Cardioprotective effects of curcumin and carvacrol in doxorubicin-treated rats: Stereological study.

Doxorubicin (DOX) is a cardiotoxic drug. To reduce the harmful effects of DOX, two plant-derived components, including curcumin (CUR) and carvacrol (CAR), were considered. This study aimed to assess the protective effects of CUR and CAR on DOX-induced cardiotoxicity using physiological and stereological evaluations. Male rats were randomly allocated to six groups. Group's I-VI received phosphate-buffered saline (PBS), CUR (100 mg kg^-1 day^-1), CAR (50 mg kg^-1 day^-1), DOX (4 mg kg^-1 week^-1), DOX-CUR, and DOX-CAR, respectively. On day 24, plasma troponin I and ECG were analyzed and the left ventricle underwent stereological assessment. The results showed a fivefold increase in troponin I in the DOX-treated animals compared to the PBS ones. Additionally, heart rate and QRS amplitude, respectively, reduced by 18% and 31% and QT interval and QRS duration, respectively, increased by 41% and 24% in the DOX group in comparison with the PBS rats (p < .05). The total volume of the myocardium and vessels and the number of cardiomyocyte nuclei also, respectively, decreased by 30%, 45%, and 43% in the DOX group compared to the PBS animals (atrophy of the ventricular tissues, p < .01). Besides, the mean volumes of the connective tissue and cardiomyocytes, respectively, increased by 46% and 52% in the DOX group (p < .01). In the DOX-CUR and DOX-CAR groups, the changes were prevented extensively in comparison with the DOX group (p < .01). Co-administration of CUR or CAR and doxorubicin for 24 days could improve the heart function and structural changes.