Our previous studies have shown that calcitonin gene-related peptide (CGRP) exerts protective effects on the acute lung injury induced by oxidative stress. This study was aimed to investigate whether autophagy was involved in the protection of CGRP against oxidative stress-induced lung injury in neonatal rats. Newborn Sprague-Dawley (SD) rats were randomly divided into five groups: Control group, oxidative stress model group (Model group), Model + CGRP group, Model + CGRP + Rapamycin (an autophagy agonist) group, and Model + CGRP + LY294002 (an autophagy inhibitor) group. The model of hyperoxia-induced lung injury was established by continuous inhalation of oxygen (FiO₂ = 90%-95%) for 14 days in neonatal SD rats. Pathological changes of lung tissue were observed by hematoxylin and eosin (HE) staining, and mean linear intercept (MLI) was measured. The quantitative changes of autophagic vesicles (AV) in type II alveolar epithelial cells (AECII) were measured under the transmission electron microscope. The protein expressions of Caspase-3, Bcl-2, mTOR, and Beclin-1 in lung tissue lysates were detected by Western blot. The results showed that, compared to the Model group at the same time point, the number of AV in AECII and the expression level of Beclin-1 protein of the lung tissue were increased, while the expression level of mTOR protein was decreased, with alleviated pathological changes, reduced MLI value and Caspase-3 protein expression level, increased Bcl-2 protein expression level in the lung tissue of Model + CGRP group. In addition, we found that the protective effect of CGRP on hyperoxia-induced lung injury could be enhanced by autophagy activator Rapamycin and abolished by autophagy inhibitor LY294002. Together, these findings indicate that CGRP could attenuate hyperoxia-induced lung injury in neonatal rats by enhancing autophagy.
Acute Lung Injury/pathology* ; Animals ; Animals, Newborn ; Autophagy ; Calcitonin/metabolism* ; Calcitonin Gene-Related Peptide/metabolism* ; Caspase 3/metabolism* ; Hyperoxia/pathology* ; Lung/pathology* ; Lung Injury/prevention & control* ; Oxidative Stress ; Proto-Oncogene Proteins c-bcl-2/metabolism* ; Rats ; Rats, Sprague-Dawley ; Sirolimus/pharmacology*

OBJECTIVETo study the effect of rhubarb on neonatal rats with bronchopulmonary dysplasia (BPD) induced by hyperoxia.

METHODSA total of 64 rats (postnatal day 4) were randomly divided into four groups: air control, rhubarb control, hyperoxia model, and hyperoxia+rhubarb (n=16 each). The rats in the hyperoxia model and hyperoxia+rhubarb groups were exposed to hyperoxia (60% O2) to establish a BPD model. The rats in the rhubarb control and hyperoxia+rhubarb groups were given rhubarb extract suspension (600 mg/kg) by gavage daily. The pathological changes of lung tissue were evaluated by hematoxylin-eosin staining on postnatal days 14 and 21. The content of malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) were measured by spectrophotometry. The mRNA and protein expression levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) were determined by RT-PCR and Western blot respectively.

RESULTSThe hyperoxia model group showed reduced alveolar number, increased alveolar volume, and simplified alveolar structure, which worsened over the time of exposure to hyperoxia. These pathological changes were significantly reduced in the hyperoxia+rhubarb group. On postnatal days 14 and 21, compared with the air control and rhubarb control groups, the hyperoxia model group had significantly reduced radical alveolar count (RAC), significantly reduced activity of SOD in the lung tissue, and significantly increased content of MDA and mRNA and protein expression levels of TNF-α and IL-6 (P<0.05). Compared with the hyperoxia model group, the hyperoxia+rhubarb group had significantly increased RAC, significantly increased activity of SOD in the lung tissue, and significantly reduced content of MDA and mRNA and protein expression levels of TNF-α and IL-6 (P<0.05).

CONCLUSIONSRhubarb may play a protective role in rats with BPD induced by hyperoxia through inhibiting inflammatory response and oxidative stress.

Animals ; Animals, Newborn ; Bronchopulmonary Dysplasia ; metabolism ; pathology ; prevention & control ; Disease Models, Animal ; Hyperoxia ; complications ; Lung ; metabolism ; pathology ; Plant Extracts ; therapeutic use ; Rats ; Rats, Sprague-Dawley ; Rheum ; Superoxide Dismutase ; metabolism ; Tumor Necrosis Factor-alpha ; genetics

OBJECTIVETo study the expression of SUMO-modified CCAAT enhancer binding protein α (C/EBPα) in preterm rat model of bronchopulmonary dysplasisa (BPD) induced by hyperoxia exposure and its role.

