Biological half-lives of zinc and manganese in rat brain

The brains of rats injected intravenously with 65ZnCl2 or 54MnCl2 were subjected to high-resolution autoradiography. The distribution of 65Zn and 54Mn in each brain region gradually decreased from 6 days to 42 days for 65Zn and from 15 days to 60 days for 54Mn after the injection. The biological half-lives of Zn in each region studied were in the range of 16-43 days; the longest was observed in the amygdaloid nuclei. The regions where the long biological half-life was observed were consistent with the ones with the high density of Zn-containing neuron terminals reported previously. The biological half-lives of Mn in each region were 51-74 days; the longest were those in the hypothalamic nuclei and thalamus.