Acute effects of dexfenfluramine (d-FEN) and methylenedioxymethamphetamine (MDMA) before and after short-course, high-dose treatment.
The acute behavioral effects of methylenedioxymethamphetamine (MDMA) and dexfenfluramine (d-FEN) were assessed in six rhesus monkeys using performance in the National Center for Toxicological Research (NCTR) Operant Test Battery (OTB); three additional animals served as controls for neurochemical endpoints. The OTB consists of five food-reinforced tasks designed to model aspects of learning, short-term memory and attention, time estimation, motivation, and color and position discrimination. Shortly after the acute effects of each drug were determined, three of the monkeys received a short-course, high-dose exposure (2x /day x 4 days, intramuscular (i.m.) injections) of MDMA (10 mg/kg), while three monkeys were exposed to an identical regimen of d-FEN (5 mg/kg). Approximately one month later, the acute effects of each drug were again determined. In monkeys exposed to high-dose d-FEN, the sensitivities of the OTB tasks to acute disruption by either MDMA or d-FEN were essentially unchanged. Conversely, monkeys treated with high-dose MDMA were less sensitive to the acute behavioral effects of both drugs, although such an effect was seen more frequently for d-FEN and was OTB task specific. Thus a residual behavioral tolerance to the acute behavioral effects of MDMA and d-FEN was noted after high-dose MDMA exposure, but not after high-dose d-FEN exposure. These findings are surprising, as similar neurochemical effects (i.e., significant decreases of ca. 50% in serotonin in frontal cortex and hippocampus) were observed in all monkeys approximately six months after short-course, high-dose MDMA or d-FEN treatment.
Division of Neurotoxicology, National Center for Toxicological Research, Jefferson Arkansas 72079, USA. df50029@GlaxoWellcome.com
D L
DL
Frederick
S F
SF
Ali
M P
MP
Gillam
J
J
Gossett
W
W
Slikker
M G
MG
Paule
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004361:Drug Tolerance; D005277:Fenfluramine / Q000008:administration & dosage* / Q000494:pharmacology; D008253:Macaca mulatta; D008297:Male; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000008:administration & dosage* / Q000494:pharmacology; D009483:Neuropsychological Tests; D012701:Serotonin / Q000378:metabolism; D013997:Time Factors
D005277:Fenfluramine; D012701:Serotonin; D018817:N-Methyl-3,4-methylenedioxyamphetamine