脊髓损伤早期及制动后大鼠股骨远端组织形态学观察

Histomorphometry observation on the distal femur after spinal cord injury and immobilization in rats

目的建立大鼠脊髓损伤及废用性模型(制动),观察建模早期两种模型大鼠股骨远端破骨细胞数量及动态组织形态学的改变。方法 24只SD大鼠随机分为3组(每组8只)。对照组:切除T10椎板,不损伤硬膜及脊髓;脊髓损伤(SCI)组:切除T10椎板后行Allen’s法(60gocm动能)造成脊髓损伤;制动组:采用大鼠双侧腿-尾缝合,造成双下肢制动。分别于伤后第1、7天采用BBB(Basso,Beattie and Bresnah-an)评分评估脊髓损伤大鼠后肢运动功能。于建模后第2、9天皮下注射钙黄绿素(10mg/kg)。饲养10天后处死,取一侧股骨远端行抗酒石酸磷酸酶(TRAP)染色,观察大鼠股骨远端破骨细胞数量的变化。取另一侧股骨远端,行动态组织形态学观察。结果 (1)与对照组和制动组比较,SCI组大鼠股骨干骺端破骨细胞数量显著增加(P<0.01);(2)对照组切片中骨小梁周围可见清晰、独立的2条荧光条带;制动组切片中大多数骨小梁周围只能看见1条荧光条带,少数的骨小梁附近形成2条荧光条带,但条带之间模糊、重叠、分界不清;SCI组切片中几乎所有的骨小梁周围只能看见1条荧光条带,且有的条带不连续。结论脊髓损伤早期及制动因素在导致骨量丢失的发生机制上有明显的不同。脊髓损伤早期所致的骨量丢失主要是由于破骨细胞大量增殖、活性增加,骨吸收加强同时骨形成严重障碍所致,而制动所造成的骨量丢失主要原因为缺乏机械应力后发生了成骨不良,但不伴有骨吸收增强。

Objective Rats models with both spinal cord injury（SCI）and disuse atrophy were established,so as to make an observation and comparison on the number of osteoclast and dynamic histomorphometry studies at the distal femoral osteoclast changes.Methods A total of 24 male rats were randomly divided into three groups： control group（sham operation group）,immobilization group and the SCI group.After anesthesia,T10 vertebral plate resection was performed to rats in both the SCI group and the control group,with weight-drop（60gocm） on spinal cords（contusion injury in SCI model） only in the former group;rats in the immobilization group were immobilized by limb-tail fixation at bilateral hindlimbs.The Basso,Beattie,Bresnahan（BBB） scales were used to confirm injury severity by rating hindlimb functional deficits on day 1 and 7 post-injury and all experimental animals were injected with calcein（10mg/kg） on day 2 and day 9 post-injury.Animals were sacrificed on day 10 post-injury for subsequent analyses.The TRAP staining was performed to the distal femur.Detection of dynamic histomorphometry studies was performed on the other distal femur.Results Compared with the control group and immobilization group,the number of osteoclast on the distal femur in the SCI group increased significantly（P0.01）;normal double labeling around the bone trabecula was seen in the control animals.In the immobilization group,single fluorescent label was seen around the majority of bone trabeculas.Some area of bone trabeculas may be seen some abnormal double fluorescent label.In the SCI group,only single fluorescent label was observed,some of which were discontinuous.Conclusion Mechanisms of bone loss following spine cord injury and immobilization are notably different.SCI results in a rapid bone loss in early stage,due to bone resorption,increased number of osteoclast and bad bone formation.However,immobilization results in the bone loss because of the bone mineralization defect without bone resorption.