| Background: According to animal studies, high-concentration oxygen can cause eyes and lung injury, such as retinopathy of prematurity and bronchopulmonary dysplasia. Hyperbaric oxygenation also belongs to high-concentration oxygen, and great amount of evidence shows that hyperbaric oxygenation is an effective form of therapy to treat Hypoxic-ischemic brain damage, which could not result in ROP or BPD in neonatal animals. However, the truth that whether there is any difference between HBO and HO on toxicity in normal neonatal rats is yet to be elucidated. Knowledge about the difference and mechanism will help us to treat neonatal brain damage better by using HBO.Objective: To investigate, after HBO and HO intervention, the toxicity in retina and lung and the expression of VEGF in normal neonatal rats of different ages.Methods: 1. Sprague-Dauleys (SD) rats were randomly divided into six groups: 3-day-old groups (1) Control-3 group; (2) HO-3 group, (3)HBO-3 group; 7-day-old groups (4) Control-7 group; (5) HO-7 group; (6) HBO-7 group. The HBO groups were administered with 2.0 ATA pressure of air and oxygen once per day, persist a series of 7 days and then raised under normal pressure. The HO groups were given high concentration oxygen (90%) inhalation for 7 days and then raised under normal air. The control groups were given no intervention. All rats were killed at 21 days old. 2. Observation for new retinal vessels of flattening retina on the slide by Chinese ink staining; pathologic examination for eyeballs and lungs: the eyeballs and lungs of all groups were stained with hematoxylin and eosin (HE). The proliferated neovascular response and morphologic change of lungs were observed under light microscope. Immunohistochemistry of VEGF: to quantitate the expression of VEGF in retina and lung and qualitative analyze the apoptosis of lung tissue cells by TUNEL (Terminal deoxynucleotidyl Transferase Biotin-dUTP Nick End Labeling) test.Results: The nuclei of the new vessels of each group was: the CON-3 group: 19.0±4.8, CON-7:20.1±8.0, HBO-3:23.6±6.8, HO-3: 82.4±15.4, HBO-7: 20.9±7.8, HO-7: 68.8±12.7. The HO groups were higher than the CON group, P< 0.005, but the difference were not significant between the CON and HBO group, P>0.05. Comparison of the HO groups of different ages indicated that the vessel proliferation was more obvious in HO-3 than HO-7, P= 0.009. The changes of retinal vessels of flattening retina on the slide showed that the HO groups increased significantly while there were not such changes in HBO groups. Immunohistochemistry of VEGF in retina was visible in HBO-3, HO-3, HO-7 groups compare with CON-3, CON-7 and HBO-7 groups, P< 0.001. The changes of lung tissue stained with HE under light microscope: There was no obvious change between HBO and CON groups. However, in HO groups, the structure of alveoli pulmonis was irregular, the normal structure disappeared, the amount of alveoli pulmonis decreased obviously, and intralobular interstitial thickening was conspicuous. The stain of VEGF in lung showed that there was no obvious change between HBO and CON groups, but the expression was diminished greatly in HO groups, P<0.05. The TUNEL test of lung tissue presented in HO groups a great deal of apoptosis cells, which could partly be seen in HBO-3 group. The HBO-7 was almost the same with CON in aspect of the amount of apoptosis cells.Conclusions: Our investigation showed that HO stimulated retinae neovascular proliferation and caused pulmonary injury in normal neonatal rats, and, HBO did not have similar function, which may be related to the expression of VEGF. The earlier to give HO intervention, the more obvious will the retinae neovascular proliferation and pulmonary injury be. |
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