ABSTRACT
Objective: To explore the protective effect of glutamine (GLN) on the hyperoxia-induced lung injury of the neonatal rats through endoplasmic reticulum stress (ERS) pathway, and to elucidate its mechanisms. Methods: A total of 90 Wistar rats were randomly divided into control group (FiO2 =21%), hyperoxia group (FiO2 85%), and hyperoxia+GLN group (Fi2 85%, the concentration of intraperitoneal injection of GLN was 0. 75 g · kg-1 · d-1); there were 30 rats in each group The body weights and water contents in the lung tissue of the neonatal rats were measured on the 3rd, 7th and 14th days of the experiment. HE staining was used to determine the morphology of lung tissue of the rats. The superoxide dismutase (SOD) activity in lung tissue of the rats was detected by nitro blue tetrazolium chloride (NBT), and the malondialdehyde (MDA) level was determined by thiobarbital acid (TBA). The expression levels of Caspase-12, GADD153, GRP78, Bel-2, and Bax in lung tissue of the rats were detected by Western blotting method. Results: Compared with control group at the same time, the body weights of the neonatal rats in hyperoxia group on the 3rd, 7th and 14th days were significantly decreased (P<0. 05), the water contents in lung tissue of the neonatal rats were increased (P<0. 05), the SOD activities were significantly decreased (P<0. 05), the levels of MDA in the lung tissue of the neonatal rats were increased (P<0. 05), the expressions levels of Caspase-12, GADD153, GRP78 and Bax proteins were significantly increased (P<0. 05), and the expression levels of Bcl-2 protein and the Bcl-2/Bax ratios were significantly decreased (P<0. 05). Compared with hyperoxia group at the same time, the body weights of the neonatal rats in hyperoxia + GLN group on the 3rd, 7th and 14th days were significantly increased (P<0. 05), the water contents in lung tissue of the neonatal rats were decreased (P<0. 05), the SOD activities were significantly increased (P< 0. 05), the levels of MDA in lung tissue of the neonatal rats were decreased (P<0. 05), the expression levels of Caspase-12, GADD153, GRP78 and Bax proteins were significantly decreased (P<0. 05), the expression levels of Bcl-2 protein and the Bcl-2/Bax ratios were increased (P<0. 05). The pathological sections of lung tissue of the rats in control group showed that lung tissue structure was regular, no alveolar edema was found, the alveolar size and alveolar septum were approximately the same, and no inflammatory cell infiltration was found; the histopathological sections of lung tissue of the rats in hyperoxia group showed swelling of brochial and alveolar epithelial cells, enlargement of alveolar lumen, edema of interstitial cells, inflammatory cell infiltration and fibrous exudation; the degrees of alveolar damage, the inflammatory exudation and the proliferation of fibrons tissue in hyperoxia+GLN group were alleviated which was between hyperoxia group and control group. Conclusion: GLN can alleviate the hyperoxia-induced lung tissue edema and inflammatory response of the neonatal rats, and one of mechanisms is that GLN can down-regulate the expression levels of Caspase-12, GADD153, GRP78 and Bax proteins and up-regulate the expression level of Bcl-2 protein through ERS pathway to protect hypoxic lung injury.
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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.
