[Effects of overall food restriction on embryo-fetal development in the rat].

The effects of different levels of food restriction on the fetal-embryo development have been tested in rats (Sprague Dawley) weighing 250 g. Experimental groups received 100 (control), 75, 50 or 25% of mean daily consumed food containing 17% of proteins, either from the coupling (Day 1) or from the nestling (Day 6) and till the sacrifice (Day 21). The weight of the mothers and the fetus is diminished in function of the degree and the duration of the food restriction. The study of the maternal growth shows an adaptation to the food restriction as well as the pregnancy anabolism. The last one is not observed in the females presenting an early embryonic mortality. The nestling is not affected in any of the groups and the embryonic mortality is only observed at the highest restricted level in 1/10 female restricted from Day 6 on and in 5/10 of the rats restricted from Day 1 on. In these last ones, the emaciation between Day 1 and Day 21 after hysterectomy is 37% and the growth of the surviving fetuses is only 40% of the controls. Embryonic mortality most often precocious (before the 10th Day) shows a phenomenon of "all or none" and touches the entire litter of the females concerned; the others maintain a normal pregnancy. The fetal growth seems privileged as compared with the maternal growth. These restrictions have neither influenced the sex ratio, nor induced any specific teratogenic effect: the delayed ossification seems to be expressed precociously on the 5th sternebra.