Infarct-Limiting Efficacy of the μ₂‑Opioid Receptor Peptide Agonist Endomorphin‑1 in Metabolic Syndrome and Aging

Infarct-limiting efficacy of endomorphin‑1, a peptide agonist of μ₂‑opioid receptors (μ₂‑OR), was studied in rats with metabolic syndrome and during aging. Metabolic syndrome was induced by HFHC diet for 84 days. Coronary artery occlusion (45 min) and reperfusion (2 h) were modeled. Endomorphin‑1 produced a pronounced infarct-limiting effect in control 5‑month-old animals; however, this effect was significantly attenuated in aged (18‑month-old) rats and did not appear in 5‑month-old rats with metabolic syndrome. The μ₂‑OR agonist endomorphin‑1 is a promising compound for cardioprotection, but its efficacy in the treatment of myocardial infarction in elderly patients and in metabolic syndrome requires additional studies.