title: Endometrium estradiol receptors type I and type II during early pregnancy of rat.
abstract: By centrifugation in a sucrose density gradient we studied the citosol 17beta-estradiol binding sites of blastocyst receptive and non-receptive endometrial zones, as well as uterine horn endometrium whose ovary was extirpated three weeks before pregnancy. The cytosol was prelabelled with [3H]-17beta-estradiol 2 and 25 nM. In this work two incubation temperatures were studied. On the other hand, at 4 degrees C unoccupied receptors were identified as different from the classic receptor 8S type I. At the same time, we found that 25 degrees C is the optimal temperature for the assay of total receptors to achieve complete exchange of [3H]-17beta-estradiol by 17beta-estradiol in the binding sites. In these conditions, the major component was the 4S type II receptor, mainly in the endometrium from ovariectomized uteri. Furthermore, 17beta-estradiol content was determined in the total homogenized by radioimmunoassay and the results were: 1.42+/-0.16, 1.22+/-0.15 and 1.75+/-0.27 pmol/g wet tissue for receptive, non-receptive and ovariectomized uteri, respectively.
authors.affiliation: Medical Research Unit in Endocrine Disease, Medical Research Coordination, Social Security Mexican Institute (IMSS), Mexico. dra_edith_salazar@yahoo.com.mx
authors.forename: Edith L
authors.initials: EL
authors.lastname: Salazar
authors.forename: Leobardo
authors.initials: L
authors.lastname: Calzada
mesh_terms: D000818:Animals; D001665:Binding Sites; D003600:Cytosol / Q000378:metabolism; D004717:Endometrium / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism*; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D047629:Estrogen Receptor beta / Q000378:metabolism*; D005260:Female; D005865:Gestational Age; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004958:Estradiol