Study of histopathological lesions in CA1 of the hippocampus after injection of beta-amyloid in a rat model of Alzheimer's disease

BACKGROUND AND OBJECTIVE: Alzheimer's disease (AD) is a neurodegenerative disorder and the most common form of degenerative dementia with progressive loss of cognitive abilities and memory loss. AD is an irreversible, progressive chronic disease that it is the cause of behavior changes and deterioration of thinking ability. Since exact mechanism of neuro-toxicity by beta amyloid has not been identified yet, in this study, the histopathological lesions in CA1 of hippocampus after injection of beta-amyloid in a rat model of AD was studied. METHODS: In this experimental study, 30 adult male Albino Wistar rats weighing (250-300 g) were used for behavioral and histopathological studies. The rats were randomly assigned to three groups; control, sham and β- amyloid (Aβ) injection. The lesion was induced by injection of 4μLof Aβ (1-40) into the hippocampal fissure. For behavioral analysis Y-maze and shuttle box were used respectively at the 14 and 16 days post-lesion. For histological studies, Nissl and Bielschowsky staining were done. FINDINGS: The mean scores of alternation behavior for sham, control, and AD group were 80.56, 86.7, and 46.2, respectively. AD group showed a significant reduction in alternation behavior as compared to control and sham group (p<0.0001). The number of neurons per square millimeter in the Alzheimer group, sham and control, respectively, 2.92, 6.35 and 6.25, and reduced neuronal density in Alzheimer's disease compared with control and sham groups were significant (p