ENHANCING EFFECT OF MATERNAL ZINC-DEFICIENCY AND CS-137 GAMMA-IRRADIATION ON THE FREQUENCY OF FETAL MALFORMATIONS IN MICE

It is well established that in mammals transitory zinc (Zn) deficiency during embryogenesis can have a negative influence on fetal developme nt. Similar to Zn deficiency, maternal exposure to low levels of ioniz ing radiation during the first day of pregnancy has been shown to nega tively affect preimplantation embryo development, and higher doses of maternal irradiation during late stages of embryogenesis can result in malformations. Here we report the effect of transitory maternal Zn de privation combined with low dose irradiation during embryogenesis on f etal outcome. Pregnant mice were acutely dosed with 0.00, 0.05, 0.10, or 0.25 Gy of gamma-radiation the day after mating (GD0), or with 0.00 or 0.50 Gy on GD8. Mice irradiated on GD0 were either fed a low Zn di et (0.4 mu g Zn/g) for 48 h prior to mating through GD0 or GD5 and the n switched to a control diet (50 mu g Zn/g) through GD18, or they were fed the control diet throughout gestation. Dams irradiated on GD8 wer e either fed the low Zn diet from GD0 through GD10 and then switched t o the control diet, or they were fed the control diet throughout gesta tion. Zn deprivation did not influence any of the maternal or embryoni c/fetal parameters measured in the cohorts fed the low Zn diet through GD0. In contrast, groups fed the low Zn diet through GD5 or GD10 had lower mean maternal body weights, fewer live fetuses/litter, and a hig her incidence of resorptions than controls. Fetuses from dams fed the low Zn diet through GD10 were smaller and shorter, and had a higher fr equency of malformations than controls. Irradiation on GD8 under adequ ate Zn conditions had no effect on any parameter, but GD8 irradiation during maternal Zn deficiency had an additive effect on the frequency of fetal malformations. (C) 1997 Wiley-Liss, Inc.