Dexmedetomidine protects cardiac microvascular endothelial cells from the damage of ogd/r through regulation of the pparδ-mediated autophagy

Background: Dexmedetomidine (Dex) exerts an effective therapeutic role in numerous diseases associated with ischemia/reperfusion (I/R) injury via its anti-apoptosis properties. Therefore, this study explores the cardioprotective effects of Dex in cardiac microvascular endothelial cells (CMECs) in response to oxygen-glucose deprivation and re-oxygenation (OGD/R) injury and its potential mechanism.

Material and methods: CMECs were pretreatment with different concentration of Dex, then exposed to OGD/R. Cell viability was measured with CCK-8 assay. Apoptosis was evaluated by flow cytometry, and apoptosis-related protein was determined by Western blot. Autophagy was assessed by transmission electron microscopy and autophagy-related proteins. Besides, the role peroxisome proliferator-activated receptors (PPARδ) in Dex-mediated anti-apoptosis property was validated with agonist and antagonist.

Results: OGD/R significantly decreased cell viability, increased Reactive Oxygen Species, caused disorder of Autophagy, and increased Apoptosis in CMECs. Dex enhanced the viability of the OGD/R-treated CMECs and effectively decreased Reactive Oxygen Species production. Autophagy in CMECs was activated by Dex, as evidenced by the increase in the ratio of LC3B-II/I, expression level of Beclin1 and number of autophagosomes in the OGD/R-induced CMECs. The mechanistic investigation indicated that PPARδ antagonist GW501516 aggravated cell damage following OGD/R, while PPARδ Agonist GW6471 partly abolished the Dex-mediated protective effects.

Conclusions: Dex activated the PPARδ-AMPK-PGC-1α pathway-mediated Autophagy in CMECs, therefore to inhibit excessive Apoptosis induced by OGD/R. Dex may potentially be a therapeutic intervention for myocardial I/R injury.