The Effects Of β-sheet Breaker Peptide H102 On CaM-CaMKⅡ-CREB Signal Pathway In Double Transgenic AD Mice

Objective:To study the effect of β-sheet breaker H102 on behavior,the expression of Aβ_1-42 protein in brain and the expression of CaMKⅡ-CREB signal pathway associated proteins p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1、CaM、p-CaMKIIα、p-CaMKIIβ、p-CREB、ATF-1 and cleaved caspase 3 proteins in APP/PS1 double transgenic mice,to discuss the effect of H102 on CaM-CaMKⅡ-CREB signal pathway in brain of double transgenic AD mice.Methods:1、Double transgenic AD mice were randomly divided into model group and H102 treatment group. In addition,a group of C57BL/6J mice with the same age and background was set as normal. H102（5.8 mg/kg） 5 μl 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.2、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 was placed in 4%paraformaldehyde fixed,embedded sections for immunohistochemistry tests to detect the expression of Aβ_1-42、p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1、p-CREB and cleaved caspase 3 proteins. The other side of the hippocampus and cerebral cortex were separated and stored at-80℃ for Western Blot tests to detect the expression of Aβ_1-42、p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1、CaM、p-CaMKIIα、p-CaMKIIβ、p-CREB、ATF-1 and cleaved caspase 3 proteins.Results:1、The ability of spatial reference memory of double transgenic AD mice of 3groups were tested by Morris Water Maze（1）、In Place Navigation Training Test:Compared with the normal group,the escape latency of the model group was significantly increased（P<0.01）;Compared with the model group,the escape latency of H102 group was significantly reduced（P<0.01）;there were no significant difference between the H102 group and the normal group（P>0.05）（2）、In Spatial Probe Test:Compared with the normal group,the time pasting the position of the platform and the residence time in the third quadrant of the model group was significantly reduced（P<0.01）,and the initial angles were significantly larger（P<0.01）;Compared with the model group,the time pasting the position of the platform and the residence time in the third quadrant of the model group was significantly increased（P<0.01）,and the initial angles were significantly smaller（P<0.01）;there were no significant difference between the H102 group and the normal group（P>0.05）.2、The expression of Aβ_1-42、 p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1、CaM、p-CaMKIIα、p-CaMKIIβ、p-CREB、ATF-1 and cleaved caspase 3 proteins in the brain of double transgenic AD mice（1）、Immunohistochemistry test:（1）. Compared with the normal group,the expression of Aβ_1-42 and cleaved caspase 3 proteins IOD values in mice hippocampus and cortex of the model group were significantly increased（all P<0.01）;Compared with the model group,the expression of Aβ_1-42 and cleaved caspase 3 proteins IOD values in mice hippocampus and cortex of H102 group were significantly reduced（all P < 0.01）; there were no significant difference between the H102 group and the normal group（all P>0.05）.（2）. Compared with the normal group,the expression of p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1 and p-CREB proteins IOD values in mice hippocampus and cortex of the model group were significantly reduced（all P < 0.01）;Compared with the model group,the expression of p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1 and p-CREB proteins IOD values in mice hippocampus and cortex of the model group were significantly increased（all P<0.01）;there were no significant difference between the H102 group and the normal group（all P>0.05）.（2）、Western Blot test:（1）. Compared with the normal group,the expression of Aβ_1-42、CaM and cleaved caspase 3 proteins level in mice brain of the model group were significantly increased（all P <0.01）;Compared with the model group,the expression of Aβ_1-42、CaM and cleaved caspase 3 proteins level in mice brain of H102 group were significantly reduced（all P<0.01）;there were no significant differencebetween the H102 group and the normal group（all P>0.05）.（2）. Compared with the normal group,the expression of p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1 、p-CaMKIIα、p-CaMKIIβ、p-CREB and ATF-1 proteins level in mice hippocampus and cortex of the model group were significantly reduced（all P<0.01）;Compared with the model group,the expression of p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1 、p-CaMKIIα、p-CaMKIIβ 、p-CREB and ATF-1 proteins level in mice hippocampus and cortex of the model group were significantly increased（all P<0.01）;there were no significant difference between the H102 group and the normal group（all P>0.05）.Conclusions:β-sheet breaker H102 could reduce the expression of Aβ_1-42 proteins level in the brain of double transgenic AD mice;could activate CaMKⅡ-CREB signal pathway in the brain of transgenic AD mice,increase the content of p-PKCα、p-PKCβ2、p-PKCγ、p-NMDAR1、p-CaMKIIα、p-CaMKIIβ、p-CREB and ATF-1 in neuronal,suppress the content of CaM and cleaved caspase 3 in neuronal. So β-sheet breaker H102 could the ability of learning in the double transgenic AD mice.