Effects Of Ozone Pretreatment On The Level Of Oxidative Stress In Nervous System In Rats In Hypobaric Hypoxic Environments

ObjectiveTo explore the effect of ozone pretreatment on the level of oxidative stress in the central nervous system of hypobaric hypoxic rats and its molecular mechanism.Methods1.Effect of acute hypobaric hypoxia exposure time on oxidative stress levels in the central nervous system in ratsAdult male SD rats were placed in a small animal hypobaric hypoxic chamber(simulated altitude 6000 m)and exposed to 0 h,12 h,24 h,48 h,and 96 h,respectively.The opening test was used to detect anxiety-like behavior changes in rats.Changes in hippocampal tissue were observed by HE histopathological section staining;The level of melatonin in serum was measured by ELISA,and the level of oxidative stress-related factors was detected by biochemical kits.2.Effect of ozone pretreatment on oxidative stress injury in the central nervous system in rats in acute hypobaric hypoxia environmentAdult male SD rats were randomly divided into atmospheric pressure normoxia control group(Con),atmospheric pressure oxygen ozone pretreatment group(O3),hypobaric hypoxia group(HH)and hypobaric hypoxic ozone pretreatment group(O3 + HH),and intraperitoneally injected ozone(50 ug/ml,0.7 mg/kg,1 time/day)or air(3 ml,1 time/day)for 5 consecutive days.After 5 days,it was placed in a small animal hypobaric hypoxic chamber(simulated altitude 6000 m)and exposed for 24 h.The opening text was used to detect anxiety-like behavior changes in rats.Changes in hippocampal tissue were observed by HE histopathological section staining;ELISA was used to detect the levels of serotonin(5-HT)and melatonin(MT)in hippocampus and serum,the level of oxidative stress correlated factors was detected by biochemical kits,the level of Nrf2/Keap1/HO-1 m RNA in hippocampal tissues was detected by Real-time PCR(q PCR),and the regulatory effect of ozone pretreatment on the expression of Nrf2 oxidative stress signaling pathway protein was detected by Western Blot.Results1.Effect of acute hypobaric hypoxia exposure time on oxidative stress levels in the central nervous system in ratsThe opening test showed that compared with the 0 h group,the number of center entries,center residence time and center/total movement distance of rats exposed to hypobaric hypoxia at 12 h,24 h and 96 h decreased significantly(P < 0.05).HE staining showed that compared with the 0 h group,neurons in the CA1,CA3 and DG regions of the hippocampus were loosely arranged,the pericellular space was widened,the cells were swollen and neurons were shrunk in the 12 h,24 h,48 h and 96 h groups.Compared with the control group,the SOD activity of hippocampal was significantly reduced in the hypobaric hypoxia exposure groups at 24 h,48 h and 96 h(P < 0.05),and the MDA content showed an upward trend.ELISA results showed that the levels of serum MT decreased significantly in both the hypobaric hypoxic exposure 24 h and 48 h groups compared with the control group(P < 0.05).2.Effect of ozone pretreatment on oxidative stress injury in the central nervous system in rats in acute hypobaric hypoxia environmentCompared with the Con group,the number of center entries,center residence time and center/total movement distance of rats in the HH group were significantly reduced in the opening test(P < 0.05).In the HH group,neurous in the hippocampus CA1,CA3 and DG regions were loosely arranged,swollen and reduced.The activities of SOD and GSH-Px enzyme in hippocampal decreased significantly,the level of MDA was significantly increased,the levels of MT in hippocampal and serum and the level of 5-HT in hippocampal decreased significantly(P < 0.05),and the levels of hippocampal Nrf2 and HO-1 m RNA and protein in rats in the HH group were significantly increased,and the levels of Keap1 m RNA and protein were significantly reduced(P < 0.05).Compared with the HH group,the number of center entries,center residence time and center/total movement distance of the rats which were given ozone pretreatment in the O3+HH group were significantly increased(P < 0.05).The number of hippocampal neurons is increased,and the boundaries are relatively clear;The activities of hippocampal SOD and GSH-Px enzyme were significantly increased,the level of MDA decreased significantly,and the levels of MT in hippocampal and the level of 5-HT in hippocampal increased significantly(P < 0.05).The levels of hippocampal Nrf2 and HO-1 m RNA and protein in the O3+HH group were significantly increased,and the levels of Keap1 m RNA and protein were significantly reduced(P < 0.05).Conclusions1.Acute hypobaric hypoxia exposure reduced the performance in the opening test,increased hippocampal tissue damage and oxidative stress levels in rats,and the effect on rats was most significant when low-pressure hypoxia exposure was 24 h.2.Ozone pretreatment could significantly improve the performance of acute hypobaric hypoxia rats in the opening test and reduce hippocampal tissue damage in acute hypobaric hypoxic rats.3.Ozone pretreatment may improve antioxidant capacity in vivo and reduce oxidative damage of hippocampal tissues by further activating the hippocampal Nrf2/Keap1/HO-1 signaling pathway.