Regional zinc staining in postmortem hippocampus from schizophrenic patients

Schizophrenia-associated deficits in learning and memory have been associated with a decrease in the volume of the hippocampus, but the specific nature of the neuronal deficit remains unknown. Many critical afferent pathways in the hippocampus contain ionic zinc. Alterations of these pathways could be manifest as a decrease in ionic zinc levels within hippocampal afferent pathways. This possibility was examined in postmortem hippocampal tissue taken from schizophrenic patients, patients with other psychiatric disorders and matched, non-mentally ill subjects using a modified Timm's silver staining method. The three groups exhibited similar patterns of zinc staining within the hippocampal formation as well as similar levels of zinc within the messy fiber projection system. A greater prevalence of zinc staining within the inner molecular layer of the dentate gyrus was observed in female as compared to male donors and in older as compared to younger donors. The results of the present study demonstrate that loss of ionic zinc within the hippocampus does not appear to be part of the pathology of schizophrenia.