Reducing oxidative stress is a crucial therapeutic strategy for ameliorating diabetic
myocardial ischemia/reperfusion (MI/R) injury.
Honokiol (HKL) acts as an effective
cardioprotective agent for its strong antioxidative activity. However, its roles and underlying mechanisms against MI/R injury in
type 1 diabetes (T1D) remain unknown. Since
SIRT1 and Nrf2 are pivotal regulators in
diabetes mellitus patients suffering from MI/R injury, we hypothesized that HKL ameliorates diabetic MI/R injury via the SIRT1-Nrf2 signaling pathway.
Streptozotocin-induced T1D rats and high-
glucose-treated H9c2 cells were exposed to HKL, with or without administration of the
SIRT1 inhibitor EX527,
SIRT1 siRNA, or Nrf2
siRNA, and then subjected to I/R operation. We found that HKL markedly improved the postischemic cardiac function, decreased the
infarct size, reduced the myocardial apoptosis, and diminished the
reactive oxygen species generation. Intriguingly, HKL remarkably activated
SIRT1 signaling, enhanced Nrf2 nuclear translocation, increased antioxidative signaling, and decreased apoptotic signaling. However, these effects were largely abolished by EX527 or
SIRT1 siRNA. Additionally, our cellular experiments showed that Nrf2
siRNA blunted the cytoprotective effects of HKL, without affecting
SIRT1 expression and activity. Collectively, these novel findings indicate that HKL abates MI/R injury in T1D by ameliorating myocardial oxidative damage and apoptosis via the SIRT1-Nrf2 signaling pathway.