Hyperbaric Oxygen Protects Against Cerebral Damage in Permanent Middle Cerebral Artery Occlusion Rats and Inhibits Autophagy Activity.

BACKGROUND: To investigate the effects of hyperbaric oxygen (HBO) on brain damage and autophagy levels in a rat model of middle cerebral artery occlusion.

METHODS: Neurologic injury and infarcted areas were evaluated according to the modified neurological severity score and 2,3,5-triphenyltetrazolium chloride staining. Western blots were used to determine beclin1, caspase-3 and fodrin1 protein expression. Beclin1 protein expression (an autophagy marker), positive terminal dUTP nick-end labeling (TUNEL) staining (an apoptosis marker) and positive propidium iodide (PI) staining (a necrosis marker) were detected by immunofluorescence.

RESULTS: Our results indicated that HBO could decrease the infarct volume and speed up the recovery of the neurological deficit scores in ischemic rats. Beclin1 was down-regulated after HBO treatment. HBO treatment inhibited fodrin1 protein expression and decreased the number of PI-positive cells. HBO also down-regulated caspase-3 and decreased the number of TUNEL-positive cells.

CONCLUSION: Cerebral ischemia caused early neuronal death due to necrosis, followed by delayed neuronal death due to apoptosis. Consequently, autophagy might be involved in all processes of ischemia. HBO could protect the brain against ischemic injury, and the possible mechanisms might be correlated with decreased autophagy activity and decreased apoptosis and necrosis levels.