Effect of NLRP3 deletion and melatonin supplementation on age-associated morphometrical changes of cardiac muscle fibers, as well as hypertrophy-associated and inflammatory cytokines genes. (A,B) Age-associated morphometrical changes in cardiac muscle fibers number (per 100 μm2) and cross-sectional area (CSA). (C) mRNA expression level of β-MHC. (D) Morphometrical analysis of cardiac fibrosis during aging. (E) mRNA expression level of IL-1α. (F) mRNA expression level of IL-6. (G) mRNA expression level of TNFα * p < 0.05, ** p < 0.01 and *** p < 0.001 vs. Y; # p < 0.05, ## p < 0.01 and ### p < 0.001 vs. aged group without melatonin; $ p < 0.05, $$ p < 0.01 and $$$ p < 0.001 vs. WT mice.