Aim: To investigate the in vivo and in vitro protective effects of pentamethylquercetin (PMQ), a member of polymethoxy flavonoids (PMFs), on cardiac hypertrophy.
Methods: An in vivo cardiac hypertrophy model established by abdominal aorta banding technique in rats was treated with PMQ in increasing dosages (2.5, 5, and 10 mg x kg(-1) x d(-1)). An in vitro cardiomyocyte hypertrophy model was induced by treating neonatal cardiomyocytes with endothelin-1 (ET-1, 0.1 μM). An in vitro fibrosis model was developed in cardiac fibroblasts by aldosterone (Ald, 20 nM) and treated with PMQ (0.3, 1, 3 and 10 μM). Hemodynamic, morphological, histological, and biochemical changes were evaluated at corresponding time points.
Results: The abdominal aorta constriction (AAC) rats demonstrated a significantly elevated blood pressure and profound systolic and diastolic cardiac dysfunction. The resultant cardiac hypertrophy and heart failure were characterized by a significant increase in the heart and lung indices (3.51 ± 0.30 vs 2.35 ± 0.24, 5.58 ± 0.85 vs 3.94 ± 0.54; both P < 0.01), cardiomyocyte cross-sectional areas (153 ± 33% vs 100 ± 5%, P < 0.01) and myocardial fibrosis (9.09 ± 1.30% vs 1.49 ± 0.20%, P < 0.01) with concomitant elevation of B-type natriuretic peptide and cardiac collagen mRNA level. Daily oral administration of PMQ (2.5, 5, and 10 mg/kg for 7 weeks) prevented the foregoing histology, gene and protein changes secondary to AAC procedure. In addition, the up-regulated inflammation factors such as TNF-α and IL-6, and the down-regulated PPAR α and PPAR β were normalizd by PMQ treatment.
Conclusion: PMQ has significant protective effects on cardiac hypertrophy through up-regulating the mRNA and protein levels of PPAR α and PPAR β involved in the process of inflammation response and cardiac fibrosis.