| Background:The premise condition to investigate the pathogenesy and therapeutic measure is to establish the proper animal model of atherosclerosis. Nowadays, there is no perfect atherosclerosis animal model. Rat is suitable animal model to set up AS model.12/15-Lipoxygenase (12/15-LOX) is a non-heme iron-containing dioxygenase that converts free (e.g. linoleic acid or arachidonic acid) and/or esterified (e.g. lipoproteins or phospholipids.) polyunsaturated fatty acids to hydroperoxy derivatives. These products are involved in several inflammatory signal systems and correlated with inflammatory vessel diseases, for example atherosclerosis. Early researches suggested that 12/15-LOX play a pro-atherogenic role by oxygenizing LDL in vitro. Transgenic mice over expressing 12/15-LOX show enhanced atherosclerotic lesion formation. Conversely, 12/15-LOX gene disruption consistently reduced lesion progression. However, in contrast to the proposed pro-atherogenic role suggested by murine experiments, rabbit studies have provided contrasting results. These studies indicated that, depending on the model, 12/15-LOX can be pro- or anti-`atherogenic and to date, the mechanistic reasons for this discrepancy are unclear. However, the regulation of 12/15-LOX gene expression may be involved in the pathophysiological progression of atherosclerosis. The 12/15-LOX gene expression is high cell and tissue specificity. DNA methylation is one of the most frequent modify mode after duplication and before transcription. It is found that the nor-methylation status of the promoter field is essential condition to transcriptional activation of 12/15-LOX gene, and the nor-methylation condition have significant effect in tissusl- and organ-specific expression of 12/15-LOX gene. For this reason, observing the methylation status of 12/15-LOX gene promoter in vivo in this regulatory mechanism in CHD (coronary heart disease), may help to understand the pathogenesis of atherosclerosis and provide theoretical foundation for the prophylaxis and therapy of CHD.Objective:1. To establish AS rat model by feed high fat diet; 2. To explore the methylation status of 12/15-LOX promoter in AS plaque of AS rat ; 3. To compare the 12/15-LOX expression between the pluque in AS rat and normal vascular tissue in common rat.Methods:(1) 40 SD rats were randomly divided into two groups: experimental group and control group, 20 rats in each group. Feed the rats of experimental group by high-lipid and vitamin D3 overload for three months,while the rats of control group were normaly fed. After three months, to sacrifice all of the rats and to take the vascular tissue from arch of aorta to abdominal aorta, observe the histomorphology changes after HE stain. (2) Half-qualified methylation specific PCR was used to analyze the status of 15-lipoxygenase gene promoter of vascular tissue from aortic arch to abdominal aorta in the rats. And calculate the A value of the methylation specificity strap and the non-methylation specificity strap.Results:(1) After HE stain, obvious atheromatous plaque has been formed in the experimental group, but there is no histopathology changes in the control group. In experiment group, AS typical histological changes were observed by microscope. By contrast, there is normal vascular tissue in the rats of control group. (2) The experimental group and control group were divided respectively into hypomethylated status and hypermethylated status. The incidence of experimental group in hypomethylated status (85%) is significantly higher than in the healthy group (25%).Conclusion:1. It is a successful AS animal model that feed rats by high fat diet. 2. The status of 15-lipoxygenase gene promoter methylation of the vascular tissue is related with the formation of atherosclerosis, and may play an important role in the pathogenesis of atherosclerosis.
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