title: Effect of in vivo estradiol administration to bilaterally ovariectomized rats on in vitro myometrial responsiveness to prostaglandin F2alpha and oxytocin.
abstract: Bilaterally ovariectomized, nonpregnant female CD rats were studied to investigate the effect of estradiol treatment on in vitro myometrial responsiveness to oxytocin and prostaglandin F2alpha. The first study investigated dose-dependent effects. Seven days after ovariectomy rats were given a single s.c. dose of corn oil (n = 4) or estradiol (5 microg, n = 5; 15 microg, n = 5; 50 microg, n = 4). A second identical injection of corn oil or estradiol was administered 24 h after the initial injection. Rats were killed 48 h after the first injection. A second study investigated time-dependent effects of estradiol treatment. A second group of ovariectomized rats received s.c. estradiol (50 microg) seven days after ovariectomy. These rats were killed either 12 h (n = 5) or 24 h (n = 4) after injection. Full-thickness cross-sections of uteri were suspended in vitro in the longitudinal direction in a superfusion system. Cumulative concentration-response curves were constructed to oxytocin and prostaglandin F2alpha. Both the duration and dose of estradiol treatment significantly (p < 0.05) attenuated baseline contractile activity, and the maximum myometrial response to oxytocin and prostaglandin F2alpha. Estradiol, in a dose-dependent manner, significantly reduced myometrial sensitivity (p < 0.05) for oxytocin and prostaglandin F2alpha.
authors.affiliation: College of Veterinary Medicine, Department of Physiology, Cornell University, Ithaca, New York 14853-6401, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Gordan
authors.forename: S L
authors.initials: SL
authors.lastname: Jenkins
authors.forename: R A
authors.initials: RA
authors.lastname: Wentworth
authors.forename: P W
authors.initials: PW
authors.lastname: Nathanielsz
mesh_terms: D000818:Animals; D015237:Dinoprost / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D009215:Myometrium / Q000187:drug effects* / Q000502:physiology; D010052:Ovariectomy; D010053:Ovary / Q000502:physiology; D010121:Oxytocin / Q000494:pharmacology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D013997:Time Factors; D014590:Uterine Contraction / Q000187:drug effects
chemical_list: D004958:Estradiol; D010121:Oxytocin; D011189:Potassium Chloride; D015237:Dinoprost