The effects of 2,4-dinitrophenol and d-glucose concentration on the development, sex ratio, and interferon-tau (IFNT) production of bovine blastocysts

The preimplantation bovine embryo displays sexual dimorphism in glucose sensitivity and interferon-tau (IFNT) secretion that are negated by inhibition of the pentose phosphate pathway, suggesting that the association between glucose metabolism and IFNT likely underpins the selective loss of female embryos. The aim of this study was to determine if altered glucose metabolism, through glucose supplementation and/or uncoupling oxidative phosphorylation with 2,4-dinitrophenol (DNP), affected embryo development. Bovine blastocyst development, sex, and IFNT production were examined in embryos cultured in the presence or absence of glucose (0, 1.5, 4mM) with or without exposure to DNP (0, 10, 100μM) between Days 5 and 8 post-fertilization. The absence or presence of high (4mM) glucose reduced blastocyst development and favored the development of male embryos (P<0.001). DNP at 10μM had no effect, whereas 100μM had a negative impact on blastocyst development. Notably, in the presence or even absence of glucose, supplementation with 10μM DNP further skewed the sex ratio toward males (P<0.05). Sexually dimorphic IFNT production was maintained in these conditions, although total production was reduced in the presence of high glucose and DNP, irrespective of embryo sex. These data suggest that the pentose phosphate pathway can modulate embryonic sex ratio and development. Therefore, bovine embryo culture should be undertaken in a low glucose (<2.5mM) medium to minimize potential embryonic stress, as higher concentrations have sexually dimorphic effects on development and an embryo's ability to signal to the maternal reproductive tract.