Uptake and localization of mercury in the brain of rats after prolonged oral feeding with mercuric chloride.

Uptake and localization of mercury was studied in rats orally intoxicated with inorganic mercury. By atomic absorption spectrophotometry large quantitative differences were found between test and control animals, particularly relating to blood, kidney and brain. By histochemical demonstration of heavy metals the uptake in the CNS was shown to occur particularly within the cytoplasm of large neurons in the cortex, pons and basal ganglia but also in other neurons, to some extent in the choroid plexus and the vessel walls, and least in the white matter. No lesions were detectable by light microscopy. The mercury was mostly in the methylated form, something that may be explained by gastrointestinal methylation by bacteria. A similar mechanism can be expected in human chronic inorganic mercury poisoning.