Assessment of astrogliosis in the hippocampus of Wistar rats with spontaneous ventriculomegaly found by magnetic resonance

Abstract

Wistar rats are widely used in preclinical research as experimental models of various pathological conditions involving the central nervous system. In general, these studies assume that animals, under basal conditions, do not present structural and functional changes. However, studies using non-invasive neuroimaging techniques before experimental manipulation showed that 43% of Wistar rats presented mild spontaneous ventriculomegaly, among other neuropathological abnormalities such as arteriovenous malformations, aneurysms, cysts, tissue necrosis, white matter lesions and astrogliosis around the ventricles and blood vessels. Once the hippocampal formation is a region close to the lateral ventricles, it is likely to be affected by the change in ventricular volume. Hippocampal sclerosis is the most common neuropathological finding in refractory mesial temporal lobe epilepsy (MTLE) and it is characterized by a neuronal loss in CA1, CA3, and dentate gyrus with no change in CA2. In addition to the loss and dispersion of the granular cells of the dentate gyrus, an intense fibrillar astrogliosis confers a sclerotic aspect to the hippocampus. A research project (FAPESP 2014/11277-6) on MTLE under development in our group, using structural neuroimaging tools, observed spontaneous ventriculomegaly in Wistar rats before any experimental intervention. Neuropathological abnormalities such as astrogliosis have been described in animals with mild spontaneous ventriculomegaly before any experimental intervention. However, the hippocampus of these animals was not analyzed. Thus, this project aims to evaluate the presence of astrogliosis in the hippocampus of Wistar rats with spontaneous ventriculomegaly through analysis of the glial fibrillary acidic protein (GFAP), since astrogliosis may be a predisposing factor for the development of MTLE and may interfere in the investigation of the mechanisms underlying epileptogenesis. (AU)