Researchers have discovered a new molecular mechanism that underpins the brain's responses to food and drugs of abuse, such as cocaine. Mice with a particular mutation in this pathway are less enthusiastic about seeking food and show reduced responses to addictive drugs.
Both food and addictive drugs trigger the accumulation of a protein called DARPP-32 in the nuclei of brain cells involved in the brain's reward systems, report researchers led by Jean-Antoine Girault in Nature. This protein seems to be a key component of the signalling pathway by which the brain learns that such substances are pleasurable. Girault's team also pinpoint a region of the DARPP-32 protein that seems to be critical to its function. Mice with a specific error in the sequence of amino acids that makes up this protein were less likely to show obsessive food - or drug-seeking behaviour - for example, they gave up more easily in 'nose-poke' trials, in which they have to poke a lever to get food, and the number of pokes required is then increased. CONTACT Jean-Antoine Girault (INSERM, Universite Pierre et Marie Curie, Paris, France)
E-mail: girault@fer-a-moulin.inserm.fr Abstract available online. (C) Nature press release.
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