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Diabetes mellitus increases the risk of heart failure independently of underlying coronary artery disease, and many believe that diabetes leads to cardiomyopathy. The underlying pathogenesis is partially understood. Several factors may contribute to the development of cardiac dysfunction in the absence of coronary artery disease in diabetes mellitus. There is growing evidence that excess generation of highly reactive free radicals, largely due to hyperglycemia, causes oxidative stress, which further exacerbates the development and progression of diabetes and its complications. Hyperglycemia-induced oxidative stress is a major risk factor for the development of micro-vascular pathogenesis in the diabetic myocardium, which results in myocardial cell death, hypertrophy, fibrosis, abnormalities of calcium homeostasis and endothelial dysfunction. Diabetes-mediated biochemical changes show cross-interaction and complex interplay culminating in the activation of several intracellular signaling molecules. Diabetic cardiomyopathy is characterized by morphologic and structural changes in the myocardium and coronary vasculature mediated by the activation of various signaling pathways. This review focuses on the oxidative stress and signaling pathways in the pathogenesis of the cardiovascular complications of diabetes, which underlie the development and progression of diabetic cardiomyopathy.

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SUMMARYAim of the study: To examine the protective effects of dietary administration of Mulberry leaves (ML) on postmyocarditis dilated cardiomyopathy (DCM) focusing on oxidative and endoplasmic reticulum stresses and adverse myocardial remodeling. Materials and methods: In this study, we used a rat model of cardiac myosin-induced experimental autoimmune myocarditis to test the effects of ML diet (MLD) (5%) on various markers of cardiac remodeling and function. After 4 weeks of immunization, the rats were fed with 5% MLD for 4 weeks. By the end of the study, echocardiography was performed to assess the myocardial dimensions. The heart tissue was used for histopathology and Western blotting analyses. Results: Our study showed that the postmyocarditis rats exhibited increased oxidative stress when compared with the control rats. MLD supplementation suppressed this change, compared with vehicle treatment. In addition, postmyocarditis rats showed significant elevation of the endoplasmic reticulum stress markers, which were prevented by the MLD supplementation. Similarly the vehicle-treated rats suffered with the adverse myocardial remodeling in the form of fibrosis as evidenced by the Azan-Mallory staining and immunohistochemistry for collagen-III levels, compared with the control rats. However, MLD treatment not only markedly attenuated cardiac fibrosis, but also improved the left ventricular ejection fraction and fractional shortening. Interestingly, the myocardial levels of endothelin-1, activated members of mitogen-activated protein kinase (MAPK) pathway, and vascular endothelial growth factor (VEGF) were significantly attenuated by MLD, indicating that the antihypertrophic effects of MLD are partially mediated via endothelin-1, MAPK, and VEGF pathway. Conclusion: Collectively, these results suggest that supplementation of rats with 5% MLD has the ability to regulate cardiac remodeling and improves cardiac function and hence contributes to prevent the development of postmyocarditis dilated cardiomyopathy.

Curcumin is a natural polyphenolic compound abundant in the rhizome of the perennial herb turmeric, Curcuma longa. It is commonly used as a dietary spice and coloring agent in cooking, and is used anecdotally as an herb in traditional Indian and Chinese medicine. It has been reported that curcumin has the potential to protect against cardiac inflammation through suppression of GATA-4 and nuclear factor-κB (NF-κB); however, no study to date has addressed the effect of curcumin on experimental autoimmune myocarditis (EAM) in rats. In this study, 8-week-old male Lewis rats were immunized with cardiac myosin to induce EAM. They were then divided randomly into a treatment or vehicle group and orally administrated curcumin (50 mg/kg/d) or 1% gum arabic, respectively, for 3 weeks after myosin injection. We performed hemodynamic, echocardiographic, hematoxylin and eosin staining, mast cell staining and Western blotting studies to evaluate the protective effect of curcumin in the acute phase of EAM. Cardiac functional parameters measured by hemodynamic and echocardiographic studies were significantly improved by curcumin treatment. Furthermore, curcumin reduced the heart weight-to-body weight ratio, area of inflammatory lesions and the myocardial protein level of NF-κB, interleukin (IL)-1β, tumor necrosis factor (TNF)-α and GATA-4. Our results indicate that curcumin has the potential to protect against cardiac inflammation through suppression of IL-1β, TNF-α, GATA-4 and NF-κB expresses, and may provide a novel therapeutic strategy for autoimmune myocarditis.