The Synergistic Action of Chronic Ethanol and Reactive Oxygen Species on Insulin Signaling in Hypertensive Vascular Smooth Muscle Cells
Chronic Ethanol (ETOH) and Reactive Oxygen Species (ROS) have been shown to have an effect on insulin signaling in Hypertensive Vascular Smooth Muscle Cells (HVSMCs). The hypothesis was tested if insulin signaling is altered by increases in oxidative stress due to ETOH exposure in HVSMCs using MAPKs as an indicator. HVSMCs were treated with increased concentrations of ETOH (1-16 mM), and 1000 µM H2O2, and stimulated with 8 µM insulin with maximum activation of ERK 1/2 occurring with 8 mM ETOH. Exposing HVSMCs to 8 mM ETOH and H2O2 1-40 min then 8 µM insulin resulted in maximum activation of ERK 1/2 within 1-10 minutes. The data indicate that Akt was inhibited between 1-10 min in both hypertensive and normal cells. RT-PCR analysis shows that Nox 1 expression in HVSMCs increased in a timely manner at 1-10 min and decreased at 20-40 min when cells were treated with ETOH for 5 min. In normal cells Nox 1 expression was not as dramatic as what was observed in HVSMCs. In a second set of experiments using mRNA isolated with Nox 4 indicated that Nox 4 mRNA expression increased at 1 min and decreased at 5 min and a dramatic increase in expression for 10-40 min. In normal cells the observable reduction was observed at 10 min. Real-time PCR quantitative analysis of the data indicated that between 1-5 min Nox 1 decreased significantly with a timely increase at 10-40 min of treating cells with ETOH. Again, this quantitative profile was observed with Nox 4. FoxO3 in hypertensive cells compared to control expresses an increase until 40 min of ETOH exposure, but in normal cells a decrease is evident beginning at 20 minutes. With FoxO4 in hypertensive cells there is a gradual increase in expression compared to control and significant increase at 10, 20 and 40 minutes after ETOH exposure. In normal cells, FoxO4 increases compared to control at 1 and 5 minutes, but a significant decrease is observed at 10, 20 and 40 minutes. The data suggests that the effect of ETOH alters insulin signaling by increasing oxidative stress in both cell types.
Sparkle D Williams,
"The Synergistic Action of Chronic Ethanol and Reactive Oxygen Species on Insulin Signaling in Hypertensive Vascular Smooth Muscle Cells"
ETD Collection for Tennessee State University.