游泳调节纹状体突触结构可塑性改善Shank3基因敲除大鼠孤独症样行为

Swimming Improves Autistic Behavior in Shank3 Knockout Rats by Modulating Synaptic Structural Plasticity in Striatum

目的:孤独症谱系障碍(autism spectrum disorder,ASD)通常发生于幼年阶段,其行为缺陷与纹状体功能密切相关。幼年期是大脑发育的重要阶段,游泳是促进大脑突触可塑性的有效运动方式。为此,研究探讨早期游泳能否调节Shank3基因敲除ASD模型大鼠纹状体突触结构可塑性,改善与纹状体功能相关的ASD样行为。方法:幼龄雄性Shank3基因敲除SD大鼠,随机分为基因敲除对照组(KC)和基因敲除游泳组(KS),同窝野生型大鼠随机分为野生型对照组(WC)和野生型游泳组(WS)。KS和WS组从8日龄起进行为期8周的游泳干预。干预完成24 h后,利用自梳理实验检测大鼠的刻板行为,旷场实验检测焦虑情绪与自由活动情况,最大抓力实验检测肌肉力量,转棒实验检测运动协调能力。行为学测试24 h后进行麻醉,取纹状体组织进行高尔基染色,观察纹状体中等多棘神经元(medium spiny neurons,MSNs)树突形态。提取纹状体组织突触后致密部(postsynaptic density,PSD)蛋白,Western blot检测兴奋性突触后支架蛋白和谷氨酸受体蛋白、γ-氨基丁酸受体蛋白的表达。结果:1)8周早期游泳干预显著改善了大鼠Shank3基因敲除导致的刻板行为和运动能力缺陷,但未能改善焦虑情绪;2)Shank3基因敲除后,大鼠纹状体MSNs树突总长度、分支数量和树突棘密度显著降低,早期游泳干预改善了树突形态的这些变化;3)Shank3基因敲除后,大鼠纹状体突触后致密部支架蛋白PSD95、Homer1表达显著降低,受体蛋白GluA1、GluA2、NR1、NR2A、NR2B表达显著降低,早期游泳干预上调了支架蛋白PSD95和受体蛋白GluA1、GluA2、NR2A、NR2B的表达。结论:Shank3基因敲除大鼠纹状体树突发育受损,兴奋性突触后谷氨酸能受体表达降低,并出现与纹状体功能异常相关的刻板行为与运动功能障碍。早期游泳干预可上调纹状体树突分支数量、树突总长度与树突棘密度,并上调部分兴奋性突触后受体蛋白的表达,从而调节突触结构可塑性,改善Shank3基因敲除导致的大鼠行为异常。

Objective:Autism spectrum disorder(ASD)typically manifests during early childhood,with its behavioral deficits intricately linked to striatal function.Early childhood represents a crucial stage in brain development,and swimming has proven to be an effective exercise regimen for enhancing synaptic plasticity in the brain.In this study,we explored whether early swimming could influence the synaptic structural plasticity of striatal synapses in Shank3 knockout ASD rats and potentially ameliorate ASDlike behaviors closely associated with striatal function.Methods:Male Shank3 knockout SD rats were randomly divided into gene knockout control group(KC)and gene knockout swimming group(KS).Wild type rats in the same litter were randomly divided into wild type control group(WC)and wild type swimming group(WS).The KS and WS groups were conducted swimming intervention for 8 weeks from postnatal day 8,and the behavioral tests including self-grooming,open field experiment,maximum grasping force experiment and rod-turning experiment were performed after intervention.After 24 h of behavioral test,the Golgi staining were performed in striatum to observe the dendritic morphology of medium spiny neurons(MSNs).The expressions of excitatory postsynaptic scaffold protein and glutamate andγ-aminobutyric acid receptors were detected with Western blot in the postsynaptic dense part(PSD)of striatum.Results:The early life swimming intervention significantly improved the stereotyped behavior and motor ability,but not anxiety symptom,in Shank3 knockout rats.The total length,number of branches and dendritic spine density of MSNs in striatum were significantly decreased in Shank3 knockout rats,and early swimming rescued these changes in dendritic morphology.The expressions of PSD95 and Homer1 in the postsynaptic dense part of striatum were significantly decreased,and the receptor protein expressions of GluA1,GluA2,NR1,NR2A and NR2B were significantly decreased.In addition,Early swimming intervention increased the expressions of PSD95 and GluA1,GluA2,NR2A and NR2B in Shank3 knockout rats.Conclusions:Shank3 knockout rats show impaired dendritic development,decreased expression of excitatory postsynaptic receptors,and stereotyped behavior and motor dysfunction associated with abnormal striatum function.Commencing swimming intervention at an early stage enhances the proliferation of striatal dendritic branches,increases total dendritic length,and elevates dendritic spine density.Furthermore,it leads to an upregulation in the expression of certain excitatory postsynaptic receptor proteins.Consequently,this intervention effectively influences synaptic structural plasticity and mitigates the behavioral abnormalities induced by Shank3 knockout in rats.