Modulation of endoplasmic reticulum stress and cardiomyocyte apoptosis by mulberry leaf diet in experimental autoimmune myocarditis rats.

Mulberry is commonly used as silkworm diet and an alternative medicine in Japan and China, has recently reported to contain many antioxidative flavanoid compounds and having the free radical scavenging effects. Antioxidants reduce cardiac oxidative stress and attenuate cardiac dysfunction in animals with pacing-induced congestive heart failure. Hence we investigated the cardioprotective effect of mulberry leaf powder in rats with experimental autoimmune myocarditis. Eight-week-old Lewis rats immunized with cardiac myosin were fed with either normal chow or a diet containing 5% mulberry leaf powder and were examined on day 21. ML significantly decreased oxidative stress, myocyte apoptosis, cellular infiltration, cardiac fibrosis, mast cell density, myocardial levels of sarco/endo-plasmic reticulum Ca(2+) ATPase2, p22(phox), receptor for advanced glycation end products, phospho-p38 mitogen activated protein kinase, phospho-c-Jun NH(2)-terminal protein kinase, glucose regulated protein78, caspase12 and osteopontin levels in EAM rats. These results may suggest that mulberry diet can preserve the cardiac function in experimental autoimmune myocarditis by modulating oxidative stress induced MAPK activation and further afford protection against endoplasmic reticulum stress mediated apoptosis.

Inhibition of cardiac oxidative and endoplasmic reticulum stress-mediated apoptosis by curcumin treatment contributes to protection against acute myocarditis.

Curcumin is used anecdotally as an herb in traditional Indian and Chinese medicine. In the present study, the effects and possible mechanism of curcumin in experimental autoimmune myocarditis (EAM) rats were further investigated. They were divided randomly into a treatment and vehicle group, and orally administrated curcumin (50 mg/kg/day) and 1% gum arabic, respectively, for 3 weeks after myosin injection. The results showed that curcumin significantly suppressed the myocardial protein expression of inducible nitric oxide synthase (iNOS) and the catalytic subunit of nicotinamide adenine dinucleotide phosphate reduced (NADPH) oxidase. In addition, curcumin significantly decreased myocardial endoplasmic reticulum (ER) stress signaling proteins and improved cardiac function. Furthermore, curcumin significantly decreased the key regulators or inducers of apoptosis. In summary, our results indicate that curcumin has the potential to protect EAM by modulating cardiac oxidative and ER stress-mediated apoptosis, and provides a novel therapeutic strategy for autoimmune myocarditis.