Nicotine gives the brain a stimulating boost, but its addictiveness means that it is set to kill 100 million people this century. New research in mice shows that the same brain system is involved in both stimulation and addiction, meaning that the two are unlikely to be separable.
Both effects are mediated by a subunit of a cell-surface protein called the nicotinic acetylcholine receptor, in a brain region called the ventral tegmental area (VTA), report Jean-Pierre Changeux and his colleagues in the 07 July 2005 issue of Nature (Vol. 436, No. 7047, pp. 99-106). They made the discovery by breeding mice to lack this molecule and then re-injecting it specifically into this brain area.
In behavioural tests, mice with restored receptor function in the VTA were more likely to seek out nicotine than those lacking the receptor. Furthermore, when their activities were monitored, the injected mice showed greater levels of inquisitive behaviours.
Jean-Pierre Changeux (CNRS/Institut Pasteur, Paris, France)
Julia A. Kauer (Brown University, Providence, RI, USA)
(C) Nature press release.
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