||Inhibin Increases and Progesterone Decreases Receptors for Gonadotropin-Releasing Hormone in Ovine Pituitary Culture.
Laws, S. C. ;
Beggs, M. J. ;
Webster, J. C. ;
Miller., W. L. ;
||North Carolina State Univ. at Raleigh. Dept. of Biochemistry.;Health Effects Research Lab., Research Triangle Park, NC.
Pituitary gland ;
In vitro analysis ;
Gonadotropin receptors ;
Cultured cells ;
Competitive binding ;
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||Treatments (48 h) with highly purified bovine or porcine inhibins (10 ng/ml) induced ovine pituitary cells to increase their binding for des-Gly(to the tenth power)-(D-Ala(to the sixth power))LHRH-ethylamide by 3.6- and 5-fold, respectively. Studies with less pure inhibin from porcine follicles showed that increased binding could reach 7-fold within 48 h and was due to higher numbers of receptors for GnRH. The 48-h increase in GnRH receptors was linear with time and was rapidly reversible, since removal of inhibin at 24 h decreased GnRH binding below control levels at 48 h. Inhibin (bovine or porcine) also increased GnRH-stimulated secretion of LH by 2-fold. The ED50 for both inhibin actions noted above was in the range of 0.5-2.0 ng/ml (in terms of highly purified bovine inhibin). Progesterone (P) totally counteracted inhibin induction of GnRH binding and GnRH-stimulated LH secretion at 48 h. (Copyright (c) 1990 by The Endocrine Society.)
||Pub. in Endocrinology, v127 n1 p373-380 Jul 90. Sponsored by Health Effects Research Lab., Research Triangle Park, NC.
|NTIS Title Notes
||Reprint: Inhibin Increases and Progesterone Decreases Receptors for Gonadotropin-Releasing Hormone in Ovine Pituitary Culture.
||PC A02/MF A01