新生期惊厥对大鼠海马NR1和GABAARα1表达的长期影响

目的 研究新生期惊厥对大鼠海马N-甲基-D-天门冬氨酸(NMDA)受体1(NR1)和γ-氨基丁酸A受体α1亚单位(GABAARα1)表达的长期影响,以期揭示发育期惊厥导致成年大鼠惊厥阈降低的机制.方法 生后6 d的Wistar大鼠48只采用完全随机法分成三氟乙醚吸入惊厥组和对照组,每组各24只,惊厥组再细分为单次惊厥组(诱导惊厥一次,持续30 min)和反复惊厥组(每天诱导惊厥一次,持续30 min,连续6 d),对照组同样操作但不吸入三氟乙醚.分别于惊厥后第7天和第75天取大鼠海马,匀浆提取膜蛋白,应用免疫印记法测定NR1、GABAARα1蛋白表达.结果 单次惊厥组和反复惊厥组75 d的海马NR1表达无显著变化,而反复惊厥组7 d的海马NR1表达较对照组显著增加(P＜0.05).同时,与对照组相比,GABAARα1亚单位在单次惊厥组第75天以及反复惊厥组的表达均有统计学意义(P＜0.05).结论 新生期大鼠反复或单次长程惊厥持续状态能够对海马NR1和GABAARα1表达产生远期影响,这种改变可能在发育期惊厥导致的脑兴奋性提高和惊厥阈降低中起重要作用.

Long-term effects of neonatal seizures on subsequent activity-dependent NR1 and GABAA receptor α1 expressions in hippocampus of the rat

Objective To evaluate the pathophysiological mechanism of reduced seizure threshold following neonatal seizures by measuring the expression changes in N-methyl-D-aspartate (NMDA)receptor 1(NR1)and gamma-aminobutyric acid receptor A α1(GABAARα1)immunoreactivity which are the basic functional subunit in NMDA receptor or GABAA receptor family. Methods Seizures were induced by the inhalant flurothyl in 24 neonatal rats,starting from postnatal day 6.The 24 rats were subdivided into single seizure group (seizure lasted 30 min) and recurrent seizure group (seizures were induced for 30 min/d, totally 6 d). At day 7 and day 75 after the last seizure, brain homogenates were made. The expressions of NR1 and GABAARα1 proteins in hippocampus were examined by Westem blotting analysis. Results NR1 expression did not change significantly in single seizure group and recurrent seizure group at day 75, but was enhanced significantly in recurrent seizure group at day 7(P＜0.05).Meanwhile,polypeptide levels of GABAARα1 receptor subullit in the rat hippocanlpus decreased significantly in single seizure-treated rats at day 75 and recurrent seizure-treated rats at day 7 and 75 (P＜0.05). Conclusions Recurrent or single prolonged status epilepticus in neonatal rats might cause long-term modification on NR1 and GABAARα1 expressions in hippocampus at post-seizure 7 d or in adult, with excessive activation of excitatory neuronal circuits involving both reduction of GABAARα1 receptor and/or enhancement of NR1. This phenomenon might play a key role in long-term reduction of seizure threshold induced by early life status seizures.