Acute cardiotoxicity induced by doxorubicin in right ventricle is associated with increase of oxidative stress and apoptosis in rats

Abstract

Doxorubicin (DOX) is one of the most effective chemotherapeutic agents, but its efficiency is seriously limited by the risk of developing cardiomyopathy. The most recognized cardiotoxic effect is left ventricular (LF) dysfunction, but MRI and echocardiography data demonstrated significant right ventricle (RV) function impairment. In order to clarify this aspect, the present study investigated the potential of DOX to induce acute RV cardiotoxicity at the same time as LV impairment. Rats were intraperitoneally (i.p.) injected with a single dose of 15 mg/kg DOX. DOX-treated rats were characterized by decreased body and heart weights, elevated levels of creatine kinase (CK-MB) and lactate dehydrogenase (LDH) activities compared to controls. Biochemical analyses on RV tissue revealed that the level of malondialdehyde (MDA) was significant increased (p<0.05) and activities of catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPX) antioxidant enzymes were decreased by 13%, 27% and 18%, respectively, compared to control. Histopathogical and electron microscopic studies revealed DOX-induced damage in both ventricles and an increase of interstitial collagen fibers compared to controls (p<0.001), whereas immunohistochemical analysis showed weak and irregular desmin expression. Furthermore, mitochondrion-induced apoptotic pathways were also activated in both ventricles, as reflected by the up-regulation of Bax/Bcl-2 mRNA expression ratio (p<0.001) and increase of Bax and caspase-3 protein expression, as well as by the significant elevation of TUNEL positive nuclei, compared to controls (p<0.001). The results showed that DOX exerted RV toxic effects at the same time as those reported in the LV, which might be mediated through the mitochondrial-dependent apoptosis.