Differential training sequence effect upon psychostimulant discrimination.

1. Previous studies indicate that rats trained to discriminate either cathinone or cathine from its vehicle have a diminished discriminative performance when tested 24 hours after a drug administration when compared to tests conducted after a vehicle administration. The phenomenon of rapid tolerance may occur to produce a lessened interceptive cue on the test day following administration of the drug. It would, therefore, be probable that when rats are trained with consecutive cathinone or cathine administrations they would perform less well than if they were trained with these drugs never given in consecutive training sessions. 2. To test this hypothesis, rats were trained with 0.8 mg/kg 1-cathinone or 4.8 mg/kg d-cathine in a two-lever, food motivated operant task. Each of these groups were divided into two subgroups with the one receiving consecutive drug administrations and the second never receiving two consecutive administrations of the drug. 3. Results indicate that in the cathine-trained group, there was a significant increase in the time that was necessary to train the animals when consecutive administrations were used in training. This, however, did not occur in the cathinone-treated group. There was, however, no significant difference between the differentially trained groups as to ED50 values. 4. It, thus, appears that there may not be a correlative relationship between speed of acquisition, as documented by sessions-to-criterion, and sensitivity, as indicated by ED50 values.