Interaction of cadmium and zinc during prenatal development in the rat

Cadmium chloride, zinc chloride, or a mixture of the two, labeled with 115m-Cd or 65-Zn was administered intraperitoneally to Wistar rats on day 9 of gestation. On day 20 fetuses of Cd-treated rats exhibited malformations, but those of rats given zinc or zinc plus cadmium did not. No radioactive cadmium was recovered in the fetuses or fetal membranes, although some was found in the placentas. Simultaneous administration of zinc did not alter the distribution of cadmium, but cadmium significantly increased the amount of zinc in the fetus and placenta. In a second experiment, cadmium or cadmium plus zinc was administered on day 9 of gestation and embryonic units were removed on days 10, 11, and 12. On day 10 cadmium was found in the embryonic unit and maternal uterus, and cadmium in both was significantly reduced by simultaneous administration of zinc. The cadmium concentration in uterus and embryonic units decreased sharply on day 11 and 12 and by day 12 did not differ in animals treated with cadmium or with cadmium plus zinc. It is concluded that cadmium reaches the placenta or embryo at an organogenetically sensitive time, and that zinc may protect the embryo by decreasing the exposure to cadmium this time.