Mechanism of the AMPK/SIRT1 pathway in gut dysbiosis-mediated postoperative cognitive dysfunction in aged mice

Objective Postoperative cognitive dysfunction (POCD) is a prevalent complication in older patients who undergo surgery that requires anesthesia. This study explored the role of the AMPK/SIRT1 pathway in gut dysbiosis-mediated POCD in aged mice. Methods POCD was induced in aged male mice via open tibial fracture surgery under isoflurane anesthesia. Mice then received the probiotic VSL#3, the SIRT1 inhibitor EX527, and the AMPK/SIRT1 activator resveratrol. Fecal microbiota transplantation was conducted in aged POCD mice. Mouse cognitive function was assessed using the Morris water maze and novel object recognition tests. Mouse histopathological changes were observed via HE staining. Iba1+/GFAP+ activation was assessed via immunofluorescence, and pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1 [IL]-1β, IL-6) in the hippocampus were determined via ELISA. Gut microbiota compositions were detected via 16S rRNA sequencing. Hippocampal pAMPK/AMPK and SIRT1 levels were assessed by western blot. Results Aged POCD mice exhibited prolonged escape latency, reduced platform crossings, and an impaired object discrimination rate on postoperative day 7. Severe hippocampal CA1 damage, increased Iba1+/GFAP+ cell numbers, elevated pro-inflammatory cytokines, and gut dysbiosis were also observed. The probiotic VSL#3 ameliorated gut dysbiosis, alleviated POCD, and reduced neuroinflammation. Gut microbiota from POCD mice exacerbated cognitive deficits and neuroinflammation in aged mice, while clearance of gut microbiota improved outcomes. VSL#3 improved POCD in aged mice by balancing gut microbiota through the AMPK/SIRT1 pathway. The AMPK/SIRT1 pathway activation mitigated POCD. Conclusion VSL#3 balanced gut microbiota and suppressed neuroinflammation in hippocampal CA1 region by activating the AMPK/SIRT1 pathway, thereby alleviating POCD in aged mice.