High cGMP and low PDE3A activity are associated with oocyte meiotic incompetence

The Implications of Insufficient Zinc on the Generation of Oxidative Stress Leading to Decreased Oocyte Quality

Zinc is a transition metal that displays wide physiological implications ranging from participation in hundreds of enzymes and proteins to normal growth and development. In the reproductive tract of both sexes, zinc maintains a functional role in spermatogenesis, ovulation, fertilization, normal pregnancy, fetal development, and parturition. In this work, we review evidence to date regarding the importance of zinc in oocyte maturation and development, with emphasis on the role of key zinc-binding proteins, as well as examine the effects of zinc and reactive oxygen species (ROS) on oocyte quality and female fertility. We summarize our current knowledge about the participation of zinc in the developing oocyte bound to zinc finger proteins as well as loosely bound zinc ion in the intracellular and extracellular environments. These include aspects related to (1) the impact of zinc deficiency and overwhelming production of ROS under inflammatory conditions on the offset of the physiological antioxidant machinery disturbing biomolecules, proteins, and cellular processes, and their role in contributing to further oxidative stress; (2) the role of ROS in modulating damage to proteins containing zinc, such as zinc finger proteins and nitric oxide synthases (NOS), and expelling the zinc resulting in loss of protein function; and (3) clarify the different role of oxidative stress and zinc deficiency in the pathophysiology of infertility diseases with special emphasis on endometriosis-associated infertility.

Effect of milrinone on the meiosis resumption and cytoplasm maturation of buffalo oocytes

Buffalo has many excellent economic traits and it is one of the greatest potential livestock. Compared with cattle, buffalo has poorer reproductivity, it is of great significance to improve the development potential of oocytes. Buffalo oocyte in vitro maturation (IVM) has been widely used in production, but the poor development ability of bovine oocytes IVM limits the development of buffalo reproductivity. Milrinone as a phosphodiesterase inhibitor could affect the maturation of oocytes in goat and mice, but there have been few reported studies in water buffalo. To optimize buffalo oocyte in vitro maturation systems, the effects of phosphodiesterase inhibitor (milrinone) on pre-maturation culture of buffalo oocytes were investigated in this study. Buffalo cumulus-oocyte complexes (COCs) were cultured in medium with different concentrations (0, 12, 25, 50 and 100 mol/l) of milrinone for different times (0, 4, 8, 12, 16, 22 and 24 h). The results showed that the buffalo COCs nuclear maturation process could be inhibited by milrinone (25-100 mol/l) in a dose-dependent manner. The inhibitory effect of milrinone on in vitro maturation of buffalo oocytes did not decrease with the extension of time. This indicated that milrinone can be used as a nuclear maturation inhibitor during the maturation process in buffalo oocytes. In addition, milrinone can inhibit the effect of follicle stimulating hormone (FSH)-induced IVM of buffalo oocytes, but with time FSH partially eliminated the inhibition. Therefore, inhibition of milrinone on the nuclear maturation of buffalo oocytes was reversible, and buffalo oocytes can mature normally after the inhibition is lessened.