatory Bowel Disease Huntingtons Disease Cancer Gene Stroke Risk Malignant Melanoma Neurofibromatosis Tuberculosis Infants Venus Express Pulsar Hepatocellular Carcinoma Plastic Surgery Premature Babies Cell Growth Cell Phone Tissue engineering Quantum cryptography Beta Cells Attractiveness Brain Activity
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Related Cocaine Current Events and Cocaine News Articles New gene discovery links obesity to the brain A variation in a gene that is active in the central nervous system is associated with increased risk for obesity. Cocaine and heroin harm placenta Cocaine and heroin increase permeability of the placenta. Researchers writing in BioMed Central's open access journal Reproductive Biology and Endocrinology have shown that exposure to the drugs causes an increase in the passage of some chemicals into the fetus. Brain-behavior disconnect in cocaine addiction Parts of the brain involved in monitoring behaviors and emotions show different levels of activity in cocaine users relative to non-drug users, even when both groups perform equally well on a psychological test. Cocaine: Perceived as a reward by the brain? Cocaine is one of the oldest drugs known to humans, and its abuse has become widespread since the end of the 19th century. Cocaine-linked genes enhance behavioral effects of addiction New research sheds light on how cocaine regulates gene expression in a crucial reward region of the brain to elicit long-lasting changes in behavior. New editorial in the FASEB Journal raises concerns over dietary supplements As the FDA warns consumers to stop using Hydroxycut products, a new editorial published in the May 2009 issue of The FASEB Journal shows that this FDA warning is not unique. BUSM researchers find prenatal cocaine exposure may compromise neurocognitive development Researchers at Boston University School of Medicine (BUSM) have found that heavier intrauterine cocaine exposure (IUCE) is associated with mild compromise on selective areas of neurocognitive development during middle childhood. Treating addiction by eliminating drug-associated memories Addicts, even those who have been abstinent for long periods of time, are often still vulnerable to their own memories of prior drug use. For example, exposure to the same environment in which they commonly used drugs -- a contextual memory -- can increase their craving for the drug dramatically and can lead to relapse. Yerkes Researchers Use Eye Tracking to Detect Mild Dementia In Humans Researchers at the Yerkes National Primate Research Center, Emory University, developed a test in nonhuman primates that is now using infrared eye tracking to detect mild cognitive impairment (MCI) in humans. Phasic firing of dopamine neurons is key to brain's prediction of rewards Researchers are one step closer to understanding the neurobiology that allows people to successfully learn motivated behaviors by associating environmental cues with rewarding outcomes, according to a study published yesterday in the Proceedings of the National Academy of Sciences' online Early Edition. More Cocaine Current Events and Cocaine News Articles |
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