Characteristics of brain cell proliferation and migration in animals with experimental Alzheimer’s disease undergoing cognitive training

Aims. Alzheimer’s disease is a multifactorial neurodegenerative disease characterized by the presence of amyloid beta peptide containing plaques, and neurofibrillary tangles. Beta-amyloid is a major risk factor and it plays a central role in the onset and progression of Alzheimer’s disease. However, question of the influence of beta-amyloid on neurogenesis in the hippocampus in the adult brain is still open. The purpose of this paper is to study cognitive functions and their association with proliferation, survival and migration of newly-formed cells in normal adult rat brain and in the experimental Alzheimer’s disease.

Materials and methods. Rats (Wistar, males, 7 months) were used. Experimental group (Alzheimer’s disease model with the intrahippocampal administration of beta-amyloid 1-42 (5 µl) bilaterally in the CA1 area) and a control group (sham-operated animals with the intrahippocampal administration of Phosphate buffered salin (5 µl) bilaterally in the CA1) have been tested. The study was conducted from February to July. Neurobehavioral test (Morris water maze) was used to assess working memory and memory consolidation. The study of cell migration was performed by introducing bromodeoxyuridine (50 mg/kg). Expression of neurogenesis markers in the subgranular zone of the dentate gyrus of the hippocampus was studied has been studied with indirect immunohistochemistry for free-floating sections followed by the confocal microscopy.

Results. Modelling of Alzheimer’s disease leads to impaired cognitive function and memory in animals. We found that these events were associated with the suppression of proliferative (р = 0,043) and migratory activity of brain cells (р = 0,031), but not survival of cells (p = 0,985) compared to the control group.Training in Morris water maze of animals with experimental Alzheimer’s disease promotes migration of progenitor cells along the rostral migration way (р = 0,011) compared with the group without training. However, the number of neuroblasts (р = 0,809) and proliferation of neuronal progenitor cells (p = 0,083) were not significantly affected compared with the group without training.

Conclusions. Decreased level of brain cells proliferation, alterations in their migration and development of cognitive dysfunction have been found in the rat model of Alzheimer’s disease, thus suggesting impairment of neurogenesis induced by amyloid. Possible involvement of local insulin resistance into the development of neurogenesis alterations is discussed.

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