Influence of dietary protein levels on the acute toxicity of methylmercury in mice.
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.
Adachi
T
T
Department of Basic Medical Scienes, National Institute for Minamata Disease, Kumamoto, Japan.
Yasutake
A
A
Eto
K
K
Hirayama
K
K
D000410:Alanine Transaminase / Q000097:blood; D000704:Analysis of Variance; D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D003404:Creatinine / Q000097:blood; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008628:Mercury / Q000378:metabolism; D008630:Mercury Poisoning / Q000401:mortality; D008767:Methylmercury Compounds / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D015996:Survival Rate
D004044:Dietary Proteins; D008767:Methylmercury Compounds; D003404:Creatinine; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D008628:Mercury