MDMA and learning: Effects of acute and neurotoxic exposure.

摘要

In two experiments, the effects of MDMA were examined on the acquisition of lever-press responding by rats exposed to procedures in which water delivery was delayed by 0, 10, or 20 seconds. In the first experiment, naive, water-deprived rats received an intraperitoneal injection of MDMA (0, 1.0, 3.2, or 5.6 mg/kg) prior to one experimental session. Response acquisition was observed under all conditions at all drug doses. MDMA increased both response rates and reinforcers earned in a dose-dependent fashion, but only when reinforcement was immediate. Under conditions of delay, MDMA had no effect on the number of lever presses emitted or reinforcers earned. Under all reinforcement conditions, higher doses of MDMA typically produced an initial reduction in lever pressing followed by accelerated rates of responding. In the second experiment, rats received an MDMA injection regimen previously shown to be neurotoxic. Control rats received saline solution according to the same injection schedule. Two weeks after completing the regimen, rats were water-deprived and exposed to behavioral procedures as described for the first experiment. Performance of rats exposed to MDMA did not differ from that of rats exposed to saline. Thus, in both experiments, MDMA failed to disrupt learning.