Kim C Y, Nakai K, Kasanuma Y, Satoh H
Environmental Health Sciences, Tohoku University School of Medicine, 980-8575, Sendai, Japan.
Neurotoxicol Teratol. 2000 May-Jun;22(3):397-403. doi: 10.1016/s0892-0362(99)00077-x.
Pregnant mice of three inbred strains (BALB/c, C57BL/6J, C57BL/6Cr) were orally given methylmercury (MMC; 3 x 3 mg/kg body weight) or the equivalent volume of phosphate-buffered saline during days 12-14 of gestation and allowed to deliver. The behaviors of their male offspring were evaluated in an open field and their home cage and in a Morris water maze. In the open field test, the BALB/c and C57BL/6Cr MMC groups exhibited less total locomotor activity than did their respective control groups. However, there was no significant difference observed between the MMC and control C57BL/6J strain. In the BALB/c strain, the MMC group exhibited significantly more central locomotion and significantly less peripheral locomotion than did the control group. These results indicated that the prenatal exposure to MMC caused decreases in open-field activity in the C57BL/6Cr and BALB/c strains, concomitantly with a change in emotional status in BALB/c strain. For spontaneous activity in their home cage, all groups moved more actively in the dark phase than in the light phase except BALB/c MMC group. The BALB/c MMC group moved in the light phase as much as in the dark phase, indicating a disturbance of nocturnal rhythm of spontaneous activity. In the Morris water maze, the C57BL/6Cr and C57BL/6J control groups perform very well over the 5 consecutive days. The prenatal exposure to MMC caused significantly prolonged latency in the C57BL/6Cr and C57BL/6J, but not in BALB/c strain. This result indicated that the prenatal exposure to MMC impaired the performance in the Morris water maze differently among the strains. This study provides a basis for evaluating strain-specific neurobehavioral changes when the widely used three inbred strains of mice are chronically exposed to MMC.
在妊娠第12至14天，给三种近交系（BALB/c、C57BL/6J、C57BL/6Cr）的怀孕小鼠经口给予甲基汞（MMC；3×3毫克/千克体重）或等体积的磷酸盐缓冲盐水，然后让其分娩。对它们雄性后代的行为在旷场、它们的饲养笼以及莫里斯水迷宫中进行评估。在旷场试验中，BALB/c和C57BL/6Cr MMC组的总运动活动比各自的对照组少。然而，MMC组和对照C57BL/6J品系之间未观察到显著差异。在BALB/c品系中，MMC组的中央运动显著更多，外周运动显著少于对照组。这些结果表明，产前暴露于MMC导致C57BL/6Cr和BALB/c品系的旷场活动减少，同时BALB/c品系的情绪状态发生变化。对于饲养笼中的自发活动，除BALB/c MMC组外，所有组在黑暗阶段的活动都比在光照阶段更活跃。BALB/c MMC组在光照阶段的活动与黑暗阶段一样多，表明自发活动的昼夜节律受到干扰。在莫里斯水迷宫中，C57BL/6Cr和C57BL/6J对照组在连续5天的表现都非常好。产前暴露于MMC导致C57BL/6Cr和C57BL/6J品系的潜伏期显著延长，但BALB/c品系没有。这一结果表明，产前暴露于MMC对不同品系在莫里斯水迷宫中的表现损害不同。本研究为评估广泛使用的三种近交系小鼠长期暴露于MMC时品系特异性神经行为变化提供了依据。
