Dexmedetomidine Reduces Propofol-Induced Hippocampal Neuron Injury by Modulating the miR-377-5p/Arc Pathway

Background: Propofol and dexmedetomidine (DEX) are widely used in general anesthesia, and exert toxic and protective effects on hippocampal neurons, respectively. The study sought to investigate the molecular mechanisms of DEX-mediated neuroprotection against propofol-induced hippocampal neuron injury in mouse brains. Methods: Hippocampal neurons of mice were treated with propofol, DEX, and propofol+DEX in vitro and in vivo . Neuronal apoptosis was evaluated by a means of TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) or Hochest 33258 staining; Arc positive expression in hippocampus tissues was detected using a microscope in immunohistochemistry assays; miRNA-377-5p expression levels were quantified by RT-PCR; the protein levels of Arc, DNMT3A, and DNMT3B were determined using western blot; CCK-8 kit was used to evaluated neuron viability; methylation analysis in miR-377-5p promoter was performed through the methylated DNA immunoprecipitation (MeDIP) assay; luciferase reporter assay was performed to confirm whether Arc was under targeted regulation of miR-377-5p. Results: In the current study, both in vitro and in vivo , propofol treatment induced hippocampal neuron apoptosis and suppressed cell viability. DNMT3A and DNMT3B expression levels were decreased following propofol treatment, resulting in lowered methylation in the miR-377-5p promoter region and then enhanced expression of miR-377-5p, leading to a decrease in the expression level of downstream Arc. Conversely, the expression levels of DNMT3A and DNMT3B were increased following DEX treatment, thus methylation in miR-377-5p promoter region was improved, and miR-377-5p expression levels were decreased, leading to an increase in the expression level of downstream Arc. Finally, DEX pretreatment protected hippocampal neurons against propofol-induced neurotoxicity by recover the expression levels of DNMT3A, miR-377-5p, and Arc to the normal levels. Conclusions: DEX reduced propofol-induced hippocampal neuron injury via the miR-377-5p/Arc signaling pathway.