DL-FENFLURAMINE INHIBITS ETHANOL-INDUCED ASCORBIC-ACID RELEASE IN RATSTRIATUM STUDIED BY MICRODIALYSIS

The effects of dl-fenfluramine, dl-5-hydroxytryptophan(5-HTP) and fluo xetine on ethanol-induced striatal ascorbic acid (AA) release in rat w ere studied by microdialysis coupled to high performance liquid chroma tography with electrochemical detection. Ethanol (3.0 g/kg, i.p) stimu lated striatal AA release to more than 200% above the baseline, dl-Fen fluramine (20 mg/kg, i.p. or 40 mu g/rat, i.c.v.), 10 min before ethan ol administration, markedly inhibited ethanol-induced AA release. A si milar result was also observed following dl-5-HTP (100 mg/kg, i.p.) ad ministration. However, fluoxetine (10, 30 mg/kg, i.p.) showed no antag onistic effect on ethanol-induced AA release. The suppressing effect o f dl-fenfluramine and dl-5-HTP on ethanol-induced AA release could be reversed by the 5-HT receptor antagonist cyproheptadine (10 mg/kg, s.c .). All these drugs had no effect on basal AA release. The results giv e a first evidence for the involvement of central serotonergic system, and suggest that differential activities may exist between dl-fenflur amine, dl-5-HTP and fluoxetine in regulating ethanol-induced AA releas e in rat striatum.