新生鼠缺氧缺血再灌注后海马p-CREB c-fos表达的变化(英文)

Changes of p-CREB and c-fos Expression in the Hippocampus of Neonatal Rats after Hypoxic-Ischemic and Reperfusion Brain Damage

目的 探讨新生鼠脑缺氧缺血再灌注后的神经保护机制。方法7d龄SD新生鼠7窝(每窝选用8只,共56只),随机分为假手术对照组、缺氧缺血脑损伤组。经弹性管穿线阻断右颈总动脉3h,低氧(8％O_2和92％N_2混合气)1h,制备HIBD模型。3h后剪开扎线予再灌注,彩色多普勒监测右侧颈总动脉血流。免疫组化检测磷酸化的CREB和c-fos在不同时间点(再灌注3h,6h,12h,24h,48h,72h和7d及假手术后24h)海马区的表达。Thionin染色观测神经元凋亡情况。结果 HIBD再灌注3h,24h新生鼠右侧海马p-CREB表达达高峰,7d后下降至假手术组水平;c-fos表达6h达高峰,24h稍降,48h又升高,7d后显著降低但仍高于对照组(P< 0.01)。Thionin染色发现:再灌注24h右侧海马CA1区已有明显的凋亡,但7d后神经元无明显丢失。结论 缺氧缺血再灌注后CREB磷酸化可能经信号转导调节c-fos的表达,这对保护损伤侧海马锥体神经元,尤其是敏感的CA1区神经元是非常重要的。 [中国当代儿科杂志,2003,5(1):12—16]

Objective To explore the protective mechanism after hypoxic-ischemic and reperfusion damage of the brain. Methods Seven-day-old SD rats from seven broods (eight rats from each brood, n = 56) were randomly divided into the HIBD group and sham operation group. The HIBD model was established by temporarily occluding the right common carotid artery for 3 hours with a thread through an elastic tube, and then they were exposed to the gas mixture of 80 ml/L oxygen and 920 ml/L nitrogen for 1 h. After 3 hs, the common carotid artery was reperfused. The blood flow of the right common carotid artery was detected by the Color Doppler. The expressions of p-CREB and c-fos in the hippocampus at different reperfusion periods (3 hs, 6 hs, 24 hs, 48 hs, 72 hs and 7 days after reperfusion and 24 hs after sham operation) were detected by immunohistochemical methods. Thionin staining was used to observe the apoptosis of neurons. Results In the HIBD group, the expression of p-CREB in the right hippocampus peaked 3 hs and 24 hs after reperfusion, and then decreased to the level of the sham group on the seventh day. The expression of c-fos reached the peak 6 hs after reperfusion, and another peak appeared 48 hs after reperfusion. Seven days after reperfusion, the number of c-fos positive cells decreased, but they were still more than those in the sham operation group ( P <0.0l). Using Thionin staining, we found that the apoptosis of neurons in the CA1 region marked 24 hs after reperfusion. Conclusions The persistent activation of CREB in the hippocampus regulates the expression of c-fos through signal transduction, and it is involved in the course of neurons' survival and repair during the period of post hypoxic-ischemia reperfusion. It is very important for the protection of pyramidal hippocampal neurons of the damaged side, especially of the sensitive CA1 region. [Chin J Contemp Pediatr, 2003, 5(1): 12 - 16]