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  • Title: [Control mechanism of ovarian function].
    Author: Okamura H.
    Journal: Nihon Sanka Fujinka Gakkai Zasshi; 1991 Aug; 43(8):890-6. PubMed ID: 1655926.
    Abstract:
    The preovulatory surge of gonadotropins causes resumption of oocyte meiosis, rupture of follicle wall and release of a fertilizable ovum, and luteinization. In the present lecture, current studies of the biochemical mechanism of follicle rupture are discussed. Over the past decade the cyclooxygenase pathway of arachidonic acid metabolism, namely prostaglandins (PGs), has received considerable attention in ovulation studies. We studied the changes in ovarian levels of eicosanoids during ovulation and the effects of indomethacin or lipoxygenase inhibitors on ovulation and ovarian eicosanoids in PMSG/hCG primed immature rats. Our data demonstrate that lipoxygenase products, especially 15-hydroxyeicosatetraenoic acid (HETE), is more essential for the ovulatory process than PGs. Ovarian steroidogenesis shifts from estradiol to progesterone after LH surge. It is not yet clarified how progesterone participates in the ovulatory process. We studied the effects of epostane and RU486 on ovulation rate, ovarian levels of steroids and eicosanoids, ovarian 3 beta-HSD activity, and ovarian proteolytic enzymes (collagenase, plasminogen activator and kallikrein) activities in the rats. The results show that progesterone plays an important role in the initial 4 hours of the ovulatory process by regulating proteolytic enzyme activities, and that an autocrine regulation may take place in progesterone production during ovulation. Morphological studies have demonstrated dilation and increased permeability of follicle vasculature during ovulation. We investigated the relation between ovarian blood volume and progesterone, and the role of active oxygen in ovarian vascular permeability by using SM-SOD.(ABSTRACT TRUNCATED AT 250 WORDS)
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