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.

With redox-sensitive fluorescene probes DCFH-DA and DHR123, the formation of cytosolic and intramitochondrial reactive oxygen species (ROS) inside immature rat cerebellar granule cells during the apoptosis induced by nitric oxide donor S-nitroso-N-acetyl-pennicillamine (SNAP) was monitored by laser confocal scanning microscopy. The cytosolic and intramitochondrial ROS increase significantly after 0.5 mmol/L SNAP treatment for 1 h. Pre-treatment with the nitric oxide scavenger hemoglobin can effectively inhibit the formation of cytosolic and intrarnitochondrial ROS and protect neurons from apoptosis. Adding glutathione can also protect neurons from apoptosis, and the cytotoxity of nitric oxide increases significantly while the synthesis of glutathione is inhibited. The results indicated that ROS might be involved in NO-induced apoptosis in neural cells and glutathione might be the endogenesis antioxidant to protect neurons from oxidative injury.

Objective:To explore the characteristics of cerebellar metabolites of autistic children using the magnetic resonance spectrum (MRS) and analyze their correlation with clinical symptoms.Methods:An autism group ( n=14) and a control group ( n=8) both underwent bilateral MRS scans of their cerebella. The NAA, Cho and Cr absolute values were recorded along with the NAA/Cr and Cho/Cr ratios. Those values were correlated with clinical symptoms of autism (the CARS and ABC scales), as well as with age. Results:There were no significant differences between the two groups in cerebellar metabolite levels, but the autism group exhibited significantly higher Cho/Cr ratios in the right cerebellum than in the left. There was a significant positive correlation between the Cho/Cr ratio in the right cerebellum and CARS scores, and between the NAA/Cr ratio in the right cerebellum and age.Conclusions:There is metabolic abnormality in the left and right cerebellar hemispheres of autistic children. The metabolic abnormality is related to the severity of clinical symptoms. However, metabolism in the cerebellum improves gradually with age.