目的 探讨脊髓压迫性损伤(CSCI)后脱髓鞘病变及硫酸软骨素蛋白多糖(CSPG,NG2)的表达变化.方法 选取健康成年SD大鼠75只,雌雄不限,采用随机数字表法将其分为正常组、假手术组、CSCI1 d组、CSCI 3 d组和CSCI 7 d组,每组15只.采用自行设计的大鼠脊髓压迫器制作脊髓压迫模型,应用BBB运动功能评分、锇酸染色及透射电镜观察CSCI后1 d、3 d及7d时大鼠的运动功能情况及白质有髓神经纤维的病理变化,计算脊髓后索有髓神经纤维的数量及髓鞘厚度与轴突直径的比值即G-ratio值,并采用免疫印迹法检测NG2蛋白的表达变化.结果 CSCI后,CSCI 1 d组、CSCI 3 d组和CSCI 7 d组的大鼠后肢BBB评分分别为(1.23±0.45)分、(0.65±0.35)分和(0.00±0.00)分,与正常组(21.00±0.00)分和假手术组(21.00±0.00)分相比,差异有统计学意义(P＜0.05),大鼠的运动功能随受压时间延长而逐渐下降.锇酸染色显示正常组和假手术组大鼠的白质正常,脊髓受压后,CSCI 1 d组、CSCI 3 d组和CSCI 7 d组的有髓神经纤维开始出现水肿、变性、崩解,正常组和假手术组脊髓后索的有髓神经纤维计数分别为(2771±108)根和(2675±199)根,CSCI 1 d组、CSCI 3 d组和CSCI 7 d组的有髓神经纤维计数分别为(2403±161)根、(1708±70)根和(810 ±95)根,压迫后有髓神经纤维数目减少,压迫后7d,有髓神经纤维数目减至最低(P＜0.05),与正常组和假手术组比较,差异有统计学意义(P＜0.05).电镜定量分析结果显示,正常组、假手术组、CSCI 1 d组、CSCI 3 d组和CSCI 7 d组的G-ratio值分别为(18.10±0.4)、(17.70±1.0)、(6.69±0.8)、(5.73±0.4)和(4.95±0.5),CSCI 1 d组、CSCI 3 d组和CSCI 7 d组的G-ratio值均较正常组和假手术组低,且在压迫后7d时降至最低,差异有统计学意义(P＜0.05).透射电镜结果显示,正常组和假手术组的轴突、髓鞘板层结构正常；脊髓受压后,轴索出现肿胀,轴浆内细胞器变性、坏死、减少；髓鞘折叠、皱缩,出现“洋葱皮”样变,髓鞘崩解；少突胶质细胞的染色质凝聚；巨噬细胞浸润.NG2蛋白免疫印迹结果显示,脊髓受压后,NG2蛋白表达水平在压迫后第1天升至最高(P＜0.05),且表达水平随压迫时间延长而逐渐下调,但均高于正常组和假手术组,差异有统计学意义(P＜0.05).结论 CSCI后,大鼠运动功能随受压时间延长而逐渐下降,有髓神经纤维发生脱髓鞘病变且数量减少,随着压迫时间延长,溃变呈现出进行性加重趋势；NG2细胞与CSCI后髓鞘的变化情况关系密切,可能增殖分化为少突胶质细胞或其它类型细胞,是脊髓髓鞘内源性修复的机制之一.
