Disposition of inorganic mercury in pregnant rats and their offspring

Environmental toxicants such as methylmercury have been shown to negatively impact fetal health. Despite the prevalence of inorganic mercury (He) in the environment and the ability of methylmercury to biotransform into Hg2+, little is known about the ability of Hg2+ to cross the placenta into fetal tissues. Therefore, it is important to understand the handing and disposition of Hg2+ in the reproductive system. The purpose of the current study was to assess the disposition and transport of Hg2+ in placental and fetal tissues, and to test the hypothesis that acute renal injury in dams can alter the accumulation of Hg2+ in fetal tissues. Pregnant Wistar rats were injected intravenously with 0.5 or 2.5 mu mol kg(-1) HgCl2 for 6 or 48 hand the disposition of Hg2+ was measured. Accumulation of Hg2+ in the placenta was rapid and dose-dependent. Very little Hg2+ was eliminated during the initial 48 h after exposure. When dams were exposed to the low dose of HgCl2, fetal accumulation of He2+ increased between 6 hand 48 h, while at the higher dose, accumulation was similar at each time point. Within fetal organs, the greatest concentration of Hg2+ (nmol/g) was localized in the kidneys, followed by the liver and brain. A dose-dependent increase in the accumulation of Hg2+ in fetal organs was observed, suggesting that continued maternal exposure may lead to increased fetal exposure. Taken together, these data indicate that He2+ is capable of crossing the placenta and gaining access to fetal organs in a dose-dependent manner. (C) 2015 Elsevier Ireland Ltd. All rights reserved.