Influence of postmenopausal hormone replacement therapy on platelet serotonin uptake site and seroton(2A) receptor binding

OBJECTIVE: To examine whether binding of [H-3]-paroxetine to the platelet s erotonin transporter or binding of [H-3]lysergic acid diethylamide (LSD) to the platelet 5-HT2A receptor are influenced by postmenopausal estrogen/pro gestogen treatment. METHODS: Twenty-three postmenopausal women with climacteric symptoms comple ted this double-blind, randomized, crossover study. The women received 2 mg of estradiol continuously during four 28-day cycles. In the last 14 days o f each cycle, 10 mg of medroxyprogesterone acetate, I mg of norethindrone a cetate, or placebo was given. Before treatment, as well as once during the last week of each treatment, blood samples were collected for analysis of [ H-3]LSD and [H-3]paroxetine binding. The power of the study setup was 81%. The study had an effect size of 0.36, corresponding to the ability to detec t a 15% difference in [H-3]paroxetine and [H-3]LSD binding between treatmen ts with alpha = .05 and beta = .20, based on a previously reported standard deviation within cells of 20% of the mean binding values. RESULTS: The number of platelet receptors (B-max), or the affinity of the r adioligand to the receptor (K-d), for [H-3]paroxetine binding did not chang e during estrogen or estrogen-progestogen treatment, nor did B-max or K-d f or [H-3]LSD binding change during the different treatments. However, in a s ubgroup of depressed patients, the decrease in B-max for [H-3]LSD binding d uring treatment was significantly more pronounced than in the nondepressed subgroup (P < .05). CONCLUSION: Estrogen treatment with or without the addition of progestogen does not affect binding to the serotonin transporter or to die serotonergic 5-HT2A receptor in healthy postmenopausal women. (C) 2001 by the American College of Obstetricians and Gynecologists.