Chronic citalopram action and the maturing mouse brain's indoleamine levels.

1. Mice of various ages between birth and adulthood were injected daily for 12 days with the serotonin specific uptake inhibitor citalopram (LU 10-171). 2. Two hours, 1 day and 3 days following the last injection animals were killed and their brains assayed for 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA). 3. Changes in levels of both metabolites varied by age of the animal, brain region and time after last injection. These patterns differed from previous studies of shorter duration citalopram exposure. 4. The data support the view that 5-HT and 5-HIAA levels are probably not dependently related in immature brain. Indeed 5-HIAA modulation in the immature seems to lack the firm control of the adult and can be modified for extended periods by citalopram action.