Effects of pyruvate and dimethyl-α-ketoglutarate, either alone or in combination, on pre- and post-implantation development of mouse zygotes cultured in vitro.

PURPOSE: Dimethyl α-ketoglutarate (dm-α-KG) promotes in vitro development to blastocysts of C57BL/6J X C3He F1 mouse zygotes cultured in medium lacking pyruvate. Here, we examined the effects of pyruvate and dm-α-KG on in vitro development to blastocysts of ICR mouse zygotes and their post-implantation developmental ability. METHODS: Zygotes were cultured in medium with pyruvate at 0-0.2 mmol/L in the presence or absence of 1 mmol/L dm-α-KG for 96 hours and evaluated for blastocyst formation rates. The resultant blastocysts were non-surgically transferred to surrogates and evaluated for birth rates. RESULTS: In medium lacking pyruvate, zygotes could not develop beyond the two-cell stage, in the presence or absence of dm-α-KG. However, the blastocyst formation rate in medium with 0.01 mmol/L pyruvate (12%) was markedly increased with addition of dm-α-KG (49%). Around 80% of embryos developed to blastocysts in medium with 0.2 mmol/L pyruvate, in the presence or absence of dm-α-KG. Importantly, birth rate was markedly improved by treatment with 0.2 mmol/L pyruvate and dm-αKG (31.0%), compared with those with pyruvate treatment alone (16.3%). CONCLUSIONS: Pyruvate and dm-α-KG synergistically work during in vitro culture to markedly improve the blastocyst formation rate and post-implantation developmental ability of the resultant blastocysts in ICR mice.

Mild hypothermia promotes the viability of in vitro-produced bovine blastocysts and their transcriptional expression of the cold-inducible transcription factor Rbm3 during in vitro culture.

In this study, we evaluated the effects of holding in vitro-produced bovine blastocysts under mild hypothermia (33°C or 35°C), by examining viability and hatching rates of day 7 blastocysts (day 0: in vitro fertilization) cultured for 6 days and transcriptional expression of cold-inducible transcription factors Cirp and Rbm3, implicated in mild hypothermia-induced cellular protection against various types of stress. In the normothermic control (38.5°C), viability of the embryos decreased rapidly after day 10, and most samples were degenerated on day 13. However, mild hypothermia, particularly at 33°C, resulted in maintenance of high embryonic survival rates until day 13 (77.1% on day 13) and significant increases in transcriptional expression of Rbm3 in day 11 embryos compared with those at 38.5°C. Thus, our results suggested that upregulation of Rbm3 may occur in response to mild hypothermia in many bovine embryos, providing insights into the effects of mild hypothermia on embryo quality.