Advantages and disadvantages of a rapid method to train drug discrimination

In an effort to reduce the often extensive period of time needed to train rats to discriminate between a drugged and nondrugged state, a fast training regimen was employed with 1.5 mg/kg 3,4-methylenedioxymethamphetamine (MDMA) used as the training drug in ten rats. This protocol consisted of one to three training sessions per day and it was compared to the more conventional method of once-per-day training in an equal number of rats. Results indicate that the fast-trained rats learned the discrimination in significantly fewer sessions than the slowly-trained rats. However, the subsequent dose-response experiments indicate that when the fast-trained rats are tested with various doses of MDMA, without prior vehicle treatment, their sensitivity to the drug is less than that of the slowly-trained rats. When a vehicle session is presented prior to drug dose-response testing, both groups perform similarly. It appears that the preceding vehicle sessions function as a reference point for the fast-trained rats and, although the more rapid training regimen allows for faster learning, these treatment regimens should be employed with caution when subsequent dose-response tests and generalization tests with other drugs are conducted.