Effects of taurine on glial cells apoptosis and taurine transporter expression in retina under diabetic conditions

Abstract

Taurine, a ß-aminosulfonic acid, has been reported to reduce the risk of a number of diseases, including cardiovascular disease, diabetes, and also perhaps to reduce neurodegeneration in the elderly. The transport of taurine is known to be mediated by taurine transporter (TauT). The purpose of this study is to examine the effects of taurine on glial cells apoptosis and on TauT expression in retina of diabetic rats and retinal glial cells cultured with high glucose. TdT-mediated dUTP-biotin nick-end labeling (TUNEL) staining analysis showed that the number of TUNEL-positive cells in taurine treated diabetic rats was significantly lower than those of untreated diabetic rats over the 8-, and 12-week time courses, respectively (all P < 0.001). No TUNEL-positive cells were observed in retina of control groups and taurine treated control groups. In cultured retinal glial cells, the apoptosis in high glucose-treated cells was significantly increased vs the control. When the cells were incubated with high glucose and taurine at 0.1, 1.0 and 10 mmol/l, the percentage of apoptosis was significantly decreased to 16.4, 5.7 and 7.6% respectively (all P < 0.05). With supplementation of taurine in diet and culture medium, higher expression of TauT in retina of diabetic rats and cultured retinal glial cells under diabetic conditions were detected by western-blotting (P < 0.05). Taken together, our data suggest that diabetes or high glucose induced retinal glial cells apoptosis can be inhibited by taurine, and that taurine reverses the diabetes-induced or high glucose-induced decrease in TauT expression.