Abstract
Intermedin (IMD) is a novel member of the calcitonin/calcitonin gene-related peptide family. We investigated the cardioprotective mechanism of IMD1–53 in the in vivo rat model of myocardial ischemia/reperfusion (I/R) injury and in vitro primary neonatal cardiomyocyte model of hypoxia/reoxygenation (H/R). Myocardial infarct size was measured by 2,3,5-triphenyl tetrazolium chloride staining. Cardiomyocyte viability was determined by trypan blue staining, cell injury by lactate dehydrogenase (LDH) leakage, and cardiomyocyte apoptosis by terminal deoxyribonucleotidyl transferase-mediated dUTP nick-end labeling assay, Hoechst staining, gel electrophoresis and caspase 3 activity. The translocation of mitochondrial cytochrome c of myocardia and expression of apoptosis-related factors Bcl-2 and Bax, phosphorylated Akt and phosphorylated GSK-3β were determined by western blot analysis. IMD1–53 (20 nmol/kg) limited the myocardial infarct size in rats with I/R; the infarct size was decreased by 54%, the apoptotic index by 30%, and caspase 3 activity by 32%; and the translocation of cytochrome c from mitochondria to cytosol was attenuated. IMD1–53 increased the mRNA and protein expression of Bcl-2 and ratio of Bcl-2 to Bax by 81 and 261%, respectively. IMD1–53 (1 × 10−7 mol/L) inhibited the H/R effect in cardiomyocytes by reducing cell death by 43% and LDH leakage by 16%; diminishing cellular apoptosis; decreasing caspase 3 activity by 50%; and increasing the phosphorylated Akt and GSK-3β by 41 and 90%, respectively. The cytoprotection of IMD1–53 was abolished with LY294002, a PI3K inhibitor. In conclusion, IMD1–53 exerts cardioprotective effect against myocardial I/R injury through the activation of the Akt/GSK-3β signaling pathway to inhibit mitochondria-mediated myocardial apoptosis.
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This work was supported by the National Natural Science Foundation of China (grant No. 30770869, 30871013) and the State Major Basic Research Development Program of the People’s Republic of China (grant No. 2006CB503807).
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Song, JQ., Teng, X., Cai, Y. et al. Activation of Akt/GSK-3β signaling pathway is involved in intermedin1–53 protection against myocardial apoptosis induced by ischemia/reperfusion. Apoptosis 14, 1299–1307 (2009). https://doi.org/10.1007/s10495-009-0398-7
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DOI: https://doi.org/10.1007/s10495-009-0398-7