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Effects of estradiol and some antiestrogens (clomiphene, tamoxifen, and hydroxytamoxifen) on luteinizing hormone secretion by rat pituitary cells in culture
- Source :
- Archives of gynecology. 237(4)
- Publication Year :
- 1986
-
Abstract
- Primary pituitary cell cultures from adult female rats were incubated for 4 or 24 h with various concentrations of estradiol (E2) or the antiestrogens (AE) tamoxifen (TMX), 4-hydroxytamoxifen (OH-TMX), and clomiphene citrate (CC). The luteinizing hormone (LH)-response of these cultures to gonadotrophin releasing hormone (GnRH) was monitored. Treatment for 4 or 24 h with high concentrations (10(-5) M) of the AE significantly decreased the GnRH-induced LH-release by the gonadotrophs. The negative E2-effect, which is observed in this model after 4 h was enhanced and the positive E2-effect, which occurs after 24 h, was completely reversed into a negative effect by these high AE-concentrations. Treatment of pituitary cells with increasing concentrations of E2 (10(-13)-10(-6) M) or AE (10(-12)-10(-5) M) for 24 h led first to a dose dependent increase of the LH-response to 5 X 10(-10) M GnRH. At higher E2- or AE-concentrations this positive effect was lost, resulting in bell shaped dose-response curves. The following maximal effective concentrations (EDmax) were found: E2 = 10(-10) M, OH-TMX = 10(-9) M, CC = 10(-7) M, TMX = 10(-6) M. Incubation of pituitary cells for 24 h with concentrations of AE near their EDmax and stimulation with increasing concentrations (10(-11)-10(-7) M) of GnRH resulted in significant increases of LH-secretion over a wide range of GnRH-concentrations. It is concluded that AE possess marked intrinsic activities on pituitary LH-secretion: at extremely high concentrations they suppress the GnRH-induced release of the gonadotrophin. At lower concentrations they increase the pituitary LH-response to GnRH in a manner which is qualitatively indistinguishable from that of E2.
- Subjects :
- endocrine system
medicine.medical_specialty
Stimulation
Gonadotropic cell
Clomiphene
Gonadotropin-Releasing Hormone
Internal medicine
medicine
Animals
Incubation
Cells, Cultured
Adult female
Luteinizing hormone secretion
Dose-Response Relationship, Drug
Estradiol
business.industry
Estrogen Antagonists
Obstetrics and Gynecology
General Medicine
Luteinizing Hormone
Rats
Rat Pituitary
Tamoxifen
Endocrinology
Pituitary Gland
Female
Luteinizing hormone
business
Secretory Rate
hormones, hormone substitutes, and hormone antagonists
medicine.drug
Subjects
Details
- ISSN :
- 01709925
- Volume :
- 237
- Issue :
- 4
- Database :
- OpenAIRE
- Journal :
- Archives of gynecology
- Accession number :
- edsair.doi.dedup.....7088ec700674a60b2b55cda1afaf8b73