Ibuprofen effects on behavioral thermoregulation with microwave radiation in albino rats

This study determined whether ibuprofen causes a disruptive behavior pattern similar to aspirin yet contrary to acetaminophen regarding thermoregulatory effects. 8 Sprague-Dawley rats (3 males and 5 females) were drawn from a population of rats which had been conditioned to press a lever for food reinforcement in an undergraduate course in operant conditioning. Animals were conditioned in a refrigerated Skinner Box on a fixed-interval 2-min. (FI-2 min.) schedule of microwave radiation (5 sec. of radiation per exposure occasion) in a repeated-measures reversal (within-subjects) design. The rats were injected intraperitoneally with doses of ibuprofen in amounts of 10-50 mg/kg or methyl-cellulose control vehicle of equal volume over 8-hr. daily sessions. A multivariate analysis of variance showed significant differences due to doses (mg/kg) of ibuprofen for number of microwave heat reinforcers per hour and rate of responding (ns) both measures of which were significantly higher during the first 2 hours of the session. Comparative differences in behavioral thermoregulation in humans reflect the likelihood of underlying biochemical mechanisms based on research by Murphy, Badia, Myers, Boecker, and Wright in 1994.