叶酸对高同型半胱氨酸血症大鼠主动脉基因组总甲基化水平影响研究

Effects of folic acid on global DNA methylation of aorta in rats with hyperhomocysteinemia

目的探讨叶酸对高蛋氨酸饮食诱导高同型半胱氨酸血症(Hhcy)大鼠主动脉组织基因组总甲基化水平的影响。方法健康6周龄雄性Wistar大鼠36只,体质量(160±10)g,适应性喂养1周后随机分为对照组、高同型半胱氨酸组和叶酸干预组,每组12只。对照组给予AIN-93G配方饲料,高同型半胱氨酸组饲以含1.7%蛋氨酸的AIN-93G配方饲料,叶酸干预组饲以含1.7%蛋氨酸和0.008%叶酸的AIN-93G配方饲料。喂养18周后,全自动生化仪测定血浆Hcy、叶酸浓度;取大鼠胸主动脉进行苏木素-伊红(HE)染色,观察主动脉组织形态学变化;改进酶联免疫吸附测定法(ELISA)检测大鼠主动脉组织DNA甲基转移酶活力和基因组总甲基化水平。结果 18周蛋氨酸饮食可以诱导大鼠高同型半胱氨酸血症,叶酸干预可以拮抗血浆同型半胱氨酸(Hcy)升高(P<0.01)及其介导的主动脉形态学变化;高同型半胱氨酸组主动脉组织DNA甲基转移酶活力和基因组总甲基化水平明显低于对照组(P<0.01,P<0.01);叶酸降低血浆Hcy的同时,主动脉组织DNA甲基转移酶活力和基因组总甲基化水平明显升高(P<0.01,P<0.05)。结论叶酸摄入不仅可以拮抗血浆Hcy水平升高,而且升高主动脉组织DNA甲基转移酶活力和基因组总甲基化水平。

【Objective】 To investigate the effects of folic acid on global DNA methylation of aorta in rats with hyperhomocystinemia induced by dingestion of excess methionine.【Methods】 36 healthy 6 week-old Wistar male rats,weighing（160±10） g,after being fed adaptable for one week,were randomly divided into control group（n =12）,hyperhomocysteinemia group（n =12）,folic acid treatment group（n =12）.The control group was fed with AIN-93G diet.The hyperhomocysteinemia group was fed with high-methionion diet,consisting of AIN-93G diet plus 1.7% methionion.The folic acid treatment group was fed with high-methionion plus folic acid-rich diet,consisting of AIN-93G diet plus 1.7% methionion and 0.008% folic acid.After be maintained for 18 weeks on the previously described diets,the homocysteine and folic acid concentrations in the plasma was measured with the IMX assays.The thoracic aorta was harvested for morphology（HE staining）.The DNA methyltransferase activity and global DNA methylation status of arotic tissue was determained using an innovative enzyme-linked immunosorbent assay（ELISA）.【Results】 A high methionine diet for 18 weeks is sufficient to induce hyperhomocystinemia;Folic acid supplementation to the rats fed the high-methionine diet prevented an elevation homocysteine（Hcy） levels in the plasma（P 0.01） and morphological changes in the thoracic aorta.Compared with the control group,the Hcy group had decreased DNA Methyltransferase Activity and global DNA methylation status（P 0.01,P 0.01）.After folic acid supplementation,the lowering of Hcy levels was accompanied by a marked elevation of DNA methyltransferase activity and global DNA methylation status in aorta（P 0.01,P 0.05）.【Conclusion】 Folic acid supplementation can blunt the rise in Hcy but also can increase DNA methyltransferase activity and global DNA methylation status in the aorta of rats with hyperhomocystinemia.