The effects of canthaxanthin on porcine oocyte maturation and embryo development in vitro after parthenogenetic activation and somatic cell nuclear transfer

<jats:title>Contents</jats:title><jats:p>The objective of this study was to examine the effects of canthaxanthin (Cx) treatment during in vitro maturation (<jats:styled-content style="fixed-case">IVM</jats:styled-content>) of porcine oocytes on embryonic development after parthenogenetic activation (<jats:styled-content style="fixed-case">PA</jats:styled-content>) and somatic cell nuclear transfer (<jats:styled-content style="fixed-case">SCNT</jats:styled-content>), on intracellular glutathione (<jats:styled-content style="fixed-case">GSH</jats:styled-content>) and reactive oxygen species (<jats:styled-content style="fixed-case">ROS</jats:styled-content>) levels in mature oocytes, and on gene expression in both <jats:styled-content style="fixed-case">PA</jats:styled-content>‐ and <jats:styled-content style="fixed-case">SCNT</jats:styled-content>‐derived blastocysts. To determine the optimal effective concentration of Cx, porcine oocytes were cultured in <jats:styled-content style="fixed-case">IVM</jats:styled-content> medium supplemented with various concentrations (0, 20, 40 and 80 μM) of Cx for 22 hr. Compared to other groups, supplementation with 40 μM Cx significantly improved blastocyst formation rates after <jats:styled-content style="fixed-case">PA</jats:styled-content> (<jats:italic>p </jats:italic><<jats:italic> </jats:italic>.05), but no significant differences were observed among groups in total blastocyst cell numbers. Subsequently, oocytes were cultured in <jats:styled-content style="fixed-case">IVM</jats:styled-content> medium supplemented with or without 40 μM Cx. Oocytes treated with 40 μM Cx showed significantly increased cleavage and blastocyst formation rates after <jats:styled-content style="fixed-case">SCNT</jats:styled-content> compared to the control group (<jats:italic>p </jats:italic><<jats:italic> </jats:italic>.05). Moreover, significantly increased intracellular <jats:styled-content style="fixed-case">GSH</jats:styled-content> and reduced <jats:styled-content style="fixed-case">ROS</jats:styled-content> levels were observed in the Cx‐treated group (<jats:italic>p </jats:italic><<jats:italic> </jats:italic>.05). In addition, both <jats:styled-content style="fixed-case">PA</jats:styled-content>‐ and <jats:styled-content style="fixed-case">SCNT</jats:styled-content>‐derived blastocysts from the 40 μM Cx‐treated group showed significantly increased <jats:styled-content style="fixed-case">mRNA</jats:styled-content> expression of <jats:italic>Bcl2</jats:italic> and <jats:italic>Oct4</jats:italic> and decreased <jats:italic>Caspase3</jats:italic> expression level (<jats:italic>p </jats:italic><<jats:italic> </jats:italic>.05), when compared with the control group. <jats:styled-content style="fixed-case">PA</jats:styled-content>‐derived blastocysts from the 40 μM Cx‐treated group also exhibited significantly decreased expression of <jats:italic>Bax</jats:italic> (<jats:italic>p </jats:italic><<jats:italic> </jats:italic>.05). Our results demonstrated that treatment with 40 μM Cx during <jats:styled-content style="fixed-case">IVM</jats:styled-content> improves the developmental competence of <jats:styled-content style="fixed-case">PA</jats:styled-content> and <jats:styled-content style="fixed-case">SCNT</jats:styled-content> embryos. Improvement of embryo development by Cx is most likely due to increased intracellular <jats:styled-content style="fixed-case">GSH</jats:styled-content> synthesis, which reduces <jats:styled-content style="fixed-case">ROS</jats:styled-content> levels in oocytes, and it may also positively regulate apoptosis‐ and development‐related genes.</jats:p>