Circulating miRNA Expression Profiling and Target Prediction in Patients Receiving Dexmedetomidine.

BACKGROUND/AIMS: Circulating miRNAs could serve as biomarkers for diagnosis or prognosis of heart diseases and cerebrovascular diseases. Dexmedetomidine has protective effects in various organs. The effects of dexmedetomidine on circulating miRNAs remain unknown. Here, we investigated differentially expressed miRNA and to predict the target genes of the miRNA in patients receiving dexmedetomidine. METHODS: The expression levels of circulating miRNAs of 3 patients were determined through high through-put miRNA sequencing technology. Target genes of the identified differentially expressed miRNAs were predicted using TargetScan 7.1 and miRDB v.5. Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to conduct functional annotation and pathway enrichment analysis of target genes respectively. RESULTS: Twelve differentially expressed miRNAs were identified. Five miRNAs were upregulated (hsa-miR-4508, hsa-miR-novel-chr8_87373, hsa-miR-30a-3p, hsa-miR-novel-chr16_26099, hsa-miR-4306) and seven miRNAs (hsa-miR-744-5p, hsa-miR-320a, hsa-miR-novel-chr9_90035, hsa-miR-101-3p, hsa-miR-150-5p, hsa-miR-342-3p, and hsa-miR-140-3p) were downregulated after administration of dexmedetomidine in the subjects. The target genes and pathways related to the differentially expressed miRNAs were predicted and analyzed. CONCLUSION: The differentially expressed miRNAs may be involved in the mechanisms of action of dexmedetomidine. Specific miRNAs, such as hsa-miR-101-3p, hsa-miR-150-5p and hsa-miR-140-3p, are new potential targets for further functional studies of dexmedetomidine.

Oxytocin ameliorates high glucose- and ischemia/reperfusion-induced myocardial injury by suppressing pyroptosis via AMPK signaling pathway.

The present study aimed to explore the role of oxytocin (OT) in myocardial injury induced by ischemia/reperfusion (I/R) and hyperglycemia and its underlying mechanisms. In this study, the isolated rat hearts underwent I/R in Langendorff perfusion model and H9c2 cells were subjected to hypoxia/reoxygenation (H/R) to establish an in vitro model. I/R injury was induced by exposing the rat hearts to 40 min of global ischemia followed by 60 min of reperfusion. H9c2 cells were cultured under the normoglycemic or hyperglycemic condition with or without pretreatment of OT, and then exposed to 4 h of hypoxia and 2 h of reoxygenation. Measurement indicators included myocardial infarct size assessed by triphenyltetrazolium chloride (TTC) staining and hemodynamic parameters in the ex vivo model as well as cell viability detected by cell counting kit 8 (CCK-8), apoptotic rate evaluated by flow cytometry, and the protein expressions by Western blot. The findings demonstrated that OT attenuated myocardial I/R injury. First, OT preconditioning significantly reduced hemodynamic disorders and myocardial infarct sizes. In addition, OT increased cell viability, decreased cell apoptosis and the expressions of IL-18, IL-1ß, cleaved-caspase-1, NLRP3, and GSDMD following H/R. NLRP3 activator nigericin eliminated the beneficial effects of OT in H9c2 cells. Furthermore, OT also activated AMPK and decreased the expressions of pyroptosis-related proteins. Administration of AMPK inhibitor compound C blunted OT-induced AMPK phosphorylation and elevated the expressions of pyroptosis-related proteins in H9c2 cells subjected to H/R with hyperglycemia. OT alleviates myocardial I/R injury with hyperglycemia by inhibiting pyroptosis via AMPK/NLRP3 signaling pathway.

Dexmedetomidine preconditioning mitigates myocardial ischemia/reperfusion injury via inhibition of mast cell degranulation.

The degranulation of cardiac mast cells is associated with occurrence and development of myocardial ischemia/reperfusion (I/R) injury. Dexmedetomidine has a cardioprotective effect from I/R injury. The purpose of this study was to investigate whether dexmedetomidine preconditioning induced cardioprotection is related to suppression of degranulation of cardiac mast cell. Both in vivo and in vitro experimental results revealed that hemodynamic disorder, arrhythmia, infarct size, histopathological score, and mast cell degranulation were dramatically increased in I/R injury groups compared with non-I/R groups, and mastocyte secretagogue compound 48/80 aggravated these damages, but it can be improved by dexmedetomidine preconditioning. Similarly, compound 48/80 increased levels of cardiac troponin I (cTnI) and tryptase, cardiomyocytes apoptosis, and expression of high-mobility group box 1 (HMGB1), toll-like receptor 4 (TLR4), and nuclear factor-kappa B p65 (NF-κB p65) in cardiac tissues induced by I/R injury, but it can be partially decreased by dexmedetomidine pretreatment. Compound 48/80 inhibited proliferation of H9C2(2-1) and RBL-2H3, exacerbated apoptosis of H9C2(2-1), and elevated levels of cTnI and tryptase, while both of which were abolished by dexmedetomidine pretreatment. Our data suggest that dexmedetomidine preconditioning alleviates the degranulation of mast cells and the apoptosis of cardiomyocytes caused by I/R injury, and inhibits the activation of inflammatory related factors HMGB1, TLR4, and NF-κB p65.