AIM: To investigate the mechanism of retinal ganglion cell apoptosis in early stage of streptozotocin(STZ)-induced diabetic rats.

METHODS: Sixty SD rats were randomly divided into two groups: control group(CON)and diabetes mellitus group(DM). Diabetic rat model was produced by intraperitoneal injection of 1% STZ in 30 adult male SD rats. At 4, 8, 12wk,the rats were killed and eyeballs were enucleated for the HE staining, TUNEL staining, transmission electron microscopy detection respectively, and laser confocal microscope detection was used to detect the calcium ion concentration.

RESULTS:At 8wk RGCs decreased gradually and appeared disordered arrangement and got worse at 12wk in DM group. In DM group, mitochondrial swelling was detected at 4wk., and became more obvious, more in number at 8wk with reduction in some cells' volume and the number of organelles decreased. In DM group, few TUNEL positive RGCs were seen at 4wk, and became more and more at 8 and 12wk. The apoptosis index was significantly higher in DM group compared with CON group in different time points(P<0.01). Intracellular calcium ion concentration of RGCs in DM group began to elevate obviously at 8 and 12wk in contrast with CON group in the same time point(P<0.01). In DM group, Intracellular calcium ion concentration of RGCs increased difference was statistically significant between 8 and 12wk(P<0.05).

CONCLUSION: The study suggested that RGCs apoptosis occurs in early stage of diabetes, the mechanism might be associated with increased intracellular calcium ion concentration.