Gonadotropin-releasing hormone binding sites in ovaries of normal cycling and persistent-estrus rats

K. Köves, P. E. Gottschall, A. Arimura

Research output: Contribution to journalArticle

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Abstract

The gonadotropin-releasing hormone (GnRH) binding capacity in ovaries and pituitaries of normal cycling rats at different stages of the estrous cycle and in ovaries of persistent-estrus rats was measured using radioligand-receptor assay (RRA). Persistent estrus was induced either by neonatal administration of testosterone propionate (1.25 mg s.c.) on the second day of life or by a hypothalamic suprachiasmatic frontal cut made with Halasz' knife. All animals were killed during the critical period (1400-1600 h), and GnRH receptor was assayed. GnRH receptor levels in both ovaries and pituitaries changed during the estrous cycle. The total number of ovarian GnRH binding sites was significantly higher in proestrus than in diestrus 1, the stage in which the lowest level was found. When binding sites were expressed in fmol/mg ovary, the highest level was observed in diestrus 2; however, no changes were observed during the estrous cycle when GnRH binding sites were expressed as fmol/mg protein. Changes noted were very similar to those demonstrated in pituitary GnRH receptors in our present and previous experiments. Higher levels of pituitary binding sites were found in diestrus 2 and proestrus than in estrus and diestrus 1. The changes in the GnRH receptor levels were more striking in the pituitary than in the ovaries. It appears that the total number of ovarian GnRH binding sites was not altered in either of the two persistent-estrus groups, but that their concentration was significantly higher (expressed in fmol/ml ovary or fmol/mg protein) than on any day during the estrous cycle. Our results differ from previous studies, which failed to demonstrate significant changes in GnRH binding capacity throughout the estrous cycle. The similarities of the high total GnRH binding capacity in rat ovaries in persistent estrus to those of controls (although ovarian weight was significantly lower than in controls) may be explained by the fact that the concentration of GnRH receptors is higher in the follicles than in corpora lutea.

Original languageEnglish
Pages (from-to)505-511
Number of pages7
JournalBiology of Reproduction
Volume41
Issue number3
Publication statusPublished - 1989

Fingerprint

Estrus
Gonadotropin-Releasing Hormone
LHRH Receptors
Ovary
Estrous Cycle
Diestrus
Binding Sites
Proestrus
Pituitary Gonadotropins
Testosterone Propionate
Radioligand Assay
Pituitary Hormones
Corpus Luteum
Proteins
Weights and Measures

ASJC Scopus subject areas

  • Cell Biology
  • Developmental Biology
  • Embryology

Cite this

Gonadotropin-releasing hormone binding sites in ovaries of normal cycling and persistent-estrus rats. / Köves, K.; Gottschall, P. E.; Arimura, A.

In: Biology of Reproduction, Vol. 41, No. 3, 1989, p. 505-511.

Research output: Contribution to journalArticle

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