Thiol oxidation-induced embryonic cell death in mice is prevented by the antioxidant dithiothreitol

The oxidation of cellular sulfhydryl (SH) groups has been implicated in the induction of apoptosis in various types of cells and in the disturbance of the meiotic spindle of murine oocytes during aging. The objective of this study was to determine whether the SH-specific oxidant diamide could inhibi t embryo development and induce cell death, and whether the antioxidant dit hiothreitol (DTT) could counteract such effects. Exposure of mouse zygotes to diamide for 3 h at 25 or 50 mu M (but not 12.5 mu M) resulted in cell cy cle arrest and cell death with evidence of apoptosis. At higher concentrati ons (100 or 200 mu M), diamide induced necrosis as evidenced by propidium i odide-positive pronuclei within 24 h of treatment. Simultaneous addition of DTT at equimolar concentration prevented these effects. However, when DTT was added later, it was no longer protective. DTT also effectively protecte d against the thiol-oxidative damage caused by diamide in blastocysts. Thes e results suggest that altering thiol-redox status in zygotes and blastocys ts may result in cell cycle arrest, apoptosis, and/or cell death.