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Objective To investigate the effects of selective cyclooxygease-2 inhibitor on pulmonary surfactant protein(SP-B) and transforming growth factor(TGF-β1) of hyperoxic lung injury in newborn rats.Methods One hundred and five SD rats were randomly divided into 3 groups (35 cases in each group):air group (group Ⅰ),in which the rats were exposed to room air;hyperoxia group(group Ⅱ),in which the rats were exposed to hyperoxia(850 mL/L oxy gen);Celecoxib group(group Ⅲ),in which the rats were exposed to heyperoxia(850 mL/L oxygen) and intraperitoneally injected with 5 mg/kg Celecoxib.The lungs of rats were removed on 3 d,7 d,14 d after birth and the following indices were measured:lung section from the lower right lung were stained with HE,and the histological changes was examined;the contents of SP-B and TGF-β1 in the bronchoalveolar lavage fluid of left lung was determinated by using enzyme-linked immunosorbent assay (ELISA);right upper lung was immunohistochemically stained to measure the contents of SP-B and TGF-β1,quantitative real-time PCR(RT-PCR) was used to detect the mRNA expression of SP-B and TGF-β1.Results There were no inflammatory cells and exudation in the lung in group Ⅰ;in group Ⅱ,the structure disorder,pulmonary edema,and inflammatory infiltrates were found;but the damage was obviously alleviated in group Ⅲ.Protein expression could be better detected by ELISA,at the time of 14 day,SP-B was expressed at different levels in3 groups:(29.93±6.40) ng/L in group Ⅰ,(18.20 ±3.70) ng/L in group Ⅱ and (19.63 ±10.20) ng/L in group Ⅲ,SP-B level in group Ⅱ was significantly lower than that in group Ⅰ (t =13.152,P ＜ 0.01),and the expres sion in group Ⅲ was significantly higher than that in group Ⅱ (t =5.190,P ＜ 0.01).TGF-β1 was expressed at different levels in 3 groups:(34.73 ±2.30) μg/L in group Ⅰ,(41.66 ± 1.80) μg/L in group Ⅱ and (38.03 ±0.20) μg/L in group Ⅲ,and the level of TGF-β1 was significantly higher in group Ⅱ than that in group Ⅰ (t =6.584,P ＜ 0.01),but the expression of group Ⅲ was significantly lower than that in group Ⅱ (t =5.609,P ＜ 0.01).The expression of mRNA was detected by RT-PCR,and at the time of 14 day,SP-B mRNA was expressed at different levels in 3 groups:3.14 ±0.10 in group Ⅰ,0.81 ±0.06 in group Ⅱ and 1.12 ±0.06 in group Ⅲ,and SP-B level in group Ⅱ was significantly lower than that in the group Ⅰ (t =55.050,P ＜0.01),and the expression in group Ⅲ was significantly higher than that in group Ⅱ (t =10.305,P ＜ 0.01).TGF-β1 mRNA was expressed at different levels in the 3 groups:1.94 ±0.03 in group Ⅰ,13.26 ±0.43 in group Ⅱ and 6.49 ±0.26 in group Ⅲ,the level of TGF-β1 was significantly higher in group Ⅱ than that in group Ⅰ (t =75.471,P ＜ 0.01),while the expression of group Ⅲ was significantly lower than that in group Ⅱ (t =38.470,P ＜ 0.01).Conclusions Cyclooxygenase-2 inhibitor can attenuate hyperoxic lung injury in rats,and the mechanism might be related to the reduction of prostaglandin.
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Objective To investigate the expression of JNK2 in hyperoxic lung injury ,and explore the protective effect of sub-stance P (SP) on hyperoxic lung injury and its mechanism .Methods Sixteen SD rats were divided into four groups with 4 rats in each group :room-air and f 9 g/L saline group (group A) ,room-air and SP group (group B) ,hyperoxia injury group and f 9 g/L sa-line group (group C) ,hyperoxia injury group and SP group (group D) .Rats ingroup B and D were injected with SP 1 × 10-6 mol · L -1 · kg -1 · d-1 intraperitoneally ,group A and group C were injected with an equal volume of 9 g/L saline .The animals were sac-rificed after 14 days of experiment .Lung pathology was examined with light microscopy ,lung wet/dry (W/D) ratio and the level of SP and PCNA and TUNEL in lung were evaluated .The Superoxide dismutase (SOD) ,malondialdehyde (MDA) and glutathione (GSH) level were assayed respectively in lung tissue .The quanlity of JNK2 protein was detected by Western blot analysis .Results Compared with group A ,the high oxygen groups all had different degrees of lung injury ,,while the lung pathological pictures in group D was improved significantly compared with group C .Western blot showed that level of JNK2 in group C was obviously higher than that of group A ;After the intervention ,level of JNK2 in group D was lower than that of group C .The lung W/D retio , TUNEL and PCNA expression and distribution SOD ,MDA and GSH was consistent with the trends of JNK2 protein expression . Conclusion High oxygen stress can activate damage lung tissue JNK 2 activity ;SP protection mechanism of high oxygen lung injury may be induced by cutting high oxygen activation of JNK 2 to inhibit oxidative damage .