The effect of chronic stress on learning and memory impairment in old mice and its related mechanisms / 安徽医科大学学报

ABSTRACT

Objective To determine whether chronic stress could potentiate learning and memory impairment in old mice, and, if so, what the underlying mechanism is. Methods Sixty male mice were divided randomly into control group and chronic stress group. Mice in stress group were stressed everyday by one of the stressors including cold exposure, restraint, level shake and so on. The ability of learning and memory was determined by Morris water maze test, and the histopathologic changes in CA3 field of the hippocampus were examined under a light micro-scope. Serum corticosterone level was determined by enzyme-linked immunosorbent assay. Western blot was per-formed to determine the expression of β-site amyloid precursor protein-cleaving enzyme 1 and Aβ1-42 in hippocam-pus of the brain. Results Compared with the control group, the results showed that chronic stress could increase the escape latency and swimming distance of old mice during training session in the Morris water maze test. The neuropathological changes were characterized by the decreased neuron number,soma shrinkage and condensation,or nuclear pyknosis in the CA3 field of hippocampus in the stress group. On the other hand, the expression of Aβ1-42 and BACE1 protein in hippocampus were increased, as well as the serum corticosterone concentration in the stress group. Conclusion Chronic stress can potentiate learning and memory impairment and pathological damage in CA3 field of the hippocampus in old mice, which may be related to chronic stress up-regulated the levels of BACE1 and Aβ1-42 mediated by corticosterone.