Antiapoptotic and embryotrophic effects of α-tocopherol and l-ascorbic acid on porcine embryos derived from in vitro fertilization and somatic cell nuclear transfer

The objective was to determine optimal concentrations of α-tocopherol and l-ascorbic acid for development of porcine embryos derived from in vitro-fertilization (IVF) or somatic cell nuclear transfer (SCNT). The frequency of blastocyst formation in IVF embryos was 17.6, 28.6, 32.4 and 21.4% for control, 50, 100 and 200 μM α-tocopherol, respectively, whereas in SCNT embryos, the frequency was 12.8, 19.0, 24.8 and 17.7% for corresponding concentrations of α-tocopherol. For both IVF and SCNT embryos, there were significantly more cells in blastocysts and the embryos had greater developmental competence when the embryo culture medium was supplemented with 100 μM α-tocopherol. Although either α-tocopherol or l-ascorbic acid reduced the proportion of apoptotic cells in blastocysts, in combination they resulted in rates of apoptosis that were similar to the control group. For IVF embryos, the apoptotic index was 0.09 and 0.11 for α-tocopherol or l-ascorbic acid at a concentration of 100 μM, respectively. Conversely, when these antioxidants were supplemented together, the apoptotic index increased significantly and was similar to the control group (i.e., 0.17 and 0.21 for combined and control group). For SCNT embryos, the apoptotic index was 0.10 for 100 μM for both α-tocopherol and l-ascorbic acid, whereas the index was 0.23 and 0.17 for control and combined group. In conclusion, we recommend supplementing porcine embryo culture medium with 100 μM α-tocopherol or 100 μM l-ascorbic (as a second choice).