| Objective:1.To determine the preclinical stage of APP/PS1 double transgenic mice for facilitating the early intervention of Alzheimer's disease;2.To evaluate the effectiveness of ultrasound as early intervention on preclinical APP/PS1 double transgenic mice.Methods:1.According to the National Institute of Aging-Alzheimer's Association(NIA-AA)diagnostic criteria and International Working Group 2(IWG-2)diagnostic criteria of Alzheimer's disease,the age of APP/PS1 double transgenic group and control group mice was begin at one month,and every other month of age mice in two groups of the same age was measured by Y maze,Enzyme-linked immune absorbent Assay(ELISA)and immunohistochemistry to test their learning and memory,beta-Amyloid,senile plaques to determine the preclinical stage of APP/PS1 double transgenic mice in Alzheimer's disease.When the differences of beta-Amyloid or senile plaques between two groups was significant,while the differences of behavior tests between two groups was no significant at the same time,this age was determined to be the preclinical stage of APP/PS1 double transgenic mice in Alzheimer's disease.2.According to the experimental parameters and Food and Drug Administration(FDA)-related standards,a set of ultrasonic experimental devices was developed for APP/PS1 double transgenic mice in preclinical stage for the ultrasonic intervention,the ultrasound intervention parameters was at f=1 MHz,P=0.3 W/cm2,the treatment time was 10 minetes every day and last for six weeks,the control group was in the same experimental condition without ultrasound intervention to verify the effectiveness of early intervention.3.The influence of ultrasound as the early intervention on the preclinical stage of APP/PS1 double transgenic mouse model was evaluated by two behavioral tests,Morris water maze and Y maze;the amyloid protein content and the senile plaques in the brain of the preclinical stage of APP/PS1 double transgenic mice was determined by ELISA and immunohistochemistry respectively.Result:1.The behavioral tests and biochemical detection were applied on both APP/PS1 double transgenic mice group and control mice group at the age of one month,two months and three months respectively.There were no observable differences between the control and treatment groups in behavioral tests(P>0.05);and the senile plaques in the brain of transgenic mice group and control mice group were also not found;There were no observable differences in the amyloid protein content between the control and treatment groups both at one month of age and two months of age(P>0.05),However,compared with controls,mice treated with ultrasound had lower levels of the amyloid protein content at three months of age(three months of age APP/PSI double transgenic mice:1310.49±131.94 pg/g,control mice group:700.10±101.65 pg/g,P<0.05).Thus,we determined that,for APP/PS1 double transgenic mice,three months of age was at the preclinical stage.2.Preclinical stage of APP/PS1 double transgenic mice were intervened by ultrasound for six weeks.The results suggest that ? In Y-maze behavioral test,the differences of four groups was significant(F=6.78,P<0.05).As for alternate selection ratio,there was no statistically difference between CN group and US group(P>0.05),but there was a differences between CN group and AD group,AD and US group(P<0.05).? The first stage of Morris water maze,the spatial acquisition ability of mice to find the platform in water between three groups were diffierent(F=15.43,P<0.05),there was no statistical difference between the US group and the CN group(P>0.05),while the escape latency of AD group mice to find the platform in water was longer than that of CN group(P<0.05).Beginning at the third day,the escape latency of CN group mice to find the platform was shorter than that of AD group(CN group:23.98±17.57 s,AD group:39.37±18.31 s,P<0.05),at the fourth day,the escape latency of US group mice to find the platform was shorter than that of AD group(US group:20.52±13.36 s,AD group:38.01±18.19 s,P<0.05),and there was no significant difference between the CN group and the US group(P>0.05),and there was no significant difference on swimming speed among three groups(F=1.16,P>0.05).The second stage was probe trial:three groups of mice showed statistically differences on residence time in the SE quadrant(US group:16.64±6.56 s,CN group:19.53±7.72 s,AD group:8.89±2.47 s,F=6.91,P<0.05);residence time of AD group in the SE quadrant was significantly less than that of CN group(P<0.05),and the residence time of AD group in the SE quadrant was also less than that of US group(P<0.05),there was no significant difference on the residence time in the SE quadrant between US group and CN group(P>0.05),and no signifcant differences were observed in the swimming speed among three groups(F=1.44,P>0.05).?The senile plaques in the hippocampus of the mice in the CN group and the US group were not found,while a little of senile plaques were found in the AD group.?The content of amyloid protein in the four groups was significant difference(F=71.12,P<0.001),the amyloid protein content of AD group was higher than CN group(AD group:4201.24±700.87 pg/g,CN group:769.83±120.50 pg/g,P<0.001),the US group,which is the ultrasound treatment group,its A?42 content was lower than AD group(US group:1371.26±229.97 pg/g,P<0.001),there was no significant difference of A?42 content between US group and CN group(P>0.05).Conclusions:1.We determined that three months of age was the APP/PS1 double transgenic mice's preclinical stage by behavior tests and biochemical detection;2.The behavior tests and biochemical detection results show that,the preclinical stage of APP/PS1 double transgenic mice's learning and memory ability was significantly improved after ultrasound intervention,and the ultrasound treatment can effectively promote the reduce of the amyloid protein and amyloid deposits.3.Ultrasound(P=0.3 W/cm2,f=1 MHz,each treatment time was ten minutes and last for six weeks)on the early intervention of APP/PS1 double transgenic mice did not cause the mice's activity ability or vision ability injuried,and there were no mice died during the treatment.It is proved that the early intervention method of ultrasound established in this study is feasible. |
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