Germ cell mutagenicity of gamma-ethyl-gamma-phenyl-butyrolactone (EPBL) detected in the CF1 mouse-dominant lethal study.

Female and male CFI mice weighing 25-30 g were given 0, 50, 100 or 200 mg/kg of gamma-ethyl-gamma-phenyl-butyrolactone (EPBL) for 5 days intraperitoneally. In the male-dominant lethal phase, males treated with EPBL were mated with untreated females following a 7-day mating schedule with three consecutive mating events. In the female-dominant lethal phase, females treated with EPBL were caged with untreated males. The above dosages and schedule treatments were used. The incidence of pregnancy of females mated on days 1-7 and 8-14 after males were given 200 mg/kg of EPBL and of females given 200 mg/kg when mated to untreated males was decreased. Upon examining surgically exposed uteri and ovaries of pregnant females during the first phase, on gestation days 13-15, an increased incidence of pre-implantation losses with 200 mg/kg of EPBL and an increased incidence of post-implantation losses with 100 and 200 mg/kg was observed. In addition, an increased frequency of pre- and post-implantation losses was seen in females treated with 200 mg/kg. These results support the conclusion that EPBL is a germ cell mutagen and its effects are more pronounced during the post-meiotic stage.