Neurobehavioral changes in metallothionein-null and wild-type mice by prenatal co-exposure prenatally exposed to mercury vapor.

点击翻译按钮获取中文摘要

We studied the neurobehavioral effects prenatal co-exposure of MT-null and wild-type mice to elemental mercury vapor (Hg^0) and methylmercury (MeHg). Four groups of pregnant mice of both strains were exposed as follows : Hg^0 group was repeatedly exposed to Hg^0 vapor at 0.03 mg/m^3 for 6h/day until the 18th day of gestation. MeHg group received diet containing 5 μg/g of MeHg during gestational periods and until 10 days after the delivery. Co-exposure group received a combination of MeHg and Hg^0 vapor as described above. The behavioral effects were evaluated with locomotor activity in the open field (OPF), learning ability in the passive avoidance response (PA) and spatial learning ability in the Morris water maze as 12 weeks. In the wild-type mice, although there is significant different in the locomotion distance (cm) among the control group and the MeHg group or the co-exposure group in males and females, no difference between the control group and the Hg^0 group in males and femal … More es was observed. On the other hand, there is no significant difference in the locomotor activity levels among the control group and the MeHg group, the Hg^0 group and the co-exposure group in the MT-null mice of males. In the MT-null mice of females, however, significant difference was observed among the control group and the Hg^0 group and the co-exposure group. In the retention trails in the passive avoidance task, there is no difference in avoidance latency among the control group and the MeHg group, the Hg^0 group and the co-exposure group in both strains of males and females. In the Morris water maze test for five consecutive days, the escape time in males of wild-type mice was significantly longer for the MeHg group in day 4 and day 5 and for the co-exposure group only in the day 4 than the control group, but there were no significant differences in the escape time among the control group and three exposed groups in the females. In contrast, the Hg^0 group and the co-exposure group in the MT-null mice showed a retarded acquisition in the Morris water maze in females as compared with the control group. Neurobehavioral changes in MT-null and wild-type mice prenatally exposed to the co-exposure appeared strongly influence by the MeHg exposure in the wild-type mice and the Hg^0 exposure in the MT-null mice under this experiment condition. From these results, we suggest that MT-null mice would be more susceptible than wild-type mice to the behavioral neurotoxicity of prenatal Hg^0 exposure. On the other hand, wild-type mice proved to be susceptible than MT-null mice to the behavioral neurotoxicity of prenatal MeHg exposure Less