The General Brain Morphological Study Of ApoE Transgenic Mice

Alzheimer's disease (AD) is a kind of age related neurodegenerative disease, a most common format of dementia, constituting 60% to 70% of all cases. Age is an important factor for onset of sporadic AD.Apolipoprotein E (ApoE) plays an important role in the distribution and metabolism of cholesterol and triglycerides. ApoE is synthesized by the liver, brain (primarily astrocytes).in humans. The ApoE gene shows polymorphism, with three different alleles (ε2,ε3,ε4), and gives rise to six different phenotypes (E2/2, E2/3, E2/4, E3/3, E3/4, E4/4). Large studies have shown that isoforms of ApoE gene is associated with onset of AD. ApoE4 allele is believed as a major genertic risk factor of AD.To our surprise, although GFAP-apoE transgenic mice have been widely used in the study of AD and other related diseases, there is limited information on the general brain morphology in the transgenic mice. In the present study, we aimed to investigate the effect of ApoE isoforms on the number and size of cells in hippocampus and the morphology of blood vessels in the brain of GFAP-apoE transgenic mice with age by the two conventional staining methods, thionin staining and HE stainging. In our results,We did not observe apparent differences in the cortical layer between apoE3/3 and apoE4/4 mice. Our results showed that the number of hippocampus cells in CA1–CA3 areas was not significantly different between apoE3/3 and apoE4/4 mice among different age groups. We observed that the size of cells in CA1 area decreased in GFAP-apoE mice with aging; in 20-21 months, this cellular atrophy in apoE4/4 mice was more significantly evident than that in apoE3/3 mice(P<0.05). In 20-21months,old apoE4 mice all showed microvascular lesion in varying degrees in thalamus, the lesion degrees were 5.24%; 1.41%; 3.97%, respectively. But there were only one of three old apoE3/3 mice, which showed microvascular lesion in thalamus, and the lesion degree was 0.85%. The current study suggests that the CA1 cellular size in hippocampus decreases with aging, which is not affected by the apoE genotype. The CA1 cell atrophy is more severe in old apoE4/4 mice as compared with age-matched apoE3/3 mice. These morphological studies will provide a basis of brain morphology for studying the relation between apoE and the mechanism of AD in GFAP-apoE transgenic mice...