Tao J Y, Fu Z, Zhang M L, Xia G, Lei L, Wu Z L
College of Biological Sciences, China Agricultural University, Beijing, China.
J Anim Physiol Anim Nutr (Berl). 2005 Feb;89(1-2):38-44. doi: 10.1111/j.1439-0396.2004.00508.x.
Nitric oxide (NO) plays an important role in many pathological processes. The present investigation was undertaken to ascertain the effects of NO at high level on porcine oocyte meiotic development. Cumulus-enclosed oocytes (CEOs) and denuded oocytes (DOs) were obtained from the follicles (2-6 mm diameter). Exogenous NO was provided with sodium nitroprusside (SNP). Control (0 mM), 0.1 mM, 1 mM or 10 mM SNP was introduced to the medium. Meanwhile, 0.1 mM, 1 mM and 10 mM preincubated SNP was also added to the medium respectively. The cumulus expansion, cumulus cells DNA fragmentation, oocyte meiotic maturation and degeneration were determined 44 h after incubation. SNP inhibited cumulus expansion and cumulus cells DNA fragmentation in a dose-dependent manner. Significantly fewer CEOs treated by any level of SNP resumed meiosis than control (p < 0.05) and more CEOs exposed to 0.1 mM or 1 mM SNP were arrested at GV stage. Moreover, SNP increased the percentage of CEOs at metaphase I (MI) stage but decreased the percentage of CEOs at metaphase II (MII) stage. 0.1 mM or 1 mM SNP showed no influence on the proportion of germinal vesicle breakdown of DOs and only 10 mM SNP reduced the proportion. SNP accelerated degeneration of both CEOs and DOs, especially at higher concentrations. DOs were more sensitive to SNP toxicity. Preincubated SNP showed no effect on cumulus expansion, cumulus cells DNA fragmentation, oocyte meiotic maturation or degeneration at lower concentration, but higher concentrations had effect, especially on the viability of porcine oocytes. Taken together, high level of NO inhibits porcine oocyte meiotic maturation, especially the transition from MI to MII, by mediating the functions of cumulus cells.
一氧化氮（NO）在许多病理过程中发挥着重要作用。本研究旨在确定高水平的NO对猪卵母细胞减数分裂发育的影响。从直径为2 - 6毫米的卵泡中获取卵丘-卵母细胞复合体（CEOs）和裸卵（DOs）。通过硝普钠（SNP）提供外源性NO。将对照（0 mM）、0.1 mM、1 mM或10 mM的SNP加入培养基中。同时，分别将0.1 mM、1 mM和10 mM预孵育的SNP也加入培养基中。孵育44小时后测定卵丘扩展、卵丘细胞DNA片段化、卵母细胞减数分裂成熟和退化情况。SNP以剂量依赖性方式抑制卵丘扩展和卵丘细胞DNA片段化。与对照组相比，任何水平SNP处理的CEOs恢复减数分裂的数量显著减少（p < 0.05），更多暴露于0.1 mM或1 mM SNP的CEOs停滞在GV期。此外，SNP增加了处于中期I（MI）期的CEOs百分比，但降低了处于中期II（MII）期的CEOs百分比。0.1 mM或1 mM SNP对DOs生发泡破裂比例无影响，只有10 mM SNP降低了该比例。SNP加速了CEOs和DOs的退化，尤其是在较高浓度时。DOs对SNP毒性更敏感。较低浓度下预孵育的SNP对卵丘扩展、卵丘细胞DNA片段化、卵母细胞减数分裂成熟或退化无影响，但较高浓度时有影响，尤其是对猪卵母细胞的活力。综上所述，高水平的NO通过介导卵丘细胞的功能抑制猪卵母细胞减数分裂成熟，尤其是从MI到MII的转变。
