Long-term treatment with fluoxetine associates with peripheral effects on rat vas deferens contractility

The aim of this work was to study whether long-term treatment with fluoxeti ne could induce peripheral effects by modifying vas deferens contractile ac tivity. For this purpose the contractile response to NE, and 5-HT of vas de ferens isolated from male Wistar rats that received fluoxetine 10 mg/kg/day ip, during 21 days, was studied using the isolated organ bath technique. R esults show that vas deferens of treated rats presented spontaneous activit y, an effect that was abolished by prazosin and isoproterenol and that was not affected by nitroprusside or indomethacin. In addition, fluoxetine did not modify the response to calcium suggesting that spontaneous activity was not a consequence of an abnormal calcium movement. Fluoxetine induced a si gnificant increase in the response of vas deferens to 5-HT and to low NE co ncentrations while NE maximal effect was unaffected. Fluoxetine treatment d id not modify the binding parameters of [H-3]-prazosin to vas deferens. It is concluded that long-term treatment with fluoxetine modifies vas deferens contractile activity. This effect could be the result of an alteration of adrenergic neurotransmission and could account for some of the untoward eff ects observed during clinical course with fluoxetine. (C) 1999 Elsevier Sci ence Inc.