Adachi T, Yasutake A, Eto K, Hirayama K
Department of Basic Medical Scienes, National Institute for Minamata Disease, Kumamoto, Japan.
Toxicology. 1996 Aug 1;112(1):11-7. doi: 10.1016/0300-483x(96)03340-9.
The influence of dietary protein levels on the acute toxicity of methylmercury (MeHg) was investigated using C57BL/6N male mice fed either a 24.8% protein diet (normal protein diet, NPD) or a 7.5% protein diet (low protein diet, LPD). When MeHg was administered to each group of mice, all mice died at a medium or high dose (80 or 120 mumol/kg, respectively) within 16 or 7 days, respectively, but not at a low dose (40 mumol/kg) in both dietary groups. Although no difference was observed in the survival rate at a medium dose, NPD-fed mice died earlier despite lower brain Hg than LPD-fed mice at a high dose. Accordingly, death, in our observations, could not be due to neural damage by MeHg. When a high dose of MeHg was administered to mice, plasma aspartate aminotransferase and alanine aminotransferase activities increased in NPD-fed mice but not in LPD-fed mice in spite of similar hepatic Hg levels. Therefore, the higher susceptibility of the liver could be reason for the shorter survival period in NPD-fed mice. Since plasma creatinine increased within 24 h after MeHg administration at a medium or high dose, renal dysfunction could be a major factor in death. The present results suggest that susceptibility to acute MeHg toxicity was higher in NPD-fed mice than in LPD-fed mice, possibly due to the difference in hepatic susceptibility.
利用喂食24.8%蛋白质饮食（正常蛋白质饮食，NPD）或7.5%蛋白质饮食（低蛋白质饮食，LPD）的C57BL/6N雄性小鼠，研究了膳食蛋白质水平对甲基汞（MeHg）急性毒性的影响。当给每组小鼠施用MeHg时，所有小鼠在中等剂量（80 μmol/kg）或高剂量（120 μmol/kg）下分别于16天或7天内死亡，但在两个饮食组的低剂量（40 μmol/kg）下均未死亡。尽管在中等剂量下未观察到存活率的差异，但在高剂量下，喂食NPD的小鼠尽管脑汞含量低于喂食LPD的小鼠，但死亡更早。因此，在我们的观察中，死亡并非由于MeHg对神经的损伤。当给小鼠施用高剂量的MeHg时，尽管肝脏汞含量相似，但喂食NPD的小鼠血浆天冬氨酸转氨酶和丙氨酸转氨酶活性增加，而喂食LPD的小鼠则未增加。因此，肝脏更高的易感性可能是喂食NPD的小鼠存活期较短的原因。由于在中等或高剂量MeHg给药后24小时内血浆肌酐升高，肾功能障碍可能是死亡的主要因素。目前的结果表明，喂食NPD的小鼠对MeHg急性毒性的易感性高于喂食LPD的小鼠，这可能是由于肝脏易感性的差异。
