Ultrastructural and Immunochemical Studies of Glial Scar Formation in Diabetic Rats

We explored the rebuilding of the brain parenchyma after surgical injury due to reactive astrogliosis. In the present study, we investigated the initial stages of rebuilding in the perilesional cortex of streptozotocin-induced diabetic rats. Our methods u

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Abstract  We explored the rebuilding of the brain parenchyma after surgical injury due to reactive astrogliosis. In the present study, we investigated the initial stages of rebuilding in the perilesional cortex of streptozotocininduced diabetic rats. Our methods utilized ultrastructural and immunohistochemical studies as well as Western blot analysis of glial fibrillary acidic protein (GFAP) and vimentin. Data was collected at 2 days, 7 days and 2 months following a unilateral sensorimotor cortex lesion. Electronmicroscopic studies revealed not only formation of glial scar tissue but also ultrastructural features of death in the elements of neurovascular unit. Immunohistochemical studies, confirmed by Western blot analysis, demonstrated the enhancement of vimentin and GFAP immunoreactivity (IR) in astrocytes located in the perilesion cortical area of the diabetic rats that were operated upon. We suggest that the process of rebuilding brain parenchyma following surgical injury may be disturbed by the induction of astrocytes and the degeneration of astrocytes, as well as by morphological changes within capillaries that are accompanied by the presence of macrophages.

M. Frontczak-Baniewicz () and M. Walski Department of Cell Ultrastructure, M. Mossakowski Medical Research Centre Polish Academy of Sciences, 5 Pawinskiego Street, Warsaw 02-106, Poland e-mail: [email protected] L. Struzynska Department of Neurochemistry, M. Mossakowski Medical Research Centre Polish Academy of Sciences, 5 Pawinskiego Street, Warsaw 02-106, Poland J. Andrychowski Department of Neurosurgery, M. Mossakowski Medical Research Centre Polish Academy of Sciences, 5 Pawinskiego Street, Warsaw 02-106, Poland J. Opertowska Department of Neuropathology, M. Mossakowski Medical Research Centre Polish Academy of Sciences, 5 Pawinskiego Street, Warsaw 02-106, Poland D. Sulejczak Department of Experimental Pharmacology, M. Mossakowski Medical Research Centre Polish Academy of Sciences, 5 Pawinskiego Street, Warsaw 02-106, Poland

Keywords  Brain injury • glial scar • GFAP • vimentin

Introduction Neurosurgical procedures associated with disrupted continuity of the meninges, followed by interventions within the cerebral parenchyma, often result in damage to the morphological components of neurovascular units as well as damage to various cells that form the cerebral parenchyma (1–4). One of the results of damage to the nervous system is the formation of glial scars. Glial scar tissue is composed of astrocytes and microglia, as well as a rich mesh of extracellular matrix proteins, including proteoglycans. In our model of surgical brain injury, a part of the cerebral cortex in the fronto-temporal region is removed. Investigating a number of time points following the operation allows us to analyze the process of rebuilding of brain parenchyma. Diabetes mellitus is the most common serious metabolic disorder, and it is characterized by functional and structural changes in the peripheral as well as in the central nervous system. Earlier studies were not able t