Partial depletion and altered distribution of synaptic zinc in the rat hippocampus after treatment with sodium diethyldithiocarbamate.

A single injection with sodium diethyldithiocarbamate (SDEDTC, 1000 mg/kg i.p.) resulted within 1 h in a significant diminution of hippocampal (-23.9%) and cortical (-13.2%) zinc level, as revealed by atomic absorption spectrophotometry. The regional zinc concentrations in other brain regions examined, however, were practically unchanged. Hippocampal zinc levels seemed to decline continuously with time up to 24 h postinjection, when more than 30% reduction was observed. It has been reported earlier that the sulphide silver staining of neuropil regions is reversibly blocked by SDEDTC. Our recent histochemical observations indicate that this phenomenon is parallelled with a different distribution of hippocampal zinc, e.g. the intensification of Timm's staining of the dentate granule cells and the CA1 pyramidal cells. The perikaryal accumulation of zinc, however, could be prevented by a previous intrahippocampal microinjection of colchicine (20 micrograms) without influencing the partial depletion of hippocampal zinc content. It is suggested that the SDEDTC treatment induces not only the partial depletion of chelatable zinc pool from the rat hippocampus, but also the perikaryal accumulation of zinc, which may signify a failure in axonal transport of zinc-binding proteins either anterogradely or retrogradely.