title: Effects of steroid hormones on calcitonin gene-related peptide receptors in cultured human myometrium.
abstract: OBJECTIVE
  This study was designed to examine whether, with the use of human myometrial explants in culture, calcitonin gene-related peptide B receptors are regulated by steroid hormones.
  
  
  METHODS
  Myometrial tissues were obtained from the lower uterine segments from women in a nonpregnant state and pregnant women who were not in labor undergoing cesarean delivery (39.1 +/- 0.2 weeks of gestation). Tissues were incubated in Dulbecco's modified Eagle's medium without phenol red, with either 17beta-estradiol (10(-9), 10(-8), 10(-7) mol/L), progesterone (10(-8), 10(-7), 10(-6) mol/L), or in a combination of 17beta-estradiol (10(-8) mol/L) and progesterone (10(-7) mol/L). Reverse transcriptase-polymerase chain reaction was performed to examine the expression of estrogen receptor-alpha, progesterone receptor, and Western blotting was used for calcitonin gene-related peptide B receptor protein measurement in the myometrium.
  
  
  RESULTS
  We found that (1) messenger RNA expression for both estrogen receptor-alpha and progesterone receptor in nonpregnant myometrium significantly declined within 48 hours explant culture; (2) estrogen receptor-alpha messenger RNA levels in the pregnant myometrium were 98.6%, 95.3%, and 89.8% at 12, 24, and 48 hours of incubation, respectively; (3) the levels of messenger RNA for progesterone receptor in the pregnant myometrium were 96.2%, 93.3%, 90.1%, at 12, 24, and 48 hours of incubation, respectively; (4) the 17beta-estradiol dose dependently inhibited calcitonin gene-related peptide B receptor protein in pregnant myometrium explant culture; (5) the progesterone dose dependently increased calcitonin gene-related peptide B receptor expression in pregnant myometrium explant culture; (6) the combined treatment with 17beta-estradiol (10(-8) mol/L) and progesterone (10(-7) mol/L) further enhanced myometrial calcitonin gene-related peptide B receptor protein expression.
  
  
  CONCLUSIONS
  We conclude from this study that (1) the messenger RNA expression of estrogen receptor-alpha and progesterone receptor in pregnant myometrium were maintained at relatively high levels (>89%) within 48 hours incubation and that this may be useful for in vitro studies that are designed to evaluate the effects of sex steroids on the human myometrium during pregnancy and that (2) estrogen inhibits and progesterone stimulates the expression of calcitonin gene-related peptide B receptors in cultured pregnant myometrial explants. We suggest that steroid hormone-regulated calcitonin gene-related peptide B receptor expression could underlie differential myometrial sensitivity to calcitonin gene-related peptide-induced relaxation.
authors.affiliation: Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston 77555, USA.
authors.forename: Yuan-Lin
authors.initials: YL
authors.lastname: Dong
authors.forename: Suril
authors.initials: S
authors.lastname: Wimalawansa
authors.forename: Chandrasekhar
authors.initials: C
authors.lastname: Yallampalli
mesh_terms: D046508:Culture Techniques; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D005260:Female; D006801:Humans; D009215:Myometrium / Q000378:metabolism*; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology*; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000187:drug effects* / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism
chemical_list: D047628:Estrogen Receptor alpha; D018015:Receptors, Calcitonin Gene-Related Peptide; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D011374:Progesterone; D004958:Estradiol