Melatonin Improves Oocyte Maturation and Mitochondrial Functions by Reducing Bisphenol A-Derived Superoxide in Porcine Oocytes In Vitro.

Hyo-Jin Park,Soo-Yong Park,Seul-Gi Yang,Deog-Bon Koo,Min-Ji Kim,Ho-Guen Jegal,Young-Kug Choo,In-Su Kim,Jin-Woo Kim

doi:10.3390/ijms19113422

Hyo-Jin Park, Soo-Yong Park + Show 7 more

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https://doi.org/10.3390/ijms19113422

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Abstract

Bisphenol A (BPA) is synthetic organic compound that exhibits estrogen-like properties and it induces mitochondrial superoxide production. Melatonin (Mela) protects against BPA-mediated cell damage and apoptosis. However, the antioxidative effects of Mela against BPA-induced superoxide production in porcine oocytes are still not known. In this study, we investigated the antioxidative effects of Mela against BPA-derived superoxide on oocyte maturation in pigs. To investigate the effects of the superoxide specific scavenger, Mito-TEMPO, on porcine oocyte maturation in response to BPA exposure apoptosis proteins, we treated the oocytes with Mito-TEMPO (0.1 µM) after pre-treating them with BPA (75 µM) for 22 h. As expected, the reduction in meiotic maturation and cumulus cell expansion of cumulus-oocyte-complexes (COCs) in the BPA (75 µM) treated group was recovered (p < 0.01) by treatment with Mito-TEMPO (0.1 µM). An increase in the levels of mitochondrial apoptotic proteins (AIF, cleaved Cas 3 and cleaved Parp1) in response to BPA-induced damage was also reduced by Mito-TEMPO treatment in porcine COCs. Interestingly, we confirmed the positive effects of Mela with respect to superoxide production upon BPA exposure during oocyte maturation and also confirmed the reduction in mitochondrial apoptosis in Mela (0.1 µM)-treated porcine COCs. These results provide evidence for the first time that antioxidative effects of Mela on BPA-derived superoxide improve porcine oocyte maturation.

Highlights

In vitro culture (IVC) system of porcine oocyte is commonly used to investigate the complex mechanism of female reproduction under IVC condition
To confirm that reactive oxygen species (ROS) production was a result of Bisphenol A (BPA) exposure during porcine oocyte maturation, we examined the mRNA expression levels of various antioxidant enzymes including glutathione peroxidase1 (Gpx1), catalase, superoxide dismutase 1 (Sod1), superoxide dismutase 2 (Sod2), and peroxiredoxins (Prdxs) through Reverse Transcription (RT)-PCR analysis
We investigated whether BPA-induced oxidative stress or mitochondrial-specific ROS production induced a reduction in meiotic maturation and cumulus cell expansion in porcine cumulus-oocyte complexes (COCs) after 44 h of in vitro maturation (IVM)

Summary

Introduction

In vitro culture (IVC) system of porcine oocyte is commonly used to investigate the complex mechanism of female reproduction under IVC condition. The regulation mechanisms of reactive oxygen species (ROS) production and antioxidant enzymes in the regulation of important events of meiotic maturation and cumulus cells expansion during in vitro maturation (IVM) of porcine oocytes are already investigated. The mechanisms of oxidative stress and the protection against ROS play important roles in improving meiotic maturation and blastocyst formation during IVC, including oocyte maturation and pre-implantation embryo development [1,2,3]. According to a recent study, superoxide production occurs naturally as the intermediary products of cellular metabolism between cumulus cells and oocytes during the maturation process of cumulus-oocyte complexes (COCs) [4]. A highly oxygenated environment induces ROS accumulation during in vitro embryo culture and lead to DNA damage impairing embryo development in porcine species [7]

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