Species difference between rat and hamster in tissue accumulation of mercury after administration of methylmercury

Abstract

The accumulation of mercury in tissues of the rat and hamster was determined after the administration of a single dose of ²⁰³Hg-methylmercury chloride (10mg/kg body weight). (1) On day 2, the mercury contents of hamster tissues were higher than those of rat tissues, except for red blood cells, in which the mercury content was about 6-fold higher in the rat than in the hamster. (2) After that time, the mercury content of hamster tissues decreased rather steeply and on day 16 it had reached 14–25% in nervous tissues and 7–15% in other tissues, of the levels on day 2. (3) In the rat, on the other hand, the mercury content of nervous tissues on day 16 was higher than that on day 2 (106–220%), except for dorsal roots and dorsal root ganglia, which showed slight decreases (75–94% of the levels on day 2). In non-neural tissues, the decreases up to day 16 were also small (71–92% of the levels on day 2). (4) Thus, both the uptake and elimination of mercury seem to be more rapid in the tissues of hamster compared with those of the rat. Similar trends of mercury accumulation and elimination were observed when animals received multiple injections of methylmercury that induced acute methylmercury intoxication. (5) Significant biotransformation of the injected methylmercury to inorganic mercury was detected in the liver, kidney and spleen of both animal species. Although the percentages of inorganic mercury in these tissues were not so different between the two species on day 2, they became exceedingly high in the tissues of hamster at the later stage, except in the kidney cytosol, in which the values were close in both animal species between day 2 and day 16.