IN-VIVO BIOGENIC-AMINE EFFLUX IN MEDIAL PREFRONTAL CORTEX WITH IMIPRAMINE, FLUOXETINE, AND FLUVOXAMINE

In vivo brain microdialysis was used to determine the effects of the s tandard tricyclic antidepressant imipramine and the two selective sero tonin reuptake inhibitors (SSRIs) antidepressants, fluoxetine and fluv oxamine, on extracellular levels of norepinephrine (NE), dopamine (DA) , and serotonin (5-HT) in rat medial prefrontal cortex. When given int raperitoneally (IF), imipramine increased NE in the microdialysis perf usate, and elevated DA and 5-HT to a lesser extent. Similar dose-depen dent increases in DA and 5-HT were detected after IF fluoxetine, altho ugh NE was less affected. In contrast, IP fluvoxamine produced no chan ge in basal NE nor DA, although a large increase in 5-HT occurred at a n intermediate dose. When administered directly into cortex, all three antidepressants increased 5-HT by the same amount in a dose-dependent fashion. Intracortical imipramine and fluoxetine increased NE, and fl uoxetine and fluvoxamine both increased DA, with fluoxetine doing so a t a lower concentration. These data suggest that the SSRIs are not ent irely selective for serotonin in vivo. (C) 1994 Wiley-Liss, Inc.