Luteinizing hormone depletes ascorbic acid in preovulatory follicles.
OBJECTIVE
The objective of the present studies was to determine whether luteinizing hormone (LH) depletes ascorbic acid in the preovulatory follicle.


METHODS
Controlled, prospective experimental study.


METHODS
University-based research center.


METHODS
Sprague-Dawley female rats.


METHODS
Follicular growth and ovulation were induced in immature rats by gonadotropin treatment.


METHODS
Analysis of ovary, follicle, and oocyte levels of ascorbic acid by colorimetric analysis and high-pressure liquid chromatography.


RESULTS
Ovarian ascorbic acid was maximally depleted (50%) within 2 h of LH treatment and was sustained for 8 h. Follicle ascorbic acid levels were unchanged 1 h after LH injection but were significantly reduced within 2 h (40%). Incubation of isolated preovulatory follicles for 3 h with hCG or with menadione (a generator of oxygen radicals) reduced ascorbic acid levels. Isolation of cumulus-enclosed or denuded oocytes depleted ascorbic acid to undetectable levels, but follicular ascorbic acid levels were only moderately depleted by isolation and incubation. Accumulation of ascorbic acid by oocytes was significantly enhanced by the presence of intact cumulus cells.


CONCLUSIONS
Elevation of LH and the production of oxygen radicals deplete ascorbic acid in the preovulatory follicle.
Guarnaccia
M M
MM
Reproductive Biology Section, Yale University School of Medicine, New Haven, Connecticut 06520-8063, USA.
Takami
M
M
Jones
E E
EE
Preston
S L
SL
Behrman
H R
HR
D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005260:Female; D005498:Follicular Phase / Q000502:physiology*; D066298:In Vitro Techniques; D007986:Luteinizing Hormone / Q000494:pharmacology*; D009865:Oocytes / Q000378:metabolism; D006080:Ovarian Follicle / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014812:Vitamin K / Q000494:pharmacology
D006063:Chorionic Gonadotropin; D014812:Vitamin K; D007986:Luteinizing Hormone; D001205:Ascorbic Acid