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Ghrelin prevents doxorubicin-induced cardiotoxicity through TNF-alpha/NF-kappaB pathways and mitochondrial protective mechanisms.

Xu Z, Lin S, Wu W, Tan H, Wang Z, Cheng C, Lu L, Zhang X

Department of Pathophysiology, ZhongShan Medical College, Sun Yat-sen University, Guangzhou 510080, China.

We had reported that increased levels of endogenous ghrelin during the progression of doxorubicin-induced cardiomyopathy and heart failure might provide a compensatory self-protective effect. We investigated which pathway(s) produced these protective effects in vitro. Primary cultured cardiomyocytes were induced with doxorubicin in the presence or absence of ghrelin or a tumor necrosis factor-alpha (TNF-alpha) antagonist (etanercept). Ghrelin up-regulated TNF-alpha in a time- and dose-dependent manner. It significantly reduced cell apoptosis and markers of oxidative stress, such as malondialdehyde (MDA) content and lactate dehydrogenase (LDH) activity; it also increased anti-oxidative enzyme activity such as superoxide dismutase (MnSOD) and catalase (CAT), retained mitochondrial membrane potential and energy metabolism compared with doxorubicin alone. Moreover, ghrelin increased mitochondrial anti-apoptosis related gene protein expression such as bcl-2 and MnSOD, reduced cytoplasmic cytochrome C (Cyt C) release and strengthened the activation of NF-kappaB. All these effects were abrogated by etanercept. This suggests ghrelin affects the TNF-alpha/NF-kappaB activation pathways, up-regulating TNF-alpha, to produce anti-oxidative and anti-apoptotic effects that protected cardiomyocytes from doxorubicin-induced cytotoxicity.

Published 2 May 2008 in Toxicology, 247(2): 133-8.
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