摘要目的 建立脂多糖致大鼠急性肺损伤的模型,观察一氧化氮对大鼠气道环氧合酶-2(cox-2)和Toll样受体4(TLR4)的分布及表达的影响.方法 健康雄性SD大鼠24只,按随机数字表法分为正常对照组、单用脂多糖(脂多糖组)、脂多糖加NO 20×10-6mg/L(低浓度NO组),脂多糖加NO 100×10-6mg/L(高浓度NO组).气管内滴注脂多糖(5 mg/kg)建立大鼠急性肺损伤模型.观察6 h后的肺水肿程度、免疫组织化学(SP染色)和实时荧光定量PCR检测肺组织中COX-2和TLR4的表达,以及分别吸入20×10-6、100×10-6mg/L浓度NO后的影响.所得数据采用单因素方差分析进行统计学分析,多个样本均数之间的两两比较采用LSD-t检验.结果 COX-2和TLR4在对照组大鼠气道内有广泛的分布和表达.脂多糖组大鼠肺水肿程度明显高于对照组,其主支气管和肺内细支气管上皮细胞内COX-2(6.5±2.8)及TLR4(44.9±11.3)表达高于对照组(分别为2.8 4±0.8、2.1±0.7),差异有统计学意义(t值分别为3.003、10.480,均P<0.01).低浓度NO组肺水肿程度明显减轻,其COX-2表达量(5.0±2.0)低于脂多糖组,但差异无统计学意义(t=1.227,P>0.05).而低浓度NO组TLR4(16.2±3.8)的表达量与脂多糖组(44.9±11.3)比较差异具有统计学意义(t=7.030,P<0.001).结论 COX-2和TLR4在大鼠气道内广泛分布,脂多糖刺激可使COX-2和TLR4的表达增强,吸入适当浓度NO可降低由脂多糖引起的COX-2和TLR4表达的增高.

abstractsObjective To study the effect of nitric oxide (NO) on the expression of cyclo-oxgenase 2 ( COX-2) and toll-like receptor 4 ( TLR4) in a rat model of acute lung injury ( ALI) induced by lipopolysaccharide ( LPS). Methods Twenty-four Sprague-Dawley rats were randomly divided into 4 groups. Group N: normal control group; Group L: ALI model by LPS intratracheal instillation; Group Za: ALI model + inhaled NO 20 × 10-6 mg/L; Group Zb: ALI model + inhaled NO 100 × 10-6 mg/L. Lung morphology was studied and COX-2 was detected by immunohistochemistry (IHC) while TLR4 by fluorescent quantitative PCR( FQ-PCR) . Results Immunohistochemistry and FQ-PCR showed that COX-2(2. 8 ± 0. 8 ) and TLR4(2. 1 ±0.7) were detected in the respiratory tract of the normal control rats. In Group L, the expression of COX-2 ( 6. 5 ±2.8) and TLR4(44. 9 ± 11.3) was increased in the main bronchus and bronchioles, compared to the normal controls (t =3.003, 10.480, both P < 0. 01). In Group Zb, the expression of COX-2(5. 0 ±2. 0) and TLR4( 16. 2 ±3. 8) were decreased as compared to Group L, but only the level of TI.R4 showed statistical difference (t = 7. 030,P < 0. 001 ). Conclusions COX-2 and TLR4 distributed widely in the respiratory tract of the rats. LPS increased the expression of COX-2 and TLR4. Low dose of nitric oxide(20 × 10-6 mg/L) inhalation reduced the bronchiolar expression of COX-2 and TLR4 induced by LPS.