Doxorubicin (Dox) is an anthracycline antibiotic that treats a variety of malignancies. Unfortunately, its cardiotoxicity limits its therapeutic usefulness. Coenzyme Q10 (CoQ10) has effectively treated and prevented various cardiac diseases and toxicities. This study aimed to evaluate the possible antioxidative and anti-apoptotic cardioprotective effects of CoQ10 against doxorubicin-induced histopathological and molecular changes in cardiomyocytes. Twenty-eight adult Wistar rats were divided into positive control, negative control, Dox-treated group, and Dox+CoQ10-treated. On the 16th day after the start of treatment, the hearts of all rats were dissected, and the left ventricles were processed for histological evaluation; immunohistochemical staining with caspase-3 and inducible nitric oxide synthase (iNOS); ultrastructural examination of cardiomyocytes; molecular assessment of proapoptotic gene Bax and anti-apoptotic gene expression Bcl-2; and biochemical study of malondialdehyde (MDA). The Dox-treated group had disorganized cardiomyocytes with increased interstitial space, vacuolated cytoplasm, and multiple small-sized pyknotic nuclei. A significant increase in caspase-3 and iNOS immunoexpression was observed. Ultrastructurally, the mitochondria were large with abnormal shapes, vacuolated cytoplasm, multiple vacuoles and autophagosomes, collagen fibril accumulation, and multiple small hyperchromatic nuclei. The intercalated discs were disorganized with loss of desmosome junction. The cardiomyocytes also showed significantly increased MDA levels and upregulation of Bax/Bcl-2 gene expression ratio. Co-administration of CoQ10 resulted in significant improvement in the histopathological picture, with a significant decrease in caspase-3 and iNOS immunoexpression and downregulation of the Bax/Bcl-2 gene expression ratio. In conclusion, CoQ10 protects against Dox-induced cardiotoxicity through the regulation of proapoptotic and anti-apoptotic gene expression.
Keywords: Bax/Bcl-2; Coenzyme Q10; Doxorubicin; cardiomyocytes.