Tolerance and sensitization to chronic and subchronic oral caffeine: effects on wheelrunning in rats

Twenty-four male Sprague-Dawley rats were tested for wheelrunning in conjunction with chronic (continuous) or subchronic (alternate day) oral caffeine administration. As expected, chronic administration led to complete tolerance to caffeine's locomotor stimulant effect, while subchronic administration produced sensitization. Results confirm earlier reports of enhanced stimulation with spaced administration of caffeine and tolerance with chronic administration.