LOCAL 5HT(3) RECEPTORS MEDIATE FLUOXETINE BUT NOT DESIPRAMINE-INDUCEDINCREASE OF EXTRACELLULAR DOPAMINE IN THE PREFRONTAL CORTEX

Fluoxetine and desipramine, two antidepressants that block selectively the serotonin and the noradrenaline carrier, increase extracellular d opamine concentrations in the prefrontal cortex of freely-moving rats. This effect is calcium dependent and is prevented, in the case of flu oxetine but not desipramine, by systemic pretreatment with low doses o r by low concentrations in the dialyzing Ringer of the potent 5-HT3 an tagonist ICS 205930. Fluoxetine, but not desipramine, increases extrac ellular serotonin concentrations in the prefrontal cortex. The results indicate that selective serotonin reuptake blockers increase extracel lular dopamine in the prefrontal cortex by stimulating local 5-HT3 rec eptors.