Dimorphic evaluation of hippocampal changes in rat model of demyelination: A comparative functional, morphometric, and histological study

Abstract

Background Multiple sclerosis (MS) is the most common autoimmune disease. Progressive depletion of the brain and spinal cord tissue appears at the onset of the disease. Several studies have shown the increased size of the ventricles of the brain and decreases in the area of the corpus callosum and the width of the brain. Other important symptoms of this disease are cognitive, learning, and memory disorders. Aim The aim of this study was to compare morphometric, histological, and functional changes in the demyelination model in both sexes. Materials and methods In this experimental study, male and female Wistar rats were studied in four experimental groups. Demyelination was induced by the injection of ethidium bromide in the ventricular region. The chronic effect of demyelination on spatial memory, movement, and coordination was investigated using the Morris Water Maze (MWM), and clinical and balance beam tests, respectively. Myelin degradation, cell death and neurogenesis were estimated using Luxol Fast Blue staining and immunohistochemistry (Caspase‐3 and Nestin markers). In addition, morphometric findings were recorded for the brain and hippocampus (weight, volume, length, width). Result Demyelination increased the time and distance index and decreased the residence time in the target quarter in the water maze test (p < .001). It also increases the neuromuscular and modified neurological severity score (p < .01). Demyelination increases caspase‐3 (p < .05) expression and decreases Nestin expression (p < .001), which are directly related to the extent of damage. Conclusion This study showed an interaction between hippocampal structural and functional networks in explaining spatial learning and memory in the early stages of MS.