Low-dose oral caffeine induces a specific form of behavioral sensitization in rats

The present study assessed the effects of a low dose of orally administered caffeine on sensitization of open-field behavior in rats. Rats had free access to untreated water every day or water containing 0.2 mg/ml of caffeine every other day of the 14-day experiment. On alternate days discrete movements (horizontal and vertical) and ambulatory distance were measured in open-field activity monitors. Although caffeine intake significantly decreased across test sessions in caffeine-treated rats, the number of discrete horizontal movements significantly increased. These findings suggest that low doses of orally administered caffeine induce a specific form of behavioral sensitization in rats.