姜黄素对低氧诱导慢性神经损伤小鼠认知功能的影响

Effect of Curcumin on Cognitive Function in Mouse Model of Low Oxygen-induced Chronic Nerve Injury

摘要:

目的 观察姜黄素对低氧诱导慢性神经损伤小鼠认知障碍的影响及其作用机制。方法 80只雄性C57BL/6小鼠随机分为8组：空白组、姜黄素低剂量组、姜黄素中剂量组、姜黄素高剂量组、模型组、模型+姜黄素低、中、高剂量组，每组10只；采用模拟拉萨海拔高度氧气浓度（3 700 m左右氧气浓度为13% O₂，可诱发低氧响应但不会造成迅速的低氧损伤）持续刺激小鼠14 d以制备低氧诱导慢性神经损伤小鼠模型（H14 d）。造模完成后，6个姜黄素组小鼠分别灌胃姜黄素（100、200、300 mg·kg^-1），空白组和模型组灌胃等体积的生理盐水，每天1次，连续1周。之后使用旷场、新物体识别及Morris水迷宫等实验检测小鼠行为学的改变，采用苏木素-伊红（HE）染色方法观察小鼠海马形态结构变化，使用实时荧光定量聚合酶链式反应（Real-time PCR）检测小鼠海马炎症因子白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α） mRNA表达变化，使用免疫荧光实验观察小鼠海马中小胶质细胞总数及激活状态，使用蛋白免疫印迹法（Western blot）检测小鼠海马中环磷酸腺苷反应结合元件（CREB）和脑源性神经营养因子（BDNF）等蛋白表达。结果 与空白组比较，模型组小鼠新物体识别率降低（P<0.01），首次找到平台时间延长（P<0.01），穿越平台次数减少（P<0.05），证实低氧小鼠认知功能受损；与模型组比较，模型+姜黄素中剂量组小鼠新物体识别率、首次找到平台时间、穿越平台次数得到明显改善（P<0.05，P<0.01），海马的异常形态结构改变得到修复、炎症因子及小胶质细胞活化减少，CREB和BDNF等表达增加（P<0.05）。结论 姜黄素对低氧诱导神经损伤小鼠的认知功能障碍具有显著的改善作用，该研究为临床高原低氧诱导的慢性脑损伤的治疗提供了新的思路。

Abstract:

Objective To observe the effect and mechanism of curcumin on cognitive function in the mouse model of low oxygen-induced chronic nerve injury.Method Eighty male C57BL/6 mice were randomized into eight groups： control， low-， medium-， and high-dose （100， 200， and 300 mg·kg^-1， respectively） curcumin， model， model + low-dose curcumin， model + medium-dose curcumin， and model + high-dose curcumin groups （n=10）. The mouse model of low oxygen-induced nerve injury was prepared by continuous stimulation with simulated oxygen concentration at Lhasa altitude （13% O₂ at about 3 700 m） for 14 days. After the completion of modeling， mice in the six curcumin groups were administrated with curcumin at corresponding doses by gavage， while those in the control group and the model group were administrated with the same amount of normal saline once a day for one week. After that， open field， novel object recognition， and Morris water maze tests were carried out to reveal the behavioral changes of mice. The morphological changes of the hippocampus were observed by hematoxylin-eosin staining. The mRNA levels of interleukin （IL）-6 and tumor necrosis factor （TNF）-α in the hippocampus and peripheral blood of mice were determined by real-time PCR. The activation of microglia in the hippocampus was observed by Iba-1 staining. The protein levels of brain-derived neurotrophic factor （BDNF） and cAMP-response element-binding protein （CREB） in the hippocampus were determined by Western blot.Result Compared with the control group， the model group showed decreased new object recognition rate （P<0.01）， extended time to find the platform （P<0.01）， and reduced platform crossings （P<0.05）， which proved that the cognitive function of mice was impaired. Compared with model group， the model + medium-dose curcumin group showed increased new object recognition rate， shortened time to find the platform， and increased platform crossings （P<0.05，P<0.01）. Moreover， the application of curcumin repaired the abnormal morphological and structural changes in the hippocampus， reduced the inflammatory cytokine levels and activation of microglia， and upregulated the expression of CREB and BDNF （P<0.05）.Conclusion Curcumin demonstrates a therapeutic effect on low oxygen-induced cognitive decline， which provide a potential cure for treating chronic brain injury induced by high-altitude low oxygen in clinical practice.