瞬时高加速度致舱内大鼠早期空间记忆障碍及其意义

Transient,high acceleration induces early deficits in spatial memory of rats in airtight cabin

目的观察爆炸致密闭舱室内大鼠瞬时高加速度负载后早期空间记忆变化,探讨其相应的临床意义。方法制作爆炸致密闭舱室内大鼠(坐姿)瞬时高加速度负载时脑损伤模型;24只SD雄性大鼠随机分为正常对照组、800mgTNT爆炸当量致伤组(致伤组)、800mgTNT爆炸当量致伤+座位悬空组(减震组),每组8只;利用wavebook516A数据采集系统记录舱室内座位加速度大小,作为大鼠加速度负载评价指标;伤前7天为Morris水迷宫定位航行训练期,伤后1小时进行空间探索实验,记录大鼠穿越平台次数(Thenumber of times of crossing the platform)与跨越目标象限时间占整个游泳时间的百分率(The percentage of thetime spent on the target quadrant to the total swimming time);空间探索实验结束后大鼠被处死,取脑固定,尼氏染色,观察海马CA1区锥体细胞损伤情况。结果致伤组座位加速度峰值为(13109±1167)g,作用时间为(11.08±1.43)ms,减震组座位加速度峰值仅为(4.0±1.2)g,作用时间仅为(0.34±0.08)ms;穿越平台次数:对照组(4.75±1.75)次,减震组(3.88±1.13)次,两者无明显差异(P>0.05),而与致伤组(1.13±0.64)次存在显著差异(P<0.01);跨越目标象限时间占总游泳时间的百分率:对照组(53.93±13.72)%,减震组(49.60±10.75)%,两者无明显差异(P>0.05),而与致伤组(22.20±10.82)%存在显著差异(P<0.01);尼氏染色示致伤组海马CA1区存在锥体细胞急性损伤或坏死性改变,而减震组、对照组则无此改变。结论爆炸致密闭舱室内大鼠瞬时高加速度负载后早期可出现空间记忆障碍,这一结果有助于提高对装甲车辆触雷爆炸、底板未击穿时乘员仍可能遭受轻度创伤性颅脑损伤(mild-TBI)的认识,对临床医生来说具有重要意义。

Objective To observe early deficits in spatial memory of rats in airtight cabin induced by transient,high acceleration of explosion and explore its corresponding clinical significance.Methods Models of brain injuries induced by transient,high acceleration of explosion in airtight cabin were established;24 SD male rats were randomly divided into 3 groups： control group,explosion equivalent to 800mgTNT injury group（injury group） and explosion equivalent to 800mgTNT injury with a hanging seat group（shock absorption group）,n=8;wavebook516A data acquisition system was used to record the size of cabin seat acceleration,which was considered as the acceleration load evaluation indicator in rats;place navigation training in Morris water maze（MWM） was performed 7 days before injury and space exploration test 1 hour after injury,meanwhile,the number of times of crossing the platform and the percentage of the time spent on the target quadrant to the total swimming time were recorded;rats were killed after space exploration test and the brain was fixed by 4% paraformaldehyde solution,and the hippocampal CA1 subfield pyramidal cell damage was observed after brain slices were stained by Nissl staining.Results The peak of acceleration and the time of duration of seat in injury group was（13109±1167）g and（11.08±1.43）ms,while（4.0±1.2） g and（0.34±0.08） ms in shock absorption group;the number of times of crossing the platform was（4.75±1.75） in control group and（3.88±1.13） in shock absorption group without significant difference（P0.05）,while compared with injury group（1.13±1.46）,there was significant difference（P0.01）;the percentage of the time spent on the target quadrant to the total swimming time was（53.93±13.72）% in control group and（49.60±10.75）% in shock absorption group,there was no significant difference（P0.05）,while compared with injury group（22.20±10.82）%,there was significant difference（P0.01）;Nissl staining showed acute injury or necrotic change of pyramidal cells in hippocampal CA1 subfield which was not observed in control group and shock absorption group.Conclusion Rats in airtight cabin exposed to transient,high acceleration of explosion might suffer from early deficits in spatial memory,which contributes to improving awareness that occupant might suffer mild-traumatic brain injury due to armored vehicles explosion attacked by landmines with absence of bottom penetration.It is very important for clinicians.