Sphingosine-1-phosphate inhibits ceramide-induced apoptosis during murine preimplantation embryonic development

Sphingolipids are a complex family of naturally occurring molecules enriched with lipid rafts that contribute to their unique biochemical properties. Sphingolipid metabolites, including ceramide (Cer) and sphingosine-1-phosphate (S1P), are bioactive signaling molecules that regulate cell movement, differentiation, survival, and apoptosis, but their effects on preimplantation development of murine embryos are not well-characterized. In this study, murine zygotes were collected, cultured in vitro, and treated with 50 μM C2-Cer plus various concentrations of S1P. The blastocyst formation rate was decreased in the C2-Cer–treated group, compared with that in the control group and the group treated with 50 μM C2-Cer plus 25, 50, or 100 nM S1P (P < 0.05), respectively. The total cell number of the blastocysts from various treatment groups was similar at 110 hours post-hCG treatment, but that from the group treated with 50 μM C2-Cer was significantly decreased at 120 hours post-hCG treatment, compared with the control group and the group treated with 50 μM C2-Cer plus 50 nM S1P. However, the apoptotic cell number of blastocysts from the group treated with 50 μM C2-Cer was significantly increased at 110 and 120 hours post-hCG treatment, compared with the control group and the group treated with 50 μM C2-Cer plus 50 nM S1P. Moreover, expression of p53 in the group treated with 50 μM C2-Cer was higher than that in the control group and the group treated with 50 μM C2-Cer plus 50 nM S1P (P < 0.05). In conclusion, Cer decreases the blastocyst formation rate and induces embryonic cell apoptosis, but S1P partly inhibits the effects of Cer during preimplantation development of murine embryos.