大鼠总基因甲基化状态改变相关危险因素的研究

Research on the relative risk factors for genomic DNA methylation in Wistar rats

目的:探讨高胆固醇血症(Hypercholesterolemia,HTC)对wistar大鼠主动脉基因组DNA总甲基化水平及总甲基转移酶活力的影响并比较高同型半胱氨酸血症(Hyperhomocysteinemia,HHCY)和HTC在影响主动脉基因组DNA总甲基化水平、总甲基转移酶活力之间的差异。方法:将wistar大鼠33只,随机分3组:对照组、蛋氨酸组、高胆固醇组,每组11只。对照组给予普通大鼠饲料,其余各组给予相应的配方饲料。持续喂养3个月后心脏取血检测血清同型半胱氨酸(Homocysteine,Hcy)、总胆固醇(Total cholesterol,TC)等相关指标。提取主动脉基因组DNA检测基因组DNA总甲基化水平、提取主动脉核蛋白检测基因组DNA总甲基转移酶活力。结果:经多个样本均数间的多重比较(Dunnett-t检验):高胆固醇组大鼠的血清TC水平明显高于对照组和蛋氨酸组,且差异有统计学意义(P<0.05),血清中甘油三酯(Triglyceride,TG)、低密度脂蛋白胆固醇(Low density lipoprotein-cholesterol,LDL-C)和高密度脂蛋白胆固醇(High density lipoprotein-cholesterol,HDL-C),差异无统计学意义(P>0.05)。蛋氨酸组大鼠血清Hcy水平明显高于对照组及高胆固醇组,且差异有统计学意义(P<0.05)。HHCY和HTC均增加基因组DNA总甲基转移酶活力,可促使基因组DNA去甲基化,与对照组相比,各组均具有统计学意义(P<0.05),但两组之间差异无显著性。结论:HTC降低大鼠主动脉基因组DNA总甲基化水平可能是HTC导致动脉粥样硬化发病重要机制之一,且HHCY和HTC在影响基因组DNA低甲基化之间的差异无显著。

Objective：To discuss the effect of hyperhomocysteinemia（HHCY） and hypercholesterolemia（HTC） on genomic DNA methylation and DNA methyltransferase activity in aortic tissue of Wistar rats and to compare their differences.Methods：Totally 33 Wistar rats were equally randomized into three groups：control group,methionine group and high-cholesterol group（n=11）.The rats in control group were fed with normal chaw while those in the other two groups were fed with formula chaw for three months.Heart blood was drawn to detect the serum homocysteine（Hcy） and total cholesterol（TC）.Aortic genomic DNA was extracted to detect genomic DNA methylation levels and aortic nucleoprotein was extracted to detect DNA methyltransferase activity.Results：The results of Dunnett-t test showed that serum TC level was significantly higher in high-cholesterol group than in control and methionine groups（P〈0.05）,but there was no statistically significant difference in triglyceride（TG）,low density lipoprotein cholesterol（LDL-C） and high density lipoprotein cholesterol（HDL-C） levels between high-cholesterol group and the other two groups（P 〉0.05）.Serum Hcy was significantly higher in methionine group than in high-cholesterol and control groups（P〈0.05）.Compared with control group,HHCY and HTC significantly increased DNA methyltransferase activity and promoted DNA demethylation in both high-cholesterol and methionine groups（P〈0.05）,though there was no significant difference between high-cholesterol and methionine groups（P 〉0.05）.Conclusions：Hypomethylation induced by HTC is one of the important mechanisms for the development of atherosclerosis.There is no significant difference between HHCY and HTC in leading hypomethylation.