Leukemia Inhibitory Factor Antisense Oligonucleotide Inhibits the Development of Murine Embryos at Preimplantation Stages

Leukemia inhibitory factor (LIF) is an essential factor for implantation and establishment of pregnancy. However, its role in the development of pre-implantation embryos remains controversy. In this study, changes in pre- implantation embryos were determined after microinjection of LIF antisense oligonucleotide at the two-pronucleus stage. Although no significant differences were found in the percentages between the untreated group and the 0.25- fmol treated group, the 0.5- or 1.0-fmol treated groups had significantly lower percentages of embryos developed to the morula or blastocyst stage and the 2.0-fmol treated group had significantly lower percentages of embryos developed to the four-cell, morula, or blastocyst stage. No embryos developed to the four-cell stage in the 4.0-fmol treated group. Moreover, there was a decreasing trend in the levels of LIF immunoactivity with the increasing amount of LIF antisense oligonucleotide injected. The diameter of blastocysts in the 2.0-fmol treated group was significantly smaller than that in the untreated group. The blastocysts in this group had significantly lower numbers of blastomeres and cells in the inner cell mass (ICM) or trophetoderm (TE) and ICM/TE ratio. The 1.0- or 2.0-fmol treated groups had significant lower implantation rates than their corresponding control groups. In the 2.0-fmol groups with supplementing exogenous LIF, significantly lower percentages were also observed in the four-cell, morula, and blastocyst stages. However, blastocysts treated with 50 ng/ml LIF had a significant higher percentage than those in the LIF gene impaired group without LIF supplement. These results indicate that LIF is a critical factor for the normal development of embryos at the pre- implantation stages.