Role of the circRNA_34414/miR-6960a-5p/SIRT3 axis in postoperative delirium via CA1 Vglut1+ neurons in older mice.

AIMS: Postoperative delirium (POD) is a common neurological complication in elderly patients after anesthesia/surgery. The main purpose of this study is to explore the effect of circRNA-targeted miRNA regulating SIRT3 on mitochondrial function through ceRNA mechanism under the surgical model of tibial fracture and to further explore the potential mechanism of postoperative delirium mediated by circRNA, so as to provide new ideas for clinical diagnosis and prevention of POD. METHODS: The surgical model of tibial fracture under sevoflurane anesthesia caused acute delirium-like behavior in elderly mice. We observed that the decrease of SIRT3 and mitochondrial dysfunction was related to POD, and miRNA and circRNA (circRNA_34414) related to SIRT3 were further studied. Through luciferase and RAP, we observed that circRNA_34414, as a miRNA sponge, was involved in the regulation of SIRT3 expression. RESULTS: Postoperative delirium in elderly mice showed decreased expression of hippocampal circRNA_34414, increased expression of miR-6960-5p, decreased expression of SIRT3, and impaired mitochondrial membrane potential. Overexpression of circRNA_34414, or knockdown of miR-6960-5p, or overexpression of SIRT3 in hippocampal CA1 glutamatergic neurons significantly upregulated hippocampal SIRT3 expression, increased mitochondrial membrane potential levels, and significantly ameliorated postoperative delirium in aged mice; CircRNA_34414 ameliorates postoperative delirium in mice, possibly by targeting miR-6960-5p to upregulate SIRT3. CONCLUSIONS: CircRNA_34414 is involved in the improvement of postoperative delirium induced by anesthesia/surgery by upregulating SIRT3 via sponging miR-6960-5p.

Metabolomic Analysis in Saliva and Different Brain Regions of Older Mice with Postoperative Delirium Behaviors.

Objective: Postoperative delirium (POD) has become a critical challenge with severe consequences and increased incidences as the global population ages. However, the underlying mechanism is yet unknown. Our study aimed to explore the changes in metabolites in three specific brain regions and saliva of older mice with postoperative delirium behavior and to identify potential non-invasive biomarkers. Methods: Eighteen-month-old male C57/BL6 mice were randomly assigned to the anesthesia/surgery or control group. Behavioral tests were conducted 24 h before surgery and 6, 9, and 24 h after surgery. Complement C3 (C3) and S100 calcium-binding protein B protein (S100beta) levels were measured in the hippocampus, and a metabolomics analysis was performed on saliva, hippocampus, cortex, and amygdala samples. Results: In total, 43, 33, 38, and 14 differential metabolites were detected in the saliva, hippocampus, cortex, and amygdala, respectively. "Pyruvate" "alpha-linolenic acid" and "2-oleoyl-1-palmitoy-sn-glycero-3-phosphocholine" are enriched in one common pathway and may be potential non-invasive biomarkers for POD. Common changes were observed in the three brain regions, with the upregulation of 1-methylhistidine and downregulation of D-glutamine. Conclusion: Dysfunctions in energy metabolism, oxidative stress, and neurotransmitter dysregulation are implicated in the development of POD. The identification of changes in the level of salivary metabolite biomarkers could aid in the development of noninvasive diagnostic methods for POD.