Acute and subacute effects of naturally occurring estrogens on luteinizing hormone secretion in the ovariectomized rat: Part 1

Reprod Toxicol. 1991;5(2):127-32. doi: 10.1016/0890-6238(91)90040-m.


Acute pretreatment of ovariectomized rats with genistein (G) alters gonadotropin-releasing hormone-(GnRH)-induced LH secretion in a fashion comparable to estradiol (E2). In the present studies we wished to (A) determine whether G can acutely inhibit tonic LH secretion by oral (po) or intravenous (iv) routes, (B) compare GnRH-induced LH responses following higher iv dose pretreatments with G or E2, and (C) determine effects of G or E2 pretreatments on progesterone (P)-induced secretion of LH. Mature Charles River CD rats were ovariectomized, and 2 to 5 weeks later intraatrial cannulae were placed. Serial blood samples were drawn and LH was measured by RIA. In experiments 1 and 2, G or E2 was administered acutely by gavage or iv, while in experiment 3, G and E2 were given subcutaneously (sc) oil 3 days prior to cannulation and sampling. Acute po administration of vehicle or G (0.1, 1.0, and 10 mg/kg BW) had no effect on tonic LH, while E2 suppressed LH at all doses (0.1, 1.0, and 10 mg/kg BW). Acute iv administration of vehicle and higher doses of G (1 and 10 mg/kg BW) had no effect on tonic LH, while the lowest dose G (0.1 mg/kg BW) and all doses of E2 (0.1, 1, and 10 mg/kg BW) suppressed tonic LH. In the iv-treated rats, GnRH-induced LH secretion was more profoundly suppressed by G at all doses than by E2.(ABSTRACT TRUNCATED AT 250 WORDS)

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Estradiol / pharmacology
  • Estrogens, Non-Steroidal / pharmacology*
  • Female
  • Genistein
  • Gonadotropin-Releasing Hormone / physiology
  • Isoflavones / pharmacology*
  • Luteinizing Hormone / metabolism*
  • Ovariectomy
  • Ovary / drug effects
  • Ovary / physiology*
  • Rats
  • Time Factors


  • Estrogens, Non-Steroidal
  • Isoflavones
  • Gonadotropin-Releasing Hormone
  • Estradiol
  • Luteinizing Hormone
  • Genistein