Modeling Alzheimer’s Disease In Zebrafish

Alzheimer’s disease (AD) is a progressive disease in central nervous system (CNS). Recently, the number of people suffering AD is steadily increasing. There are no efficient medicines and methods for treating AD, and the pathogenesis of AD is not clear. Thus, it is important to analyze the pathogenesis and explore medicines of AD. However, the primary challenge we have to face is to develop disease models that can recapitulate both the genetic and phenotypic aspects of the disease. There are more than a dozen of different genetic mouse models of AD that only partially satisfy few requirements, and mouse models are time-consuming and poor repetitive.Zebrafish is a new model organism. Their bodies are small, the female can spawn every week, the amount of embryos is large, embryos can in vitro fertilize and develop,the embryo and larve are transparent to easy to observe. Zebrafish are easily raised and sensitive to drugs and poisons, so they are suitable for the establishment of disease models, and for the study of the mechanisms of disease and drug screening. Nowadays, zebrafish are used as an animal model for a wide variety of human diseases.In this assay, zebrafish were exposed in AlCl3solution to establish zebrafish aluminum model. Then we used T-maze, transmission electron microscope(TEM), HE staining, biochemical parameters and RT-qPCR to explore whether zebrafish could become a new model of AD.1.The T-maze results show that, the latency of zebrafish in aluminum group to find enriched chamber(EC) in last trail compared with the first trail is significant increase (P <0.05),and the latency of zebrafish in the control group is significantly decrease (P <0.01), Zebrafish in aluminum group has impair in learning and memory2.Under TEM we observed mitochondria swelling and ridges reducing or even disappearing and endocytoplasmic reticulum showed a typical swell and deformation in zebrafish brain of aluminum group.3.HE staining showed that the number of neurons in zebrafish brain of the aluminum group are decreased.The biochemical parameters in zebrafish brain of the aluminum group comparing with the control group showed that,AchE activity is significantly increased (P<0.05), ChAT activity is significantly decrease (P<0.05),SOD activity is significantly decrease (P<0.01) and MDA content is significantly increased (P<0.01). The AchE and ChAT are the enzyme of Ach synthesis and hydrolase, their activity can indirectly description the content of Ach which related to learning and memory.The ACh content of zebrafish in aluminum group, resulting in the ability of learning and memory decline. The SOD activity and MDA content are related to free radicals. The results show that aluminum can produce free radicals accumulate in the brain leading to neuronal death, which lead to the occurrence of neurodegenerative diseases.4.The appb and psenl mRNA expression levels of zebrafish brain decrease in aluminum group zebrafish, compared with the control group (P<0.05), psen2and bacel mRNA expression levels are increased,but have no significant(P>0.05). the four genes in AD research are related to Aβ production, although we failed to find the way to detect the Aβ in zebrafish brain, gene expression results showed that zebrafish may have similar AB substance produces. All results suggest that the aluminum can induce the zebrafish neuron damage and induced AD-like changes and may produce similar pathological changes,which indicate zebrafish aluminum model may be used as a new model for AD research.In this assay we used zebrafish appb promoter regulation of human APP Swedish mutant gene (APPsw) and insert in Tol2transposon vector to establish the AD transgenic model by microinjection the plasmid. The experimental results show that the pTol2-appb-APPsw-CMV-EGFP vector was successfully constructed,and through microinjection we generate transgenic zebrafish expressing green fluorescence in the brain, eyes, heart and vascular specificity. The F0generation zebrafish hybrid with wild-type zebra fish to get the F1.By extracting the F1generation RNA and using RT-PCR,we identified that the foreign gene was inserted,successfully.