Cell Physiology Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, 221005 Uttar Pradesh, India.
J Cell Biochem. 2010 Oct 15;111(3):521-8. doi: 10.1002/jcb.22736.
Mammalian ovary is metabolically active organ and generates by-products such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) on an extraordinary scale. Both follicular somatic cells as well as oocyte generate ROS and RNS synchronously and their effects are neutralized by intricate array of antioxidants. ROS such as hydrogen peroxide (H(2)O(2)) and RNS such as nitric oxide (NO) act as signaling molecules and modulate various aspects of oocyte physiology including meiotic cell cycle arrest and resumption. Generation of intraoocyte H(2)O(2) can induce meiotic resumption from diplotene arrest probably by the activation of adenosine monophosphate (AMP)-activated protein kinase A (PRKA)-or Ca(2+)-mediated pathway. However, reduced intraoocyte NO level may inactivate guanylyl cyclase-mediated pathway that results in the reduced production of cyclic 3',5'-guanosine monophosphate (cGMP). The reduced level of cGMP results in the activation of cyclic 3',5'-adenosine monophosphate (cAMP)-phosphodiesterase 3A (PDE3A), which hydrolyses cAMP. The reduced intraoocyte cAMP results in the activation of maturation promoting factor (MPF) that finally induces meiotic resumption. Thus, a transient increase of intraoocyte H(2)O(2) level and decrease of NO level may signal meiotic resumption from diplotene arrest in mammalian oocytes.
哺乳动物的卵巢是一个代谢活跃的器官，会产生大量的副产物，如活性氧（ROS）和活性氮（RNS）。卵泡体细胞和卵母细胞都会同步产生 ROS 和 RNS，它们的作用会被复杂的抗氧化剂体系中和。ROS 如过氧化氢（H2O2）和 RNS 如一氧化氮（NO）可以作为信号分子，调节卵母细胞生理的各个方面，包括减数分裂细胞周期的阻滞和恢复。卵内 H2O2 的产生可以通过激活 AMP 激活的蛋白激酶 A（PRKA）或 Ca2+ 介导的途径，诱导从双线期阻滞的减数分裂恢复。然而，卵内 NO 水平的降低可能会使鸟苷酸环化酶介导的途径失活，导致环鸟苷酸（cGMP）的产生减少。cGMP 水平的降低会激活环腺苷酸（cAMP）-磷酸二酯酶 3A（PDE3A），从而水解 cAMP。卵内 cAMP 的减少会激活促进成熟因子（MPF），最终诱导减数分裂恢复。因此，卵内 H2O2 水平的短暂增加和 NO 水平的降低可能会发出信号，使哺乳动物卵母细胞从双线期阻滞中恢复减数分裂。
