组蛋白H3乙酰化在电离辐射所致神经发生障碍中的作用

Association of irradiation-induced hippocampal neurogenesis impairment with histone H3 acetylation

目的 探讨组蛋白乙酰化在电离辐射所致神经发生障碍过程中的作用.方法 建立急性放射性脑损伤大鼠模型,检测照射对海马区神经发生的影响,同时检测H3乙酰化及组蛋白去乙酰化酶1 （HDAC1）的表达变化.并应用HDAC1抑制剂曲古霉素A（TSA）进行干预实验验证.结果 免疫荧光染色显示照射后7d,大鼠5-溴脱氧尿嘧啶核苷（BrdU）、神经元抗核抗体（Anti-NeuN）双阳性（BrdU＋ NeuN＋）细胞数较对照组相比下降67％（P＜0.01）,照射后30 d基本观察不到BrdU＋NeuN＋细胞（P＜0.01）.Western印迹显示照射后7及30 d,H3乙酰化水平分别降低了30％和61％（P＜0.05）,免疫荧光染色进一步验证了该结果.HDAC1在照射后7d表达量即有所升高（P＞0.05）,照射后30 d其表达量为对照组的近2倍（P＜0.05）.注射HDAC1抑制剂TSA后,海马区神经发生得到了明显保护.结论 HDAC1依赖的H3乙酰化的降低在电离辐射所致海马神经发生损害过程中具有重要作用.

Objective To explore the effect of whole brain irradiation （WBI） on neurogenesis in hippocampus and its relationship with histone acetylation.Methods A signal dose of 30Gy 4MeV electron beam was offered to male Sprague-Dawley rats （150-200 g）.At Days 7 and 30,immunohistochemistry and Western blot were used to analyze the effects of WBI on neurogenesis and the expression of acetyl-H3 and histone deacetylase 1 （HDAC1） in hippocampus.Finally trichostatin A （TSA）,a HDAC1 inhibitor,was used to verify whether H3 acetylation was associated with neurogenesis impairment.Results Immunofluorescence showed that,at Day 7 post-irradiation,the number of BrdU ＋ NeuN ＋ cells reduced by 67% （P 〈 0.01） and it approached zero at Day 30 （P 〈 0.01）.Meanwhile,a significant decrease of HDAC1-dependent H3 acetylation was observed.Western blot showed 30% （P 〈 0.05） and 61% （P 〈0.01） reductions in H3 acetylation at Days 7 and 30 post-irradiation respectively.These results were further confirmed by immunofluorescent staining.Also HDAC1 levels significantly increased in a time-dependent manner at Days 7 and 30 post-irradiation.And TSA rescued neurogenesis impairment after WBI.Conclusion Radiation-induced HDAC1-dependent H3 acetylation decline is associated with long-term neurogenesis impairment in dentate gyrus.