METHODSEighteen preterm rats were randomly divided into an air group and a hyperoxia group (n=9 each). The model of BPD was prepared in preterm rats exposed to hyperoxia. The rats from the two groups were sacrificed on postnatal days 4, 7 and 14 respectively (3 rats at each time) and lung tissues were harvested. Periodic acid-Schiff (PAS) staining was used to observe the differentiation of rat lung tissues. Ki67 expression was detected by immunohistochemistry. Western blot was used to measure the protein expression of small ubiquitin-related modifier-1(SUMO1) and C/EBPα. A co-immunoprecipitation assay was performed to measure the protein expression of SUMO-modified C/EBPα.

RESULTSCompared with the air group, the hyperoxia group showed a decreased glycogen content in the lung tissue on postnatal day 4, and an increased content on postnatal days 7 and 14. Over the time of hyperoxia exposure, the hyperoxia group showed an increased expression of Ki67 in the lung tissue compared with the air group at all time points. Compared with the air group, the protein expression of C/EBPα increased on postnatal day 4 and decreased on postnatal days 7 and 14 in the hyperoxia group (P<0.05). The hyperoxia group had significantly upregulated expression of SUMO1 and SUMO-modified C/EBPα compared with the air group at all time points (P<0.05). In the hyperoxia group, the protein expression of SUMO-modified C/EBPα was positively correlated with the glycogen content (r=0.529, P<0.05) and the expression of Ki67 (r=0.671, P<0.05).

CONCLUSIONSHyperoxia may induce over-proliferation and differentiation disorders of alveolar epithelial cells in preterm rat model of BPD, possibly through an increased expression of SUMO-modified C/EBP&alpha.

Animals ; Animals, Newborn ; Bronchopulmonary Dysplasia ; etiology ; metabolism ; pathology ; CCAAT-Enhancer-Binding Protein-alpha ; metabolism ; Cell Proliferation ; Disease Models, Animal ; Hyperoxia ; complications ; pathology ; Ki-67 Antigen ; analysis ; Pulmonary Alveoli ; pathology ; Rats ; Rats, Sprague-Dawley ; Sumoylation

OBJECTIVETo investigate the protective effect of prostaglandin E1 (PGE-1) against brain injury induced by hyperoxia in neonatal rats and observe the changes in the expression of glucose-regulated protein 78 (GRP78) and cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP), and to provide a theoretical basis for the clinical application of PGE-1 in the treatment of neonatal brain injury induced by hyperoxia.

METHODSSixty neonatal Wistar rats were randomly divided into air control group, hyperoxic brain injury model group, and hyperoxic brain injury+PGE-1 group. All rats except those in the air control group were treated to establish a hyperoxic brain injury model. From the first day of modeling, the rats in the hyperoxia brain injury+PGE-1 group were intraperitoneally injected with PGE-1 2 μg/kg daily for 7 consecutive days, while the other two groups were treated with normal saline instead. The water content of brain tissue was measured; the pathological changes of brain tissue were evaluated by hematoxylin-eosin staining; the apoptosis of brain cells was assessed by nuclear staining combined with TUNEL staining; the protein expression of GRP78 and CHOP in brain tissue was measured by Western blot.

RESULTSThe water content of brain tissue in the hyperoxic brain injury model group was significantly higher than that in the hyperoxic brain injury+PGE-1 group and air control group (P<0.05); the water content of brain tissue in the hyperoxic brain injury+PGE-1 group was significantly higher than that in the air control group (P<0.05). The pathological section of brain tissue showed inflammatory cell infiltration and mild cerebrovascular edema in the brain parenchyma in the hyperoxic brain injury model group; the periparenchymal inflammation and edema in the hyperoxic brain injury+PGE-1 group were milder than those in the hyperoxic brain injury model group. The apoptosis index of brain tissue in the hyperoxic brain injury model group was significantly higher than that in the hyperoxic brain injury+PGE-1 group and air control group (P<0.05); the apoptosis index of brain tissue in the hyperoxic brain injury+PGE-1 group was significantly higher than that in the air control group (P<0.05). The protein expression of GRP78 and CHOP in brain tissue was significantly higher in the hyperoxic brain injury model group than in the hyperoxic brain injury+PGE-1 group and air control group (P<0.05); the protein expression of GRP78 and CHOP was significantly higher in the hyperoxic brain injury+PGE-1 group than in the air control group (P<0.05).

