Ultrastructural Changes of Microglia and Oligodendrocytes in the Caudate Nucleus in Different Types of Schizophrenia

Background: previously, we identi ed interactions between microglia and oligodendrocytes in the prefrontal cortex in continuous schizophrenia (CSch). Aim of study: to examine ultrastructural changes in microglia and oligodendrocytes in contact with each other within the head of the caudate nucleus using post-mortem brain samples from patients with CSch compared to controls and patients with attack-like schizophrenia (ASch) and to identify associations between oligodendrocyte and microglial parameters across the study groups. Material and Methods: An electron-microscopic morphometric study of microglia and oligodendrocytes in the head of the caudate nucleus was conducted on autopsy material comprising 9 CSch samples, 10 Asch samples and 20 control samples from individuals without psychiatric pathology. Group comparisons were made by ANCOVA and Pearson correlation analyses. Results: A reduced numerical density of microglia was observed in the CSch compared to the control and ASch; reduced mitochondrial volume fraction and number were found in both groups, while an increased number of lipofuscin granules in microglia was noted in the CSch group compared to controls. In oligodendrocytes, an increased number of lipofuscin granules was found in the CSch, and reduced mitochondrial volume fraction and number were observed in both groups compared to the control group. The mitochondrial volume fraction in oligodendrocytes correlates positively with the number of mitochondria in microglia in the CSch and control groups. The volume fraction of lipofuscin in oligodendrocytes correlates positively with the number of lipofuscin granules in microglia in CSch. In this group, microglial nuclear area correlates positively with disease duration, whereas the areas of oligodendrocytes and their nuclei correlate negatively with it. Conclusion: Reduced energy metabolism and energy potential within microglia and oligodendrocytes may underlie the diminished reactivity of these cells in the caudate nucleus in CSch and ASch.

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