中文摘要：

目的研究脆性X智力低下蛋白（FMRP）缺失对感觉皮质功能柱神经可塑性的影响。方法从纯合子鼠血液提取DNA，对FMR1基因片段进行扩增，电泳观察结果。并选用子代幼龄FMR1基因敲除及野生型小鼠共16只，按基因型和年龄分为1周龄FMR1基因敲除型组（KO^1），1周龄野生型组（WT^1），4周龄FMR1基因敲除型组（KO^4），4周龄野生型组（WT^4），每组各4只。采用快速Golgi染色法分别观察不同发育时间段感觉皮质功能柱区域神经元的功能柱中心和周边两个方向上树突分支、树突棘密度和长度。结果与对照组相比，幼龄FMR1基因敲除鼠树突棘密度显著增高（P〈0．05）而长度无变化，感觉皮质功能柱区域中心朝向的树突棘密度无显著性差异，而周边朝向的树突棘密度KO^1、KO^4分别高于WT^1、WT^4，并且主要表现在距胞体10～80μm段的密度异常（P〈0．01）。结论FMRP缺失导致树突棘密度增高和感觉皮质功能柱区域树突棘修剪异常，并且树突棘修剪和树突修剪的机制不同。

英文摘要：

Objective To investigate neural pruning or neural plasticity of mouse somatosensory cortical barrel in the absence of fragile X mental retardation protein （FMRP）. Methods The genome DNA was extracted from the blood of the filial generation and PCR method was employed to amplify the aberrant fragments of FMR1, and gene types were observed after electrophoresis. Sixteen infant FMR1 knock-out and wild type mice were randomly divided into 4 groups according to their genetype and age： 1 week-FMR1 knock-out group （KO^1, n=4）, 1 week-wild type group （WT^1, n=4）, 4 week-FMR1 knockout group （KO^4, n=4）, 4 week-wild type group （WT^4, n=4）. The dendritic pruning and spine pruning in the somatosensory barrel cortex stained by fast Golgi method were observed under a microscope. The spine density, spine length, and dendritic materials towards barrel center or barrel wall were measured. All analysis was conducted using the automatic image analysis system. Results There was a significant increase in dendritic spine density in infant FMR1 knock-out mice （P〈0.05） and no change in dendritic spine length, the density of dendritic spine towards barrel wall was higher in KO^1 and KO^4 than in WT^1 and WT^4, while the one towards barrel center was not significantly different between them. The infant FMR1 knock-out mice maintained normal dendrite pruning in somatosensory barrel cortex. There was manifest pruning disorder of the dendritic spine in somatosensory barrel cortex and the disorder affects mainly on spine density 10～80 μm proximate to the soma （P〈0.01）. Conclusion FMRP may participate in the development process of dendritic spine pruning in somatosensory barrel cortex and the mechanisms of pruning between dendrite and dendritic spine are different.