CONCLUSIONSPGE-1 has a protective effect against hyperoxia-induced brain injury in neonatal rats, which may be related to the inhibition of cell apoptosis by down-regulating the expression of GRP78 and CHOP.

Alprostadil ; therapeutic use ; Animals ; Animals, Newborn ; Apoptosis ; drug effects ; Brain ; pathology ; Brain Injuries ; metabolism ; pathology ; prevention & control ; Heat-Shock Proteins ; analysis ; Hyperoxia ; complications ; Neuroprotective Agents ; therapeutic use ; Rats ; Rats, Wistar ; Transcription Factor CHOP ; analysis

OBJECTIVETo study the effect of hyperoxia and paired immunoglobin-like receptor B (PirB) on rat oligodendrocyte precursor cells (OPCs) in vivo and the neuroprotective effects of 17β-estradiol (E2) on these cells.

METHODSRat OPCs were treated with different concentrations of E2 and the cells were harvested for RT‑qPCR analysis at different time points. PriB was silenced with small interfering siRNA. The effects of E2 treatment and silencing of PriB on OPCs viability and apoptosis under hyperoxic stimulation were detected using 3‑(4,5‑dimethylthi‑azol‑2‑yl)‑2,5‑diphenyltetrazolium bromide (MTT) assay and flow cytometry analysis.

RESULTSHyperoxia induced apoptosis in OPCs and decreased their viability. E2 treatment markedly down-regulated the expression of PirB. E2 treatment or PirB silencing markedly decreased hyperoxia-induced apoptosis and increased cell viability in OPCs.

CONCLUSIONSE2 can protect OPCs from hyperoxia-induced apoptosis.

Animals ; Apoptosis ; drug effects ; Estradiol ; pharmacology ; Hyperoxia ; pathology ; Neuroprotective Agents ; pharmacology ; Oligodendroglia ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, Immunologic ; physiology ; Stem Cells ; drug effects ; physiology

OBJECTIVETo study the association between endoplasmic reticulum stress (ERS) pathway mediated by inositol-requiring kinase 1 (IRE1) and the apoptosis of type II alveolar epithelial cells (AECIIs) exposed to hyperoxia.

METHODSThe primarily cultured AECIIs from preterm rats were devided into an air group and a hyperoxia group. The model of hyperoxia-induced cell injury was established. The cells were harvested at 24, 48, and 72 hours after hyperoxia exposure. An inverted phase-contrast microscope was used to observe morphological changes of the cells. Annexin V/PI double staining flow cytometry was performed to measure cell apoptosis. RT-PCR and Western blot were used to measure the mRNA and protein expression of glucose-regulated protein 78 (GRP78), IRE1, X-box binding protein-1 (XBP-1), and C/EBP homologous protein (CHOP). An immunofluorescence assay was performed to measure the expression of CHOP.

RESULTSOver the time of hyperoxia exposure, the hyperoxia group showed irregular spreading and vacuolization of AECIIs. Compared with the air group, the hyperoxia group showed a significantly increased apoptosis rate of AECIIs and significantly increased mRNA and protein expression of GRP78, IRE1, XBP1, and CHOP compared at all time points (P<0.05). The hyperoxia group had significantly greater fluorescence intensity of CHOP than the air group at all time points. In the hyperoxia group, the protein expression of CHOP was positively correlated with the apoptosis rate of AECIIs and the protein expression of IRE1 and XBP1 (r=0.97, 0.85, and 0.88 respectively; P<0.05).

CONCLUSIONSHyperoxia induces apoptosis of AECIIs possibly through activating the IRE1-XBP1-CHOP pathway.

Animals ; Apoptosis ; Cells, Cultured ; Endoplasmic Reticulum Stress ; physiology ; Endoribonucleases ; physiology ; Epithelial Cells ; physiology ; Female ; Hyperoxia ; metabolism ; pathology ; Multienzyme Complexes ; physiology ; Protein-Serine-Threonine Kinases ; physiology ; Pulmonary Alveoli ; pathology ; Rats ; Rats, Sprague-Dawley ; Transcription Factor CHOP ; physiology ; X-Box Binding Protein 1 ; physiology

OBJECTIVETo explore the expression of CASZ1 and its relationship with the pulmonary microvascular development in lung tissue of newborn rats exposed to hyperoxia which induced bronchopulmonary dysplasia (BPD).

