Hyperthermia-enhanced serotonin (5-HT) depletion resulting from D-fenfluramine (D-Fen) exposure does not evoke a glial-cell response in the central nervous system of rats

D-Fen-induced hyperthermia has been shown to coincide with an enhanced depl etion of 5-HT and 5-hydroxyindole acetic acid (5-HIAA). Because these obser vations have relied on D-Fen exposure at multiple environmental temperature s, some have questioned the validity of the findings. Therefore, this exper iment was designed to determine if the correlation between elevated body te mperature and 5-HT depletion could be observed when D-Fen exposure occurred in one warm environment (28 degrees C) and to determine if a hyperthermia- enhanced glial-cell response could be evoked by D-Fen exposure. Hyperthermi a-enhanced 5-HT and 5-HIAA depletion resulting from D-Fen exposure was depe ndent on body temperature during drug exposure. In the frontal cortex, 5-HT concentrations ranged from 3 to 45% of control values. Likewise, in the st riatum and hippocampus, 5-HT concentrations ranged from 13 to 53% and 6 to 40%, respectively. The 5-HIAA concentrations had a wider range than the 5-H T concentrations for each brain region. In the frontal cortex, striatum and hippocampus, 5-HIAA ranged from 0 to 93%, 15 to 72% and 0 to 83% of contro l, respectively. In spite of the substantial reductions in 5-HT, there was no detectable glial-cell response. D-Fen-induced hyperthermia does not appe ar to cause generalized damage to neurons in the frontal cortex, striatum a nd hippocampus. (C) 1999 Published by Elsevier Science B.V. All rights rese rved.