[Changes of estrogen receptor contents in the uterine myometrium of rats during gestation].
It is well known that estrogen plays an important role in the uterine contraction during labor, and should be mediated through estrogen receptor (ER) in the uterine muscle. This study shows the changes in the amount of ER in the myometrium during pregnancy and labor in rats. The uterus was dissected from pregnant rats (SD strain) on days 9, 12, 15, and 21 of pregnancy, and during labor. The uterine tissues were divided into those from the site (placental site) and those from opposite the site (non-placental site), of the placental attachment. ER concentrations were determined with ER-EIA kits (Abbot Co.). ER content in the non-placental site was almost the same at diestrus 1, and days 9, 12, 15, of pregnancy and also during labor, except on day 21 when ER content was significantly (p < 0.05) lower than on any other day tested. ER content in the placental site was significantly (p < 0.01) higher on day 9 than in the non-pregnant status (diestrus 1), but decreased thereafter until day 21, showing significantly (p < 0.01) lower values on day 21 than on day 12 or diestrus 1. The decrease in ER values on day 21 was eliminated by removing all fetuses, but not the placentas, on day 12. During labor, ER content in the non-placental site was increased significantly (p < 0.01), but in the placental site it did not increase significantly.(ABSTRACT TRUNCATED AT 250 WORDS)
Hattori
M
M
Department of Obstetrics and Gynecology, Yamaguchi University School of Medicine.
D000818:Animals; D005260:Female; D007743:Labor, Obstetric / Q000502:physiology*; D009215:Myometrium / Q000737:chemistry*; D010920:Placenta / Q000737:chemistry; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000032:analysis*
D011960:Receptors, Estrogen