大鼠脊髓全横断诱导芳香族氨基酸脱酸酶细胞产生5-羟色胺的机制研究

Spinal cord transection induce aromatic L-amino acid decarboxylase cells to produce 5-HT

中文关键词:  脊髓损伤  芳香族氨基酸脱羧酶  5-羟色胺

英文关键词:Spinal cord injury  Aromatic amino acid decarboxylase  5-hydroxytryptamine

中文摘要:

  【摘要】 目的：探讨大鼠脊髓损伤（spinal cord injury，SCI）前后芳香族氨基酸脱酸酶（Aromatic L-amino acid decarboxylase，AADC）细胞的分布以及SCI后不同时间段AADC细胞表达5-羟色胺（5-HT）的特点。方法：60只成年雄性Wistar大鼠随机分为正常对照组（12只）、脊髓损伤2d组（24只，其中假手术/Sham组12只）及脊髓损伤60d组（24只，其中假手术/Sham组12只）。使用负压吸引器将大鼠T10-T11脊髓完全离断1～3mm，建立脊髓胸段T10-T11全横断模型。使用BBB评分评价SCI大鼠不同时间点后肢运动功能。各组大鼠在相应时间点灌注取材，并且在灌注前30min腹腔注射外源性5-羟色胺酸（5-HTP）（100mg/kg），免疫荧光法检测脊髓腰段（L段）和骶尾段（S+C段）中AADC和5-HT表达水平。结果：SCI大鼠在术后1～2、3、7、14、28、60d时BBB评分别为0、1.00±0.58、3.30±0.95、6.30±0.10、7.50±0.36、7.87±0.08分。AADC细胞主要在脊髓的背角、中间带、中央管周围等部位表达。正常对照组、脊髓损伤2d组和脊髓损伤60d组AADC表达数量在脊髓L段为：46.75±5.50、49.50±4.87、48.50±6.38个，在脊髓S+C段为1026.50±66.59、1066.75±80.56、1046.25±67.79个，三组结果相比无显著性差异（P>0.05）。正常对照组大鼠脊髓L段和S+C段中AADC细胞中未见5-HT的表达，但在SCI 2d组和SCI 60d组均观察到AADC细胞表达5-HT，L段两组表达率分别为（44.43±6.03）%和（96.20±1.53）%，S+C段分别为（44.45±5.71）%和（95.14±3.02）%，两组间差异有显著性（P＜0.05）。结论：AADC细胞在脊髓胸段T10～T11全横断损伤前后脊髓中表达数量和部位相似。SCI后，损伤平面以下脊髓中的AADC细胞功能增加，可利用外源性5-HTP生成5-HT。

英文摘要:

  【Abstract】 Objectives: To reveal the role of aromatic L-amino acid decarboxylase cells(AADC) after spinal cord injury(SCI) by investigating the AADC distribution in spinal cord and the 5-HT expression in AADC following SCI at different postoperative intervals. Methods: Sixty adult male Wistar rats were randomly divided into normal control group(12 rats), spinal cord injury 2 days group(24 rats, sham in 12 rats), and spinal cord injury 60 days group(24 rats, sham in 12 rats). By using negative pressure suction device, T10-11 spinal cord was completely separated from 1-3mm, and the spinal cord complete transection model at T10-11 level was established. The BBB score of different time points was used to evaluate the hindlimb motor function in SCI rats. Each group was perfused and drawed at each time point and the 5-HTP(100 mg/kg) was intraperitoneally injected 30min before perfusion. Immunofluorescence technology was used to detect the expression of AADC and 5-HT in lumbar(L segment) and sacrocaudal segments(S+C segment) of spinal cord. Results: The BBB score of SCI rats was 0, 1.00±0.58, 3.30±0.95, 6.30±0.10, 7.50±0.36 and 7.87±0.08 at 1-2, 3, 7, 14, 28 and 60 days respectively. AADC cells were mainly expressed in the dorsal horn of spinal cord, intermediate zone, and around the central canal. In control group, SCI 2d group and SCI 60d group, the number of AADC in L segment was 46.75±5.50, 49.50±4.87 and 48.50±6.38 cells respectively; it was 1026.50±66.59, 1066.75±80.56 and 1046.25±67.79 cells in S+C segment respectively. There was no significant difference between the three groups(P>0.05). The expression of 5-HT was not seen in the AADC cells in the L segment and S+C segment of the normal control group. But 5-HT expression was observed in the AADC cells in SCI 2d and 60d group, which was (44.43±6.03)% and (96.20±1.53)% in L segment, (44.45±5.71)% and (95.14±3.02)% in S+C segment. There was significant difference between the two groups(P＜0.05). Conclusions: There is no significant difference in SCI and normal rats respect to AADC cells distribution and numbers. Following complete transection of the rat spinal cord at T10-11 level, the function of AADC cells in the spinal cord distal to the lesion was increased, and exogenous 5-HTP can be used to generate 5-HT.