丰富环境对重复轻度脑损伤小鼠记忆功能及神经再生的影响

关键词：重复轻度脑损伤  丰富环境  记忆  海马  神经再生

Keywords:repetitive mild traumatic brain injury  environmental enrichment  memory  hippocampus  nerve regeneration

摘要：

      摘要 目的：探讨丰富环境（environmental enrichment， EE）对重复轻度创伤性脑损伤（repetitive mild traumatic brain injury， rmTBI）小鼠学习、记忆功能和海马组织神经细胞再生的影响。 方法：60只雄性C57BL/6小鼠随机分为3组：普通环境-假手术组（NC-sham组）、普通环境-脑损伤组（NC-TBI）和丰富环境-脑损伤组（EE-TBI）（n=20/group）。根据前期研究中探索的rmTBI模型建立方法，对脑损伤组（EE-TBI和NC-TBI）小鼠进行重复轻度创伤性脑损伤造模，假手术组只予相应天数、次数的麻醉，不予损伤；造模前3天及造模后4周内，丰富环境组小鼠被安置在具有大空间、玩具、探险、运动器械、水食充足的丰富环境中；普通环境组小鼠置于水食充足、小笼饲养的普通环境；造模4周后，通过Morris水迷宫实验（morris water maze， MWM）进行行为学测试，分析比较各组小鼠学习和空间记忆等行为学差异；取小鼠海马组织，通过免疫组化法，检测分析各组小鼠海马DG区Doublecortin(DCX)的表达差异。 结果：与假手术组小鼠相比，重复轻度脑损伤后，小鼠逃避潜伏期延长，60s内穿越平台次数减少，学习与记忆能力减退（均P<0.05）；与普通环境中的脑损伤小鼠相比，丰富环境中的脑损伤小鼠学习能力和记忆力增强（P<0.05）；与假手术组相比，重复轻度脑损伤后小鼠海马DG区DCX蛋白表达显著降低（P<0.01），丰富环境可显著升高脑损伤后海马组织DCX蛋白的表达（P<0.05）。 结论：重复轻度创伤性脑损伤后，丰富环境可有效改善小鼠的学习和空间记忆能力，并增加海马DG区神经细胞的再生。

Abstract:

      Abstract Objective： To explore the effects of environmental enrichment (EE) on the learning and memory function and the regeneration of neural cells in hippocampus of mice with repetitive mild traumatic brain injury (rmTBI). Method： A toll of 60 male C57BL/6 mice were randomly divided into 3 groups： sham-normal environment group (NC-sham)， brain injury-normal environment group (NC-TBI) and brain injury-enriched environment group (EE-TBI) (n=20/group). According to the rmTBI model established in our previous study， the brain injury groups (EE-TBI and NC-TBI) mice were repetitively subjected to a mild traumatic brain injury. Mice in the sham-NC group underwent anesthesia exposure only. 3 days before and 4 weeks after modeling， the EE-TBI mice were placed in a environmental environment with plenty of space， toys， adventure， sports equipment， and ample water supplies. Mice in the normal environment group were placed in an small cages and ordinary environment with adequate water feeding. After 4 weeks of modeling， behavioral studies were performed using Morris Water Maze (MWM) to analyze and compare the behavioral differences of learning and spatial memory in each group. Take the hippocampus tissue and analyze the expression of doublecortin in hippocampal DG area by immunohistochemistry. Result： Compared with the sham-NC mice， after repeated mild brain injury， the escape latency was prolonged， the number of crossing platforms decreased within 100s， the learning and memory capacity decreased (both P<0.05). Compared with the brain injury mice in the general environment， there was a significant better learning ability of brain injury mice in a rich environment (P<0.05). Compared with the sham-NC group， the expression of DCX protein in the hippocampal DG area was significantly decreased (P<0.01) after brain injury， and the enriched environment had a significant increased expression of DCX protein in hippocampus after brain injury compared to the mice in the NC-TBI group(P<0.05). Conclusion： Environmental enrichment can effectively improve the study and spatial memory ability of mice and increase the regeneration of nerve cells in hippocampal DG area after repetitive mild traumatic brain injury.