[Effects of 40 Hz multisensory stimulation on trauma-induced anxiety-like behavior in rats].

OBJECTIVE: To investigate the effects of 40 Hz acousto-optical stimulation on anxiety like symptoms of post-traumatic stress disorder (PTSD), with emphasis on the possible molecular mechanism stimulation. METHODS: Thirty SD rats were randomly divided into three groups: Control group, PTSD group and PTSD+40 Hz group,ten rats in each group. The SPS&S model was established in the rats of the PTSD group and PTSD+40 Hz group and, then PTSD+40 Hz group rats were stimulated with 40 Hz acousto-optical stimulation for 7 days. The behavior of anxiety was tested by elevated plus maze (EPM) and open field test (OFT). The expressions of brain-derived neurotrophic factor (BDNF), tyrosine kinase receptor B (TrkB), synapsinⅠand postsynaptic density protein 95 (PSD95) in the rat prefrontal cortex (PFC) and hippocampus (HIP) were detected by Western blot. The mRNA transcription level of BDNF genes in the PFC and HIP was verified by real-time quantitative PCR (RT-PCR) and the distribution of BDNF in the PFC and HIP was determined by immunofluorescence. RESULTS: Compared with the Control group, in the OFT the total distance and the time spending in the center, and in the EPM the total distance were decreased significantly (P＜0.05), the number of entering into the open arm as a percentage of the total number of entering in two arms was decreased,and the expression levels of BDNF, TrkB, PSD95, Synapsin I protein in HIP and PFC, and the mRNA expression level of BDNF were reduced significantly (P＜0.01), the immunofluorescence expression of BDNF was reduced in CA1, DG and PFC in the PTSD group rats; Compared with the PTSD group, the total distance and the time spending in the center in OFT (P＜0.05), the total distance and the number of entering into the open arm as a percentage of the total number were increased significantly (P＜0.05), the protein expression levels of BDNF, TrkB, PSD95, SynapsinⅠin the PFC and HIP, the mRNA expression level of BDNF were increased significantly (P＜0.05), and the immunofluorescence expression of BDNF was increased significantly in CA1, DG and PFC in the PTSD+40 Hz group rats. CONCLUSION: 40 Hz acousto-optical stimulation improves the formation of anxiety-like symptoms in rats with PTSD, which may be related to the synaptic plasticity influenced by BDNF-TrkB signaling pathway.

[The effects of Sestrin2 on apoptosis of heat-exposed lung epithelial cells and its mechanism].

OBJECTIVE: To investigate the protective effects of Sestrin2 protein on lung epithelial Beas-2B cells in the heat-exposure environment and its mechanism. METHODS: Lung epithelial Beas-2B cells were cultured at 37℃, 39℃, 40℃ and 41℃ respectively. Cells were harvested at different times (0, 3, 6 and 12 h) after pancreatin digestion. The expressions of Sestrin2, superoxide dismutase(SOD), reactive oxygen species(ROS), cell mitochondrial membrane potential and apoptosis rate of cells were detected by Western blot, fluorescence spectrophotometer and flow cytometry, respectively. Gene expression sequence was cloned into high expression plasmid pcDNA3.1+. Beas-2B cells were transfected by Lipfectamine 2000 to construct Sestrin2 and SOD high expression cells. The changes of mitochondrial membrane potential and cell apoptosis were observed in the Sestrin2 and SOD high expression cells. RESULTS: With the increase of temperature, the expression level of Sestrin2 protein in heat treatment group was decreased compared with the control group. When Beas-2B cells were exposed to 41℃, the ROS level was increased, mitochondrial membrane potential was decreased significantly and apoptosis rate was increased at different time points. After high expression of Sestrin2 and SOD in the Beas-2B cells, the expression level of ROS was decreased and the change tendency of mitochondrial membrane potential was decreased, and the apoptosis rate was reduced at 41℃ exposure. CONCLUSION: Sestrin2 can alleviate the apoptosis of lung epithelial cells induced by heat exposure through mitochondrial membrane potential and SOD, which has protective effect on lung epithelial Beas-2B cells.

The involvement of homocysteine in stress-induced Aß precursor protein misprocessing and related cognitive decline in rats.

