Sertraline increases extracellular levels not only of serotonin, but also of dopamine in the nucleus accumbens and striatum of rats.

Selective serotonin reuptake inhibitors (SSRIs) are a first-line treatment for depression. Recent reports in the literature describe differences in antidepressant effects among SSRIs. Although each SSRI apparently has different pharmacological actions aside from serotonin reuptake inhibition, the relations between antidepressant effects and unique pharmacological properties in respective SSRIs remain unclear. This study was designed to compare abilities of three systemically administered SSRIs to increase the extracellular levels of serotonin, dopamine, and noradrenaline acutely in three brain regions of male Sprague-Dawley rats. We examined effects of sertraline, fluvoxamine, and paroxetine on extracellular serotonin, dopamine, and noradrenaline levels in the medial prefrontal cortex, nucleus accumbens and striatum of rats using in vivo microdialysis. Dialysate samples were collected in sample vials every 20 min for 460 min. Extracellular serotonin, dopamine, and noradrenaline levels were determined using high-performance liquid chromatography with electrochemical detection. All SSRI administrations increased extracellular serotonin levels in all regions. Only sertraline administration increased extracellular dopamine concentrations in the nucleus accumbens and striatum. All SSRI administrations increased extracellular noradrenaline levels in the nucleus accumbens, although fluvoxamine was less effective. These results suggest that neurochemical differences account for the differences in clinical antidepressant effects among SSRIs.