兔海水浸泡脊髓损伤的病理变化观察

Pathological changes in spinal cord injury of rabbit with seawater immersion

目的探讨经海水浸泡后的脊髓损伤的病理变化特点,为海水浸泡脊髓损伤的救治提供理论指导。方法采用改良Allen's打击器制作兔脊髓损伤模型。96只大耳白兔随机分为A组(即假手术组,仅切除椎板不损伤脊髓,n=6)、B组(切除椎板并建立脊髓损伤模型,但不浸泡,n=30)、C组(切除椎板并建立脊髓损伤模型,生理盐水浸泡60min,n=30)、D组(切除椎板并建立脊髓损伤模型,海水浸泡60min,n=30)。除假手术组外,后3组分别于处理后1、6、12、24、48h时间点各随机选取6只实验动物,采用Tarlov法进行神经功能评分,然后处死动物并取伤段脊髓,光镜下观察组织病理学变化,免疫组化法检测Bax、Bcl-2的表达,TUNEL法检测脊髓神经细胞凋亡情况。结果与A组比较,其余3组动物Tarlov评分均明显降低,1h时间点3组评分差异不明显,6h时间点D组评分明显高于B、C组,而12h时间点D组评分明显下降至低于B和C组,差异均有统计学意义(P<0.05)。B、C、D组伤后均出现脊髓水肿,其中,B、C组在6h时间点即出现明显的创伤性脊髓水肿,两组在同一时间点脊髓水肿情况差异不明显,而D组在12h时间点才出现明显的创伤性脊髓水肿,D组6h时间点肿胀较B、C组轻,12h时间点较B、C组重;24、48h时间点各组脊髓肿胀、充血程度均减轻。免疫组化检测显示B、C、D组各时间点均有Bax和Bcl-2阳性表达,D组Bax表达水平在6h时间点低于B、C组,12、24、48h时间点高于B、C组,而Bcl-2表达水平在6、12、24、48h各时间点均低于B、C组(P<0.05)。TUNEL法检测显示,B、C、D组凋亡细胞均明显增多且于12h达峰值,其中D组凋亡细胞数在12h时间点明显高于B、C组,而在6、24、48h明显低于B、C组(P<0.01)。结论海水浸泡早期可抑制脊髓损伤,延迟了创伤性脊髓损伤的病理改变及细胞凋亡,但后期可加重脊髓损害。

Objectives To explore the pathological changes in spinal cord injury with seawater immersion,and provide guidance for the treatment of such injury.Methods The rabbit model of spinal cord injury was reproduced by the modified Allen＇s method.Ninety-six rabbits were randomly divided into 4 groups： group A（normal control,n=6）,in them only the vertebral plate was cut off but the spinal cord was not injured;group B（n=30）,vertebral plate was resected and the spinal cord was damaged without sea water immersion;group C（n=30）,the vertebral plate was resected and the spinal cord was damaged and treated with normal saline;and group D（n=30）,the vertebral plate was resected and the spinal cord was damaged followed by seawater immersion.The immersion time was 60 minutes.In group B,C and D,6 rabbits were randomly selected from each group at 1,6,12,24 and 48 hours after immersion,and the neurological function of rabbits were evaluated using the Tarlov scale,then the animals were sacrificed,and the histopathological features were studied with light microscopy,the expressions of Bax and Bcl-2 were determined by immunohistochemistry,and the apoptosis of neurons in spinal cord was evaluated by TUNEL method.Results Compared with group A,the Tarlov scores of group B,C and D decreased significantly,but no significant difference was found between the 3 groups at 1h after treatment,while the Tarlov scores were higher at 6h and lower at 12h in group D as compared with those in group B and C（P0.05）.Edema of spinal cord was observed in group B,C and D after injury.Distinct traumatic spinal cord edema was found at 6h in group B and C and at 12h in group D,but no signiicant diference was observed between group B and C.Compared with group B and C,the spinal cord edema in group D was less distinct at 6h and more serious at 12h.he spinal cord edema and hyperemia were alleviated in all 3 groups at 24h and 48h.Positive expression of Bcl-2 and Bax was found at each time point ater injury in group B,C and D.Compared with group B and C,the expression of Bax decreased at 6h and increased at 12,24 and 48h in group D,while the expression of Bcl-2 decreased at 6,12,24 and 48h in group D（P0.05）.he number of apoptotic cells increased signiicantly in group B,C and D,and all of them reached peak at 12h.Compared with group B and C,the number of apoptotic cells increased at 12h and decreased at 6,24 and 48h in group D（P0.01）.Conclusion In early stage,seawater immersion may inhibit the spinal cord injury,delay the pathological changes in traumatic spinal cord injury and neuron apoptosis,but may aggravate spinal cord injury in later stage.