Abstract
We reported the dose-response relationship between the accumulation of mercury and its toxic effect with thimerosal (ethylmercuric thiosalicylic acid, sodium salt) in mice in a previous paper. In this experiment, the toxic effects of thimerosal on the peripheral nerve were studied by light and electron microscopy since the involvement of the peripheral nerve in organic mercurial intoxication has been frequently reported in rodents. The accumulation of mercury was also examined in the cerebrum, cerebellum, liver, and kidney.
A thimerosal solution of 0.2 ml at 0.1% was injected twice into the intraperitoneal cavity of 5 week-old female BALB/c mice. The minimum dose injected in the mice was 33 μg Hg/g and the maximum was 116 μg Hg/g body weight.
The sciatic nerves were affected with the minimum dose of 33 μg Hg/g body weight. Electron microscopically, there were whorl formation and deformations of the myelin sheaths, which were irregularly swollen and thickened. The axons showed atrophy with high electron density and degeneration of Schwann cells was also noted.
The cerebrum, cerebellum, liver, and kidney demonstrated strong positive reactions to mercury-histochemistry with photoemulsion method. An assay of the total and inorganic mercury content in these organs was also performed since the ratio of inorganic mercury to total mercury in the brain increased with time because of biotransformation of organic to inorganic mercury. No definite relationship was noted between the mercury dose injected into the mice and the accumulation of mercury in the organs of mice. Thimerosal was suspected to be poorly absorbed through the peritoneal cavity because multiple intraperitoneal injections caused severe peritonitis.
