Adiponectin elevation by telmisartan ameliorates ischaemic myocardium in zucker diabetic fatty rats with metabolic syndrome

Abstract

This study investigated whether telmisartan, a selective angiotensin type 1 (AT1) receptor antagonist and gamma peroxisome proliferator-activated receptor (PPAR-γ) partial agonist, reduces myocardial ischaemia/reperfusion (I/R) injury in an experimental model of metabolic syndrome. Zucker Diabetic Fatty (ZDF) rats were treated for 3 weeks with telmisartan at doses of 2, 7 and 12 mg/kg/day. After treatment, rats were subjected to a 25-min occlusion of the left descending coronary artery followed by 2-h reperfusion (I/R). Telmisartan reduced the extension of the infarct size in a dose-dependent fashion and decreased the levels of plasma troponin I, a specific marker of myocardial damage. Telmisartan also caused a dose-dependent increase in adiponectin both in plasma and cardiac tissue of infarcted ZDF rats. These levels were minimally increased (p < 0.05 vs. vehicle) by telmisartan 7 mg/kg/day and reached the maximum values with the highest dose of 12 mg/kg/day (p < 0.01 vs. vehicle). In contrast, within the infarcted tissue telmisartan decreased the expression of markers of inflammation such as the transcription factor NF-κB, the toll-like receptors TLR2 and TLR4 as well as TNF-α cytokine. Nitrosative stress was maximal in vehicle-treated infarcted hearts as evidenced by increased expression of iNOS, which was almost abolished after treatement with telmisartan. Treatment of ZDF rats for 3 weeks with telmisartan, a dual angiotensin II receptor antagonist and partial PPAR-γ receptor agonist, resulted in a significant reduction of myocardial damage induced by I/R and was associated with increased adiponectin and a decrease in inflammatory markers.