The effects of magnesium pemoline, caffeine and picrotoxin on a food reinforced discrimination task

Effects of caffeine on discrimination learning, consolidation, and learned behavior in mice

Three sets of experiments were carried out in a Y water maze in which mice had to swim toward the light or the dark, in two different procedures. The first procedure involved, orientation toward a light source (L procedure), corresponding to natural preference, the latter involved orientation toward the dark (D procedure), corresponding to the acquisition of a new pattern of behavior. In pretrial drug treatments caffeine was administered to two groups of naive mice, tested under one of two experimental conditions. Posttrial drug treatments were made in animals learning the D procedure. Pretrained mice in the L or D procedure were finally injected with increasing doses of the drug. The results show that caffeine administration to naive animals was followed, in the D procedure, by a facilitation of learning and consolidation processes, and in the L procedure by improvements of the natural tendencies. Behavioral disruption followed treatment with the drug in mice pretrained in the D procedure, while only very high doses caused disruption in mice pretrained in the L procedure.

Effects of magnesium pemoline in dimethylsulfoxide on reversal learning, motor activity, and water intake

52 rats were given reversal training in a T-maze under magnesium pemoline either dissolved in dimethylsulfoxide (DMSO) or suspended in gum tragacanth. The course of reversal learning was unaltered as a consequence of drug administration except for the deleterious performance of the magnesium pemoline in DMSO animals on the 10th reversal. Regardless of vehicle, magnesium pemoline enhanced motor activity in an L-maze. While both magnesium pemoline groups exhibited reduced water consumption relative to controls, both DMSO groups exhibited an increase, concurrent with reduced body weight. It is suggested that DMSO is not an inert placebo and should be used with caution in repeated-administration behavioral studies.