AbstractsMedical & Health Science

The effect of 2-aminoethyl-2-thiopseudourea[superscript .]Br[superscript .]HBr (AET), 2-mercaptoethylamine[superscript .]HC1 (MEA) and trisodium calcium chelate of diethylenetriaminepentaacetic acid (CaNa₃DTPA) on the radiosensitivity of rat fetus was investigated. A total of 1256 fetuses were critically examined. Exposure of rats to 200 r whole-body X-irradiation at 9.5 days of gestation resulted in a high incidence of uterine resorption (50%) and eye defects in fetuses (90%) when examined at 19th day of gestation, and only about 27% of the fetuses survived to term. However, when AET (50 mg per rat) or MEA (25 mg per rat) was given to rats through I.P. injection before X-irradiation, the incidence of uterine resorption and fetal abnormalities was significantly reduced. The irradiated pregnant rats receiving AET or MEA prior to irradiation were able to give birth to young of normal litter size and birth weight. These offspring, though some still carried eye defects, survived beyond puberty and showed apparent normal growth and reproduction. Greater protection to fetuses against X-irradiation was obtained when AET and MEA were given simultaneously to pregnant rats shortly before irradiation than when either of the two chemicals was administered separately. The study also revealed that the chelating agent CaNa₃DTPA, which is now increasingly used in plant and animal nutrition and in removing toxic elements from the human body, had a detrimental effect on fetal development. It induced uterine resorption and eye defects in fetuses when administered to rats at 9.5 days of gestation. At a low dose level (62.5 mg per rat) it protected the fetus slightly against the irradiation effect. Unfortunately, a synergistic action in damaging of the rat fetuses was observed when large doses of CaNa₃DTPA were administered to pregnant rats prior to 200 r whole-body X-irradiation. The findings should warrant a reappraisal of the use of DTPA in animal nutrition and human therapy.