Human follicular fluid from superovulated women inhibits progesterone receptor-dependent gonadotropin-releasing hormone self-priming in an estrous cycle-dependent manner in the rat.
These experiments investigated the involvement of gonadotrope progesterone receptor (PR) in the effects of the putative gonadotropin surge-attenuating factor (GnSAF) on gonadotropin (LH and FSH) secretion. Human follicular fluids (hFF) used in this study were aspirated from follicles in gonadotropin-treated women for in vitro fertilization. Samples were subjected to two-fold charcoal extraction of steroid hormones and two-fold inhibin immunoprecipitation. Gonadotropin secretion parameters were assessed by specific radioimmunoassays. In the first experiment, the effects of hFF on both basal and GnRH-stimulated gonadotropin secretion and GnRH self-priming were studied in incubated hemipituitaries from rats on each day of the 4-day estrous cycle. hFF inhibited only GnRH self-priming in pituitaries from rats in diestrus. In the second experiment, immunohistochemical PR expression and action were evaluated in pituitaries from rats in diestrus. PR-positive (PR10A9 antibody) gonadotropes were detected (4-5/field 40x), and antiprogestins added to the incubation media blocked the ligand-independent (GnRH) activation of PR effects on GnRH selfpriming. Finally, the third experiment evaluated the effects of hFF on P-induced potentiation of GnRH-stimulated LH secretion. GnSAF bioactivity, as evidenced by inhibition of PR-induced potentiation of GnRH-stimulated LH secretion, was found in diestrous pituitaries incubated with hFF. The results indicate that GnSAF attenuated GnRH-dependent LH secretion in diestrus through the inhibition of PR-dependent GnRH self-priming.
Gordon
A
A
Department of Cell Biology, Physiology and Immunology, University of Córdoba, Córdoba, Spain.
Aguilar
R
R
Garrido-Gracia
J C
JC
Bellido
C
C
Millán
Y
Y
Guil-Luna
S
S
García-Velasco
J A
JA
Bellido-Muñoz
E
E
de las Mulas
J Martín
JM
Sánchez-Criado
J E
JE
D000818:Animals; D030762:Estrous Cycle / Q000187:drug effects*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism; D015571:Follicular Fluid / Q000187:drug effects / Q000502:physiology*; D042341:Gonadal Hormones / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology*; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism; D010902:Pituitary Gland / Q000187:drug effects; D011506:Proteins / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011980:Receptors, Progesterone / Q000378:metabolism; D013480:Superovulation / Q000378:metabolism
D042341:Gonadal Hormones; D011506:Proteins; D011980:Receptors, Progesterone; C080538:attenuin; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone