Idebenone relieves the damage of heat stress on the maturation and developmental competence of porcine oocytes

Abstract

The reproductive function of animals is often affected by climatic conditions. High‐temperature conditions can cause damage to oocyte maturation and embryonic development in a variety of ways. The purpose of this study was to prove that supplementation idebenone (IDB) to the maturation medium can improve the maturation and development of porcine oocytes after heat stress (HS). Porcine cumulus‐oocyte complexes (COCs) were cultured in the maturation medium with different concentrations of IDB (0, 0.1, 1 and 10 μM) for 44 hr at either 38.5°C or under the HS conditions. The cumulus oophorus expansion, nuclear maturation and blastocyst rate after parthenogenetic activation (PA) were measured. We found that HS (in vitro maturation 20–24 hr, 42°C) exposure significantly reduced cumulus expansion index and maturation rate of oocytes and the blastocyst rate of PA embryos, while IDB supplementation significantly improved oocyte maturation and development to the blastocysts stage after PA. Moreover, the addition of IDB decreased the intracellular level of ROS and increased GSH content, hence enhancing the antioxidant capacity of oocytes under HS. Meanwhile, IDB treatment also obviously improved the mitochondrial membrane potential and ATP synthesis of oocytes under HS conditions. Furthermore, IDB treatment increased the expression of GDF9 and BMP15 in IVM oocytes which attribute to improve the quality and outcome of IVM oocytes and the development competence of PA embryos in pigs. In summary, we demonstrated that IDB supplementation into the maturation medium exerted protective effects and improved the ability of maturation and developmental competence of porcine oocytes exposed to HS.

Disorder of Biological Quality and Autophagy Process in Bovine Oocytes Exposed to Heat Stress and the Effectiveness of In Vitro Fertilization

“…An additional objective was to determine the effect of heat shock on autophagy processes in oocytes (experiment 3). Studies show that exposure of cows to heat stress contributes to hyperthermia and disorders within the reproductive system [ 28 , 39 ].…”

“…Mitochondria play an essential role in oocytes. They participate in calcium homeostasis; the production of mitochondrial ATP, which is the primary source of energy, during respiration; the regulation of oxidation and reduction reactions in the cytoplasm; and they participate in oocyte apoptosis [ 26 , 28 , 51 ]. Thermal shock opens the permeability transition pores, reducing mitochondrial activity in immature and mature oocytes [ 42 , 49 ].…”

“…In turn, lipid metabolism disorders, including increased amounts of fatty acids and incredibly saturated fatty acids in the oocyte, may inhibit the process of fertilization and embryo development [ 26 ]. These organelles also maintain Ca 2+ ion homeostasis, which is necessary during oocyte IVM and fertilization [ 27 , 28 ]. Another role of the mitochondria is to support the early development of the oocyte and embryo, as glycolysis is limited during oocyte maturation, which is observed until early pre-implantation embryonic development.…”

“…It has been found that dysfunction or reduction in the number of mitochondria in oocytes can affect the abnormal growth of these cells and early embryos [ 20 ]. Mitochondria are structured in a manner causing them to be highly sensitive to thermal stress [ 25 , 28 ].…”