The present study aimed to quantitatively compare the normal and diabetic hearts of rats using stereological methods. Diabetic and control rats received streptozotocin (60 mg/kg) and no treatments, respectively. On the 56(th) day, the hearts were removed and their total volume was estimated using isotropic Cavalieri method. The total volume of the connective tissues and vessels, total length and diameter of the vessels, total number of cardiomyocytes nuclei, and the mean volume of the cardiomyocytes were estimated, as well. In comparison to the control animals, 60 and 43% increase was observed in the total volume of the connective tissue and microvessels of the diabetic rats, respectively (P<0.05). The percent of the vessel profiles with the diameter of 2-4 µm was decreased, while the percent of the vessel profiles with the diameter of 4.1-8 µm was increased in the diabetic hearts (P<0.05). No significant difference was found in the vessels with more than 8 µm diameters. The total number of the cardiomyocytes' nuclei and the number-weighted mean volume were respectively decreased by 37 and 64% in the diabetic group (P<0.01). A significant difference was observed between the two groups concerning the left ventricle volume to body weight ratio as an index for ventricular hypertrophy (P<0.05), while no difference was found regarding the right ventricle to body weight ratio. It can be concluded that diabetes can induce structural changes, including loss and/or atrophy of the cardiomyocytes, accompanied with increase in the connective tissue in the rats' hearts.
Keywords: Stereology; diabetes; heart.