Regulation of Nitric Oxide Synthase to Promote Cytostasis in Ovarian Follicular Development

• Published in: Biology of reproduction Vol. 63; no. 1; pp. 141 - 146
• Main Authors: MATSUMI, H, YANO, T, KOJI, T, ESUMI, H, TAKETANI, Y, OSUGA, Y, KUGU, K, XIAOHUI TANG, JI PING XU, YANO, N, KURASHIMA, Y, OGURA, T, TSUTSUMI, O
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01.07.2000
• Subjects: Animals; Apoptosis - drug effects; Biological and medical sciences; Buserelin - pharmacology; Cell Division - drug effects; Cells, Cultured; Epidermal Growth Factor - pharmacology; Female; Fundamental and applied biological sciences. Psychology; Gonadotropin-Releasing Hormone - agonists; Granulosa Cells - drug effects; Mammalian female genital system; Morphology. Physiology; Nitric Oxide Donors - pharmacology; Nitric Oxide Synthase - genetics; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type II; Ovarian Follicle - drug effects; Ovarian Follicle - enzymology; Ovarian Follicle - physiology; Ovary - drug effects; Ovary - enzymology; Penicillamine - analogs & derivatives; Penicillamine - pharmacology; Rats; Rats, Wistar; Thymidine - metabolism; Vertebrates: reproduction; Rat; Enzyme; Folliculogenesis; Rodentia; Gene expression; Nitric-oxide synthase; Ovary; Vertebrata; Mammalia; Female genital system; Development; Oxidoreductases; Ovarian follicle; Apoptosis
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod63.1.141

Our own recent studies have demonstrated that inducible nitric oxide synthase (iNOS) is predominantly localized in granulosa cells of healthy immature follicles in the rat ovary, whereas granulosa cells of either healthy mature follicles or follicles destined to be atretic are devoid of iNOS. These findings suggest that iNOS is pivotal for immature follicles to remain dormant. To test this hypothesis, we examined the effects of a GnRH agonist (buserelin), a proapoptotic substance, and epidermal growth factor (EGF), a mitogenic and, consequently, antiapoptotic factor, on the amount of iNOS mRNA in rat granulosa cells. Administration of buserelin in immature female rats transiently diminished iNOS mRNA levels in the ovaries as determined by Northern blot analysis. In cultured rat granulosa cells, buserelin and EGF increased the incidence of apoptosis and DNA synthesis, respectively, whereas both reduced iNOS mRNA levels as determined by reverse transcription-coupled polymerase chain reaction. The concomitant addition of S -nitroso- N -acetyl- dl -penicillamine, an NO donor, together with buserelin or EGF eliminated the observed effects of these substances (i.e., induction of apoptosis and stimulation of DNA synthesis, respectively). These results suggest that the changes in developmental status of immature follicles either into development or atresia are associated with reduced iNOS levels in granulosa cells, thus reinforcing the notion of NO as a cytostatic factor in ovarian follicles.