METHODForty-eight newborn Sprague Dawley(SD) rats (male and female unlimited) were randomly divided into two groups: experimental group and control group according to random digits table with 24 in each.The rats in experimental group were exposed to high oxygen volume fraction of 800 ml/L and the rats in control group were exposed to normal air. Eight rats were randomly selected from each group on day 3 and 7 after oxygen exposure.The sections of lung were stained with HE method in order to assess lung histological changes, the alveolar development was evaluated by the number of radial alveolar count (RAC) and septal wall thickness. CD31 was detected by immunohistochemistry (IHC) method and the capillary density was calculated. The location, distribution and expression of CASZ1 in the lung tissue were detected by the immunohistochemistry, Western blotting, and quantitative PCR (qPCR).

RESULT(1) Stained by HE, lungs of experimental group showed destroyed alveoli, alveoli fusion and increased septal wall thickness, RAC were significantly lower than those in control group(14 d: septal wall thickness (12.69 ± 0.63) μm vs. (6.53 ± 0.16) μm, RAC 5.9 ± 0.4 vs. 8.4 ± 1.0, t = 19.046, 4.760, P both = 0.000). (2) CD31 protein was expressed predominantly in cytoplasm of pulmonary microvascular endothelial cells. The experimental group CD31 average optical density (AIOD) were decreased compared with control group((16.6 ± 1.6) × 10(3) vs.(40.1 ± 2.4) × 10(3), (18.1 ± 1.4) × 10(3) vs.(83.2 ± 5.2) × 10(3), (49.2 ± 5.4) × 10(3) vs.(136.2 ± 28.1) × 10(3), t=16.185, 16.066 and 6.078, P<0.01 for all comparisons). Capillary density in experimental group was also significantly decreased compared with control group ((3.84 ± 0.15)% vs.(6.01 ± 0.22)%, (4.17 ± 0.38)% vs.(6.15 ± 0.24)%, (5.43 ± 0.44)% vs. (9.13 ± 0.25)%, t = 16.124, 8.773 and 14.076, P all < 0.01). (3)RT-qPCR and Western blotting showed that the CASZ1 mRNA significantly increased in experimental group compared with control group(0.56 ± 0.17 vs. 1.00 ± 0.26, 0.32 ± 0.29 vs. 0.58 ± 0.14, 0.14 ± 0.22 vs. 0.56 ± 0.15, t=3.890, 3.303 and 2.388, P < 0.05 for all comparisons), and the protein expression of CASZ1 also significantly increased in experimental group compared with control group (0.65 ± 0.02 vs. 0.78 ± 0.23, 0.46 ± 0.03 vs. 0.75 ± 0.05, 0.34 ± 0.22 vs. 0.75 ± 0.04, t=6.200 and 10.485 and 14.998, P < 0.05 for all comparisons). (4)The protein level of CASZ1 in experimental group was positively correlated with capillary density (r=0.519, P<0.01).

CONCLUSIONCASZ1 is involved in the whole process of newborn rats BPD and may be linked to pulmonary microvascular dysplasia.

Animals ; Animals, Newborn ; Bronchopulmonary Dysplasia ; pathology ; Female ; Hyperoxia ; pathology ; Lung ; blood supply ; pathology ; Male ; Oxygen ; adverse effects ; Pulmonary Alveoli ; RNA, Messenger ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Transcription Factors ; metabolism

OBJECTIVETo investigate the effect of γ-secretase inhibitor (N-[N-(3,5-difluorophenacetyl)-l -alanyl]-S-phenylglycine t-butyl ester, DAPT) on hyperoxia-induced brain white matter injury in mice.

MWTHODSThree-day-old C57BL/10J mouse pups were divided into air control (C) group, control+DAPT (10 mg/kg, injected intraperitoneally) group, hyperoxia group (exposed to 80% oxygen for 48 h), and hyperoxia+DAPT group. The brain and body weights of the mice were measured at postnatal days 3, 5, 12, and 28. Real-time PCR was used to detect Notch intracellular domain (NICD) mRNA expression in the brain after modeling, and the expressions of NG2 and myelin basic protein (MBP) were detected by double-labeled immunofluorescence assay to verify the oligdendrocycle type at postnatal day 12. The mice in each group were bred until postnatal day 28 for Morris water maze test.

RESULTSThe brain and body weights were significantly decreased in mice in hyperoxia group compared to the control mice, but increased significantly after DAPT treatment (P<0.05). Real-time PCR showed that a 48-hour hyperoxia exposure significantly increased NICD mRNA expression in the brain (P<0.05), which was decreased by co-treatment by DAPT (P<0.05). Hyperoxia also resulted in enhanced NG2 expression and lowered MBP expression in the brain (P<0.05). Compared with the control mice, the mice exposed to hyperoxia showed prolonged escape latency (P<0.05) and spent less time in the target quadrant with a lowered number of passing through the virtual platform (P<0.05). All these parameters were significantly improved by co-treatment with DAPT.

