Caffeine effects on behavioral thermoregulation.

Caffeine has a wide range of behaviorally active properties. Varying doses of caffeine solutions were administered (ip) prior to fixed-interval 2-min. schedules of microwave reinforcement in rats tested in a cold environment. Four Sprague-Dawley rats were conditioned to regulate their thermal environment with 5-sec. exposures of microwave reinforcement. Graphic descriptions showed that small doses of caffeine produced higher response rates for microwave heat than high doses of caffeine and saline controls, yet Friedman's nonparametric test showed no significant differences between dose levels. Synergism between thermogenic and discriminative properties of caffeine is proposed.