[The role of the glutamatergic system in alcohol addiction]

New animal models have been developed which mimic several aspects of alcoholism. These models provide the basis to study the neurobiological mechanisms of "addicted behaviour". At least two different neurobiological pathways which are involved in the development and maintenance of addicted behaviour have been identified. The first pathway involves the opioidergic system and probably the mesolimbic dopaminergic system and may induce alcohol craving and relapse due to the mood enhancing, positive reinforcing effects of alcohol consumption. A second pathway involves several components of the glutamatergic system (in particular NMDA receptors) and may induce alcohol craving and relapse by negative motivational states including withdrawal and stress. In particular conditioned withdrawal and stress-induced relapse are mediated by a hypertrophic glutamatergic system. Thus it has recently been shown that the NMDA receptor modulator acamprosate inhibits conditioned abstinence behaviour in rats. Although more systematic work is needed to fully define these different neurobiological pathways involved in addicted behaviour, preclinical studies have identified low affinity non-competitive NMDA receptor antagonists as a novel potential generation of anti-relapse compounds and clinical studies have already been initiated in order to test these compounds in alcoholic patients.