Postoperative cognitive dysfunction (POCD) is frequently observed in elderly patients following anesthesia, but its pathophysiological mechanisms have not been fully elucidated. Sevoflurane was reported to repress autophagy in aged rat neurons; however, the role of mitophagy, which is crucial for the control of mitochondrial quality and neuronal health, in sevoflurane-induced POCD in aged rats remains undetermined. Therefore, this study investigated whether mitophagy impairment is involved in sevoflurane-induced cognitive dysfunction. We found sevoflurane treatment inhibited mitochondrial respiration and mitophagic flux, changes in mitochondria morphology, impaired lysosomal acidification, and increased Tomm20 and deceased LAMP1 accumulation were observed in H4 cell and aged rat models. Rapamycin counteracted ROS induced by sevoflurane, restored mitophagy and improved mitochondrial function. Furthermore, rapamycin ameliorated the cognitive deficits observed in aged rats given sevoflurane anesthesia as determined by the Morris water maze test; this improvement was associated with an increased number of dendritic spines and pyramidal neurons. Overexpression of PARK2, but not mutant PARK2 lacking enzyme activity, in H4 cells decreased ROS and Tomm20 accumulation and reversed mitophagy dysfunction after sevoflurane treatment. These findings suggest that mitophagy dysfunction could be a mechanism underlying sevoflurane-induced POCD and that activating mitophagy may provide a new strategy to rescue cognitive deficits.
Keywords: aged rat; mitophagy; postoperative cognitive dysfunction; rapamycin; sevoflurane.