Exposure to α-Tocopherol, Lutein or Ascorbic Acid improve Cumulus Expansion, Viability and Maturation of Swine Oocytes

Abstract

Protection of the fatty acid and lipid components of oocytes that render them susceptible to free radical or other oxidative injury may prevent the damage currently associated with culture. The goal of this study was to establish the influence of several α-tocopherol, lutein and ascorbic acid concentrations on swine oocyte maturation, viability and the function of cumulus cells in order to improve culture media. Pig oocytes were cultured for 45 hours at 37°C in 5% CO₂ atmosphere; in M199 containing several α-tocopherol (5, 10, 20, 40, 80 µM), lutein (2.5, 4, 5, 8, 10 mM) or ascorbic acid (50, 150, 250, 500, 750 µM) concentrations and cumulus expansion was assessed. Afterwards oocytes were coloured using FDA, PI and Hoechst 33258. The differences between treatments were analyzed by the analysis of variance and interpreted using the Newman-Keuls method. When cultured in α-tocopherol supplemented medium the number of expanded COCs to be scored as 3 was significantly greater (p<0.05) for the 5 and 40 µM concentrations. The addition of 8 mM lutein to the maturation medium lead to a significant (p<0.05) increase in the number of COCs that were scored at 4. For both α-tocopherol and lutein additions the numbers of oocytes stained by FDA, as well as those stained by Hoechst were greater than the control without being statistically significant. When cultured in 150 and 500 µM ascorbic acid the percentages of COCs scored at 4 were significantly lower (p<0.05) than the control. Also, significantly (p<0.05) fewer oocytes were stained with FDA when matured in 500 µM. Differences between the control and the several concentrations were significant (p<0.05) for 150 and 750 µM and distinctly significant (p<0.01) for 250 µM.