AIM To examine the effect and mechanism of κ-opioid receptor (κ-OR) activation by U50,488H on Drp1 mitochondria translocation in primary cardiomyocytes subjected to hypoxia/ reoxygenation (H/R).
METHODS Cardiomyocytes were divided into 6 groups: Control group, H/R group, H/R+U50,488H group, control+Scramble RNAi group, H/R+Scramble RNAi group, and H/R+Mid51 RNAi group. Cell viability was measured by CCK-8 detecting kit. Cell apoptosis was determined by flow cytometry. Mitochondria morphology and the colocalization of Drp1 and mitochondria were observed by laser confocal microscope. Western blotting was used to examine the Drp1-related protein’s expression levels of Fis1, Mff, Mid49 and Mid51.
RESULTS Compared with the control group, cell apoptosis, cell death and mitochondrial fission increased significantly in the H/R group (P<0.01). In addition, the amount of Drp1 translocated to mitochondrial surface and Mid51 were significantly increased (P<0.01) in the H/R group, while no significant changes were found in the expression of Fis1, Mff and Mid49. κ-OR stimulation by U50,488H reduced cell apoptosis and death rate (P<0.01), inhibited mitochondrial fission (P<0.01), reduced the colocalization level of Drp1 and mitochondria, and downregulated the expression of Mid51 (P<0.01). There were no significant changes in the expression of Fis1, Mff and Mid49 in the H/R group. Knockdown of Mid51 with small interfering RNA decreased the apoptosis and death rate (P<0.01, P<0.05), inhibited the mitochondrial fission (P<0.01) and reduced the mitochondrial translocation of Drp1.
CONCLUSION H/R triggers cardiomyocyte injury and increases mitochondrial fission. Activation of κ-OR by U50,488H reduces Drp1 translocation to mitochondria by inhibiting Mid51, and suppresses the abnormal mitochondrial dynamics induced by H/R, so as to alleviates cell injury.
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