Effects of rosiglitazone (PPAR γ agonist) on the myocardium in non-hypertensive diabetic rats (PPAR γ).

Background: There is ongoing controversy regarding the safety of rosiglitazone and its effects on the myocardium, in some cases causing severe cardiac pathology and even in some instances mortality. In this study we aimed at examining the effects of pharmacologic doses of rosiglitazone on cardiomyocytes in diabetic non-cardiac rats receiving sub-optimal doses of insulin.

Methods: Animals were distributed into six groups: normal, diabetic, and diabetic receiving insulin, each subdivided into a control group and an experimental group receiving pharmacologic doses of rosiglitazone. Cardiomyocyte hypertrophy was assessed using heart to body weight index and microscopic examination using the number of cardiomyocytes per quadrant of high power field and intercalated disks in a sector of 100 × field. Fibrosis was assessed using Masson Trichrome staining. A number of sections of each group were stained with periodic acid Shiff and others with Sudan III for glycogen and fat accumulation, respectively. One way ANOVA was used for statistical analysis as appropriate.

Results: Diffuse cardiomyopathic changes in diabetic control animals were observed consisting of cardiomyocyte hypertrophy, loss of striations and widespread vacuolation. These changes were reduced and even prevented by treatment with insulin and rosiglitazone. Masson staining showed that all rat groups had no more than +1 fibrosis that is equal to what was present in the normal controls.

Conclusion: Rosiglitazone, in combination with even sub-optimal doses of insulin therapy, has protective effects on cardiac muscle in diabetic animals especially those expressed as muscle hypertrophy, muscle cell death, and fibrosis.