Early embryonic development of bovine oocytes challenged with LPS in vitro or in vivo

: The aim of this study was to evaluate the effect of exposing bovine oocytes to lipopolysaccharides (LPS) in vivo and in vitro on early embryo development. In experiment 1, cumulus oocytes complexes (COCs, n=700/group) were challenged with 0, 0.1, 1.0 or 5.0 μg mL-1 of LPS during in vitro maturation (IVM). After, in vitro fertilization (IVF) and in vitro culture (IVC) was performed. In experiment 2, COCs (n=200/group) matured and in vitro fertilized without LPS were subjected to IVC with the same doses of LPS from experiment 1. In experiment 3, heifers received two injections of saline solution (n=8) or 0.5 μg Kg-1 of LPS (n=8) 24 hours apart and three days later COCs were recovered and submitted to IVM, IVF, and IVC. In experiments 1 and 3, the expression of TLR4, TNF, AREG and EREG genes in cumulus cells was evaluated. Exposure to 1 and 5 μg mL-1 of LPS during IVM decreased nuclear maturation (39.4 and 39.6%, respectively) compared to control (63.6%, P < 0.05). Despite that, no effect in cleavage and blastocyst rate were observed. Exposure to LPS during IVC did not affect embryonic development. In vivo exposure to LPS decreased the in vitro cleavage rate (54.3% vs 70.2%, P = 0.032), but cleaved embryos developed normally. Number of cells per embryo and gene expression were not affected by the LPS challenge in any experiment. In conclusion, although in vitro exposure to LPS did not affect early embryo development, in vivo LPS exposure reduced cleavage rate.