中文摘要：

目的评价机械牵张预处理对机械牵张诱导人Ⅱ型肺泡上皮细胞（AECⅡ）γ-氨基丁酸（GABA）信号通路活化的影响。方法体外培养人AECⅡ细胞株（A549细胞），分为对照组（C组）、机械牵张组（P1组）和机械牵张预处理组（P2组）。C组常规培养；P1组给予20％应变率的机械牵张6h；P2组给予5％应变率预牵张60min后，将应变率调整为20％继续牵张6h。采用甲基噻唑蓝法测定细胞活性；采用比色法测定乳酸脱氢酶（LDH）释放率；采用酶联免疫吸附试验（ELISA）测定细胞培养液中白细胞介素（IL-1β、IL-6）及肿瘤坏死因子-α（TNF-α）含量；采用反转录-聚合酶链反应（RT—PCR）测定IL-1β、IL-6及TNF—α的mRNA表达；采用蛋白质免疫印迹试验（Western Blot）测定谷氨酸脱羧酶（GAD）和γ-氨基丁酸A受体（GABAR）的蛋白表达。结果与C组比较，P1组细胞活性明显降低（A值：0．196±0．071比0．886±0．107），LDH释放率明显升高[（12．3±2．4）％比（1．9±0．5）％]；细胞培养液中IL-1β、IL-6及TNF—α含量和mRNA表达量均明显升高[IL-1β（ng／L）：138．6±19．7比32．7±7．4，IL-6（ng／L）：196．5±31．7比55．4±13．8，TNF-α（ng／L）：111．3±21．8比20．8±7．6；IL-1βmRNA（2^-△△CT）：2．79±0．44比0．83±0．12，IL-6mRNA（2^-△△CT）：1．99±0．25比0．56±0．11，TNF—α．mRNA（2^-△△CT）：2．54±0．37比0．72±0．09]；GAD和GABA。R蛋白表达均明显下调[GAD（灰度值）：0．38±0．12比1．75±0．45，GABAAR（灰度值）：0．29±0．09比1．68±0．39；均P〈0．05]。与P1组比较，P2组细胞活性明显上调（A值：0．523±0．132比0．196±0．071），LDH释放率明显降低[（6．9±1．7）％比（12．3±2．4）％]；细胞培养液中IL-1β、IL-6及TNF—α含量和mRNA表达量均明显降低[IL-1β（ng／L）：79．2±11．6比138．6±19．7，IL-6（ng／L）：89．

英文摘要：

Objective To evaluate the effect of mechanical stretch preconditioning on pathological stretchinduced activation of γ-aminobutyric acid （GABA） signaling pathway in human type Ⅱ alveolar epithelial cells （AEC Ⅱ）. Methods AEC Ⅱ cell line （A549 cells） cultured in vitro were divided into control group （group C）, pathological stretch group （group P1） and mechanical stretch preconditioning group （group P2）. In group C, A549 cells were cultured routinely. In group P1, A549 cells were exposed to 20% cyclic stretch for 6 hours. In group P2, A549 cells were exposed to 5% cyclic stretch for 60 minutes, and then exposed to 20% cyclic stretch for 6 hours. The cells were harvested for determination of the cell viability by methyl thiazolyl tetrazolium assay, lactate dehydrogeuase （LDH） release was determined by colorimetric method, the levels of interleukin （IL-1β and IL-6） and tumor necrosis factor-α （TNF-α） were determined by enzyme linked immunosorbent assay （ELISA）, the mRNA expressions of IL-1β, IL-6 and TNF-α were determined by reverse transcription-polymerase chain reaction （RT-PCR）, and the protein expressions of glutamic acid decarboxylase （GAD） and γ-aminobutyric acid A receptor （GABAAR） were determined by Western Blot. Results Compared with group C, the cell viability of group P1 was significantly decreased （A value： 0.196 ± 0.071 vs. 0.886 ± 0.107）, the release rate of LDH was significantly increased [（12.3 ± 2.4）% vs. （1.9±0.5）%]; the contents and mRNA expressions of IL-1 β, IL-6 and TNF-α in cell euhure medium were significantly increased [IL-1 β （ng/L）： 138.6± 19.7 vs. 32.7±7.4, IL-6 （ng/L）： 196.5±31.7 vs. 55.4± 13.8, TNF- α （ng/L）： 111.3 ± 21.8 vs. 20.8 ± 7.6; IL-1β mRNA （2^-△△CT）： 2.79 ± 0.44 VS. 0.83 ± 0.12, IL-6 mRNA （2^-△△CT）： 1.99 ± 0.25 vs. 0.56 ± 0.11, TNF-α mRNA （2^-△△CT）： 2.54 ± 0.37 VS. 0.72 ± 0.09]; the protein expressions of GAD and GABAAR were signific