Sakamoto M, Nakano A, Kajiwara Y, Naruse I, Fujisaki T
Department of Epidemiology, National Institute for Minamata Disease, Kumamoto, Japan.
Environ Res. 1993 Apr;61(1):43-50. doi: 10.1006/enrs.1993.1048.
Rats on Postnatal Days 1 (PD 1), 14 (PD 14), and 35 (PD 35) were orally administered 0, 2.60, 3.64, 5.10, 7.14, and 10 mg/kg/day of methyl mercury chloride (MMC) for 10 consecutive days. Mercury (Hg) accumulation in the brain of the rats treated with 10 mg/kg/day of MMC for 10 consecutive days was highest in PD-14 rats, followed by PD-35 and PD-1 rats. Hg accumulations in the liver and kidney were lowest in PD-1 rats and increased markedly with development in postnatal phase. The effect of MMC treatment on body weight change was most severe in PD-35 rats. The body weight loss began on Day 5 in PD-35 rats and on Day 10 in PD-14 rats treated with 10 mg/kg/day of MMC, but not in PD-1 rates under the same treatment. The phenomenon of hindlimb-crossing was induced on Day 11 in PD-14 rats and on Day 14 in PD-35 rats treated with 10 mg/kg/day of MMC, but was not observed in PD-1 rats. The deficit of rotarod performance was apparent only at the dose of 7.14 mg/kg/day of MMC in PD-35 rats, whereas rotarod performance was dose-dependently inhibited by MMC treatment in PD-14 rats, and lowered even at the dose of 2.6 mg/kg/day of MMC. However, the performance was gradually restored to the control level by 1 month except in rats given 7.14 mg/kg/day of MMC. These findings indicated that the Hg distribution and the effects of MMC treatment on body weight gain and motor coordination were different among the rat postnatal developing phases.
出生后第1天（PD 1）、第14天（PD 14）和第35天（PD 35）的大鼠连续10天口服给予0、2.60、3.64、5.10、7.14和10 mg/kg/天的氯化甲基汞（MMC）。连续10天给予10 mg/kg/天MMC治疗的大鼠大脑中汞（Hg）蓄积量在PD-14大鼠中最高，其次是PD-35和PD-1大鼠。肝脏和肾脏中的Hg蓄积量在PD-1大鼠中最低，并在出生后阶段随着发育而显著增加。MMC治疗对体重变化的影响在PD-35大鼠中最为严重。用10 mg/kg/天MMC治疗的PD-35大鼠在第5天开始体重减轻，PD-14大鼠在第10天开始体重减轻，但相同治疗下的PD-1大鼠未出现体重减轻。用10 mg/kg/天MMC治疗的PD-14大鼠在第11天出现后肢交叉现象，PD-35大鼠在第14天出现后肢交叉现象，但PD-1大鼠未观察到。转棒试验表现的缺陷仅在PD-35大鼠中MMC剂量为7.14 mg/kg/天时明显，而在PD-14大鼠中转棒试验表现受到MMC治疗的剂量依赖性抑制，甚至在MMC剂量为2.6 mg/kg/天时也降低。然而，除给予7.14 mg/kg/天MMC的大鼠外，1个月内该表现逐渐恢复到对照水平。这些发现表明，在大鼠出生后发育阶段，Hg分布以及MMC治疗对体重增加和运动协调性的影响是不同的。
