Effect of caffeine on bronchopulmonary dysplasia in neonatal rats induced by hyperoxia through autophagy
Objective To explore the effect of caffeine on hyperoxia-induced bronchopulmonary dysplasia (BPD) in neonatal rats and related mechanism.Methods Forty-eight SD neonatal rats were randomly divided into air group,hyperoxia group,air+caffeine group,and hyperoxia+caffeine group,with 12 rats in each.The animals were exposed to hyperoxia to induce BPD model,and rats in air+caffeine and hyperoxia+caffeine groups were injected intraperitoneally with 20 mg/kg of caffeine,lung tissue samples were collected on 7th and 14th days after modelling.HE staining was used to evaluate the morphological changes in lung tissue,immunohistochemistry was used to detect the average optical density (AOD) value of CD31 protein in lung tissue,qRT-PCR was used to detect the relative expression of CD31,microtubule-associated protein 1 light chain 3B (LC3B) and p62 mRNA,immunofluorescence was used to detect the immunofluorescence intensity of LC3B and p62 protein,and Western blot was used to detect the ratio of LC3B-Ⅱ to LC3B-Ⅰ protein (LC3B-Ⅱ/LC3B-Ⅰ) and the relative expression of p62 protein in lung tissue.Results On the 7th and 14th days after birth,compared with the air group,the value of radial alveolar count (RAC) was significantly decreased,the mean linear intercept (MLI) was significantly increased,the the AOD value of CD31 protein and the relative expression of CD31 mRNA in lung tissue were significantly decreased in the hyperoxia group;The relative expression of LC3B mRNA,the immunofluorescence intensity of LC3B protein,and the LC3B-Ⅱ/LC3B-Ⅰ in lung tissue were significantly decreased,while the relative expression of p62 mRNA,the immunofluo-rescence intensity of p62 protein,and the relative expression of p62 protein were significantly increased (all P<0.05).Compared with the hyperoxia group,the hyperoxia+caffeine group showed a significant increase in RAC value and a decreased in MLI value,a significant increase in the AOD value of CD31 protein and the relative expression of CD31 mRNA,the relative expression of LC3B mRNA,the immunofluorescence intensity of LC3B protein,and the LC3B-Ⅱ/LC3B-Ⅰ were significantly increased,as well as the relative expression of p62 mRNA,the immunofluorescence intensity of p62 protein and the relative expression of p62 protein were significantly decreased,with all differences being statistically significant (all P<0.05).Conclusion Hyperoxia induces insufficient autophagy in the lung tissue of newborn rats with BPD;and caffeine intervention may attenuate autophagy and lung development arrest in BPD rats.
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