持续惊厥后海马神经营养因子表达及其影响因素

目的 观察持续惊厥(status convulsion, SC)发作后海马神经细胞内BDNF、NGF表达的规律,探讨年龄、惊厥持续时间对BDNF、NGF表达的影响.方法 选用幼年和成年Wistar鼠诱发SC,分别于30 min SC及3 hSC后不同时间点处死实验动物.采用免疫组化观察海马表达BDNF、NGF的细胞类型与定位,并应用酶联免疫吸附实验对海马BDNF、NGF含量进行定量分析.结果 ①Wistar 鼠BDNF、NGF主要分布于齿状回颗粒细胞和锥体细胞.②SC后,幼年和成年鼠海马BDNF、NGF的表达均呈增加趋势.但NGF增加的水平和持续时间均较BDNF明显为低,呈现双相升高的特点.③海马BDNF的表达与惊厥时程呈正相关性;而NGF表达却并未随惊厥时间的延长而增加.④无论是短时或长程的SC发作,幼鼠海马内BDNF的表达速度和强度均快于、强于成年鼠;且随惊厥发作持续时间的延长,此种年龄差异性更为明显.结论 ①SC主要诱发大鼠海马神经细胞BDNF表达,对NGF表达的影响较小.②SC后大鼠海马神经细胞BDNF的表达受惊厥持续时间和年龄的影响.幼年鼠的表达速度和强度均优于成年鼠,其差异与惊厥持续时间呈正相关(P＜0.05).

Expression of neurotrophic factor in hippocampus and its correlative factors after status convulsion

Objective To investigate the expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in hippocampus after status convulsion (SC) and explore the influence of age and duration of SC on the expression of BDNF and NGF. Methods Animal model with the different durations of SC (30 min,3h) were established by intraperitoneal injection of 3 mEq/kg lithium chloride,18-20 h later,followed by 5 mg/kg pilocarpine in 40 adult Wistar rats aged 2-3 months and 40 20-day-old Wistar rats. The normal control and experimental control were made in ten adult rats and ten 20-day-old rats (n=5 for each control). The rats were sacrificed at 3 h,6 h,12 h,1 d,3 d,7 d after 30-minute SC,or 3 h,1 d after 3-hour SC respectively. The location and cell type expression of BDNF and NGF in the hippocampus were observed by immunohistochemistry. The levels of BDNF and NGF at different time points were quantitatively analyzed by enzyme-linked immunosorbent assay (ELISA). Results The cells expressing BDNF and NGF located mainly in the dentate granule cells and CA1-CA4 pyramidal cells of hippocampus. The most positive immunoreactivity was in cytoplasm,partly in axons. The expression of BDNF had the tendency of increase in all rats after 3-hour SC,peaked at 1 d and 3 d respectively. These increases lasted for at least 7 d. Moreover,a several-fold increase was observed at the peak levels. The patterns of NGF expression were similar to that of BDNF after SC. The elevated degree and duration of NGF expression were remarkably lower than that of BDNF,declining abruptly to below control levels by 12 h with the characteristic of biphasic increase. The expression of hippocampal BDNF had the positive correlation with the duration of SC,but that of NGF was not. No matter the duration of SC,there was more rapid and evident induction of BDNF in 20-day-old rats and adult rats. Moreover,the age-related difference was more obvious for the longer duration of SC. Conclusion SC induced the expression of BDNF chiefly in hippocampus,and had minor influence on that of NGF. The expression of BDNF was related to age and duration of SC. There was a more rapid and marked induction of BDNF in 20-day-old rats and adult rats. The age-related difference had the positive correlation with the duration of SC.