Cysteamine in Maturation Medium Enhances Nuclear Maturation and Fertilization Rate of Sheep Oocytes In Vitro

Abstract

Low nuclear maturation and fertilization rate is one obstacle in the in vitro embryo production which decrease embryo yield. This problem is presumable related with high production of reactive oxygen species (ROS) during maturation process. Glutathione (GSH) as an antioxidant is well known to overcome effect of ROS production. GSH synthesis in the cytosol part of the oocyte cytoplasm is influenced by cysteine availability. It is therefore, this research was conducted to evaluate the ability of cysteamine to provide cysteine availability as GSH precursor on the nuclear maturation and fertilization rate of sheep oocytes. Results of this experiment revealed additional cysteamine at 150 µm and 200 µm could significantly improve nuclear maturation rate. On the other side, although additional of cysteamine at 50 µm could not improve nuclear maturation rate, however 50 µm cysteamine in the maturation medium could significantly improve the fertilization rate. Based on those experiment results, it seems that the additional cysteamine might be improve not only GSH availability but also the oocyte quality which characterized the ability of pronuclear formation. This finding strongly suggested that additional cysteamine in the maturation medium could improve nuclear maturation and fertilization rate of sheep oocytes.

The impact of various antioxidant supplementation on ram's sperm quality, fertilization, and early embryo development, in vitro

“…ROS elevated levels can overwhelm the limited antioxidant defense of sperms, precipitating a state of oxidative stress (33). Oocytes and sperms, in reality, have a defensive mechanism to defend themselves from oxidative stress (21); despite this, if the formation of ROS and the availability of antioxidants are out of balance during gamete coincubation in IVEP processes, it can cause cellular damage and even early embryo mortality (34).…”

“…For sheep IVPE media, many researchers have utilized many antioxidants like cysteamine, Vit E, Vit A, and Vit C to detect their impact on IVEP (21). The addition of cysteamine to the maturation medium improved nuclear maturation and the fertilization rate of sheep oocytes (21).…”

“…For sheep IVPE media, many researchers have utilized many antioxidants like cysteamine, Vit E, Vit A, and Vit C to detect their impact on IVEP (21). The addition of cysteamine to the maturation medium improved nuclear maturation and the fertilization rate of sheep oocytes (21). Many studies in buffalo have discovered that cysteamine supplementation improves nuclear maturation rates by increasing GSH synthesis and improving male pronucleus formation (22).…”

Nuclear Maturation Competence and Pronuclear Formation in Ovine Oocytes Supplemented with L-ergothioneine in Maturation Medium

“…Nevertheless, in vitro-matured oocytes usually have less developmental capacity than in vivo-matured oocytes due to abnormalities that occur during cytoplasmic maturation (Quan et al 2017). Meanwhile, oocyte quality after in vitro maturation is essential in supporting fertilization and embryo development (Gulo et al 2020). It is generally known that in vitro oocyte maturation is the crucial process in the whole procedure of IVEP since immature oocytes have to undergo synchronized nuclear and cytoplasmic maturation to acquire fertilization and developmental competence (Paramio & Izquierdo 2014;Soto-Heras & Paramio 2020).…”

“…Several studies have been performed to control ROS levels during in vitro systems. One of them is to change the composition of the maturation medium by adding an antioxidant to increase intracellular antioxidant capacity and neutralize free radicals (Gulo et al 2020).…”