Influence of postmenopausal hormone replacement therapy on platelet serotonin uptake site and serotonin 2A receptor binding.
OBJECTIVE
To examine whether binding of [3H]paroxetine to the platelet serotonin transporter or binding of [3H]lysergic acid diethylamide (LSD) to the platelet 5-HT(2A) receptor are influenced by postmenopausal estrogen/progestogen treatment.


METHODS
Twenty-three postmenopausal women with climacteric symptoms completed this double-blind, randomized, crossover study. The women received 2 mg of estradiol continuously during four 28-day cycles. In the last 14 days of each cycle, 10 mg of medroxyprogesterone acetate, 1 mg of norethindrone acetate, or placebo was given. Before treatment, as well as once during the last week of each treatment, blood samples were collected for analysis of [3H]LSD and [3H]paroxetine binding. The power of the study setup was 81%. The study had an effect size of 0.36, corresponding to the ability to detect a 15% difference in [3H]paroxetine and [3H]LSD binding between treatments 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 radioligand to the receptor (K(d)), for [3H]paroxetine binding did not change during estrogen or estrogen-progestogen treatment, nor did B(max) or K(d) for [3H]LSD binding change during the different treatments. However, in a subgroup of depressed patients, the decrease in B(max) for [3H]LSD binding during treatment was significantly more pronounced than in the nondepressed subgroup (P <.05).


CONCLUSIONS
Estrogen treatment with or without the addition of progestogen does not affect binding to the serotonin transporter or to the serotonergic 5-HT(2A) receptor in healthy postmenopausal women.
Wihlbäck
A C
AC
Department of Clinical Sciences/Obstetrics and Gynecology, University Hospital of Umeå, Umeå, Sweden. anna-carin.wihlback@obstgyn.umu.se
Sundström-Poromaa
I
I
Allard
P
P
Mjörndal
T
T
Spigset
O
O
Bäckström
T
T
D001792:Blood Platelets / Q000378:metabolism*; D002352:Carrier Proteins / Q000502:physiology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004958:Estradiol / Q000494:pharmacology / Q000627:therapeutic use; D015914:Estrogen Replacement Therapy; D005260:Female; D006801:Humans; D008238:Lysergic Acid Diethylamide / Q000378:metabolism; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology / Q000627:therapeutic use; D008875:Middle Aged; D017374:Paroxetine / Q000378:metabolism; D011293:Premenstrual Syndrome / Q000097:blood*; D045167:Progesterone Congeners / Q000494:pharmacology / Q000627:therapeutic use; D011869:Radioligand Assay; D011985:Receptors, Serotonin / Q000097:blood*
D002352:Carrier Proteins; D045167:Progesterone Congeners; D011985:Receptors, Serotonin; D017374:Paroxetine; D004958:Estradiol; D008238:Lysergic Acid Diethylamide; D017258:Medroxyprogesterone Acetate