<scp>l</scp>‐carnitine Mediated Reduction in Oxidative Stress and Alteration in Transcript Level of Antioxidant Enzymes in Sheep Embryos Produced <i>In Vitro</i>

<jats:title>Contents</jats:title><jats:p>The objective of this study was to find out the effect of <jats:sc>l</jats:sc>‐carnitine on oocyte maturation and subsequent embryo development, with <jats:sc>l</jats:sc>‐carnitine‐mediated alteration if any in transcript level of antioxidant enzymes (GPx, Cu/Zn‐<jats:styled-content style="fixed-case">SOD</jats:styled-content> (<jats:styled-content style="fixed-case">SOD</jats:styled-content>1) and Mn‐<jats:styled-content style="fixed-case">SOD</jats:styled-content> (<jats:styled-content style="fixed-case">SOD</jats:styled-content>2) in oocytes and developing sheep embryos produced <jats:italic>in vitro</jats:italic>. Different concentrations of <jats:sc>l</jats:sc>‐carnitine (0 m<jats:sc>m</jats:sc>, 2.5 m<jats:sc>m</jats:sc>, 5 m<jats:sc>m</jats:sc>, 7.5 m<jats:sc>m</jats:sc> and 10 m<jats:sc>m</jats:sc>) were used in maturation medium. Oocytes matured with 10 m<jats:sc>m l</jats:sc>‐carnitine showed significantly (p < 0.05) higher cleavage (66.80% vs 39.66, 41.76, 44.64, 64.31%), morula (48.50% vs 20.88, 26.01, 26.99, 44.72%) and blastocyst (33.22% vs 7.66, 9.19, 10.71, 28.57%) percentage as compared to lower concentrations (0 m<jats:sc>m</jats:sc>, 2.5 m<jats:sc>m</jats:sc>, 5 m<jats:sc>m</jats:sc> and 7.5 m<jats:sc>m</jats:sc>). Cleavage percentage between 10 m<jats:sc>m</jats:sc> and 7.5 m<jats:sc>m l</jats:sc>‐carnitine were not significantly different. Maturation rate was not influenced by supplementation of any experimental concentration of <jats:sc>l</jats:sc>‐carnitine. There was a significant (p < 0.05) decrease in intracellular <jats:styled-content style="fixed-case">ROS</jats:styled-content> and increase in intracellular <jats:styled-content style="fixed-case">GSH</jats:styled-content> in 10 m<jats:sc>m l</jats:sc>‐carnitine‐treated oocytes and embryos than control group. Antioxidant effect of <jats:sc>l</jats:sc>‐carnitine was proved by culturing oocytes and embryos with H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub> in the presence of <jats:sc>l</jats:sc>‐carnitine which could be able to protect oocytes and embryos from H<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>‐induced oxidative damage. <jats:sc>l</jats:sc>‐carnitine supplementation significantly (p < 0.05) upregulated the expression of GPx and downregulated the expression of <jats:styled-content style="fixed-case">SOD</jats:styled-content>2 genes, whereas the expression pattern of <jats:styled-content style="fixed-case">SOD</jats:styled-content>1 and <jats:styled-content style="fixed-case">GAPDH</jats:styled-content> (housekeeping gene) genes was unaffected in oocytes and embryos. It was concluded from the study that <jats:sc>l</jats:sc>‐carnitine supplementation during <jats:italic>in vitro</jats:italic> maturation reduces oxidative stress‐induced embryo toxicity by decreasing intracellular <jats:styled-content style="fixed-case">ROS</jats:styled-content> and increasing intracellular <jats:styled-content style="fixed-case">GSH</jats:styled-content> that in turn improved developmental potential of oocytes and embryos and alters transcript level of antioxidant enzymes.</jats:p>