Department of Psychology, McGill University, Montreal, Canada.
Although depressive symptoms occur in a considerable number of women following a decrease in circulating estrogen levels, a biological correlate of these mood changes has not been identified. In a prospective, double-blind, cross-over investigation of surgically menopausal women, an increase in the number of tritiated imipramine binding sites on platelets and an improvement of mood occurred with estrogen treatment and were reversed when placebo was administered. In vitro studies indicated that this effect was not due to a direct interaction of the steroid with the imipramine binding site at the same concentrations of estradiol induced in the in vivo study. Together with other evidence, these findings suggest that pharmacological but not physiological doses of estrogen can enhance the density of tritiated imipramine binding sites on platelets in women.