Estrogen increases affinity of oxytocin receptors in the medial preoptic area-anterior hypothalamus.
Analysis of binding data from saturation experiments using a radiolabeled oxytocin antagonist ([125I]OTA) demonstrated an increase in binding affinity after treatment with 5 micrograms estradiol benzoate (EB) for 3 days in membrane fractions from the medial preoptic area-anterior hypothalamus (MPOA-AH) of ovariectomized (OVX) rats. Analysis of data from competition experiments revealed high- and low-affinity [125I]OTA binding sites in the MPOA-AH, the medial basal hypothalamus (MBH), and hippocampus of OVX controls. Three days of EB treatment reduced low-affinity binding sites in the MPOA-AH and MBH, but not in the hippocampus. Treatment of membrane fractions from the MPOA-AH of oil-treated OVX rats in vitro with 100 nM OT or with estrogen or progesterone conjugated to bovine serum albumin (E-BSA and P-BSA) also reduced low-affinity [125I]OTA binding sites but BSA alone did not.
Caldwell
J D
JD
Brain and Development Research Center, School of Medicine, University of North Carolina at Chapel Hill 27599.
Walker
C H
CH
Pedersen
C A
CA
Barakat
A S
AS
Mason
G A
GA
D000818:Animals; D001667:Binding, Competitive; D004958:Estradiol / Q000031:analogs & derivatives*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D006624:Hippocampus / Q000378:metabolism; D008566:Membranes / Q000378:metabolism; D010052:Ovariectomy; D011301:Preoptic Area / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D017207:Rats, Sprague-Dawley; D018045:Receptors, Oxytocin / Q000378:metabolism*; D014668:Vasotocin / Q000031:analogs & derivatives* / Q000378:metabolism
D004967:Estrogens; D018045:Receptors, Oxytocin; C076093:vasotocin, (beta-mercapto-beta,beta-cyclopentamethylenepropionic acid)-O-methyl-Tyr(2)-Thr(4)-Orn(8)-Tyr(9)-NH2; D004958:Estradiol; D014668:Vasotocin