Objective To study the effect of hydrogen sulfide (H2S) on iNOS/NO in neonatal rats with hyperoxia-induced lung injury.Method Eighty full-term neonatal SD rats were randomly assigned into 4 groups (each group 20 rats including control group,hyperoxia group,NaHS + hyperoxia group,PPG + hyperoxia group.Rats in NaHS + hyperoxia group had 90 μmol/kg NaHS injected intraperitoneally,those in PPG + hyperoxia group had PPG 50 mg/kg injected,and those in the other 2 groups had the same amount of 0.9％ normal saline injected.Except for the control group that exposed to air,the other three groups were exposed to 95％ O2 for 7 days.Then pulmonary histopathology was studied by HE staining,the ratios of lung wet/dry weight (W/D) were determined as measurement of the severity of pulmonary edema,maleic dialdehyde (MDA),iNOS activity and NO levels in lung tissue were measured using commercial kits,iNOS mRNA expression was detected by Real-time PCR.Analysis of variance and LSD-t test were used for statistical analysis.Result (1) Compared with control group,the hyperoxia group showed erythrocyte extravasation and leukocyte infiltration in the alveoli with inflammatary cell infiltrations,alveolar septum edema,whereas pathological injury changes induced by hyperoxia were alleviated by NaHS and the damage was exacerbated by PPG.(2) In hyperoxia group,H2S was decreased compared with control group (117.6±20.4 μmol/L vs.184.3 ± 13.7 μmol/L).In NaHS + hyperoxia group,H2S was apparently increased compared with the hyperoxia group (247.3 ±32.4 μmol/L vs.117.6 ±20.4 μmol/L),while in PPG + hyperoxia group H2S was decreased compared with the hyperoxia group (89.2 ± 8.3 μmol/L vs.117.6 ±20.4 μmol/L) (P ＜0.01).(3) In the hyperoxia group,the ratios of lung W/D (5.81 ±0.22),the contents of MDA (1.69 ± 0.14) nmol/ml,iNOS activity (2.24 ± 0.19) U/mg prot,NO levels (22.37 ±3.04) × 10-3 μmol/g prot,iNOS mRNA expression (1.43 ±0.09) showed significant increase respectively (P ＜ 0.01) compared with the control group (5.06 ± 0.15),(0.78 ± 0.08)nmol/ml,(1.18 ± 0.18) U/mg prot,(7.49 ± 1.91) × 10-3 μmol/g prot,(0.90 ± 0.08).NaHS administration showed a significant decrease in lung W/D,lung tissue MDA content,iNOS activity,NO level,iNO SmRNA expression (5.59 ±0.19),(1.44±0.11) nmol/ml,(1.84 ±0.27) U/mg prot,(14.23 ±2.00)× 10-3 μmol/g prot,(1.28 ±0.10) compared with the hyperoxia group (P ＜0.01).The above markers were significantly increased after PPG administration (6.18 ± 0.26),(1.99 ± 0.19) nmol/ml,(2.66 ± 0.23) U/mgprot,(30.94 ±3.31) × 10-3 μmol/g prot,(1.73 ±0.06) (P ＜0.01).Conclusion Exogenous H2S can relieve hyperoxia-induced lung injury by down-regulating the expression of iNOS mRNA,decreasing iNOS activity and decreasing NO production.%目的 探讨硫化氢(hydrogen sulfide,H2S)对高氧肺损伤新生大鼠肺损伤的作用及机制.方法 将80只新生SD大鼠随机分为对照组、高氧组、硫氢化钠(sodium hydrosulfide,NaHS)+高氧组、H2S释放抑制剂炔丙基甘氨酸(propargylglycine,PPG)+高氧组4组,每组20只.NaHS+高氧组入组时腹腔注射1次NaHS 90 μmol/kg,PPG+高氧组注射PPG 50 mg/kg,对照组和高氧组给予等量0.9％ NaCl腹腔注射.对照组在空气中饲养,其余3组均置于自制氧箱中并保持氧浓度≥95％.7d后留取肺组织标本,观察肺组织形态学改变,检测肺组织匀浆H2S含量及肺湿重/干重(wetweight/dry weight,W/D)比值,测定肺组织匀浆丙二醛(malondialdehyde,MDA)、诱生型一氧化氮合酶(inducible NOS,iNOS)活性、一氧化氮(nitricoxide,NO)含量及iNOS mRNA表达.多组间比较采用方差分析,两两比较采用LSD-t检验.结果 与对照组相比,高氧组肺泡腔内有少量红细胞外渗及炎性细胞渗出,肺泡间隔炎症细胞浸润并增宽,NaHS+高氧组较高氧组病变程度轻,PPG+高氧组较高氧组病变程度重.高氧组肺组织H2S含量[(117.6 ±20.4) μmol/L]低于对照组[(184.3 ±13.7) μmol/L]和NaHS+高氧组[(247.3 ±32.4) μmol/L],高于PPG+高氧组[(89.2±8.3)μmol/L];高氧组W/D[(5.81±0.22)]、MDA含量[(1.69 ±0.14) nmol/ml]、iNOS活性[(2.24 ±0.19) U/mg prot]、NO含量[(22.37 ±3.04)×10-3μmol/g prot]、iNOS mRNA表达量[(1.43±0.09)]高于对照组[W/D:(5.06±0.15),MDA:(0.78±0.08)nmol/ml,iNOS:(1.18 ±0.18) U/mg prot,NO:(7.49±1.91)×10.μmol/g prot,iNOS mRNA:(0.90±0.08)]和NaHS+高氧组[W/D:(5.59±0.19),MDA:(1.44±0.11) nmol/ml,iNOS:(1.84±0.27) U/mg prot,NO:(14.23±2.00)×10-3 μmol/g prot,iNOS mRNA:(1.28±0.10)],低于PPG+高氧组[W/D:(6.18 ±0.26),MDA:(1.99 ±0.19) nmol/ml,iNOS:(2.66±0.23) U/mg prot,NO:(30.94±3.31)×103 μmol/g prot,iNOS mRNA:(1.73±0.06)],差异均有统计学意义(P＜0.05).结论 外源性H2S可能通过下调肺组织iNOS mRNA的表达降低iNOS活性、减少NO生成,从而发挥对新生大鼠高氧肺损伤的保护作用.
展开▼
