Experimantal Study on the Hyperpigmentation of Generalized Argyria

—Using Rabbits with Oral Administration of AgNO₃—

Abstract

Olive oil suspension containing 0.2g of AgNO₃ was administered orally once daily to 9 rabbits who were divided into 2 groups consisting of 6 and 3 rabbits, with or without irradiation of fluorescent light, respectively. To the 3rd group comprising 3 rabbits, a control group, only olive oil was administered in the same manner. Macroscopically, microscopically and quantitatively, a comparative study on the differences of hyperpigmentation as well as deposition of silver particles in the skin and viscera of these 3 groups was performed at 40, 70 and 125 days after oral administration of AgNO₃. The results were as follows;
1) In the skin, no hyperpigmentation was observed clinically in the 3 groups at any times, but silver particles were found very sparely in the basement zone of the follicles, and 2 to 5 ppm of silver was detected after administration of 14 g and 25 g of AgNO₃.
2) In the intestines, very slight pigmentation was noted after administration of 14 g 25 g of AgNO₃, and only about the same amount as in the skin was obtained.
3) In the kidney and the liver, an apparent hyperpigmentation was seen even when 8 g of AgNO₃ had been administered, and it became more intense with the increase of total dose. Deposition of silver particles in the kidney was detected in greater amounts from the medulla (162.5 ppm) than from the cortex (32.6 ppm) after administration of 25 g AgNO₃.
The reason why rabbit skin did not exhibit any apparent hyperpigmentation may be due to the lack of eccrine as well as sebaceous glands which are an external secretory gland. In conclusion, the bluish gray pigmentation in generalized argyria can be principally attributed to deposits of silver particles.