Masuda M, Kubota T, Karnada S, Aso T
Department of Obstetrics and Gynecology, Faculty of Medicine, Tokyo Medical and Dental University, Japan.
Mol Hum Reprod. 1997 Apr;3(4):285-92. doi: 10.1093/molehr/3.4.285.
Recent evidence suggested that nitric oxide (NO) acts as an important factor in a variety of physiological and pathological roles, including reproductive functions. The purpose of the present study was to investigate whether NO might significantly induce any change in steroidogenesis in cultured porcine granulosa cells (PGC). An NO donor, NOC18, significantly suppressed the oestradiol release from basal (unstimulated) and gonadotrophin-stimulated PGC in a 2 h culture. NOC18 also significantly inhibited the aromatase activity of basal and gonadotrophin-stimulated PGC as measured by a modified tritiated water method. However, the cGMP analogue, 8-bromo-cGMP, had no significant effect on the accumulation of oestradiol and progesterone in basal and gonadotrophin-stimulated PGC during 24 h culture. An NO synthase (NOS) inhibitor, NG-monomethyl-L-arginine (LNMMA), significantly stimulated the basal oestradiol release and dose-dependently enhanced the oestradiol and progesterone release from follicle stimulating hormone (FSH)-stimulated PGC in a 24 h culture. However, NG-monomethyl-D-arginine, which does not inhibit NOS, did not enhance the release of oestradiol and progesterone under the same experimental conditions. LNMMA also significantly suppressed the nitrite concentrations in the media as measured by chemiluminescence. These results demonstrate for the first time that NO inhibits oestradiol secretion independent of cGMP by inhibiting P450 aromatase activity in moderately mature PGC.
最近的证据表明，一氧化氮（NO）在包括生殖功能在内的多种生理和病理过程中发挥着重要作用。本研究的目的是探讨NO是否可能显著诱导培养的猪颗粒细胞（PGC）类固醇生成的变化。NO供体NOC18在2小时培养中显著抑制基础（未刺激）和促性腺激素刺激的PGC释放雌二醇。通过改良的氚水法测定，NOC18还显著抑制基础和促性腺激素刺激的PGC的芳香化酶活性。然而，cGMP类似物8-溴-cGMP在24小时培养期间对基础和促性腺激素刺激的PGC中雌二醇和孕酮的积累没有显著影响。NO合酶（NOS）抑制剂NG-单甲基-L-精氨酸（LNMMA）在24小时培养中显著刺激基础雌二醇释放，并剂量依赖性地增强促卵泡激素（FSH）刺激的PGC中雌二醇和孕酮的释放。然而，不抑制NOS的NG-单甲基-D-精氨酸在相同实验条件下并未增强雌二醇和孕酮的释放。LNMMA还通过化学发光法显著抑制培养基中的亚硝酸盐浓度。这些结果首次证明，NO通过抑制中度成熟PGC中的P450芳香化酶活性，独立于cGMP抑制雌二醇分泌。
