Effects of tamoxifen and estradiol on estrogen binding sites in the urogenital tract: an experimental study in the rabbit.
The aim of the study was to investigate the effects of estradiol and tamoxifen alone and in combination on the estrogen binding site status of the urogenital tract in the rabbit. Bilaterally ovariectomized rabbits were divided into four groups of six. Whereas the control group received no treatment, the remaining rabbits were treated with estrogen or/and tamoxifen. Cytosolic and nuclear fractions were isolated from the uterus, vagina, urethra and urinary bladder and used for binding site assay, by radioligand binding. The total weight of the rabbit vagina and uterus was increased significantly by both estradiol, tamoxifen and the combination of the two. The total weight of the urethra was increased only in the combination group. The cytosol binding site was downregulated by estradiol, tamoxifen and combination in the uterus, and in the vagina. Cytosol binding site in the urethra was not detected. The combination of estrogen-tamoxifen markedly reduced the nuclear binding site in the urethra and decreased affinity of the nuclear binding sites in all three tissues. The data suggest that tamoxifen has a specific ability to modulate the transcriptional activity of the estrogen binding sites in the rabbit urogenital tract.
Iosif
C S
CS
Department of Obstetrics and Gynccology, University Hospital, Lund, Sweden.
al-Hijji
J
J
Samsioe
G
G
D000818:Animals; D001665:Binding Sites / Q000187:drug effects; D002467:Cell Nucleus / Q000737:chemistry; D003600:Cytosol / Q000737:chemistry; D004347:Drug Interactions; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D009929:Organ Size / Q000187:drug effects; D010052:Ovariectomy; D011817:Rabbits; D011960:Receptors, Estrogen / Q000187:drug effects*; D020845:Selective Estrogen Receptor Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D013629:Tamoxifen / Q000008:administration & dosage / Q000494:pharmacology*; D014521:Urethra / Q000033:anatomy & histology / Q000737:chemistry / Q000648:ultrastructure; D014566:Urogenital System / Q000737:chemistry* / Q000648:ultrastructure; D014599:Uterus / Q000033:anatomy & histology; D014621:Vagina / Q000033:anatomy & histology
D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; D004958:Estradiol