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Effects of phytoestrogens on GnRH-induced luteinizing hormone secretion in ovariectomized rats.

Publication ,  Journal Article
Hughes, CL
Published in: Reprod Toxicol
1987

Ovariectomized rats were pretreated with intravenous estradiol-17 beta (E2), coumestrol or genistein and were challenged 2 h later with GnRH (50 ng/kg BW, i.v.). Blood samples, drawn at the time of GnRH administration and 15 min afterwards, were assayed for luteinizing hormone (LH). While low-dose E2 pretreatment (10 ng/kg BW) significantly enhanced GnRH-induced LH release, high dose E2 pretreatment (1000 ng/kg BW) blocked the GnRH-induced rise. Intermediate-dose E2 pretreatment (100 ng/kg BW) yielded a GnRH response that did not differ from that in the vehicle pretreatment group. At all doses studied, coumestrol pretreatment (10 ng/kg BW, 100 ng/kg BW, and 1000 ng/kg BW) appeared to diminish but not abrogate GnRH-induced LH release. While intermediate-dose genistein pretreatment (100 ng/kg BW) significantly enhanced GnRH-induced LH release, high-dose genistein pretreatment (1000 ng/kg BW) yielded a GnRH response that did not differ from that in the vehicle pretreatment group. Both low-dose (10 ng/kg BW) and very high-dose (10,000 ng/kg BW) genistein pretreatment appeared to inhibit GnRH-induced LH release. The results demonstrate that acute exposure to phytoestrogens alters GnRH-induced LH release in ovariectomized rats. The dose-response pattern of enhanced GnRH-induced LH release at lower pretreatment doses but inhibited GnRH-induced LH release at higher pretreatment doses was observed for E2 and genistein. The potency of genistein appears to be approximately 1/10 that of E2 in this system. Phytoestrogens acutely perturb reproductive neuroendocrine function.

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Published In

Reprod Toxicol

DOI

ISSN

0890-6238

Publication Date

1987

Volume

1

Issue

3

Start / End Page

179 / 181

Location

United States

Related Subject Headings

  • Toxicology
  • Rats
  • Ovary
  • Ovariectomy
  • Luteinizing Hormone
  • Isoflavones
  • Gonadotropin-Releasing Hormone
  • Genistein
  • Female
  • Estradiol
 

Citation

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Hughes, C. L. (1987). Effects of phytoestrogens on GnRH-induced luteinizing hormone secretion in ovariectomized rats. Reprod Toxicol, 1(3), 179–181. https://doi.org/10.1016/s0890-6238(87)80030-8
Hughes, C. L. “Effects of phytoestrogens on GnRH-induced luteinizing hormone secretion in ovariectomized rats.Reprod Toxicol 1, no. 3 (1987): 179–81. https://doi.org/10.1016/s0890-6238(87)80030-8.
Hughes, C. L. “Effects of phytoestrogens on GnRH-induced luteinizing hormone secretion in ovariectomized rats.Reprod Toxicol, vol. 1, no. 3, 1987, pp. 179–81. Pubmed, doi:10.1016/s0890-6238(87)80030-8.
Journal cover image

Published In

Reprod Toxicol

DOI

ISSN

0890-6238

Publication Date

1987

Volume

1

Issue

3

Start / End Page

179 / 181

Location

United States

Related Subject Headings

  • Toxicology
  • Rats
  • Ovary
  • Ovariectomy
  • Luteinizing Hormone
  • Isoflavones
  • Gonadotropin-Releasing Hormone
  • Genistein
  • Female
  • Estradiol