The effect of experimental methyl mercury poisoning on the number of sulfhydryl (SH) groups in the brain, liver and muscle of rat.

Fifteen adult male rats, the “experimental” rats, were fed a daily diet which contained methyl mercury hydroxide combined with liver homogenate. The daily dose of methyl mercury in terms of metallic mercury was 1.8 mg per rat. Six similar rats, the “controls”, were fed the same diet without methyl mercury. After the experimental rats had developed symptoms typical of methyl mercury poisoning, which occurred on the 15th day of the experiment, all the test animals were decapitated. The average total dose of methyl mercury producing toxic symptoms was 58,1 ± 6.1 mg Hg per kg body weight. The sulfhydryl groups and the mercury content of the brains, livers and caudal femoral muscles of the animals were determined. The SH determinations were made by amperometric titration and the mercury determinations by neutron activation analysis. The mean number of SH groups in the brains (14.95 ± 1.97 µM/g) and livers (35.89 ± 4.10 µM/g) of the methyl mercury-fed rats was found to be significantly (P < 0.001 and P < 0.01 respectively) lower than the corresponding means of the livers (17.63 ± 1.12 µM/g) and brains (44.75 ± 5.60 µM/g) of the controls. The number of SH groups in the muscles did not differ significantly between the animal groups (0.5 < P < 0.6). The mean mercury content of the brains, livers and muscles was found to be 26.0, 124.6 and 39.1 p.p.m. respectively, corresponding to 0.12, 0.62 and 0.19 µM per g of tissue. The decrease in the number of SH groups in the brains, 2.68 µM/g, and in the livers, 8.86 µM/g, of the methyl mercury-fed rats is thus considered to be due mainly to other effects of methyl mercury than to the direct binding of this compound to the tissue SH groups.