Neurobehavioral changes in metallothionein-null mice prenatal and postnatal exposed to mercury vapor.

我们研究了MT基因敲除小鼠和野生型小鼠在出生前和出生后暴露于元素汞蒸气（Hg^0）对神经行为的影响。将两种品系的孕鼠重复暴露于0.50和0.56 mg/m^3的Hg^0蒸气中，每天6 h，直至妊娠第18天。在12周龄时，通过旷场自主活动（OFT）、被动回避反应（PA）和Morris水迷宫空间学习能力来评价行为学效应。与对照组相比，暴露于Hg^0的MT基因敲除小鼠雄性的总运动活动显著减少，雌性的被动回避反应学习障碍和Morris水迷宫习得延迟。相反，暴露于汞的野生型小鼠在三个行为测量方面与对照组没有差异。接下来，我们研究了MT基因敲除小鼠和野生型小鼠出生后暴露于元素汞蒸气（Hg^0）的神经行为效应。分娩后，母鼠和仔鼠分别暴露于0.023和0.043 mg/m^3的Hg^0蒸气中，每天6 h，直至断奶，并于12周龄时进行行为学评价。在OFT中，暴露于Hg^0的MT基因敲除小鼠的雌性动物的总运动活动显著减少。但两品系小鼠的PA试验学习能力和空间学习能力均未受到影响。结果表明，MT基因敲除的雌性小鼠比野生型小鼠更容易受到产前和产后汞暴露的行为神经毒性的影响。汞浓度在大脑中的两个菌株在女性中的暴露组略高于对照组，表明残留的汞，甚至12周后停止曝光。根据这些结果，我们认为MT缺失的雌性动物对产前和产后Hg^0暴露引起的行为变化的敏感性增加。

We studied the neurobehavioral effects of prenatal and postnatal exposure of MT-null and wild-type mice to elemental mercury vapor (Hg^0). Pregnant mice of both strains were repeatedly exposed to Hg^0 vapor at 0.50 and 0.56 mg/m^3 for 6 h per day until the 18th day of gestation. The behavioral effects were evaluated with locomotor activity in the open field (OFT), learning ability in the passive avoidance response (PA) and spatial learning ability in the Morris water maze at 12 weeks of age. Hg^0-exposed MT-null mice showed a significant decrease in total locomotor activity in males, and a learning disability in the passive avoidance response and a retarded acquisition in the Morris water maze in females as compared with the control. In contrast, Hg^0-exposed wild-type mice did not differ from controls in three behavioral measurements.Next, we studied the neurobehavioral effects of postnatal exposure of MT-null and wild-type mice to elemental mercury vapor (Hg^0). After parturition, the dam and neonates were exposed to Hg^0 vapor at 0.023 and 0.043 mg/m^3 for 6 h per day until weanling and the behavioral effects of evaluation was carried out at 12weeks of age. In OFT, Hg^0-exposed MT-null mice showed a significant decrease in total locomotor activity in females. However, the learning ability in the PA test and spatial learning ability was not affected the exposed mice of both strains. The results indicate that MT-null mice in females would be more susceptible than wild-type mice to the behavioral neurotoxicity of prenatal and postnatal Hg^0 exposure. Mercury concentrations in the brain of both strains in females were slightly higher in the exposed group than in the control group, indicating the retention of residual mercury even 12 weeks after the cessation of the exposure. From these results, we suggest that the increased susceptibility of MT-null females to behavioral changes caused by prenatal and postnatal Hg^0 exposure.