Study on the mercury toxicity to pregnant rats and their fetus by the method of stable-isotope label

Mercury and its compounds are regarded as one of the notorious environmental contaminations owing to their high biological toxicity to human and animals, their difficulty to degrade in the environment and their consecutive bioaccumulation via the food chain. According to the latest reports, mercury pollution remains quite serious in many countries, especially in China. Recently, more concerns of public health over mercury toxicity have been focused on the environmental level of mercury. To the issues of mercury toxicity, a number of reports were published in the past decades. However, up to now, whether the environmental level of mercury has adverse effects on pregnant women and their fetus as well as toxic mechanism of low level of mercury is still in debate. Our work was designed to investigate the distribution of mercury-containing proteins in the brains of dam and pup rats. Such investigation is expected to give some useful information about whether the environmental level of mercury has adverse effects on pregnant women and their fetus as well as molecular toxic mechanism of low level of mercury The speciation study of mercury would be helpful to understand whether there is any difference between mothers and offspring about the toxicity of mercury under the environmental level. The enriched stable isotopes of Hg-196 (14% of 196Hg) and Hg-198 (39% of 198Hg) were used as tracers in the experiment. CH3196Hg+ and CH3198Hg+ were synthesized from 196HgO and 198HgO using tetramethyltin and the rats were administered with isotopic labeled HgCH3+ at a low and relatively high dose of 1 μg Hg/kg bw and 10 μg Hg/kg bw, respectively. The Hg-containing proteins in the serum and brain were separated and purified by gel chromatography, ion-exchange chromatography and HPLC. The proteins were identified by electrophoresis (SDS-PAGE, IEF, etc.). The mercury content in each species was determined by neutron activation analysis (NAA) for isotope Hg-196 and ICP-MS for isotope Hg-198. The preliminary results indicated that the distribution of mercury-containing proteins in serum of mothers and infants were significantly different, which suggests that the prenatal and postnatal exposure to low level of methylmercury can cause different toxic effects between mother and their offspring.