[Intervention effects of estradiol on myocardial ischemia- reperfusion injury of rat and its mechanisms].

Objective: To study the effects of estradiol (E2) on alleviating myocardial ischemia/reperfusion(I/R) injury through estrogen receptorβ(ERβ) mediated extracellular regulated protein kinases(ERK) pathway activation. Methods: Eighty-four adult female SD rats were ovariectomized and randomly divided into control group, NC siRNA adeno-associated virus (AAV) group received sham operation, the myocardial I/R injury model was prepared by ligation of the left anterior descending coronary artery in I/R group, E2+I/R group, NC siRNA AAV+I/R group, NC siRNA AAV+E2+I/R group and ERβ-siRNA AAV+E2+I/R group. E2+I/R group, NC siRNA AAV+E2+I/R group and ERβ-siRNA AAV+E2+I/R group were treated with E2 0.8 mg/kg by gavage for 60 days before modeling. NC siRNA AAV+I/R group, NC siRNA AAV+E2+I/R group, and ERβ-siRNA AAV+E2+I/R group were treated with AAV by caudal vein injection 24 h before modeling. After 120 min of reperfusion, the contents of serum lactate dehydrogenase (LDH), phosphocreatine kinase (CK), phosphocreatine kinase isoenzyme (CK-MB), myocardial infarction area and the expressions of ERβ, p-ERK, the contents of tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1 β), malondialdehyde (MDA) and total antioxidant capacity (T-AOC) in myocardium were measured. Results: The contents of serum LDH, CK, CK-MB, myocardial infarction area and the contents of TNF-α, IL-1 β, MDA in myocardium of I/R group were higher than those of the control group, the expression levels of ERβ and p-ERK and the content of T-AOC were lower than those in the control group (P＜0.05). The contents of serum LDH, CK and CK-MB, myocardial infarction area and the contents of TNF-α, IL-1 β and MDA in myocardium of E2+I/R group were lower than those of the I/R group, the expression levels of ERβ and p-ERK and the content of T-AOC were higher than those of the I/R group(P＜0.05). After knockdown ERβ by caudal vein injection of ERβ-siRNA AAV, the contents of serum LDH, CK and CK-MB, myocardial infarction area and the contents of TNF-α, IL-1 β and MDA in myocardium of ERβ-siRNA AAV+E2+I/R group were higher than those of NC-siRNA AAV+E2+I/R, the expression levels of ERβ and p-ERK and the content of T-AOC were lower than those of NC-siRNA AAV+E2+I/R(P＜0.05). Conclusion: E2 has protective effects on myocardial I / R injury in ovariectomized rats, which are related to the promotion of ERβ mediating the activation of ERK pathway, reducing inflammatory and oxidative stress responses.