Chronic stress is a risk factor in the development of cognitive decline and even Alzheimer's disease (AD), although its underlying mechanism is not fully understood. Our previous data demonstrated that the level of homocysteine (Hcy) was significantly elevated in the plasma of stressed animals, which suggests the possibility that Hcy is a link between stress and cognitive decline. To test this hypothesis, we compared the cognitive function, plasma concentrations of Hcy, and the brain beta-amyloid (Aß) level between rats with or without chronic unexpected mild stress (CUMS). A lower performance by rats in behavioral tests indicated that a significant cognitive decline was induced by CUMS. Stress also disturbed the normal processing of Aß precursor protein (APP) and resulted in the accumulation of Aß in the brains of rats, which showed a positive correlation with the hyperhomocysteinemia (HHcy) that appeared in stressed rats. Hcy-targeting intervention experiments were used to verify further the involvement of Hcy in stress-induced APP misprocessing and related cognitive decline. The results showed that diet-induced HHcy could mimic the cognitive impairment and APP misprocessing in the same manner as CUMS, while Hcy reduction by means of vitamin B complex supplements and betaine could alleviate the cognitive deficits and dysregulation of Aß metabolism in CUMS rats. Taken together, the novel evidence from our present study suggests that Hcy is likely to be involved in chronic stress-evoked APP misprocessing and related cognitive deficits. Our results also suggested the possibility of Hcy as a target for therapy and the potential value of vitamin B and betaine intake in the prevention of stress-induced cognitive decline.

[Establishment and evaluation of oxidative stress injury model of in vitro rat aortic endothelial cells].

OBJECTIVE: To establish a model of oxidative stress injury in cultured rat aortic endothelial cells, and to provide a basis for the research of cell injury and apoptosis. METHODS: The rats were decapitated to get the aorta in thoracic operation under aseptic conditions. By subculture after tissue block culture method to get sufficient aortic endothelial cells, cultured in 96-well plates or grow on cover glass for the following test. Without H2O2 group as a control group, with different doses of H2O2 (100,200,300,400,500 µmol/L) treated endothelialcells in 12 h to screen the optimal dose. Based on the results, with the same dose of H2O2 (100 or 200 µmol/L) acted on endothelial cells respectively in different time (3, 6, 9, 12 and 24 h) to screen the optimal duration. Each group was made in sextuplicate. The establishment of the model was evaluated by immunofluorescence,cell viability testing, biochemical indicators detection (lactate dehydrogenase(LDH), nitric oxide(NO), malondialdehyde(MDA), superoxidedismutase(SOD))and apoptosis index testing. RESULTS: Endothelial cells were cultured successfully and verified by immunofluorescence staining of intracellular antigen Ⅷ collagen. With the increase of H2O2 doses at the same action time 12 h, the cell viability was significantly decreased (77.63%±5.20% to 40.90%±2.10%). The same dose(100 µmol/L group and 200 µmol/L group)with the action time increasing, the cellviability was significantly decreased (100 µmol/L group was 86.83%±12.11% to 44.26%±5.70%, 200 µmol/L group was 78.28%±11.98% to 34.45%±5.87%). At dose of H2O2 was 100 µmol/L and treated in 3,6,9,12 and 24 h, LDH-L and MDA were significantly increased after 9 h while NO and SOD were significantly decreased. In H2O2 dose of 100 µmol/L and action time 12 h, flow cytometry showed endothelial cellapoptosis rate was 16.92%±2.37%, significantly higher than the control group of 2.68%±0.47%(P<0.01); TUNEL detected endothelial cell apoptosis index was17.65%±2.36%, which was significantly higher than that in the control group of 3.23%±0.57%(P<0.01). CONCLUSIONS: The method was successfullyestablished a model of oxidative stress injury in cultured rat aortic endothelial cells, explore the moderate conditions that induced cells injury and apoptosis which could be a basis for the research.

[Level and effect of anti-HSP70 antibody changed in the procession of rat atherosclerosis].

AIM: To explore the level of anti-HSP70 antibody in plasma during atherosclerosis procedure induced by high-fat diet in rat and the relationship of them. METHODS: Twenty eight rat were divided into high-fat diet group (H) and control group (C). The total cholesterol (TC), Glyceride (TG), low density lipoprotein cholesterol (LDL-C) in serum, pathology change of rat Arch of the aorta were determined, the level of anti-HSP70 antibody and their Phenotype were evaluated by ELISA. RESULTS: After two weeks, the serum concentrations of TC and LDL-C in rat supplemented by high-fat diet were significantly higher than those in control group (P < 0.01), the serum TG were much lower than those in control group (P < 0.01). Four weeks later the level of anti-HSP70 antibody, IgM, IgG phenotype were significantly higher than those in control group (P < 0.01). There were lipin deposition and mottling formation in rat Arch of the aorta in rat supplemented by high-fat diet in 12th week. CONCLUSION: Atherosclerosis could be induced by high-fat diet in rat. Accompany with the atherosclerosis procession, the level of anti-HSP70 antibody was continuously elevated, the level of anti-HSP70 antibody was related to atherosclerosis. The level of anti-HSP70 antibody was closely associated with atherosclerosis.