Dexmedetomidine alleviates postoperative cognitive dysfunction through circular RNA in aged rats

Circular RNA (circRNA) has been well studied in many diseases, whereas their role in patients with postoperative cognitive dysfunction (POCD) remains largely unclear. Here, we investigated the therapeutic effects of dexmedetomidine (Dex) on POCD and analyzed the role of circRNA as well as the pathways that may be involved. The Morris water maze test demonstrated that POCD rats have a longer incubation period than the normal group, but the latency of POCD rats was significantly lower after Dex treatment. Moreover, HE staining showed that Dex improved hippocampal pathological changes. RNA sequencing showed 164 differentially expressed circRNAs between POCD and Dex groups; 74 were upregulated and 90 were downregulated in the Dex group. A total of 20,790 target genes for differentially expressed circRNAs were observed in RNAhybrid and Miranda databases. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that the target genes of differentially expressed circRNAs are mainly focused on positive regulation of intrinsic apoptotic signaling pathway in response to DNA damage, negative regulation of cell adhesion mediated by integrin, and response to cytokines and other function of life activities and involved in the P53 signaling pathway and nuclear factor kappa B (NF-κB) signaling pathway. Furthermore, the expression of five candidate circRNAs (circ-Shank3, circ-Cdc42bpa, circ-chrx-24658, cir-chr17-3642 and circ-Sgsm1) and target genes were consistent with the RNA sequencing results, which was verified by quantitative real-time polymerase chain reaction (qRT-PCR). These results indicate that circ-Shank3 participate in the process of Dex improved POCD through regulating the P53 and NF-κB signaling pathways and may potentially facilitate POCD treatment through the development of clinical drugs.