Objective To investigate the effect of remote ischemic preconditioning ( RIPC) on the expression of brain-derived neurotrophic factor (BDNF) in rats with spinal cord ischemia-reperfusion injury (SCII) .Methods From May to November in 2014, using random number table, 88 male Sprague Dawleys rats were randomly divided into three groups: the Sham group ( n=8 ) , the ischemia-reperfusion group ( I/R group, n=40 ) and the remote ischemic preconditioning group ( RIPC group, n=40) .For I/R group and RIPC group, 5 observation time points were set, including 0, 6, 12, 24 and 72 hours after reperfusion (designated as group 1a -1e for I/R group and group 2a -2e for RIPC group), 8 rats at each time point.For the rats in Sham group, only abdominal aorta below renal artery was isolated but without blocking; SCII model was built for the rats in I/R group by using Zivin method; for the rats in RIPC group, the lower limb blood flow was blocked with a tourniquet for 10 min and then was loosen for 10 min for reperfusion, which was done twice, and then SCII model was built using Zivin method 30 minutes later.Spinal cord was sampled from the rats.HE staining was used to observe pathological changes, the number of BDNF positive cells were detected by immunohistochemistry test, the cell apoptosis were assessed by TUNEL staining, Western blotting method was employed to detect the protein expression level of BDNF, and the BBB scores of the rats were evaluated.Results No evident pathological changes were noted in Sham group, while pathological changes were evident in I/R group, and the pathological changes in RIPC group were slighter than I/R group at five time points.Group 1a-1e and group 2a-2e were higher (P<0.05) than Sham group in the number of BDNF positive cells, the protein expression level of BDNF; group 1a-1e and group 2a-2e were lower (P<0.05) than Sham group in BBB score; group 1a-1e and group 2b-2e were higher (P<0.05) than Sham group in the number of TUNEL positive cells; group 2b-2e were higher (P<0.05) than group 1b-1e in the number of BDNF positive cells; group 2a-2e were higher (P<0.05) than group 1a-1e in the protein expression level of BDNF and BBB score; group 2a-2e were lower (P<0.05) than group 1a-1e in the number of TUNEL positive cells, group 1b-1e were higher (P<0.05) than group 1a in the number of BDNF positive cells, the number of TUNEL positive cells, the protein expression level of BDNF and BBB score; group 2b-2e were higher (P<0.05) than group 2a in the number of BDNF positive cells, the number of TUNEL positive cells, the protein expression level of BDNF and BBB score.Conclusion Remote ischemic preconditioning can increase the expression of BDNF in rats with spinal cord ischemia-reperfusion injury, and it may play a protective role through increasing the expression of BDNF.%目的：研究远程缺血预处理（ RIPC）对大鼠脊髓缺血再灌注损伤（ SCII）后脑源性神经营养因子（ BDNF）表达的影响。方法2014年5—11月，将88只雄性SD大鼠按照随机数字表法分为假手术组（ Sham组， n＝8）、缺血再灌注组（I／R组， n ＝40）和RIPC组（n＝40）。 I／R组及RIPC组分别设再灌注0、6、12、24、72 h 5个观察时间点（分别记为1a组～1e组、2a组～2e组），每个时间点8只大鼠。 Sham组大鼠只分离肾动脉下腹主动脉，但不阻断； I／R组大鼠采用Zivin法建立SCII模型； RIPC组大鼠双下肢用驱血带短暂缺血10 min，放开10 min，重复2次，30 min后用Zivin法建立SCII模型。取材，苏木素-伊红（ HE）染色观察脊髓病理变化，免疫组化法检测BDNF阳性表达细胞数，原位细胞凋亡（ TUNEL）法检测细胞凋亡情况， Western blotting法检测BDNF表达水平，并进行大鼠后肢运动功能（ BBB）评分。结果 Sham组脊髓未见明显病理学改变， I／R组脊髓病理学改变明显， RIPC组各时间点脊髓病理学改变均较I／R组轻。1a组～1e组、2a组～2e组BDNF阳性表达细胞数、 BDNF表达水平均高于Sham组（P＜0.05）；1a组～1e组、2a组～2e组BBB评分均低于Sham组（P＜0.05）；1a组～1e组、2b组～2e组TUNEL阳性表达细胞数均高于Sham组（P＜0.05）；2b组～2e组BDNF阳性表达细胞数分别高于1b组～1e组（P＜0.05）；2a组～2e组BDNF表达水平、 BBB评分分别高于1a组～1e组（ P＜0.05）；2a组～2e组TUNEL阳性表达细胞数分别低于1a组～1e组（P＜0.05）；1b组～1e组BDNF阳性表达细胞数、 TUNEL阳性表达细胞数、 BDNF表达水平、 BBB评分均高于1a组（P＜0.05）；2b组～2e组BDNF阳性表达细胞数、 TUNEL阳性表达细胞数、 BDNF表达水平、 BBB评分均高于2a组（ P＜0.05）。结论 RIPC可增加大鼠SCII后BDNF的表达水平，并可能通过增加BDNF的表达水平来达到脊髓保护作用。
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