Enhancement of serotonin uptake by cortisol: a possible link between stress and depression.

Stress and depression are characterized by elevation of circulating cortisol, as well as by changes in physiological functions. In this study, we addressed the possibility that elevated cortisol is also associated with the origin and development of depression. We report here that cortisol at the nM-microM concentration range induces a substantial increase in serotonin uptake both in vitro, by human peripheral blood lymphocytes (PBLs) and cortical neuronal cells, and in vivo, by rabbit PBLs, owing to promotion of synthesis of the serotonin transporter. These findings offer a novel molecular mechanism for depression associated with stress. Accordingly, the elevated cortisol induced by stress increases serotonin uptake, under both rest and nerve stimulation, which is overtly expressed in symptoms of depression.