Aβ3-10 Repeat Fragment Plasmid Immunization Delays Learning And Memory Impairment In APP/PS1 Transgenic Mice By Reducing Aβ Plaque Deposition And Regulating Neural Regeneration In The CA3 And CA1 Regions

Objective : To observe the effect of Aβ3-10 repeat fragment plasmid on delaying impairment of learning and memory in APP/PS1 transgenic mice,and determine whether it exerts effect by reducing amyloid deposition and regulating neurogenesis in the CA3 and CA1 regions of hippocampus.Methods :(1)Three 12-month-old APP/PS1 transgenic mice were used as the experimental group(AD group),and three 12-month-old C57BL/6J wild-type mice were used as the control group(C57 group).(2)Ten 2-month-old male APP/PS1 transgenic mice injected with Aβ3-10 repeat fragment plasmid were used as the experimental group(Aβ3-10 group),and ten 2-month-old male APP/PS1 transgenic mice injected with PBS were used as the control group(PBS group).(3)Water Morris Maze was performed to evaluate the learning ability and memory of AD group and C57 group;and immunohistochemistry was employed to detect the Aβ deposition in cortex and hippocampus of AD group and C57 group.(4)Water Morris Maze was performed to evaluate the learning ability and memory of Aβ3-10 group and PBS group;and immunohistochemistry was employed to detect the Aβ deposition in cortex and hippocampus and the expression of Neu N and ki-67 in the CA3 and CA1 regions of Aβ3-10 group and PBS group.Results :(1)The learning ability and memory in AD group were significantly impaired as compared with C57 group(P<0.05)。Aβ plaque deposition increased significantly in the hippocampus and the cortical area of AD group compared with C57 group(P<0.05).(2)The impairment of learning ability and memory were obviously delayed in Aβ3-10 group of 5 month old,7 month old and 9 month old as compared with PBS group of same age.The total distance(P<0.05,P<0.01,P<0.05),the number of platform crossings(P<0.05,P<0.05,P<0.05),the fourth quadrant activity time(P<0.05,P<0.01,P<0.01),the surrounding activity time(P<0.05,P<0.01,P<0.01).Aβ plaque deposition reduced significantly in the hippocampus and the cortical area of Aβ3-10 group of 5 month old,7month old and 9 month old as compared with PBS group of same age(P<0.05,P<0.05,P<0.05).The number of Neu N positive cells and ki-67 positive cells increased significantly in the CA3 and CA1 regions of Aβ3-10 group of 5 month old,7 month old and 9 month old as compared with PBS group of same age(P<0.05,P<0.05,P<0.05).Conclusion:(1)AD group shows worse learning ability and memory,and more obvious Aβ deposition.(2)Aβ3-10 repeat fragment plasmid can delay impairment of learning and memory in APP/PS1 transgenic mice by reducing Aβ deposition in the hippocampus and the cortical area,reducing loss of neurons and downregulating proliferation in the CA3 and CA1 regions of hippocampus.