Doxorubicin (DOX) is a potent available antitumor agent; however, its clinical use is limited because of its cardiotoxicity. Cell death is a key component in DOX-induced cardiotoxicity, but its mechanisms are elusive. Here, we explore the role of superoxide, nitric oxide (NO), and peroxynitrite in DOX-induced cell death using both in vivo and in vitro models of cardiotoxicity. Western blot analysis, real-time PCR, immunohistochemistry, flow cytometry, fluorescent microscopy, and biochemical assays were used to determine the markers of apoptosis/necrosis and sources of NO and superoxide and their production. Left ventricular function was measured by a pressure-volume system. We demonstrated increases in myocardial apoptosis (caspase-3 cleavage/activity, cytochrome c release, and TUNEL), inducible NO synthase (iNOS) expression, mitochondrial superoxide generation, 3-nitrotyrosine (NT) formation, matrix metalloproteinase (MMP)-2/MMP-9 gene expression, poly(ADP-ribose) polymerase activation [without major changes in NAD(P)H oxidase isoform 1, NAD(P)H oxidase isoform 2, p22^phox, p40^phox, p47^phox, p67^phox, xanthine oxidase, endothelial NOS, and neuronal NOS expression] and decreases in myocardial contractility, catalase, and glutathione peroxidase activities 5 days after DOX treatment to mice. All these effects of DOX were markedly attenuated by peroxynitrite scavengers. Doxorubicin dose dependently increased mitochondrial superoxide and NT generation and apoptosis/necrosis in cardiac-derived H9c2 cells. DOX- or peroxynitrite-induced apoptosis/necrosis positively correlated with intracellular NT formation and could be abolished by peroxynitrite scavengers. DOX-induced cell death and NT formation were also attenuated by selective iNOS inhibitors or in iNOS knockout mice. Various NO donors when coadministered with DOX but not alone dramatically enhanced DOX-induced cell death with concomitant increased NT formation. DOX-induced cell death was also attenuated by cell-permeable SOD but not by cell-permeable catalase, the xanthine oxidase inhibitor allopurinol, or the NADPH oxidase inhibitors apocynine or diphenylene iodonium. Thus, peroxynitrite is a major trigger of DOX-induced cell death both in vivo and in vivo, and the modulation of the pathways leading to its generation or its effective neutralization can be of significant therapeutic benefit.

Oxidative and reductive stress are dual dynamic phases experienced by the cells undergoing adaptation towards endogenous or exogenous noxious stimulus. The former arises due to the imbalance between the reactive oxygen species production and antioxidant defenses, while the latter is due to the aberrant increase in the reducing equivalents. Mitochondrial malfunction is the common denominator arising from the aberrant functioning of the rheostat that maintains the homeostasis between oxidative and reductive stress. Recent experimental evidences suggest that the maladaptation during oxidative stress could play a pivotal role in the pathophysiology of major cardiovascular diseases such as myocardial infraction, atherosclerosis, and diabetic cardiovascular complications. In this review we have discussed the role of oxidative and reductive stress pathways in the pathogenesis of myocardial ischemia/reperfusion injury and diabetic cardiomyopathy (DCM). Furthermore, we have provided impetus for the development of subcellular organelle targeted antioxidant drug therapy for thwarting the deterioration of the failing myocardium in the aforementioned cardiovascular conditions.

The platinum compound cisplatin is one of the most potent chemotherapy agents available to treat various malignancies. Nephrotoxicity is a common complication of cisplatin chemotherapy, which involves increased oxidative and nitrosative stress, limiting its clinical use. In this study, we have investigated the effects of a nonpsychoactive cannabinoid cannabidiol, which was reported to exert antioxidant effects and has recently been approved for the treatment of inflammation, pain, and spasticity associated with multiple sclerosis in patients in a mouse model of cisplatin-induced nephropathy. Cisplatin induced increased expression of superoxide-generating enzymes RENOX (NOX4) and NOX1, enhanced reactive oxygen species generation, inducible nitric-oxide synthase expression, nitrotyrosine formation, apoptosis (caspase-3/7 activity, DNA fragmentation, and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining), poly(ADP-ribose) polymerase activity, and inflammation (tumor necrosis factor-α and interleukin-1β) in the kidneys of mice, associated with marked histopathological damage and impaired renal function (elevated serum blood urea nitrogen and creatinine levels) 72 h after the administration of the drug. Treatment of mice with cannabidiol markedly attenuated the cisplatin-induced oxidative/nitrosative stress, inflammation, and cell death in the kidney, and it improved renal function. Thus, our results suggest that cannabidiol may represent a promising new protective strategy against cisplatin-induced nephrotoxicity.