THE EFFECT OF SELENIUM ON THE LOCALIZATION OF AUTOMETALLOGRAPHIC MERCURY IN DORSAL-ROOT GANGLIA OF RATS

The autometallographic technique was used to demonstrate the localizat ion of mercury in dorsal root ganglia of adult Wistar rats. The animal s were either exposed to mercury vapour, 100 mu g Hg m(-3), 6 h day(-1 ), 5 days per week, or treated with organic mercury in the drinking wa ter, 20 mg CH3HgCl per litre, for 4 weeks. The effect of orally admini stered sodium selenite on the pattern of intracellular distribution of mercury in these two situations was investigated. In rats exposed to mercury vapour alone, faint staining was present in ganglion cells. Th e selenite induced a conspicuous increase in the number of stained cel ls and in the intracellular staining intensity. In rats treated with o rganic mercury, mercury deposits were detected within ganglion cells a nd macrophages. The number of mercury-containing cells was increased b y co-administration of selenite. In addition, satellite cells, the cap sule and vessel walls were faintly stained. Twenty weeks after cessati on of the organic mercury treatment, mercury staining was reduced. Aga in, selenite treatment enhanced staining intensity. When studied using the electron microscope, mercury was restricted to lysosomes, irrespe ctive of treatments. The present study shows that the deposition of au tometallographic mercury in the dorsal root ganglia depends on the che mical type of mercury, the co-administration of selenite and the lengt h of the survival period.