SELENIUM KINETICS, PLACENTAL-TRANSFER, AND NEONATAL EXPOSURE IN CYNOMOLGUS MACAQUES (MACACA-FASCICULARIS)

Forty pregnant cynomolgus macaques were treated daily from gestational day 20 to 50 by nasogastric intubation of 0, 25, 150, or 300 mu g sel enium as L-selenomethionine/kg body weight. In each group, 7-8 pregnan cies were terminated by hysterotomy at gestational day 100 +/- 2 and t he fetuses were examined, while 2-3 pregnancies in each group were all owed to proceed to term. Selenium and soluble glutathione peroxidase w ere measured in: maternal, neonatal, and fetal plasma and erythrocytes ; fetal kidney, liver, muscle, and placenta; and maternal breast milk. The area under the multidose maternal plasma selenium concentration:t ime curve, the maximum maternal plasma selenium concentration, and the maternal urinary selenium excretion rates were proportional to the L- selenomethionine dose. Selenium concentrations in all fetal and neonat al tissues were also proportional to maternal L-selenomethionine dose. Glutathione peroxidase was affected only in maternal erythrocytes, fe tal kidney, and neonatal plasma. The selenium concentration in fetal p lasma was an average 33% of that in maternal plasma. Although selenium concentrations in macaque milk were doubled by the highest dose, intr auterine selenium accumulation accounted for the majority of the neona tal selenium body burden. Despite the elevated selenium concentrations in fetal tissues, neonatal blood, and milk, no deleterious effects on neonates were observed. These results suggest that primate fetuses ar e well protected against selenium toxicity arising from high maternal L-selenomethionine intakes. (C) 1994 Wiley-Liss, Inc.