SIRT3 Enhances the Protective Role of Propofol in Postoperative Cognitive Dysfunction via Activating Autophagy Mediated by AMPK/mTOR Pathway

Background: Postoperative cognitive dysfunction (POCD) is a common complication after surgery and anesthesia. In this study, we aimed to determine the neuroprotective mechanism of Sirtuin 3 (SIRT3) and propofol in POCD. Methods: The cognitive dysfunction models in C57BL/6J mice were induced and treated, then cognitive function of mice were tested using morris water maze and novel object recognition tests. Primary neurons were stimulated by lipopolysaccharide (LPS) to mimic neuroinflammation during POCD. Meanwhile, cells were treated with propofol. 3-methyladenine (3-MA) was administrated to inhibit autophagy in neurons. SIRT3 overexpression vector was constructed to upregulate SIRT3. Biomarker changes in inflammation, oxidative stress and autophagy were determined in vivo and in vitro. Results: Propofol enhanced the spatial cognitive ability and novel objective recognition of POCD mice. Inflammation and oxidative stress were observed in the hippocampus, which were inhibited by propofol treatment. During POCD, SIRT3 expression and autophagy in the hippocampus was decreased; propofol activated autophagy and upregulated SIRT3. In LPS-stimulated neurons, SIRT3 upregulation enhanced the anti-inflammation and anti-oxidative stress roles of propofol; SIRT3 elevated propofol-activated autophagy in neurons undergoing LPS administration. Moreover, 3-MA reversed propofol-induced biomarker changes in inflammation, oxidative stress and autophagy in LPS-stimulated neurons. In POCD mice, SIRT3 upregulation enhanced the cognitive function during propofol treatment; SIRT3 overexpression elevated the inhibitory role of propofol in inflammation, oxidative stress and autophagy. AMPK/mTOR pathway was activated in response to propofol treatment and SIRT3 enhanced the signaling activation. Conclusions: SIRT3 enhances the protective effect of propofol on POCD by triggering autophagy that eliminates oxidative stress and inhibits the production of pro-inflammatory cytokines.