Synergy between tumor necrosis factor and endotoxin decreases early embryo development in vitro

The purpose of the present study was to investigate the individual and combined effects of low levels of endotoxin and physiological levels of tumor necrosis factor on in vitro fertilization and preimplantation embryo development. B6D2F1 mice were superovulated by utilizing pregnant mare serum gonadotropin and human chorionic gonadotropin. Oocyte-cumulus complexes (3221 oocytes) were collected, pooled, and randomized into control and treatment groups. Sperm were collected from the caudae epididymides of mature male mice and allowed to capacitate. Treatments included culture media supplemented with increasing amounts of endotoxin (0.5, 1.0, and 2.0 ng/ml; sp act, 3000 IU/ng) and/or tumor necrosis factor (1, 10, and 50 pg/ml; sp act, 0.01 IU/pg) throughout the fertilization and preimplantation development process. Percentage cleavage and percentage expanded blastocyst formation were evaluated. No significant effects were observed for percentage cleavage or percentage expanded blastocyst formation in either the endotoxin (E) or the tumor necrosis factor (TNF) groups. The combination of endotoxin and tumor necrosis factor at any of the levels tested did not significantly decrease cleavage; however, percentage blastocyst formation was decreased with any combination of TNF and E (P less than 0.05-P less than 0.001). We conclude that TNF and E exert significant synergistic effects which are detrimental to in vitro preimplantation embryonic development.