Luteinizing hormone depletes ascorbic acid in preovulatory follicles

Objective: The objective of the present studies was to determine whether lu tascorbic acid in the preovulatory follicle. Design: Controlled, prospective experimental study. Setting: University-based research center. Animal(s): Sprague-Dau ley female rats. Intervention(s): Follicular growth and ovulation were induced in immature r ats by gonadotropin treatment. Main Outcome Measure(s): Analysis of ovary, follicle, and oocyte levels of ascorbic acid by colorimetric analysis and high-pressure liquid chromatogra phy. Result(s) : Ovarian ascorbic acid was maximally depleted (50%) within 2 h o f LH treatment and was sustained for 8 h. Follicle ascorbic acid levels wer e 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 level s. Isolation of cumulus-enclosed or denuded oocytes depleted ascorbic acid to undetectable levels, but follicular ascorbic acid levels were only moder ately depleted by isolation and incubation. Accumulation of ascorbic acid b y oocytes was significantly enhanced by the presence of intact cumulus cell s. Conclusion(s): Elevation of LH and the production of oxygen radicals deplet e ascorbic acid in the preovulatory follicle (Fertil Steril(R) 2000;74:959- 63. (C) 2000 by American Society for Reproductive Medicine.)