抑制AMPARs内吞可改善创伤性脑损伤大鼠的运动和认知功能

Inhibition of GluA2-containing AMPA receptor endocytosis improves motor and cognitive functions in a rat model with traumatic brain injury

摘要

目的 研究抑制含GluA2亚基的α-氨基-3-羟基-5-甲基-4-异恶唑丙酸受体（α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors，AMPARs）的内吞对创伤性脑损伤（traumatic brain injury，TBI）大鼠模型运动和认知能力的作用及相关机制。 方法 构建中度TBI模型大鼠，分为Sham（仅开放颅窗）组，saline（生理盐水处理）组，scr-GluA2_3Y（对照肽scrambled Tat-GluA2_3Y处理）组和GluA2_3Y（实验肽Tat-GluA2_3Y处理）组，通过改良神经功能评分（Mahmood’s method neurological severity score，mNSS）及抓力实验检测大鼠运动及神经功能改善情况，之后用新物体实验和水迷宫实验评估大鼠的探索能力与空间学习记忆能力。后期通过Western blot分别检测海马体的突触蛋白和总蛋白中AMPARs表达情况的变化。 结果 mNSS及抓力实验显示：随时间推移，GluA2_3Y组的神经功能状态（P=0.013）及抓力（P<0.001）相较于saline组明显改善。新物体实验显示：GluA2_3Y组的接触次数（0.60±0.02，P<0.01）及接触时间（0.57±0.03，P=0.011）与scr-GluA2_3Y组相比明显增加（P<0.01，P=0.010）。水迷宫结果显示：与scr-GluA2_3Y组相比，GluA2_3Y组（21.43±1.76）的学习（P<0.001）与记忆（P=0.037）能力提高。Western blot显示：与对照组相比，GluA2_3Y治疗（0.98±0.03，P=0.981 vs. Sham组，P=0.025 vs. saline组，P=0.025 vs. scr-GluA2_3Y组）可特异性提高海马中GluA2的含量。 结论 AMPARs内吞抑制剂，如Tat-GluA2_3Y可通过提高大鼠海马体中GluA2的含量来修复TBI引起的运动和认知功能受损。

Abstract

Objective To investigate the effects of inhibition of GluA2-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor（AMPAR） endocytosis on motor and cognitive functions in a rat model with traumatic brain injury（TBI） and related mechanisms. Methods The model rats with moderate TBI were established and divided into the Sham group （with open cranial window only），saline group（treated with normal saline），scr-GluA2_3Y group （treated with the control peptide scrambled Tat-GluA2_3Y），and GluA2_3Y group（treated with the test peptide Tat-GluA2_3Y）. The improvement in motor and neurological functions of rats was measured by the Mahmood’s method neurological severity score（mNSS） and grip strength test. Then，the exploration ability and spatial learning and memory ability of rats were assessed by the new object experiment and water maze experiment. The change in AMPAR expression of synaptic and total proteins in the hippocampus was measured by Western blot. Results The mNSS and grip strength test showed that the neurofunction status（P=0.013） and grip strength（P<0.001） of the GluA2_3Y group improved significantly over time compared with the saline group. The new object experiment showed that the number of contacts （0.60±0.02，P<0.01） and contact time（0.57±0.03，P=0.011） of the GluA2_3Y group were significantly increased compared with the scr-GluA2_3Y group（P<0.01，P=0.010）. The water maze experiment results showed that the learning（P<0.001） and memory ability（P=0.037） were improved in the GluA2_3Y group （21.43±1.76） compared with the scr-GluA2_3Y group. Western blot revealed that the content of GluA 2 in the hippocampus was specifically increased after treatment with GluA2_3Y（0.98±0.03，P=0.981 vs. Sham，P=0.025 vs. saline，P=0.025 vs. scr-GluA2_3Y）. Conclusion AMPAR endocytosis inhibitors，such as Tat-GluA2_3Y，repair the impaired motor and cognitive function induced by TBI by increasing the content of GluA2 in the rat hippocampus.

关键词

创伤性脑损伤 / α-氨基-3-羟基-5-甲基-4-异恶唑丙酸受体内吞作用 / 学习和记忆 / 海马体

Key words

traumatic brain injury / α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor endocytosis / learning and memory / hippocampus

基金资助

重庆市教委青年资助项目(KJQN202400423)