Melatonin Attenuates Extracellular Matrix Accumulation and Cardiac Injury Manifested by Copper

Copper-induced cardiac injury is not widely reported in spite of its ability to cause oxidative damage and tissue injury. Structural and morphological changes in the cardiac tissue are triggered via oxidative stress and inflammatory responses following copper exposure. The varied and unavoidable exposure of copper through contaminated food and water warrants a safe and effective agent against its harmful effects. Since the heart is highly sensitive to changes in the redox balance, the present study was undertaken to examine the protective effects of melatonin against copper-induced cardiac injury. Sprague Dawley (SD) rats were exposed to 100 ppm of elemental copper via drinking water for 4 months. The cardiac tissue was evaluated for various biochemical, histological, and protein expression studies. Animals exposed to copper exhibited induced oxidative stress and cardiac injury compared to normal control. To this end, we found that melatonin treatment ameliorated copper-induced alterations in tissue oxidative variables like ROS, nitrate, MDA, and GSH. In addition, histological examinations unravelled decreased cardiac muscle dilation, atrophy, and cardiomyopathy in melatonin-treated rats. Furthermore, melatonin-treated rats were associated with reduced tissue copper levels, collagen deposition, α-SMA, and increased HO-1 expression as compared to rats exposed exclusively to copper. Moreover, the levels of NF-κB and cardiac markers such as CK-MB, cTnI, and cTnT were found to be decreased in the melatonin-treated animals. Altogether, melatonin-triggered increase in antioxidant capacity resulting in reduced aggregation of ECM components demonstrates the therapeutic potential of melatonin in the treatment of cardiac injury and tissue fibrosis.