CircUBE3B High Expression Participates in Sevoflurane-Induced Human Hippocampal Neuron Injury via Targeting miR-326 and Regulating MYD88 Expression

Silencing CircHIPK3 improves sevoflurane-explore learning and memory dysfunction and nerve damage via enhancing miR-338-3p

Background

Sevoflurane (Sev), a widely used volatile anesthetic, can cause neurotoxicity, and impair learning and memory.

Objective

This study investigates the role and mechanisms of circHIPK3 in Sev-exposed neurotoxicity and learning and memory impairment.

Methods

SD rats and hippocampal neuronal cells were exposed to Sev. RT-qPCR analysis of circHIPK3 and miR-338-3p levels. MWM test was performed to examine the behavioral changes in rats. The levels of circHIPK3 and miR-338-3p levels were investigated using RT-qPCR. ELISA assay to analyze the expression of pro-inflammatory factors. CCK-8, flow cytometry, and commercial ROS assay kits were analyzed to detect cell viability, apoptosis, and ROS production. DLR and RIP assays validate circHIPK3 binding to miR-338-3p.

Results

Sev increased circHIPK3 expression in rat hippocampal tissue as well as in neuronal cells but decreased miR-338-3p levels compared to controls. circHIPK3 binding to miR-338-3p. Furthermore, silencing of circHIPK3 rats attenuated Sev-induced decline in learning and memory functions . silencing circHIPK3 also reduced Sev-induced secretion of inflammatory factors in rat and neuronal cells. Reducing circHIPK3 partially reversed the Sev-induced decrease in cell viability, increased apoptosis, and overproduction of ROS. However, the inhibitory effect of circHIPK3 on Sev neurotoxicity was restored upon downregulation of miR-338-3p.

Conclusion

Collectively, silencing circHIPK3 alleviates Sev exposure-induced learning and memory deficits and neurotoxicity by enhancing miR-338-3p expression.

Liraglutide improves sevoflurane-induced postoperative cognitive dysfunction via activating autophagy and inhibiting apoptosis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common postoperative complication in elderly patients. Liraglutide (LRG) has high homology (97%) with natural glucagon like peptide-1, and it has been proved to be effective in some nervous system diseases. Whether LRG could regulate POCD has not been reported.

METHODS

Sevoflurane (Sev) was used to simulate postoperative cognitive dysfunction (POCD) model. Morris water maze test was performed to evaluate the memory ability and neurological function of rats. Escape latency, swim distance, crossing platform times, average velocity, and targeting quadrant time were analyzed. The cell apoptosis, mRNA and protein expression were measured through flow cytometry, PCR, and western blotting, respectively.

RESULTS

LRG significantly improved the memory ability and neurological function of Sev-treated rats, but 3-MA reversed the effects of LRG. LRG remarkably inhibited apoptosis but up-regulated autophagy related proteins both in vivo and in vitro levels. However, knocking down AMPK could markedly reverse the influence of LRG on apoptosis, autophagy, and cell apoptosis.

CONCLUSIONS

LRG induced autophagy activation can maintain cell homeostasis and promote cell survival by blocking the apoptotic pathway. LRG could improve Sev-induced POCD via activating autophagy, inhibiting apoptosis, and regulating AMPK/mTOR signaling pathway. This study provides a novel therapeutic strategy for the prevention and treatment of POCD.

Dexmedetomidine attenuates neuroinflammation and microglia activation in LPS-stimulated BV2 microglia cells through targeting circ-Shank3/miR-140-3p/TLR4 axis

It has been shown that dexmedetomidine (Dex) could attenuate postoperative cognitive dysfunction (POCD) via targeting circular RNAs (circRNAs). Circ-Shank3 has been found to be involved in the neuroprotective effects of Dex against POCD. However, the role of circ-Shank3 in POCD remains largely unknown. Reverse transcription quantitative PCR (RT-qPCR) was performed to detect circ-Shank3 and miR-140-3p levels in lipopolysaccharide (LPS)-treated microglia BV-2 cells in the absence or presence of Dex. The relationship among circ-Shank3, miR-140-3p and TLR4 was confirmed by dual-luciferase reporter assay. Additionally, Western blot and immunofluorescence (IF) assays were conducted to evaluate TLR4, p65 and Iba-1 or CD11b levels in cells. In this study, we found that Dex notably decreased circ-Shank3 and TLR4 levels and elevated miR-140-3p level in LPS-treated BV2 cells. Mechanistically, circ-Shank3 harbor miR-140-3p, functioning as a miRNA sponge, and then miR-140-3p targeted the 3'-UTR of TLR4. Additionally, Dex treatment significantly reduced TLR4 level and phosphorylation of p65, and decreased the expressions of microglia markers Iba-1 and CD11b in LPS-treated BV2 cells. As expected, silenced circ-Shank3 further reduced TLR4, p65 and Iba-1 and CD11b levels in LPS-treated BV2 cells in the presence of Dex, whereas these phenomena were reversed by miR-140-3p inhibitor. Collectively, our results found that Dex could attenuate the neuroinflammation and microglia activation in BV2 cells exposed to LPS via targeting circ-Shank3/miR-140-3p/TLR4 axis. Our results might shed a new light on the mechanism of Dex for the treatment of POCD.