Parathion toxicity in perinatal rats exposed in utero

Effects of intrauterine exposure to parathion on the activity of renal ATPases in offspring

The effects of ethyl parathion on the activities of various renal enzymes were studied in the offspring from dams treated with this insecticide during pregnancy. The enzymes tested were the (Na+-K+)- and the Mg2+-dependent ATPases, the glutathione S-transferases and carboxylesterases. The postnatal effects of parathion on kidney ATPases from undernourished rats were also assessed. The organophosphate was administered per os to pregnant rats at a dose of 1 mg kg-1 body weight per day throughout gestation, and suspended after delivery. The offspring were divided in groups of normally-fed and undernourished rats. In the undernourished group, food restriction produced a decrease of 43% in body weight as compared to the normally-fed group. Offspring were sacrificed 6 weeks after birth and the enzymatic activities were determined in kidney homogenates. We found a decrease in the enzymatic activity of total ATPases, at the expense of the Mg2+-dependent ATPase. However, the activities of the (Na+-K+)-dependent ATPase, the glutathione S-transferases and the carboxylesterases did not show significant changes. On the other hand, undernutrition did not potentiate the effects of parathion on the ATPases. Thus, this organophosphate administered during pregnancy produced a selective inhibition on the renal Mg2+-dependent ATPase from offspring, which was not potentiated by our undernutritional model.

Potential human developmental toxicants and the role of animal testing in their identification and characterization

Some 50 chemicals have been identified from environmental, occupational, or therapeutic exposure data as being potential developmental toxicants in humans. The toxicity pattern of these chemicals in humans has been characterized and correlated with developmental toxicity end points in laboratory animal models in order to determine the relevance and predictiveness of the results of testing in animals in extrapolation to human data. In general, animal developmental toxicity data closely paralleled human outcomes, and while humans in most cases were more sensitive than animals, the data support the concept that, imperfections aside, studies in animals serve a vital role in the hazard identification process.