Neuropharmacological effects of low and high doses of repeated oral dexfenfluramine in rats: A comparison with fluoxetine

Silvio Caccia, S. Confalonieri, A. Bergami, C. Fracasso, M. Anelli, S. Garattini

Research output: Contribution to journalArticlepeer-review


The neuropharmacological effects of repeated oral doses of dexfenfluramine (DF; 1.25-10 mg/kg, twice daily for 21 days) were examined in rats and related to the drug brain levels. Results were compared with fluoxetine (FL) given at similar doses relative to its anorectic ED 50. Both drugs dose-dependently slowed body weight gain and reduced brain serotonin (5-HT). However, at 1.25 mg/kg DF caused only a slight and transient decrease in cortical 5-HT. Comparable doses of FL (6.25-12.5 mg/kg) lowered 5-HT more than DF, besides slightly reducing striatal dopamine. At higher doses DF markedly reduced 5-HT in all regions, and to a lesser extent noradrenaline in hippocampus. There was a negative relationship between 5-HT and log total active drug levels and the indole was approximately halved at drug levels about 50 times lower with DF than FL. However, the ratio between drug levels causing marked 5-HT reductions and those considered anorectic was similar for DF and FL because brain levels at the anorectic ED 50 were higher with FL than DF. Long-lasting reductions of 5-HT were also observed but recovery was only consistently slow beginning from 5 mg/ kg DF. Comparable doses of FL could not be used because its general toxicity leads to the death of rats after only 2-4 multiples of its anorectic ED 50.

Original languageEnglish
Pages (from-to)851-856
Number of pages6
JournalPharmacology, Biochemistry and Behavior
Issue number4
Publication statusPublished - Aug 1997


  • Dexfenfluramine
  • Drug brain concentrations
  • fluoxetine
  • Indole and catecholamine contents
  • Repeated dosing

ASJC Scopus subject areas

  • Biochemistry
  • Behavioral Neuroscience
  • Pharmacology


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