Prenatal and Postnatal Transfer of Zinc-65

Abstract

The occurrence of Zn65 as a fallout element and its detection in food (1, 2), farm produce (3), and man (3-7) have led to interest in its distribution in body tissues. Previous studies in rats have shown that injected Zn65 reaches high concentrations in the prostate (8) and is elaborated in the prostatic secretion (9). In mating studies on male rats administered Zn65, the radioisotope was traced up the female genital tract after ejaculation (10). In these studies, radioactivity was also detected in the livers of the females a few hours after mating. Since a placental transfer of Zn65 was known (11-14), experiments were initiated to determine whether Zn65 present in male rats and mice could ultimately be detected in their progeny. These preliminary studies showed that the progeny of Zn65-injected male and noninjected female rodents were radioactive at birth. Furthermore, it was noted that the Zn65 content of pups had increased after a week of nursing. The transfer of Zn65 through the milk had been reported by others (12). In view of the susceptibility of the young to radiation effects, further studies were conducted to determine the extent of Zn65 transfer by lactation and the rate of loss of Zn65 from radioactive pups nursing on nonradioactive foster mothers. Experiments were done to determine whether the rate of excretion of injected Zn65 differed in mice of various ages.