Abstract: Aim The aim of the study is to investigate whether ghrelin could inhibit palmitate-induced apoptosis in rat aortic endothelial cells and the involvement of PI3K/Akt pathway. Methods Rat aortic endothelial cells were cultured in DMEM or DMEM containing 0.3mM palmitate, with or without ghrelin and PI3K/Akt inhibitor, LY294002. Apoptosis was detected using an annexin V /PI double staining assay. Spectrofluorometer assay caspase-3 activity. Western blot analysis was used to examine the expression of total Akt and P-Akt. Results Exposure of cells to 0.3mM palmitate for 24h increased apoptosis in rat aortic endothelial cells. Ghrelin inhibited palmitate-induced apoptosis. Exposure of the cells to palmitate for 24 hours caused significant inhibition of Akt phosphorylation. While ghrelin caused activation of Akt. Ghrelin-induced activation of Akt was markedly blocked by PI3K inhibitor, LY294002. Moreover, LY294002 abolished ghrelin cytoprotective activity against palmitate-induced apoptosis in endothelial cells. Conclusions Ghrelin inhibits palmitate-induced apoptosis in rat aortic endothelial cells. The anti-apoptosis effect of ghrelin is at least partly mediated by PI3K/Akt pathway.

Key words: Ghrelin, palmitate, apoptosis, endothelial cells, PI3K/Akt