Brain Damage And Differential Gene Expression With Injury Time Estimation Experiments

Objective:To study the expression levels of large number of genes and to identify genes not previously implicated in rat after traumatic brain injury,which may provide valuable information on therapies and may be helpful in search of forensic markers of vitality.Methods:The model of traumatic brain injury originally described by Feeney was employed with modification.Wistar rats were randomly divided into cortical impact injury group and shame operated control group.Each group comprised 12 Wistar rats. At 5 hours following cortical impact injury, animals were anaesthetised by intraperioneal injection of 4% chloral hydrate and sacrificed by decapitation .Then the brain tissue were dissected and stored in the liquid nitrogen until required for RNA isolation. The total RNA of tissues were extracted and the probes were prepared by reverse transcriptase reaction(RT)and then hybridized with cDNA microarray.Results:Of 4096 randomly selected arrayed genes or expressed sequence tags from a rat cDNA library,124 genes or expressed sequence tags were found to be differently expressed at 5 hours following cortical impact injury(28 genes and 24 ESTs were increased, and 46 genes and 26 ESTs were decreased);Genes involved in cell homeostasis such as Secretory leukocyte protease inhibitor, transthyretin and inflammatory response such as phospholipase A2,interliukin-1 were primarily up-regulated while those encoding mitochondrial enzymes(such as ATP synthase,ATP citrate lyase),metobolic molecules, calcium signaling protein ,and cellular structure protein(such as tublin) were predominantly down-regulated; Down-regulated genes were also seen in neutrophic factor/receptors(Ciliary neutrophic factor, Glial cell line-derived neutrophic factor ); Partly channels and transporters were down-regulated whereas partly channels and transporters were up-regulated at same time.To our best knowledge,A number of genes were found which have not been previously report in traumatic brain injury.Conclusions:The geneomic response to traumatic brain injury is complex and a great number of genes involved in this pathophysiological course. The molecular mechanism of traumatic brain injury could not be fully disclosed by investigating only one changes of a gene or a few genes.The microarray methods is an ideal tools for researching multi-genes involved diseases.