Mitogenic and antioxidant mechanisms of estradiol action in preovulatory ovine follicles: relevance to luteal function.
The objectives of this investigation were to determine the intrafollicular mechanisms and physiological consequences of estradiol actions in preovulatory ovine follicles. Acute suppression of estradiol production in proestrous ewes by an aromatase inhibitor (Arimidex) was associated with follicular lipid peroxidation, testosterone accumulation, and a granulosa cell deficiency (decreased proliferation/increased apoptosis). Estradiol-17beta stimulated granulosa proliferating cell nuclear antigen (PCNA) and protected cells from oxidative (H(2)O(2)) stress-induced apoptosis in vitro; the PCNA, but not the antiapoptotic response, was negated by the transcriptional inhibitor actinomycin D. Thus, it appears that genomic/mitotic and cytoprotective (oxygen-scavenging) modes of estradiol action operate in preovulatory follicles. Luteal (large steroidogenic cell) function was diminished following ovulation induction of estradiol-deficient follicles. It is suggested that inadequate exposure of the preovulatory follicle to estradiol caused the granulosa lutein insufficiency.
Lund
S A
SA
Department of Animal Science, University of Wyoming, Laramie, Wyoming 82071, USA.
Murdoch
J
J
Van Kirk
E A
EA
Murdoch
W J
WJ
D000077384:Anastrozole; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D017209:Apoptosis; D047072:Aromatase Inhibitors; D003338:Corpus Luteum / Q000187:drug effects* / Q000378:metabolism; D053938:DNA Fragmentation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008938:Mitosis / Q000187:drug effects*; D009570:Nitriles / Q000494:pharmacology; D006080:Ovarian Follicle / Q000187:drug effects* / Q000378:metabolism; D018384:Oxidative Stress; D011374:Progesterone / Q000097:blood; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D012756:Sheep; D014230:Triazoles / Q000494:pharmacology
D000975:Antioxidants; D047072:Aromatase Inhibitors; D004791:Enzyme Inhibitors; D009570:Nitriles; D018809:Proliferating Cell Nuclear Antigen; D014230:Triazoles; D000077384:Anastrozole; D011374:Progesterone; D004958:Estradiol