Influence of dietary protein levels on the fate of methylmercury and glutathione metabolism in mice

Sex Difference in the Influence of Dietary Protein Deficiency on the Fate of Methylmercury in Mice and Rats

“…The composition of the diets was reported previously. 14) All experimental procedures were approved by the Ethics Committee on Animal Experiment of the National Institute for Minamata Disease (NIMD).…”

“…We have demonstrated that dietary protein deficiency affects the metabolism of thiol compounds and/or the transport activity of the neutral amino acids, and these changes would be the reasons for the differences in the fate of MeHg. 14,16,19,20) In addition, we previously reported that sex hormones controlled the turnover rates of GSH in the liver and kidney, and this would cause the marked sex differences in the MeHg levels in these tissues and urine.…”

“…4,[8][9][10] In contrast to C57BL mice, urinary Hg excretion in rats is higher in females than in males. 4,9) We earlier demonstrated that dietary protein levels, which modulated GSH metabolism, [11][12][13][14][15] were a modifying factor in the fate and toxicity of MeHg using C57BL male mice fed on a 24.8% protein diet (normal protein diet, NPD) or a 7.5% protein diet (low protein diet, LPD). 14,[16][17][18][19] Even within 24 hr after a single administration of MeHg at a dose of 20 µmol/kg, LPD-fed mice showed a higher brain Hg concentration and lower urinary Hg excretion compared with NPD-fed mice.…”

“…4,9) We earlier demonstrated that dietary protein levels, which modulated GSH metabolism, [11][12][13][14][15] were a modifying factor in the fate and toxicity of MeHg using C57BL male mice fed on a 24.8% protein diet (normal protein diet, NPD) or a 7.5% protein diet (low protein diet, LPD). 14,[16][17][18][19] Even within 24 hr after a single administration of MeHg at a dose of 20 µmol/kg, LPD-fed mice showed a higher brain Hg concentration and lower urinary Hg excretion compared with NPD-fed mice. 14,16,19) As described above, the fate of MeHg in C57BL male mice was, however, very different from that in female mice of this strain 3,4,6) and furthermore, was different from that in another strain of male mice.…”

“…14,[16][17][18][19] Even within 24 hr after a single administration of MeHg at a dose of 20 µmol/kg, LPD-fed mice showed a higher brain Hg concentration and lower urinary Hg excretion compared with NPD-fed mice. 14,16,19) As described above, the fate of MeHg in C57BL male mice was, however, very different from that in female mice of this strain 3,4,6) and furthermore, was different from that in another strain of male mice. 4,5) Accordingly, it is possible that the influence of dietary protein deficiency on the fate of MeHg may be specially observed in C57BL male mice.…”