Possible alteration of tryptophan metabolism following repeated administration of sertraline in the rat brain.

The levels of tryptophan and the serotonin (5-HT) turnover were examined in various brain regions of rats after single or repeated treatment with the selective 5-HT uptake inhibitor, sertraline. A single administration of sertraline (10mg/kg, i.p.) increased tryptophan and 5-HT levels in all the brain regions investigated. The levels of 5-hydroxyindolacetic acid (5-HIAA) decreased in various brain regions. The 5-HIAA/5-HT ratio as turnover index was significantly decreased by a single administration of sertraline in all the brain regions investigated. Daily treatment with sertraline (10mg/kg) for 21 days did not affect tryptophan and 5-HT levels in various brain regions 1h after last injection. The 5-HT turnover was not changed in any of the brain regions investigated by a repeated administration of sertraline. In conclusion, the data show that the increase in tryptophan levels and the decrease in 5-HT turnover in rat brain are attenuated by repeated treatment of sertraline.