3-甲基腺嘌呤对大鼠新生期惊厥致神经行为损伤的干预

目的 探讨大鼠新生期反复惊厥急性期应用自噬抑制剂3-甲基腺嘌呤(3-MA)对惊厥所致神经行为损伤的干预作用及机制。方法 实验在苏州大学衰老与神经疾病实验室进行。日龄6d(P6,下同)的Sprague-Dawley大鼠45只随机(随机数字法)分成三组,每组15只,惊厥组在P6吸入三氟乙醚诱导惊厥发作,持续30 min,连续6d;对照组同样操作但不吸入三氟乙醚;3-MA组惊厥前腹腔注射3 -MA(总量2μL),同样方法吸入三氟乙醚诱导惊厥,方法同惊厥组。三组大鼠于P12进行游泳行为评分测试大鼠神经运动发育,P17进行旷场实验,P43～P49行Morris水迷宫测试大鼠学习记忆功能,于PS0取海马组织,采用免疫印迹技术(Western blot)检测抗凋亡基因Bcl-2及自噬标记蛋白Beclin1的表达。各组行为学指标和蛋白水平采用方差分析进行统计。结果 惊厥后各组大鼠游泳行为测评,各项评分惊厥组明显低于对照组及3-MA组(P＜0.01),旷场实验显示惊厥组延迟时间(13.33±6.69)8]较对照组(7.11±2.37)8]和3-MA组(9.91±4.23)s]显著延长,差异具有统计学意义(F=4.39,P＜0.05);Morris水迷宫测试RS组第4、5天逃避潜伏期较对照组和3-MA组明显延长(P＜0.05)。惊厥组海马Bcl-2表达水平(0.587±0.139)较对照组(0.782±0.083)及3-MA组(0.799±0.163)显著降低,差异具有统计学意义(F=4.71,P＜0.05)。各组Beclin1的表达差异无统计学意义(F =0.27,P＞0.05)。结论 3-MA能显著改善大鼠惊厥后神经行为损伤,并可能与上调海马抗凋亡基因Bcl-2表达有关。

Effects of 3-Methyladenine on neonatal seizure induced behavioral damage and the underlying bcl-2,beclin-1 expressions in rat hippocampus

Objective To explore the intervention effect and the underlying molecular mechanism of 3-Methyladenine on behavioral damage of neonatal rat with prolonged seizures. Methods Forty-five 6-dayold SD rats were randomly ( random number) divided into the recurrent prolonged neonatal seizure group ( RS group), the 3-MA-treated seizure group and control group. The volatile agent flurothyl was used to induce 30 min seizure attack. At postnatal day 6 (P6), recurrent seizures were induced once daily for successive 6 days in both RS group and 3-MA group. In 3-MA group, 3-MA (2 μL) was injected daily before seizures induced. Neural-behavior changes were observed with double-blind method including swimming development, open field test and Morris water maze analysis. Bcl-2 and Beclinl protein levels in hippocampus were detected by western blot method at P50. Results The total scores of swimming behavior in RS rats were decreased significantly compared with those of control and 3-MA rats ( control: 7. 44 ±1. 13, RS: 5.06±1.63, 3-MA: 7.33 ±1.08, F=16.19, P＜0. 01) . The start-latency time of open filed behavior in RS rats ( 13. 33 ±6. 69) were increased significantly compared with that of control (7. 11 ±2. 37) and 3-MA rats (9. 91 ±4. 23) (F=4. 39, P＜0. 05). The escape latency was significantly longer in rats of RS group than that of control and 3-MA rats on the 4th and 5th days (P ＜ 0.05). The level of Bcl-2 in hippocampus of RS group (0. 587 +0. 139) were significantly lower than that of control (0. 782 +0. 083) and 3-MA groups (0. 799 + 0. 163) (F =4. 7 1, P ＜ 0. 05 ). There were no significant differences in the level of Beclin1 protein in hippocampus among the three groups ( F =0. 27, P ＞ 0. 05 ). Conclusions Pretreatment with autophagy inhibitor 3-MA in acute phase of neonatal seizures could significantly improve neurobehavioral capacity, which might be associated with the increased in the level of Bcl-2 protein in hippocampus.