海马小白蛋白阳性神经元对缺血反应的区域性特征

背景短暂全脑缺血再灌流早期海马各区域小白蛋白(parvalbumin,PV)阳性神经元的变化程度以及变化时间是否存在敏感性差异?目的研究缺血敏感脑区海马的PV阳性神经元的改变以及缺血性脑损伤的细胞分子机制.设计随机对照的实验设计.地点和对象实验在中山大学中山医学院人体解剖学教研室完成.40只成年健康雄性大鼠,由中山大学中山医学院实验动物中心提供.干预建立4管阻塞缺血大鼠模型,随机分为正常对照组,缺血再灌流0,6,12,24 h共5组,每组8只.全脑缺血20 min后再分别灌流0～24 h.PV免疫组织化学反应观察海马各区域PV阳性神经元表达水平及定量PV阳性神经元数目.主要观察指标海马各区域PV阳性神经元表达水平及定量PV阳性神经元数目.结果正常对照组大鼠海马各区域(CAl,CA2,CA3)的始层、锥体层、放射层和腔隙分子层,齿状回的颗粒层、分子层及多形层(门区)的切片观察均出现PV阳性反应.再灌流6～12 h内见PV阳性神经元出现胞体肿胀、胞浆染色变淡等变化.放射层突起密度减少;PV阳性终末的颗粒密度稀疏,以锥体细胞胞体周围的变化为明显.PV阳性神经元数目缺血再灌流0 h时,海马CA2区从(20.67±1.16)个减少为(11.66±3.06)个,CA3区从(12.33±2.52)个减少为(4.33±1.53)个;再灌流6 h时,海马CA2区从(20.67±1.16)个减少为(11.33±3.51)个,CA3区从(12.33±2.52)个减少为(5.00±1.73)个;再灌流24 h时,海马CA1区从(0.33±1.53)个减少为(2.33±4.93)个,门区从(1.67±1.53)个减少为(3.33±4.51)个;上述缺血再灌流组PV阳性神经元数目减少与缺血前比较有统计学意义(t=4.4505～9.2258.P＜0.05).结论海马PV阳性神经元对全脑缺血存在区域敏感性差异.

Spatial characteristics of the reaction of hippocampal parvalbumin positive neurons to cerebral ischemia

BACKGROUND:It remains unclear whether the changes of parvalbumin (PV)-positive neurons in different hippocampal regions exhibit sensitivity difference in response to temporary global ischemia-reperfusion at early stages.OBJECTIVE: To observe the changes of PV-positive neurons in different hippocampal regions in global ischemia-reperfusion.DESIGN: A randomized controlled study was conducted.SETTING and PARTICIPANTS: The experiment was performed in the Department of Human Anatomy, Zhongshan Medical College of Sun Yat-sen University. Forty healthy male rats were purchased from the Experimental Animal Center of Zhongshan Medical College, Sun Yat-sen University.INTERVENTIONS: Rat models of cerebral ischemia induced by 20-minute 4-vessel occlusion were randomly divided into 4 groups subject to reperfusion for 0, 6, 12, and 24 hours( n = 8), respectively, with the rest 8 rats serve as control group. PV immunohistochemistry was performed.MAIN OUTCOME MEASURES: The expression levels of PV in different regions of the hippocampus were observed.RESULTS: The number of PV-positive neurons decreased only under the following conditions: 0 hour after ischemia in the hippocampal CA2 region (11.66±3.06 vs 20.67±1.16) and CA3 region(4.33±1.53 vs 12.33 ± 2.52); 6 hours of the reperfusion in the hippocampal CA2 region (11.33±3.51 vs 20.67±1.16) and CA3 region(5.00±1.73 vs 12.33 ± 2.52);24 hours of the reperfusion in the hippocampal CA1 region (2.33 ±4.93 vs 0.33 ± 1.53)and portal area(3.33 ±4.51vs1. 67±1.53).CONCLUSION: Rat hippocampal PV-positive neurons exhibit regional difference in their sensitivity to global cerebral ischemia.