Effect of acute and chronic 17 beta-estradiol treatment on serotonin and 5-hydroxyindole acetic acid content of discrete brain nuclei of ovariectomized rat.

Increased serotonin content of the dorsal raphe nucleus and of the substantia nigra were seen following acute (12 h or 24 h) administration of 17 beta-estradiol to ovariectomized rats. No changes were seen in numerous other nuclei of forebrain or hindbrain, and no changes occurred during chronic (1 month) estradiol administration. Changes in the concentration of the major serotonin metabolite, 5-hydroxyindole acetic acid, paralleled those of serotonin. These results show that, under precisely defined conditions and in specific locations only, estradiol can modulate serotonergic neuronal systems.