Dietary apigenin regulates high glucose and hypoxic reoxygenation-induced reductions in apelin expression in human endothelial cells.

The early stages of vascular endothelial dysfunction enhance angiogenic stimulation and strongly influence vascular rearrangement. The aim of this study was to determine whether a short period of high glucose (HG, 30 mM glucose) plus tumor necrosis factor alpha (TNFα) treatment or reoxygenation after hypoxia (H/R) alters the expression levels of apelin in human endothelial cells. In addition, we also examined the effects of the dietary flavonoid apigenin on apelin expression. Human endothelial cell lines were treated with HG plus TNFα or subjected to H/R. The expression levels of genes and proteins were then assessed by the reverse transcriptase polymerase chain reaction, Western blotting and immunofluorescence analyses. The expression level of apelin was significantly higher in the HG group following exposure to reoxygenation or TNFα. Reoxygenation after hypoxia decreased the expression levels of apelin and fatty acid transport protein (FATP) 1 compared with those observed during hypoxia alone and normoxia in a normal glucose concentration. Inversely, apigenin augmented H/R-reduced apelin and FATP1 expression in endothelial cells. Based on our findings, we propose that the early stages of endothelial disorder subtly influence angiogenesis and that HG and H/R stimulate vascular rearrangement and are involved in fatty acid uptake. Furthermore, dietary apigenin might improve the expression of angiogenic genes and fatty acid uptake.

Stroke status evoked adhesion molecule genetic alterations in astrocytes isolated from stroke-prone spontaneously hypertensive rats and the apigenin inhibition of their expression.

We examined the possibility that the expression of adhesion molecules is regulated differently in cultured astrocytes from stroke-prone spontaneously hypertensive rats (SHRSP/IZM) rats than in those from Wistar Kyoto rats (WKY/IZM) by tumor necrosis factor-alpha (TNF-alpha) or hypoxia and reoxygenation (H/R) and the inhibitory effects of apigenin. It was found that the expression of vascular cell adhesion molecule-1 (VCAM-1) by TNF-alpha in astrocytes isolated from SHRSP/IZM was increased compared with that in WKY/IZM. The expression of monocyte chemotactic protein-1 (MCP-1) mRNA induced by H/R in SHRSP/IZM astrocytes was increased compared with that in normal oxygen concentrations. Apigenin strongly attenuated TNF-alpha-induced VCAM-1 mRNA and protein expression and suppressed the adhesion of U937 cells and SHRSP/IZM astrocytes. These results suggest that the expression levels of adhesion molecules during H/R affect disease outcome and can drive SHRSP/IZM to stroke. It is suggested that apigenin regulates adhesion molecule expression in reactive astrocytes during ischemia.