Comparison of mercury accumulation among the brain, liver, kidney, and the brain regions of rats administered methylmercury in various phases of postnatal development.

Abstract

Several animal studies have indicated that a developing organism in its prenatal and early postnatal stage may be at higher risk in toxic metal exposure than in adult stage. Many infants were congenitally affected by methylmercury in the epidemics in Japan and Iraq. The infants reported from Minamata, Japan, had severe cerebral palsy, whereas their mothers had mild or no manifestations of poisoning. Some of the high susceptibility in infants may resulted from the specific features of the methylmercury metabolism in the developing organisms. Prenatal or postnatal development is characterized by functional immaturity of organs, which may affect the mercury (Hg) accumulation among organs. It seems possible that the Hg distribution might, in fact, reflect the toxic effects of methylmercury during a given developing phase. Thus, its distribution deserves closer examination. In our previous study, when a toxic level of methylmercury was administered, the Hg distribution and its effects on body weight gain and neurological disorders were found to be different among the rat postnatal developing phases. In the present study the Hg distribution among organs and brain regions was investigated during the several development phases with a nontoxic level of methylmercury treatment. 24 refs., 1 fig., 2 tabs.