Melatonin treatment attenuated obesity-related heart failure with preserved ejection fraction without affecting the cardiac hypertrophy phenotype. (A) Alterations in body weight after melatonin treatment for 3 weeks (n = 9 per group). (B) Blood glucose levels with melatonin treatment (n = 9 per group). (C-D) Alterations in Mes WAT and SC WAT after melatonin treatment (n = 9 per group). (E) Representative images of HE-stained heart sections. (F). Results for the of the HW/TL ratio (n = 9 per group). (G) The left ventricular cross-sectional area in the indicated groups (n = 5 per group). (H) The wet LW-to-dry LW ratio (n = 9 per group). (I–K) Anp, Bnp and β-Mhc mRNA levels after melatonin treatment (n = 6 per group). (L) LVEDP after melatonin treatment (n = 9 per group). (M) -dP/dt with melatonin treatment (n = 9 per group). (N) Alteration in the Tau index after melatonin treatment (n = 9 per group). (O) Alteration in the EDPVR (n = 9 per group).All data are expressed as the mean ± SD. For (A), one-way repeated measure analysis of variance (ANOVA) was used, *P < 0.05. For (B–O), differences were compared by one-way ANOVA followed by Tukey's post hoc test. *P < 0.05 compared with the ND+vehicle group, #P < 0.05 compared with the HFD+vehicle group.