目的 探討脊髓壓迫性損傷(CSCI)後脫髓鞘病變及硫痠軟骨素蛋白多糖(CSPG,NG2)的錶達變化.方法 選取健康成年SD大鼠75隻,雌雄不限,採用隨機數字錶法將其分為正常組、假手術組、CSCI1 d組、CSCI 3 d組和CSCI 7 d組,每組15隻.採用自行設計的大鼠脊髓壓迫器製作脊髓壓迫模型,應用BBB運動功能評分、鋨痠染色及透射電鏡觀察CSCI後1 d、3 d及7d時大鼠的運動功能情況及白質有髓神經纖維的病理變化,計算脊髓後索有髓神經纖維的數量及髓鞘厚度與軸突直徑的比值即G-ratio值,併採用免疫印跡法檢測NG2蛋白的錶達變化.結果 CSCI後,CSCI 1 d組、CSCI 3 d組和CSCI 7 d組的大鼠後肢BBB評分分彆為(1.23±0.45)分、(0.65±0.35)分和(0.00±0.00)分,與正常組(21.00±0.00)分和假手術組(21.00±0.00)分相比,差異有統計學意義(P＜0.05),大鼠的運動功能隨受壓時間延長而逐漸下降.鋨痠染色顯示正常組和假手術組大鼠的白質正常,脊髓受壓後,CSCI 1 d組、CSCI 3 d組和CSCI 7 d組的有髓神經纖維開始齣現水腫、變性、崩解,正常組和假手術組脊髓後索的有髓神經纖維計數分彆為(2771±108)根和(2675±199)根,CSCI 1 d組、CSCI 3 d組和CSCI 7 d組的有髓神經纖維計數分彆為(2403±161)根、(1708±70)根和(810 ±95)根,壓迫後有髓神經纖維數目減少,壓迫後7d,有髓神經纖維數目減至最低(P＜0.05),與正常組和假手術組比較,差異有統計學意義(P＜0.05).電鏡定量分析結果顯示,正常組、假手術組、CSCI 1 d組、CSCI 3 d組和CSCI 7 d組的G-ratio值分彆為(18.10±0.4)、(17.70±1.0)、(6.69±0.8)、(5.73±0.4)和(4.95±0.5),CSCI 1 d組、CSCI 3 d組和CSCI 7 d組的G-ratio值均較正常組和假手術組低,且在壓迫後7d時降至最低,差異有統計學意義(P＜0.05).透射電鏡結果顯示,正常組和假手術組的軸突、髓鞘闆層結構正常；脊髓受壓後,軸索齣現腫脹,軸漿內細胞器變性、壞死、減少；髓鞘摺疊、皺縮,齣現“洋蔥皮”樣變,髓鞘崩解；少突膠質細胞的染色質凝聚；巨噬細胞浸潤.NG2蛋白免疫印跡結果顯示,脊髓受壓後,NG2蛋白錶達水平在壓迫後第1天升至最高(P＜0.05),且錶達水平隨壓迫時間延長而逐漸下調,但均高于正常組和假手術組,差異有統計學意義(P＜0.05).結論 CSCI後,大鼠運動功能隨受壓時間延長而逐漸下降,有髓神經纖維髮生脫髓鞘病變且數量減少,隨著壓迫時間延長,潰變呈現齣進行性加重趨勢；NG2細胞與CSCI後髓鞘的變化情況關繫密切,可能增殖分化為少突膠質細胞或其它類型細胞,是脊髓髓鞘內源性脩複的機製之一.
목적 탐토척수압박성손상(CSCI)후탈수초병변급류산연골소단백다당(CSPG,NG2)적표체변화.방법 선취건강성년SD대서75지,자웅불한,채용수궤수자표법장기분위정상조、가수술조、CSCI1 d조、CSCI 3 d조화CSCI 7 d조,매조15지.채용자행설계적대서척수압박기제작척수압박모형,응용BBB운동공능평분、철산염색급투사전경관찰CSCI후1 d、3 d급7d시대서적운동공능정황급백질유수신경섬유적병리변화,계산척수후색유수신경섬유적수량급수초후도여축돌직경적비치즉G-ratio치,병채용면역인적법검측NG2단백적표체변화.결과 CSCI후,CSCI 1 d조、CSCI 3 d조화CSCI 7 d조적대서후지BBB평분분별위(1.23±0.45)분、(0.65±0.35)분화(0.00±0.00)분,여정상조(21.00±0.00)분화가수술조(21.00±0.00)분상비,차이유통계학의의(P＜0.05),대서적운동공능수수압시간연장이축점하강.철산염색현시정상조화가수술조대서적백질정상,척수수압후,CSCI 1 d조、CSCI 3 d조화CSCI 7 d조적유수신경섬유개시출현수종、변성、붕해,정상조화가수술조척수후색적유수신경섬유계수분별위(2771±108)근화(2675±199)근,CSCI 1 d조、CSCI 3 d조화CSCI 7 d조적유수신경섬유계수분별위(2403±161)근、(1708±70)근화(810 ±95)근,압박후유수신경섬유수목감소,압박후7d,유수신경섬유수목감지최저(P＜0.05),여정상조화가수술조비교,차이유통계학의의(P＜0.05).전경정량분석결과현시,정상조、가수술조、CSCI 1 d조、CSCI 3 d조화CSCI 7 d조적G-ratio치분별위(18.10±0.4)、(17.70±1.0)、(6.69±0.8)、(5.73±0.4)화(4.95±0.5),CSCI 1 d조、CSCI 3 d조화CSCI 7 d조적G-ratio치균교정상조화가수술조저,차재압박후7d시강지최저,차이유통계학의의(P＜0.05).투사전경결과현시,정상조화가수술조적축돌、수초판층결구정상；척수수압후,축색출현종창,축장내세포기변성、배사、감소；수초절첩、추축,출현“양총피”양변,수초붕해；소돌효질세포적염색질응취；거서세포침윤.NG2단백면역인적결과현시,척수수압후,NG2단백표체수평재압박후제1천승지최고(P＜0.05),차표체수평수압박시간연장이축점하조,단균고우정상조화가수술조,차이유통계학의의(P＜0.05).결론 CSCI후,대서운동공능수수압시간연장이축점하강,유수신경섬유발생탈수초병변차수량감소,수착압박시간연장,궤변정현출진행성가중추세；NG2세포여CSCI후수초적변화정황관계밀절,가능증식분화위소돌효질세포혹기타류형세포,시척수수초내원성수복적궤제지일.
