Background and purpose
Energy depletion is a critical factor leading to cell death and brain dysfunction after ischemic stroke. In this study we investigated whether energy depletion is involved in hyperglycemia-induced hemorrhagic transformation (HT) after ischemic stroke and determined the pathway underlying the beneficial effects of hyperbaric oxygen (HBO).
Methods
After 2 hours MCAO, hyperglycemia was induced by injecting of 50% dextrose (6 ml/kg) intraperitoneally at the onset of reperfusion. Immediately after it rats were exposed to HBO at 2 atmospheres absolutes (ATA) for 1 hour. ATP synthase inhibitor Oligomycin A (Olig A), NAMPT inhibitor FK866 or Sirt1 siRNA was administrated for interventions. Infarct volume, hemorrhagic volume, neurobehavioral deficits were recorded; the level of blood glucose, ATP and NAD+ and the activity of NAMPT were monitored; the expression of Sirt1, acetylated P53, acetylated NF-κB and cleaved caspase 3 were detected by western blots; the activity of MMP-9 was assayed by zymography.
Results
Hyperglycemia deteriorated energy metabolism and reduced the level of ATP and NAD+, exaggerated hemorrhagic transformation, blood-brain barrier disruption and neurological deficits after MCAO. HBO treatment increased the levels of the ATP and NAD+ and consequently increased Sirt1, resulting in attenuation of hemorrhagic transformation, brain infarction as well as improvement of neurological function in hyperglycemic MCAO rats.
Conclusion
HBO induced activation of ATP/NAD+/Sirt1 pathway and protected blood-brain barrier in hyperglycemic MCAO rats. HBO might be promising approach for treatment of acute ischemic stroke patients, especially patients with diabetes or treated with rtPA.