轻型脑外伤对大鼠空间学习记忆的影响及机制研究

目的:探讨轻型脑外伤对大鼠空间学习记忆功能的影响及可能的机制。方法:成年SD大鼠120只,雌雄各半,随机分为雌性对照组、雌性实验组、雄性对照组及雄性实验组,各30只;实验组建立侧位液压冲击轻型颅脑外伤模型;术后8d,水迷宫测试大鼠学习记忆能力;水迷宫测试结束后,放射免疫法检测血清皮质醇(COR)水平;免疫组化法检测海马脑源性神经营养因子(BDNF)及酪氨酸激酶受体(TrkB)的表达。结果:水迷宫定位航行实验第4天,同性别大鼠实验组逃逸潜伏期较对照组显著延长(P<0.01);空间探索实验中,同性别大鼠实验组寻找平台潜伏期长于对照组(P<0.05),穿越平台次数少于对照组(P<0.05);同性别大鼠实验组血清COR水平显著高于对照组(P<0.01),海马BDNF及TrkB平均灰度值均低于对照组(P<0.05)。结论:轻型脑外伤导致大鼠认知功能缺损,可能与海马BDNF及TtkB表达减少,BDNF-TrkB通路受损有关。

Mild Traumatic Brain Injury Produces Spatial Learning and Memory Deficits in Rats

Objective: To investigate the effect of mild brain trauma on the spatial learning and memory of rats and its underlying mechanism.Methods: One-hundred and twenty SD rats(bisexual each half) were randomly divided into four groups: female control group,female experimental group,male control group and male experimental group(n=30,respectively).All rats in the experimental groups were developed a lateral fluid percussion model of mild brain trauma.Morris water maze(MWM) test was used to assess the spatial learning and memory of rats at day 8 after operation.Serum COR levels were determined by using a standard radioimmunoassay kit and the expressions of brain-derived neurotrophic factor(BDNF) and tyrosine protein kinase B(TrkB) in hippocampus were measured by immunoreactivity quantitative analysis after MWM test.Results: At the 4th day of navigation task,the escape latency of rats in the experimental groups were significantly longer than those in the control groups(P<0.01).In the probe trial,compared with those in the control groups,the times to reach platform location were longer and crossings over the platform area were less in the experiment groups(P<0.05).The serum COR levels in the experiment groups were significantly higher(P<0.01) and the expressions of BDNF and TrkB in hippocampus were lower(P<0.05) than those in the control groups.Conclusion: Mild brain trauma leads to cognitive deficits in rats.The reduced expressions of BDNF and TrkB in hippocampus may underlie the cognitive impairment.