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S. Roy, N. Tane, S. Roy; Insulin Reduces High Glucose–Induced Apoptosis by Inhibiting ROS Production in Rat Retinal Endothelial Cells . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2901.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the effect of insulin on high–glucose induced increased reactive oxygen species (ROS) production and apoptosis in rat retinal endothelial cells (RRECs).
RRECs were grown for 9 days in normal (5 mM) glucose medium or high (30 mM) glucose medium. Cells grown in high glucose medium were treated with either 10µ units insulin or 100µM N–acetyl cysteine (NAC, an antioxidant), or both. Similarly, cells grown in normal medium were exposed to insulin, NAC, or both. Dichlorofluorescein diacetate (DCFDA) assays were performed for measuring intracellular ROS levels, and TUNEL assays were performed to determine apoptotic cell count.
In high glucose (HG) cells, ROS level and TUNEL+ cell counts were significantly increased compared to cells grown in normal medium (285±56% of control, p<0.05; 260±40% of control, p<0.05, respectively). When HG cells were exposed to either insulin or NAC, or both, ROS level and number of TUNEL+ cells significantly decreased compared to cells grown in high glucose condition (ROS: 127±50% of control, p<0.05, 134±74% of control, p<0.05, 134±57% of control, p<0.05; TUNEL+ Cells: 134±23% of control, p<0.05, 150±42% of control, p<0.05, 151±47% of control, p<0.05, respectively). In cells grown in normal medium and exposed to either insulin or NAC, or both, ROS level was reduced (76±25% of control, p>0.05, 78±51% of control, p>0.05, 67±50% of control, p>0.05, respectively). However, the number of TUNEL+ cells was increased (145±47% of control, p>0.05, 138±17% of control, p>0.05, 160±70% of control, p>0.05, respectively) compared to untreated normal cells.
Our findings indicate that insulin exhibits an anti–apoptotic effect by suppressing high glucose–induced ROS production in RRECs. The anti–apoptotic function of insulin may have a direct beneficial effect on the vascular cells of the diabetic retina.
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