Microglia-Oligodendrocyte Interactions in White Matter of the Prefrontal Cortex in Attack-Like Schizophrenia

Abstract

Background: the authors previously reported the ultrastructural pathology of oligodendrocytes in contacts with microglia in white matter of the prefrontal cortex in attack-like schizophrenia supposedly associated with microglial activation. Aim of the study: to perform morphometry of the ultrastructural parameters of microglia in contact with oligodendrocytes and to analyze correlations between the parameters of microglia and oligodendrocytes previously studied in the schizophrenia group as compared to the control group. Material and methods: a postmortem ultrastructural morphometric study of microglia in contact with oligodendrocytes in white matter of the prefrontal cortex was performed in 8 cases of attack-like schizophrenia and 20 healthy controls. Group comparisons were performed using ANCOVA and Pearson correlation analyses. Results: we found reduced volume fraction (Vv) and the number of mitochondria and increased Vv, area and number of vacuoles of endoplasmic reticulum and area of heterochromatin in microglia in the schizophrenia group as compared to the control group. Area of microglial cytoplasm correlated positively with area and number of vacuoles in microglia, and Vv and the number of mitochondria in microglia correlated positively with Vv and the number of vacuoles in microglia in the schizophrenia but not in the control group. Positive correlations were found between area of lipofuscin granules in oligodendrocytes and areas of microglial cell, nucleus and cytoplasm and the number of mitochondria in microglia only in the schizophrenia group. Also, area of vacuoles in oligodendrocytes correlated positively with the number of mitochondria in microglia in the schizophrenia group. In contrast, in the control group but not in the schizophrenia group the parameters of mitochondria and lipofuscin granules correlated positively with the same parameters in oligodendrocytes. Conclusion: these data suggest that normal relationships between energy and lipid metabolism of microglia and oligodendrocytes are disturbed in schizophrenia. Dystrophic changes of oligodendrocytes in attack-like schizophrenia might be associated with the effects of microglial activation on lipid and protein metabolism.