Acute Effects of Dexfenfluramine (d‐FEN) and Methylenedioxymethamphetamine (MDMA) before and after Short‐Course, High‐Dose Treatment
Annals of the New York Academy of Sciences May 1, 1998 David Frederick, Syed F. Ali, Michael Gillam et al. 32 citations
In rhesus monkeys, the acute behavioral effects of MDMA and dexfenfluramine (d-FEN) were assessed using five food-reinforced tasks measuring learning, memory, attention, time estimation, motivation, and discrimination. After a short-course, high-dose exposure to MDMA (10 mg/kg twice daily for four days), monkeys became less sensitive to the acute behavioral disruption by both drugs, especially d-FEN, and this tolerance was task-specific. In contrast, monkeys similarly exposed to high-dose d-FEN (5 mg/kg) showed no change in sensitivity. Surprisingly, both groups showed similar neurochemical effects—approximately 50% decreases in serotonin in the frontal cortex and hippocampus six months later—yet only MDMA pretreatment induced behavioral tolerance.