Estrogen, serotonin, and mood disturbance: where is the therapeutic bridge?

A growing body of literature describes the effects of estrogen and other gonadal steroids on the central nervous system. The ability of estrogen to modulate serotonergic function, in particular, raises the possibility that sex steroids may play a role in the mechanisms associated with depression and its treatment. This review will focus on those aspects of the estrogen-serotonin interaction that relate to possible increased vulnerability to affective disorders and on hormonal treatments that may be clinically applicable to women. After a discussion of the potential relationship between estrogen and mood disorders across the female life cycle, a model is proposed in which differential sensitivity to mood disorders explains the differential response by some women to periods of normal hormonal changes. Possible serotonin receptor-mediated and intracellular mechanisms by which estrogen may exert its effects on mood are also reviewed. These are compared to putative mechanisms of standard antidepressant effect. Lastly, treatment studies in which estrogen has been used as 1) monotherapy for depression, 2) an augmentation strategy, or 3) a prophylactic intervention against recurrence of depression are reviewed.