| Objective : To explore the change of NF-κB signal pathway in the brains of double transgenic AD mice and to explore the probability of β-sheet breaker H102 plays a role of treatment for alzheimer’s disease through influence NF-κB signal pathway associated proteins by studying the effect of β-sheet breaker H102 on the expression and activity of NF-κB signal pathway associated proteins,i NOS、cleaved caspase-3 and BACE1 proteins in APP/PS1 double transgenic mice。Methods: 30 APP/PS1 double transgenic mice who were 8 weeks old were randomly divided into model group and treatment group. A group of C57BL/6J mice with the same age and background were served as controls(n=15). H102 5μl(5.8mg/kg)was infused by intranasal administration to mice in H102 treatment group,and equal volume of blank solution of H102(chitosan, BSA) was given to mice in control group and model group. After 16 weeks, the ability of spatial reference memory was tested by Morris Water Maze. H102(5.8 mg/kg) 5μl was infused by intranasal administration to mice in H102 treatment group,and equal volume of blank solution of H102(chitosan, BSA) was given to mice in control group and model group. The administration of drugs once daily at the same time. The ability of spatial reference memory was tested by Morris Water Maze after 4 months treatment.Mainly includes the orientation navigation experiment and spatial probe experiment.After the end of Morris Water Maze test,All mice were decapitated and the brains were taken out on the ice, the side of the brain which separate the hippocampus and cerebral cortex were separated and stored at-80℃ 。The other side of the brain was placed in 4% paraformaldehyde, fixed,then embedding paraffin block and cut into slices. Then using immunohistochemical staining and western blotting technology to detect the expression of Aβ1-42、p-IKK、IKK、p-NF-κB、NF-κB、p-IκB、IκB、i NOS、cleaved caspase-3 and BACE1 proteins in mice brain.Results:(1)Morris Water Maze The orientation navigation experiment: The escape latent period of the model group were longer than the control group; Started from the second, compared with the model group, the escape latency of the treatment group was significantly reduced(P<0. 05);there were no significant difference between the treatment group and the normal group, in addition to the first day and the fourth day(P>0.05).The patial probe experiment: Select the residence time in the third quadrant、the time pasting the position of the platform and the activity time in the central region as the indicator to evaluate the the ability of learning and memory in mice. Compared with the control group, the time pasting the position of the platform and the residence time in the third quadrant and the activity time in the central region of the model group was significantly reduced(P<0. 05);Compared with the model group,the time pasting the position of the platform and the residence time in the third quadrant and the activity time in the central region of the treatment group was significantly increased(P<0. 05).Compared with the control group,the ability of learning and memory in the mice of the model group was significantly reduced; Compared with the model group, the ability of learning and memory in the mice of the treatment group was significantly increased(P<0. 05).(2)immunohistochemical staining and western blotting The immunohistochemical staining results: Compared with the control group,the expression of Aβ1-42 protein in mice brain of the model group were significantly increased(P < 0.05); Compared with the model group, the expression of Aβ1-42 protein in mice brain of the treatment group were significantly reduced(P < 0.05).p-IKK、p-NF-κB and p-IκB proteins are found in the cell cytoplasm and nucleus.p-IKK、p-NF-κB and p-IκB proteins’ IOD values in the mice brain of the control group is lower. Compared with the control group,the expression of these proteins in mice brain of the model group were significantly increased(P < 0.05);Compared with the model group, the expression of these proteins in mice brain of the treatment group were significantly reduced(P < 0.05). NF-κB protein was found in the cell cytoplasm and nucleus. In the hippocampus, the expression of NF-κB protein in the model group is significantly increased than that in the control group, and the expression of NF-κB protein in mice hippocampus of the treatment group were significantly reduced.But the expressions of NF-κB protein were no significant difference in cortex between the three groups. i NOS and cleaved caspase-3 proteins are found in the cell cytoplasm. i NOS and cleaved caspase-3 proteins’ IOD values in the mice brain of the control group is lower. Compared with the control group,the expression of i NOS and cleaved caspase-3 proteins in mice brain of the model group were significantly increased(P < 0.05); Compared with the model group, the expression of i NOS and cleaved caspase-3 proteins in mice brain of the treatment group were significantly reduced(P < 0.05). BACE1 protein is found in the membrane. BACE1 protein’s IOD values in the mice brain of the control group is lower. Compared with the control group,the expression of BACE1 protein in mice brain of the model group were significantly increased(P < 0.05);Compared with the model group, the expression of BACE1 protein in mice brain of the treatment group were significantly reduced(P < 0.05).The western blotting results: Compared with the control group,the expression of p-IKK、p-NF-κB、p-IκB、i NOS、cleaved caspase-3、BACE1 and intranuclear NF-κB proteins in mice brain of the model group were significantly increased(P < 0.01);Compared with the model group, the expression of these proteins in mice brain of the treatment group were significantly reduced(P < 0.05). There were no significant difference between the three groups in the expression of IKK protein(P > 0.05).Compared with the control group,the expression of IκB protein in mice brain of the model group was significantly reduced(P < 0.05). Compared with the model group,the expression of IκB protein in mice brain of the treatment group was significantly increased(P < 0.05).Conclusions : The NF-κB signal pathway was over-activated in the brains of APP/PS1 double transgenic AD mice. β-sheet breaker H102 could suppress the over-activation of the NF-κB signal pathway in the brain of double transgenic AD mice and reduce the expression of i NOS、cleaved caspase-3 and BACE1 proteins level, and significantly improve the ability of learning and memory in transgenic AD mice. |
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