Nitric oxide production by pre-implantation embryos in response to embryotoxic factors

In this report, we examined whether nitric oxide (NO) is involved in early embryo death. We have chosen various experimentally defined embryotoxic sti muli in mice and determined their ability to induce NO production by 2-cell stage embryos. The embryotoxic factors used were interferon-gamma (IFN-gam ma), tumor necrosis factor-a (TNF-a), lipopolysaccharide (LPS), 5-Azacytidi ne (5-AzaC) and the murine embryotoxic antibody DF4. We showed that in all cases the embryotoxic stimuli induced NO production by early stage embryos that correlated with the induction of the inducible and/or endothelial isof orms of NO synthase. This study was also extended to the human system where sera from women who aborted were tested for their ability to act embryotox ically by inducing NO in early mouse embryos and mature murine placenta. Th e results obtained confirmed the embryotoxic character of NO found in these particular sera leading to the hypothesis that NO plays a potential role i n early embryo death. Copyright (c) 2000 S. Karger AG, Basel.