Evaluation of retinal function in streptozotocin-induced diabetic rats by using the electroretinography and immunohistochemistry methods

Streptozotocin-induced diabetic rat (STZ rat) was used in many studies for the diabetic mellitus. In this study, we demonstrated whether the electroretinograms (ERG) was changed in the retina of STZ rats. In addition, we investigated the histopathological alteration in the retina of STZ rats by using the immunological method. The 100 mg/kg of STZ was injected continuously for 2 d (100 mg/kg×2). The insulin level was decreased, and the glucose level was enhanced 14 d after the injection of STZ. Moreover, the levels of a-wave, b-wave and OP amplitude were decreased in the rat at 14 d after the injection of STZ. Although, the damage and apoptosis was not observed in the retinal ganglion cell of STZ rats by the immunological experiment using the phospho-H2A.X and cleaved caspase-3, the distance between cell and cell was increased in both of outer- and inner- nuclear (granule) layer in retina of STZ rats. In conclusion, we showed that the enhanced thickening in retina was caused by the injection of excessive STZ. The thickening in retina of STZ rats may lead to the dysfunction of retina, resulting in the decrease in ERG. These findings provide significant information that can be used in the design of a model of diabetic retinopathy.