| Objective:1.To investigate the expression and duration of autophagy after spinal cord injury (SCI)in rats. Meanwhile we wish to explore the effect of autophagy in the process of SCI, whichwill provide new scientific targets and theoretical basis.2.To observe the changes of autophagy after SCI treated by hyperbaric oxygen therapyand explore the potential therapeutical mechanism.Methods:A total of72Sprague Dawley (SD) rats, weighing250±30g, were randomly dividedinto sham-operated group(n=8), spinal cord injury group(n=32), hyperbaric oxygengroup(n=32). The sham-operated group only laminectomy does not damage the spinal cordtissue and the spinal cord injury models were established in SCI group and hyperbaricoxygen group according to the improved Allen’s method. The hyperbaric oxygen groupwas treated by hyperbaric oxygen with2ATA, inhalation of pure oxygen,100minutes perevery time, once per day for totally seven days. The changes of locomotor scores after SCIwas evaluated with Basso-Beattie-Bresnahan (BBB) scores system during the preoperationand postoperation8hours and1,3,5,7days. The changes of autophagy-related proteinLC3(microtubule associated protein1light chain3, MAP1-LC3) were detected by Westernblotting at8hours and1,3,7days in every group. At every time point, we used theTransmission Electron Microscope (TEM) to observe the ultrastructure of spinal cordtissue in order to find the autophagosome.Results:1. Compared to the SCI group, the BBB scores in hyperbaric oxygen group werehigher from the first postoperation day and the differences were statistically significant at7days (P<0.05).2. In contrast to low expression in the sham operation group, the expression levels ofLC3in the SCI group and hyperbaric oxygen group were higher (P<0.05) in every time point. The levels of LC3in the hyperbaric oxygen group were significantly lower than theSCI group at the same time points (P<0.05).3. The electron microscopy demonstrated that the neurons of nuclear membraneintegrity, cytoplasmic organelles form of normal distribution and no autophagosome wasfound in the sham operation group; In contrast, the the formation of numerous autophagicvacuoles including autophagosome were observed in the SCI group, and there wassignificantly edema, degeneration, vacuolization, irregular nucleus and so on after SCI inrats. A small amount of autophagosome was also observed in the hyperbaric oxygen group.Conclusion:1. The level of autophagy was low in the normal spinal cord tissue to maintain cellhomeostasis. Autophagy was clearly activated after spinal cord injury in rats, and theexpression of autophagy-related protein LC3peaked at3d and still higer expression at7d,indicating that autophagy was triggered after SCI, aggravate the neuron injury anddysfunction. Autophagy may play an important role in the process following spinal cordtrauma to some extent.2. The hyperbaric oxygen therapy can reduce the expression of autophagy-relatedprotein LC3after SCI in rats. The decreased expression of autophagy-related protein LC3in SCI in rats by hyperbaric oxygen treatment might be one of the possible mechanisms oftreating SCI. |
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