褪黑素对急性脊髓损伤大鼠炎症反应的影响

The impact of melatonin on inflammatory response after acute spinal cord injury

目的探讨褪黑素（MT）对大鼠急性脊髓损伤后白细胞介素-6（IL-6）、白细胞介素-8（IL-8）和自细胞介素-10（IL-10）表达的影响及其对损伤后炎症反应和神经修复的作用。方法选取成年SD大鼠108只，按随机数字表法分为脊髓损伤组、MT治疗组和假手术组，每组36只。脊髓损伤组和MT治疗组采用改良垂直打击（WD）法（打击量5×10g．cm）建立T12脊髓损伤模型，假手术组只切除T12椎板不损伤脊髓。脊髓损伤组和MT治疗组在脊髓损伤后10rain分别注射含5％乙醇的生理盐水和MT制剂（按大鼠体重100mg／kg计算）。分别于模型建立手术后6、12、18、24和48h从每组大鼠中按随机数字表选取6只大鼠，取脊髓标本及血液，并检测血清中IL-6、IL-8和IL-10含量及脊髓中IL-10mRNA的表达水平。术后18h时，再分别于3组中选取6只行主动脉灌流后取出脊髓标本甲醛固定，切片后行HE染色观察大体变化，用免疫组化SP法观察IL-10的表达特点。结果术后6、12、18、24和48h脊髓内IL-10mRNA水平和血清中IL-10含量对比，褪黑素治疗组均最高、脊髓损伤组次之、假手术组最低，各组间其差异均有统计学意义（P〈0．01）；相应时间点脊髓损伤组的IL-6和IL-8水平最高、MT治疗组次之、假手术组最低，各组间差异均有统计学意义（P〈0．01）。术后18h脊髓标本中IL-10mRNA阳性细胞数（个／高倍视野）对比，MT治疗组最高（5．7±0．80）、脊髓损伤组次之（4．6±0．83），假手术组最低（3．8±0．77），各组间差异均有统计学意义（P〈0．01）。组织形态学观察显示MT治疗后脊髓中央管及其周围的灰质IL-10水平改善。结论MT可以通过提高IL-10的表达及抑制IL-6和IL-8的表达来改善损伤后神经的脂质过氧化反应和炎症反应来修复损伤神经。

Objective To explore the effects of melatonin （MT） on the expression of interleukin （IL）-10, interleukin-6 and interleukin-8 as well as the inflammatory reaction and nerve repair after acute spinal cord injury （SCI）. Methods One hundred and eight Sprague-Dawley rats were randomly divided into a spinal cord injury group （group A） , an MT treatment group （group B） and a sham operation group （group C） , each with 36 rats. SCI models were established in the rats of groups A and B using a version of Allen＇s weight drop method （50gcf at the TI2 level）. Group C had removal of the lamina only. Ten minutes later, group A was injected with 5% ethanol in saline （the MT solvent） and group B with 100 mg/kg of melatonin preparation. At 6, 12, 18 and 24 hours, IL-6, IL-8 and IL-10 levels in serum were detected in 6 rats of each group. At 18 hours post-surgery, spinal cord specimens were taken from 6 rats of each group for hematoxylin eosin staining, morphological examination and immunohistoehemical SP detection of IL-10 expression. Results The specimens of group A showed inflammatory reaction and ulceration at 48 h; groups B and C had no ulcers. Group B showed the highest levels of IL-10 in serum and IL-10 mRNA in the spinal cord, while group C showed the lowest level. The differences were statistically significant. Group A had the highest levels of IL-6 and IL-8 and group C had the lowest. The difference between group B and groups A and C was significant. The morpho- logical observation showed that after melatonin treatment the IL-10 levels in the spinal cord＇s central canal and around the gray matter improved. Conclusions Melatonin can improve nerve lipid peroxidation and inflammatory reaction in the treatment of spinal cord injury by increasing IL-10 expression and inhibiting IL-6 and IL-8 expression.