α-Ketoglutarate Improves Meiotic Maturation of Porcine Oocytes and Promotes the Development of PA Embryos, Potentially by Reducing Oxidative Stress through the Nrf2 Pathway

Abstract

α-Ketoglutarate (α-KG) is a metabolite in the tricarboxylic acid cycle. It has a strong antioxidant function and can effectively prevent oxidative damage. Previous studies have shown that α-KG exists in porcine follicles, and its content gradually increases as the follicles grow and mature. However, the potential mechanism of supplementation of α-KG on porcine oocytes during in vitro maturation (IVM) has not yet been reported. The purpose of this study was to explore the effect of α-KG on the early embryonic development of pigs and the mechanisms underlying these effects. We found that α-KG can enhance the development of early pig embryos. Adding 20 μM α-KG to the in vitro culture medium significantly increased the rate of blastocyst formation and the total cell number. Compared with to that of the control group, apoptosis in blastocysts of the supplement group was significantly reduced. α-KG reduced the production of reactive oxygen species and glutathione levels in cells. α-KG not only improved the activity of mitochondria but also inhibited the occurrence of apoptosis. After supplementation with α-KG, pig embryo pluripotency-related genes (OCT4, NANOG, and SOX2) and antiapoptotic genes (Bcl2) were upregulated. In terms of mechanism, α-KG activates the Nrf2/ARE signaling pathway to regulate the expression of antioxidant-related targets, thus combating oxidative stress during the in vitro culture of oocytes. Activated Nrf2 promotes the transcription of Bcl2 genes and inhibits cell apoptosis. These results indicate that α-KG supplements have a beneficial effect on IVM by regulating oxidative stress during the IVM of porcine oocytes and can be used as a potential antioxidant for IVM of porcine oocytes.

Luteolin supplementation during porcine oocyte maturation improves the developmental competence of parthenogenetic activation and cloned embryos

“…Oxidative stress also disrupts the mitochondrial membrane potential, which reduces the oxidative phosphorylation reaction and ATP synthesis ( Aiken, Cindrova-Davies & Johnson, 2008 ). Numerous studies have reported that antioxidant supplementation during IVM is commonly able to overcome mitochondria injury by reducing ROS levels ( Chen et al, 2022 ; Li et al, 2022 ; Liu et al, 2023 ). A previous study reported that Lut increased PGC-1α and nitric oxide levels, which would correct cellular impairment and may reduce mitochondrial ROS production, suggesting that Lut may promote mitochondrial biogenesis ( Suh, Chon & Choi, 2016 ).…”

NRF2 attenuation aggravates detrimental consequences of metabolic stress on cultured porcine parthenote embryos

“…The primary negative regulator of NRF2 is KEAP1, which facilitates the degradation of NRF2 36 , 42 , 43 . Various molecules have been shown to stimulate NRF2 in reproductive tissues and cells, thereby reducing oxidative stress, such as quercetin 37 , N-acetylcysteine 44 , α-ketoglutarate 45 , sulforaphane 43 , 46 and melatonin 28 – 30 .…”

Rapamycin Treatment During Prolonged In Vitro Maturation Enhances the Developmental Competence of Immature Porcine Oocytes

“…antioxidants [8,9] and cumulus features [10] can enhance the quality of porcine oocytes in IVM. Specifically, supplementation of antioxidant to IVM medium improved embryo quality, reduced early apoptosis levels, increased GSH content and reduced ROS accumulation, promoting embryonic development [11]. However, further research is needed to improve IVM of porcine oocytes.…”