Effects of N, N-Dimethylglycine on the development of in vitro produced bovine embryos

Abstract

This study investigated the effects of N, N-Dimethylglycine (DMG) on the development of in vitro produced (IVP) bovine embryos. IVP embryos were obtained by in vitro fertilization of in vitro matured oocytes for 6 h. In Experiment 1, IVP embryos were cultured in mSOFaa supplemented with bovine serum albumin but without glucose (SOF1) for 4 days, transferred to mSOFaa (with 5% fetal bovine serum and 1.5 mM glucose; SOF2) supplemented with 0 (control), 0.1,1 or 10 μM DMG and cultured for an additional 7 days (11 days in total) to assess their development in vitro. When cultured in the medium with 0.1 μM DMG, a significantly higher number of IVP embryos developed to the blastocyst and hatched blastocyst stages (40.3 and 40.8%, respectively) compared with the other groups (18.7-31.0% and 15.0-28.7%, respectively; P<0.05, analysis of variance). In Experiment 2, IVP embryos were cultured in SOF1 with or without 0.1 μM DMG for 4 days, transferred to SOF2 with or with out 0.1 μM DMG and further cultured as in Experiment 1; DMG was added to either SOF1 or SOF2 and to both of them to assess its exposure effects on embryo development. When cultured continuously with DMG for 11 days, significantly higher rates of IVP embryos developed into blastocyst and hatched blastocyst stages (39.0 and 47.7%, respectively) compared with the other groups (31.0-32.2% and 29.5-31.0%, respectively; P<0.05). In Experiment 3, we examined developmental speed of IVP embryos cultured with or without addition of 0.1 μM DMG to IVC medium after 7 days of IVC. When DMG was added to IVC medium, the ratio of embryos developed to advanced developmental stages (No. of embryos developed to the blastocyst and expanded blastocyst stages/No. of embryos developed to the morula stage) was 28.7% (86/3) and 7 times higher than that of those cultured without DMG, 4.0% (52/13). These results suggest that addition of 0.1 μM DMG to mSOFaa during IVC of IVP bovine embryos has a promoting effect on their development.