| Alzheimer's disease (AD) is one of the most prevalent progressive, neurodegenerative diseases, which primarily affects the elderly population. The aetiology of AD remains unknown and as yet, there is no known cure. Cholinesterase inhibitors are most widely used drugs for the treatment of AD, but their effect is only to ameliorate symptoms and they do not achieve any permanent improvement. To develop more effective AD therapeutic drugs with lower toxicity and lower side-effect remains an urgent task. The development of technologies in molecular biology provides ideas and methods to study the mechanism, and to screen or identify the therapeutic targets of this disease. Closely combining the techniques of genomics, proteomics, microarray and bioinformatics in drug discovery has been proposed as a rapid and efficient approach to search and find new potential drug targets and new active compound.The main symptoms of AD are primarily memory loss, as well as other cognitive impairments. Many genes and their proteins regulate learning and memory process. At present, genes of Apo E-4, APP, PS-1 and PS-2 are known publicly as some of reasons of AD. Furthermore, there are still lots of unknown genes that may play important roles in AD. Learning and memory is one of the functions of the central nervous system (CNS). Hippocampus is one of the most important brain regains for learning and memory. The expression levels of mRNA in the brain may provide a profile of some function of CNS and for this reason the differential expression of mRNA is also termed as functional molecular fingerprint of the neurons.The senescence-accelerated mouse/prone 8 (SAMP8) is now the relatively ideal animal model for AD research. It develops accelerated deficits in learning and memory with aging, companying with a lot of neuropathologic changes similar to AD occur inthe central nervous system. It is used to elucidate the fundamental mechanism of senescence, and senescence-related learning and memory dysfunction and to evaluate effects of drugs for senescence-related diseases and learning and memory deficiency.In order to screen gene targets of AD, the cDNA libraries of differental expression genes in the hippocampus of SAM were constructed, and then cDNA microarray of differential gene expression was prepared and was used to screen the differential expressed genes in the hippocampus of SAMP8. The obtained ESTs were validated by bioinformatics and real time quantitative RT-PCR technique. At last, the effects of Liuwei Dihuang decoction (LW), a traditional Chinese medicinal prescription, and Huperzine A (HupA), a cholinesterase inhibitor, on the gene expression of hippocampus in SAMP 8 was investigated.1. Construction of suppression subtractive library of hippocampus of senescence accelerated mouseSuppression subtractive hybridization (SSH) is a kind of effective and rapid technique with low false-positive ratio and good repeatability to isolate differential expressed genes. This paper employs SSH technique to construct the cNDA libraries with differentially expressed genes in the hippocampus of 12mon male SAMP8 and SAMR1 successfully. PolyA+ RNA was purified with the Oligotex mRNA Kits (QIAGEN) from total RNA in the hippocampus of SAMP8 and SAMR1. The forward library of SAMP8's cDNA as tester and SAMRl's cDNA as driver includes 864 colonies and the reverse library of SAMP8's cDNA as driver and SAMRl's cDNA as tester includes 960 colonies. The libraries were evaluated by PCR. The positive ratio of libraries is 96.18% and the length of cDNA fragments is ranged from 250 to 2000bp. The two libraries provide abundance material to the following study.2. Preparation of cDNA microarray and screening on the two subtractive cDNA librariesGene microarray is a kind of rapid, effective, sensitive and high throughput technique to detect differentially expressed genes. It is widely used in gene expression, mutation detection, SNP, gene diagnosis and medicine targets screening. In this paper, two SSH libraries amplified by PCR and purified w...
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