Novel, selective EPO receptor ligands lacking erythropoietic activity reduce infarct size in acute myocardial infarction in rats

Pharmacol Res. 2016 Nov;113(Pt A):62-70. doi: 10.1016/j.phrs.2016.08.013. Epub 2016 Aug 10.

Abstract

Erythropoietin (EPO) has been shown to protect the heart against acute myocardial infarction in pre-clinical studies, however, EPO failed to reduce infarct size in clinical trials and showed significant safety problems. Here, we investigated cardioprotective effects of two selective non-erythropoietic EPO receptor ligand dimeric peptides (AF41676 and AF43136) lacking erythropoietic activity, EPO, and the prolonged half-life EPO analogue, darbepoetin in acute myocardial infarction (AMI) in rats. In a pilot study, EPO at 100U/mL significantly decreased cell death compared to vehicle (33.8±2.3% vs. 40.3±1.5%, p<0.05) in rat neonatal cardiomyocytes subjected to simulated ischemia/reperfusion. In further studies (studies 1-4), in vivo AMI was induced by 30min coronary occlusion and 120min reperfusion in male Wistar rats. Test compounds and positive controls for model validation (B-type natriuretic peptide, BNP or cyclosporine A, CsA) were administered iv. before the onset of reperfusion. Infarct size (IS) was measured by standard TTC staining. In study 1, 5000U/kg EPO reduced infarct size significantly compared to vehicle (45.3±4.8% vs. 59.8±4.5%, p<0.05). In study 2, darbepoetin showed a U-shaped dose-response curve with maximal infarct size-reducing effect at 5μg/kg compared to the vehicle (44.4±5.7% vs. 65.9±2.7%, p<0.01). In study 3, AF41676 showed a U-shaped dose-response curve, where 3mg/kg was the most effective dose compared to the vehicle (24.1±3.9% vs. 44.3±2.5%, p<0.001). The positive control BNP significantly decreased infarct size in studies 1-3 by approximately 35%. In study 4, AF43136 at 10mg/kg decreased infarct size, similarly to the positive control CsA compared to the appropriate vehicle (39.4±5.9% vs. 58.1±5.4% and 45.9±2.4% vs. 63.8±4.1%, p<0.05, respectively). This is the first demonstration that selective, non-erythropoietic EPO receptor ligand dimeric peptides AF41676 and AF43136 administered before reperfusion are able to reduce infarct size in a rat model of AMI. Therefore, non-erythropoietic EPO receptor peptide ligands may be promising cardioprotective agents.

Keywords: 2,3,5-Triphenyltetrazolium chloride (PubChem CID:9283); Acute myocardial infarction; B-type natriuretic peptide; Cardioprotection; Cyclosporine A (PubChem CID:16404350); Darbepoetin; Erythropoietin; Erythropoietin, Darbepoetin, B-type natriuretic peptide (PubChem CID:16132422); Evans blue dye (PubChem CID:5359386); Na-pentobarbital (PubChem CID:4737); Non-erythropoietic EPO receptor ligand; Trypan blue (PubChem CID:6364561).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cardiotonic Agents / pharmacology*
  • Erythropoietin / metabolism*
  • Ligands
  • Male
  • Myocardial Infarction / drug therapy*
  • Myocardial Infarction / metabolism
  • Myocardial Reperfusion Injury / drug therapy
  • Myocardial Reperfusion Injury / metabolism
  • Myocardium / metabolism*
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / metabolism
  • Natriuretic Peptide, Brain / pharmacology
  • Pilot Projects
  • Rats
  • Rats, Wistar

Substances

  • Cardiotonic Agents
  • Ligands
  • erythropoietin, rat
  • Erythropoietin
  • Natriuretic Peptide, Brain