Sirtuin-3 activation by honokiol attenuated anesthesia/surgery-induced cognitive impairment and neuronal ferroptosis via inhibiting mitochondrial GPX4 acetylation.

Abstract

Background: Perioperative neurocognitive disorder (PND), a prevalent neurological complication in elderly patients following anesthesia and surgery, has recently been linked to ferroptosis as a central pathogenic mechanism. Sirtuin-3 (SIRT3), a NAD⁺-dependent deacetylase, exhibits neuroprotective properties in neurodegenerative disorders, including PND. However, its role in neuronal ferroptosis during PND remains unclear. This study investigates the impact of SIRT3 on ferroptosis modulation in PND and its underlying mechanism.

Methods: A murine model of PND was established using tibial fracture surgery under isoflurane anesthesia to assess SIRT3 expression and cognitive function. Mice were treated with Honokiol (HKL) or erastin to evaluate hippocampal ferroptosis. RNA sequencing (RNA-seq) was performed to identify the underlying neuroprotective mechanisms. In vitro, PC12 and HT22 cells were treated with erastin or HKL to analyze ferroptosis markers. GPX4 silencing in HT22 cells was used to validate the effect of HKL in modulating ferroptosis. Adeno-associated virus (AAV)-mediated overexpression of SIRT3 and Co-immunoprecipitation (Co-IP), were employed to further elucidate its mechanism in suppressing ferroptosis.

Results: SIRT3 expression was found to be reduced in the hippocampal CA1 and CA3 regions post-surgery. HKL alleviated cognitive decline by inhibiting ferroptosis, evidenced by suppression of iron accumulation, oxidative stress, and mitochondrial dysfunction. In erastin-treated PC12 and HT22 cells, HKL effectively counteracted ferroptosis, which was abolished by GPX4 silencing. SIRT3 overexpression in the mouse hippocampus suppressed anesthesia/surgery-induced neuronal ferroptosis. Mechanistically, HKL-activated SIRT3 upregulated mitochondrial GPX4 expression and reduced its acetylation, thereby inhibiting neuronal ferroptosis.

Conclusions: SIRT3 activation by HKL alleviates hippocampal neuronal ferroptosis in PND by suppressing mitochondrial GPX4 acetylation, providing a novel therapeutic strategy for the management of PND.