Objective To investigate the role of demyelination and the alteration of chondrotin sulfate proteoglycan (CSPG,NG2) expression after compression injury of the spinal cord (CSCI).Methods Seventy-five adult Sprague-Dawley rats were randomly divided into a normal group,a sham-operation group,a CSCI 1 day group,a CSCI 3 day group,and a CSCI 7 day group.There were 15 rats in each group.The injuries in the CSCI groups were inflicted using a technique devised in our laboratory.Basso-Beattie-Bresnahan (BBB) neurological function assessment was used to assess the rats' motor function,osmic acid staining and transmission electronic microscopy (TEM)were used to observe any pathological changes of myelinated nerve fibers in the white matter at 1,3 and 7 days after CSCI.The amount of myelinated nerve fibers in the posterior funiculus of the spinal cord and the ratio of myelin sheath thickness to axon diameter (the G-ratio) were calculated.Any alteration in NG2 expression was observed by Western blotting.Results The average neurological function assessment scores in the CSCI groups were (1.23 ±0.45),(0.65 ± 0.35) and (0.00 ± 0.00) respectively.Compared with the normal group (21.00 ± 0.00) and the sham operation group (21.00 ± 0.00),the differences were all statistically significant.The rats' motor function deteriorated gradually with time after the CSCI.Osmic acid staining showed that the white matter was intact in the normal and sham groups.After being compressed the myelinated nerve fibers became swollen,degenerated and broke down.The amount of myelinated nerve fibers in the normal group,the sham operation group and the three CSCI groups was (2771 ± 108),(2675 ± 199),(2403 ± 161),(1708 ± 70) and (8 10 ± 95) respectively.The amount of myelinated nerve fibers decreased in the CSCI groups and reached a minimum on the 7th day.The difference was statistically significant.The TEM quantity analysis showed that the G-ratios in the normal,sham operation,and CSCI 1 day,3 day and7 day groups were (18.10±0.4),(17.70±1.0),(6.69 ±0.8),(5.73 ±0.4) and (4.95 ±0.5) respectively.Compared with the normal and sham operation groups,the G-ratios in the 3 CSCI groups were lower and reached their minimum on the 7th day after injury.The difference was statistically significant.TEM observation showed that the axons and myelin sheaths were intact in the normal and sham groups.After CSCI the axons became swollen and cell organelles in the axoplasm degenerated and decreased.The layers of myelin sheath shrank,folded and even wrinkled,which had an onion-like appearance.The oligodendrocytes exhibited chromatin condensation.Macrophages showed infiltration.Western blotting showed that the expression of NG2 in the CSCI groups reached a maximum on the 1st day after injury and then decreased with time.The expression of NG2 in the CSCI groups was higher than in the normal and sham groups,and the difference was statistically significant.Conclusion Demyelination occurs after CSCI-the amount of myelinated nerve fibers decreases and neurological deficits increase with time.The expression of NG2 was associated with changes in the myelin sheaths after CSCI and contributed to recovery of the myelin sheath through proliferation and differentiation to oligodendrocytes and perhaps other kinds of cells.
