AIM: To investigate the expressions time and the position of VEGF and PEDF in the retina and choroid of diabetic rats and compare them with the expressions in the normal rats.

METHODS: Healthy male Wistar rats were selected and randomly divided into diabetic group and normal group(M0). Type 1 diabetes rat model was induced by being injected of large-dose streptozotocinum(STZ)into abdominal cavity. The retina and choroid of rats was obtained to detect the VEGF and PEDF expressions by immunohistochemistry at 1^st(M1), 2^nd(M2), 3^rd(M3), 5^th(M5)month after diabetes induction.

RESULTS:VEGF expression in retina and choroid of rats had no obvious difference between M1and M0. M2 VEGF expression in choroid was positive(33.3%), while in retina was not significantly different with M0. M3 VEGF expression in choroid was positive(55.6%), and in inner nuclear layer and ganglion cells layer of retina was positive(33.3%). M5 VEGF expression in choroid was and the whole retina positive(88.9%). PEDF expression in retina of rats had no obvious difference between normal group and M1, M2 group, and there was no PEDF expression detected in choroid of all the groups. In M3 and M5 group, PEDF expression in retina was lower than M0, the expression gradually weakened with the extension of the course(P<0.05), and there was also no PEDF expression detected in choroid of all the groups. The ratio of VEGF/PEDF gradually increased with the extended duration of diabetes, and there was significant difference compared with M0(P<0.01)

CONCLUSION: The expression of VEGF and PEDF in retina of rats was related with the diabetes course, VEGF expression in retina and choroid was increased, while PEDF expression was gradually decreased in the course. There was no PEDF expression in choroid, it might because the experimental model was not in proliferative stage.