Punicalagin inhibits excessive autophagy and improves cerebral function in neonatal rats with hypoxia-ischemia brain injury by regulating AKT-FOXO4

Background

Neonatal hypoxic-ischemic encephalopathy (HIE) has a high incidence and mortality rate, representing a significant patient burden. Therefore, treatment strategies that work synergistically with hypothermic therapies are urgently required. Punicalagin (PUN) is a natural and safe polyphenol with anti-inflammatory functions whose excellent water solubility and safety make it an advantageous perinatal medication. However, its underlying mechanisms of action in HIE remain unclear.

Objectives

This study investigated the role and associated mechanism of action PUN in HIE.

Methods

We used the Rice Vannucci method to construct an in vivo HIE model in rats, from which we extracted primary cortical neurons to construct an in vitro oxygen and glucose deprivation/reoxygenation (OGD/R) model. The mechanisms of action of PUN were investigated using transcriptome sequencing, laser speckle contrast imaging, 2,3,5-triphenyltetrazolium chloride-staining, the Morris water maze test, western blotting, qPCR, immunofluorescence, and histochemistry.

Results

HIE rats demonstrated excessive autophagy and inflammation. PUN reduced brain tissue damage and neuronal apoptosis, and improved cerebral blood flow perfusion, learning, and cognitive abilities. PUN attenuated autophagic overexpression following HIE and inhibited the AKT-FOXO4 (forkhead box O4) signaling pathway. The neuroprotective effects of PUN were inhibited by treatment with the AKT signaling pathway and autophagy inhibitor 3-MA. Furthermore, brain tissue damage was significant and PUN was ineffective in siFOXO4 rats.

Conclusions

PUN significantly reduces cerebral infarction, neuroinflammation, and excessive autophagy caused by HIE, thereby exerting short- and long-term neuroprotective effects. Mechanistically, the neuroprotective effect of PUN is mediated by activation of the AKT-FOXO4 pathway. Therefore, PUN may be a potential therapy for HIE.