Record Display for the EPA National Library Catalog


Main Title Estradiol Alters the Effectiveness of Gonadotropin-Releasing Hormone (GnRH) in Ovine Pituitary Cultures: GnRH Receptors versus Responsiveness to GnRH.
Author Laws, S. C. ; Webster, J. C. ; Miller., W. L. ;
CORP Author North Carolina State Univ. at Raleigh. Dept. of Biochemistry.;Health Effects Research Lab., Research Triangle Park, NC.
Publisher c1990
Year Published 1990
Report Number EPA/600/J-90/173;
Stock Number PB91-115790
Additional Subjects Estradiol ; Physiology ; Pituitary gland ; Sheep ; Kinetics ; Reprints ; Pituitary hormone releasing hormones ; Gonadotropin receptors ; LH ; Inhibin ; Cultured cells ; Radioimmunoassay ; Dose-response relationships
Library Call Number Additional Info Location Last
NTIS  PB91-115790 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 8p
Estradiol-17 beta (E) rapidly (5-12h) induced ovine pituitary cultures to increase their binding for des-Gly10-(D-Ala6)-GnRH ethylamide by 2.5 to 4.5-fold. The ED50 for E was near 0.1 nM. Scatchard analysis indicated the E increased binding by increasing receptors for gonadotrophin releasing hormone (GnRH). GnRH-stimulated release of luteinizing hormone (LH) increased 2-fold along with the increase in GnRH receptors but heightened responsiveness to GnRH disappeared after 27h of E-treatment even though GnRH receptors remained elevated. These data are consistent with the concept that: (1) E increased GnRH receptors which initially enhanced gonadotroph responsiveness to GnRH, and (2) E subsequently nullified the increased response to GnRH by blocking a mechanism of LH secretion not associated with GnRH receptor number. Further support for this hypothesis came from studies with porcine follicular inhibin. Inhibin, in ovine pituitary culture, concomitantly increased GnRH receptors by 5-fold and GnRH-stimulated LH secretion by 2-fold. Inhibin maintained both effects long term (48h).