Subject(s)
Adaptation, Psychological/drug effects , Cholinesterase Inhibitors/therapeutic use , Down Syndrome/drug therapy , Indans/therapeutic use , Piperidines/therapeutic use , Adult , Dementia/drug therapy , Donepezil , Drug Administration Schedule , Female , Humans , Intelligence Tests , Male , Middle Aged , Treatment OutcomeABSTRACT
Tissue samples were obtained from 115 swine fetuses from 10 litters and analyzed for tissue-bound Hg 24 h after mothers were exposed to low levels of methylmercury by iv injection. Absorption of Hg by the fetus and placenta increased throughout gestation in concert with increasing fetal weight, as did fetal hepatic Hg. Fetal renal Hg increased throughout gestation, but the increase appeared to be much greater than would be expected on the basis of weight increase alone. Blood Hg concentrations did not change significantly. Fetal brain Hg content and concentration increased dramatically toward the end of pregnancy, the gestational period during which the rate of brain growth is greatest in swine. The finding that a period of increased Hg concentration in brain corresponded with the period of maximal brain growth velocity is particularly interesting because of the hypothesis that the brain is especially sensitive to nutritional and, presumably, toxicological perturbation while it is growing most rapidly.
Subject(s)
Fetus/metabolism , Mercury/metabolism , Methylmercury Compounds/metabolism , Animals , Chromium Radioisotopes/blood , Female , Gestational Age , Maternal-Fetal Exchange , Pregnancy , Protein Binding , SwineABSTRACT
Pregnant guinea pigs were injected with approximately 1 microgram/kg of CH3 203HgCl at 22,40,47,59,and 66 days of gestation, and fetal tissues were obtained 24 hours later. Autologous fetal erythrocytes were labeled with 51Cr and used to label the fetal blood pool at each gestational age except 22 days so that tissue-bound Hg could be calculated. In general, Hg absorbed by the whole fetus increased during gestation, in parallel with increasing tissue mass, while Hg found in whole placentas remained the same. Hg concentrations in the whole fetus and placenta were closely correlated, as were Hg concentrations in brain, liver, and kidney. Liver, kidney, blood, and brain contained the highest Hg concentration early in gestation. While it is difficult to interpret the potential effects of the increased Hg concentrations, particular attention should be paid to the brain, since it is considered a target tissue in MeHg toxicity.
