Concentration of triacylglycerols (TAG) in the left ventricle (LV) of Control and ZDF rats. ZDF rats were untreated (ZDF) or received fenofibrate (ZDF+F) or metformin (ZDF+M) after the first metabolic investigation at the age of 7 weeks. These parameters were measured only in rats sacrificed for tissue sampling (n = 5 for each group), therefore they were measured at 7 weeks only in a group of control and ZDF rats.* p < 0.05, ** p < 0.01 vs the corresponding control group; $$ p < 0.01 versus the corresponding untreated ZDF groups. For the sake of clarity, differences within the control group and the ZDF group between values at 7, 14 and 21 weeks are not indicated; these differences are indicated in the results section.