合并脑损伤大鼠骨折愈合过程中转化生长因子β1血清含量及在骨折位点的表达

Serum content and expression of transforming growth factor beta 1 at fracture site of rats combined with traumatic brain injury in fracture healing

目的:观察合并脑损伤的骨折愈合过程转化生长因子β1的血清含量变化及骨折位点转化生长因子β1的表达。方法:实验于2003-10/2005-02在河北医科大学生化实验室完成。选择清洁级成年雄性SD大鼠84只,随机数字表法分为4组:正常对照组6只,脑损伤组6只,骨折组36只,脑损伤+骨折组36只。脑损伤组按Gruner改良法制作中度脑损伤模型(将400g砝码于100cm高处通过导向管坠落,撞击置于人字缝与失状缝之间的圆锥上,致中度脑损伤)。骨折组充分显露一侧胫骨后,在胫骨结节下1cm处横断胫骨,以直径1mm的克氏针作髓内固定。正常对照组不作任何处理。正常对照组于实验开始后第3天,其他3组分别于术后3d,1,2,3,4,5周采用ABC-ELISA法测定血清中转化生长因子β1含量。脑损伤组与骨折组分别于术后3d,1,2,3,4,5周取骨折标本进行免疫组织化学染色及图像分析,观察转化生长因子β1在骨折位点局部的表达。结果:纳入动物84只,均进入结果分析。①脑损伤组术后第3天血清转化生长因子β1含量高于正常对照组,为正常对照组的4倍[分别为(17.80±11.75),(4.42±2.10)μg/L,P<0.01],2周以后降至正常。骨折组术后1周血清转化生长因子β1含量高于正常对照组[分别为(11.70±4.56),(4.42±2.10)μg/L,P<0.05],第5周降至正常。脑损伤+骨折组术后第3天血清转化生长因子β1含量明显高于正常对照组,为正常对照组的7倍,术后第1周时达到8倍,术后第3天及第1周时脑损伤+骨折组血清转化生长因子β1含量高于骨折组,差异均有显著性意义[分别为(29.30±20.96),(5.93±3.34)μg/L,P<0.05;(31.73±21.57),(11.70±4.56)μg/L,P<0.01],术后2周两组比较差异无显著性意义(P>0.05)。②在图像分析中,术后3d,1,2,3,4周脑损伤+骨折组骨折位点转化生长因子β1染色的吸光度始终高于骨折组,且差异有显著性意义(分别为0.206±0.055,0.135±0.029;0.271±0.043,0.181±0.035;0.234±0.059,0.188±0.036;0.209±0.057,0.166±0.033;0.187±0.037,0.169±0.031,P<0.05)。术后第5周两组比较差异无显著性意义。结论:血浆和骨折位点中转化生长因子β1的表达在合并脑损伤骨折时增高,可能是合并脑损伤时骨折愈合加速的体液因子之一。

AIM： To observe the serum concentration of transforming growth factor β1 （TGF-β1） and its expression on fracture position in healing process combined with traumatic brain injury. METHODS： The experiment was conducted in the Biochemical Laboratory of Hebei Medical University from October 2003 to February 2005. Totally 84 clean grade adult male SD rats were selected and randomly divided into 4 groups： normal control group （n=6）, traumatic brain injury group （TBI, n=6）, fracture group （n=36）, and fracture group combined with traumatic brain injury （TBI＋F, n=36）. The TB1 group was model of moderate brain injury established according to the modified Gruner （caused by a falling of 400 g standard weight from 100 em through a tube onto the conus between the lambdoid suture and sagittal suture）. The fracture group： The tibia 1 cm below the tibial tubercle was traversed after exposed one side of tibia, and Kirschner wire of 1 mm in diameter was used for intrmedullary fixation. The normal control group was not given any treatment. The content of TGF-β1 in serum of the control group was measured by ABC-ELISA on the 3^rd day, and the other groups were measured on the 3^rd day and 1^st, 2^nd, 3^nd, 4^th, 5^th weeks after operation. The fracture samples of the TBI and TBI＋F groups were taken on the 3^rd day and 1^st, 2^nd, 3^rd, 4^th, 5^th weeks after operation for immunohistochemistry and graph analysis to observe the expression of TGF-β1 on the fracture position. RESULTS： All the 84 animals were involved in the result analysis. ①On the 34 day after operation, the TGF-β1 concentration in the TBI group was 4 times as that of the normal control group [（17.80±11.75）, （4.42±2.10） μg/L, P 〈 0.01], and fell to normal level 2 weeks later. One week after operation, the TGF-β1 concentration in the fracture group was higher than the normal control group [（11.70±4.56）, （4.42±2.10） μg/L, P 〈 0.05], and fell to normal level at the 5^th week. In the TBI ＋F group, the TGF-β1 concentration on day 3 raised to 7 times as that of the control group, and to 8 times at the 1^st week. The TGF-β1 concentration of the TBI＋F group on the 3^nd day and 1 week after operation was higher than the fracture group, which had significant differences [（29.30±20.96）, （5.93±3.34） μg/L, P 〈 0.05; （31.73±21.57）, （11.70±4.56） μg/L, P 〈 0.01], but no difference was found after 2 weeks （P 〉 0.05）. ②In the graph analysis, the absorbanee of TGF-β1 in the TBI＋F group was higher than the fracture group, which had significant differences （0.206±0.055, 0.135±0.029; 0.271±0.043, 0.181±0.035; 0.234±0.059, 0.188±0.036; 0.209±0.057, 0.166±0.033; 0.187±0.037, 0.169±0.031, P〈 0.05）. But there was no significant difference after 5 weeks. CONCLUSION： The expression of TGF-β1 in plasma and fracture site increases when combined with traumatic brain injury, which may be one of humoral factors accelerating the fracture healing.