Protective Effect And Mechanism Of Hyperbaric Oxygen Preconditioning On Decompression Sickness In Rats And Its Mechanism

When Pressure reduction of the ambient atmospheric, the gas dissolved in the bloodor tissue formation of bubbles, a special disorders can occur, that is decompressionsickness (DCS). Neurological decompression sickness (NDS) is a decompression sicknesswhich have more severe nervous system symptoms. Hyperbaric oxygen as safe andeffective treatment methods, which can induce ischemic tolerance (IT) on tissues. Webelieve that by hyperbaric oxygen preconditioning, increase tissue tolerate fromdecompression damage. HBO pre-treatment of decompression sickness protectionmechanism is not clear.The rat model of decompression sickness were established. The neurons loss, cell death of the cerebral cortex and hippocampus were acquired by technique ofhistopathology and immunohistochemistry staining. The contents of redox-active metals(magnesium, zine, manganese and iron） were determined by flame atomic absorptionspectrometry (FAAS). The antioxidant capacity was defined by chemical colorimetricmethod. Explore the HBO protective effect of pre-treatment of decompression sicknessand possible protection mechanisms, and to provide new experimental evidence and newideas to further clarify HBO pretreatment induced ischemic tolerance mechanism.Results were showed as following：(1) Hyperbaric oxygen preconditioning can improve organizational glutathioneperoxides (GPx), superoxide dismutase (SOD), catalase (CAT) activity and reducemalondialdehyde (MDA) accumulation; increase in lung tissue iron, magnesium contentand brain tissue manganese, zinc, iron, magnesium content, suggesting that hyperbaricoxygen preconditioning can improve decompression sickness rat antioxidant capacity ofthe brain and lung tissue, and the antioxidant mechanisms related to the metal elementshaving redox activity.(2) Hyperbaric oxygen preconditioning group rat brain nerve cell degeneration andnecrosis significantly reduced. Bcl-2-positive cells was significantly increased and Baxpositive cells was significantly reduced, hyperbaric oxygen preconditioning group werehigher than the ratio of Bcl-2/Bax decompression group;Caspase-3positive cells in thehyperbaric oxygen preconditioning group compared with decompression groupsignificantly reduced. HBO pretreatment can reduce acute decompression due to rat nervecell degeneration and necrosis，reduce hypoxic-ischemic brain tissue damage by inhibitingneuronal apoptosis.(3) Hyperbaric oxygen preconditioning has a protective effect of neurologicaldecompression sickness. Hyperbaric oxygen preconditioning by reducing thedecompression pathological damage of the brain and lung tissue, increase the antioxidantcapacity of the organization and the metal element content, inhibition of rat brain tissue incortex and hippocampus neuronal apoptosis induced tissue produce ischemic tolerance, soas to achieve the protective effect of neurological decompression sickness. In conclusion，this study proved HBO pretreatment of decompression sickness rathas a protective effect. The mechanism of the protective effects may be associated withantioxidant, cell necrosis, and injury-related apoptosis. Although basic research to clinicalapplication, there is a great distance, but the results of this study for the prevention ofdecompression sickness is to provide new ideas, and also for HBO this toxic side effects,the use of safe and convenient antioxidants in clinical more experimental basis.