CONCLUSIONSpecific inhibition of Notch signaling pathway activation in the brain by the γ-secretase inhibitor DAPT can ameliorate white matter injury and learning and memory impairment in newborn mice with hyperoxia exposure.

Amyloid Precursor Protein Secretases ; antagonists & inhibitors ; Animals ; Body Weight ; Brain ; metabolism ; pathology ; Dipeptides ; pharmacology ; Hyperoxia ; physiopathology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred Strains ; Organ Size ; Receptors, Notch ; metabolism ; Signal Transduction ; White Matter ; pathology

OBJECTIVETo explore the effect of silence of Pin1 expression on hyperoxia-induced apoptosis in alveolar epithelial cells A549.

METHODSA549 cells were divided into four groups: control, hyperoxia, negative lentivirus and Pin1-shRNA hyperoxia. The hyperoxia group was exposed to a mixture of 95%O2 and 5%CO2 for 10 minutes. Then cells were cultured in a closed environment. After 24 hours, the changes of morphology were observed under an inverted microscope. Cell apoptosis was detected by flow cytometry (FCM). The expression of X-linked inhibitor of apoptosis protein (XIAP) and Caspase-9 were detected by immunohistochemistry. The production of reactive oxygen species (ROS) and cellular mitochondria membrane potential (△Ψm) were determined by fluorescence microscopy.

RESULTSUnder the inverted microscope, the A549 cells grew slowly and the changes in morphology of the cells were most obvious in the hyperoxia and negative lentivirus groups. The changes in morphology of A549 cells were obviously improved in the Pin1-shRNA hyperoxia group. The FCM results showed that the apoptosis rate of A549 cells increased, Caspase-9 expression increased, XIAP expression decreased, mitochondrial ROS production increased and mitochondrial membrane potential decreased in the hyperoxia and negative lentivirus groups compared with the control group (P<0.05). Compared with the hyperoxia and negative lentivirus groups, the apoptosis rate of A549 cells decreased, Caspase-9 expression decreased, XIAP expression increased, mitochondrial ROS production decreased and mitochondrial membrane potential increased in the Pin1-shRNA hyperoxia group (P<0.05), although the levels of the indexes did not reach to those of the control group.

CONCLUSIONSSilencing of Pin1 could suppress hyperoxia-induced apoptosis of A549 cells.

Apoptosis ; Caspase 9 ; genetics ; Humans ; Hyperoxia ; pathology ; Membrane Potential, Mitochondrial ; NIMA-Interacting Peptidylprolyl Isomerase ; Peptidylprolyl Isomerase ; physiology ; Reactive Oxygen Species ; metabolism ; X-Linked Inhibitor of Apoptosis Protein ; genetics

OBJECTIVETo explore the effect of low-concentration lipopolysaccharide (LPS) pretreatment on hyperoxia-induced immature brain injury in neonatal mice and explore and the related mechanisms.

METHODSForty-eight neonatal mice on postnatal day 3 (PND3) were randomized into normal control group, LPS (0.3 mg/kg) group, hyperoxia group (hyperoxia exposure for 24 h), and hyperoxia+LPS group (hyperoxia exposure for 24 h 30 min after 0.3 mg/kg LPS treatment). At PND5, all the neonatal mice were sacrificed to examine the morphological changes of microglia in the periventricular white matter using Tomato lectin staining, measure malondialdehyde (MDA) content in the immature brain, detect mRNA expression of tumor necrosis factor-α (TNF-α) using real-time PCR, and determine caspase-3 protein expression with Western blotting.

RESULTSCompared with the control group, exposures to LPS, hyperoxia, and both all resulted in microglia activation in the periventricular white matter. The number of activated microglia, MDA content, TNF-α mRNA expression and caspase-3 protein expression in the immature brain were significantly higher in hyperoxia group than in the control group and LPS group (P<0.05). LPS pretreatment significantly enhanced hyperoxia-induced microglia activation in the immature brain (P<0.05).

CONCLUSIONHyperoxia causes immature brain injury mediated by microglia activation, and LPS pretreatment can enhance such brain injury in neonatal mice.

Animals ; Animals, Newborn ; Brain ; metabolism ; pathology ; Caspase 3 ; metabolism ; Hyperoxia ; Lipopolysaccharides ; adverse effects ; Malondialdehyde ; metabolism ; Mice ; Mice, Inbred C57BL ; Microglia ; metabolism ; pathology ; Tumor Necrosis Factor-alpha ; metabolism