Possible neural substrates of beer-craving in rats

Rats voluntarily consumed beer in a distinctive environment during 30 min daily sessions over 21 days, ingesting a daily average of 0.96 g/kg of ethanol. On a final test day, rats in a 'craving' condition were denied access to the beer in the drinking environment. The expression of c-fos in the brain of 'craving' rats was compared with that in rats given free access on the test day ('beer' condition), and to rats which had been repeatedly placed in the drinking environment without ever having access to beer ('control' condition). Rats in the 'craving' condition showed significantly higher c-fos counts than either the 'beer' or 'control' rats in a variety of corticolimbic and brainstem structures, indicating that activation of these regions occurs when a desirable alcoholic beverage is expected but not received.