Relationship between Catalase Activity and Uptake of Elemental Mercury by Rat Brain

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Abstract
Uptake of Hg by brain after i.v. injection of elemental Hg was investigated in the rat. Catalase activity was inhibited by aminotriazole either by i.p. injections affecting catalase in most tissues of the animal or by intraventricular [i.c.v.] injections affecting catalase in the brain selectively. Uptake of elemental Hg by rat brain was not influenced by i.p. administration of aminotriazole resulting in 50% inhibition of brain catalase. When the inhibitor was injected i.c.v. in concentrations to give a 50% inhibition of brain catalase, the Hg uptake by the brain was significantly decreased. In the latter case when only brain catalase was inhibited and the supply of elemental Hg to brain was maintained, Hg uptake by brain was porportional to the activity of catalase in brain tissue and to the injected amount of elemental Hg. Contrary to the i.c.v. injection of aminotriazole, in animals receiving aminotriazole i.p. prior to elemental Hg injection, the lower activity of brain catalase may be compensated by an increased supply of elemntal Hg caused by the generally lower oxidation rate in the animal. This view is supported by the finding that Hg uptake by liver increased due to aminotriazole i.p. although activity of catalse was depressed.