Analysis of the MRI characteristics in tree shrew model of Alzheimer’ s disease induced by intracerebroventricular injection of Aβ1-40 / 中国比较医学杂志

ABSTRACT

Objective To analyze the neuroimaging changes of tree shrew models of Alzheimer’ s disease.Methods Nineteen healthy adult female tree shrews were randomly divided into control (5 animals) and model group (14 animals). The model of Alzheimer’s disease was induced by intracerebroventricular injection of Aβ1-40 using a stereotaxic devise and proved successfully by visuospatial congnitive task.The in vivo microstructural changes in the brain of tree shrew AD models and control group (0, 1, 2, 3, 4 weeks) were observed on 1.5T MRI (T2WI), and on 7.0T MRI (12 week)(T2WI, DTI). Results Reference memory errors were increased in the model group at 3 or 4 weeks (P<0.05), and so working memory errors (P<0.05) and period of time to perform (P<0.05, P<0.05, P<0.01) from 2 to 4 weeks.Thus the model was proved to be established successfully.T2WI test and DTI test were carried out.Hippocampus atrophy of the model group at 3 and 4 weeks was observed compared with that at 0 or 1 week or 2 weeks on a 1.5T Philips Gyroscan.Compared with the control group, the temporal horn width in the model group was significantly increased (P<0.01) at 12 weeks on a 7.0T Bruker Biospec Scanner.DTI test at 12 weeks showed that ADC of bilateral hippocampus was up-regulated in the model group ( P<0.01 ) .In the color coded orientation view, loss of the corpus callosum fibers was obvious in the model group. Conclusions Intracerebroventricular injection of Aβ1-40 can lead to learing and memory impairment in tree shrews.There are abnomal MRI signal changes in the brain, and the temporal horn width, hypocampal apparent diffusion coefficient ( ADC) value and corpus callosum damage may provide reference value for the diagnosis of Alzheimer’ s disease.