Objective     To investigate the expression time and the position of VEGF in the choroid of diabetic rats and compare them with the VEGF expression in the choroid and retina of normal rats.      Methods     Healthy male Wistar rats were selected and randomly divided into diabetic group and normal group. Type 1 diabetes rat model was induced by being injected of large-dose streptozotocinum (STZ) into abdominal cavity. The retina and choroid o

f rats were obtained to detect the VEGF expression by immunohistochemistry at 1

st

2

nd

3

rd

4

th

5

th

month after diabetes induction.      Results     VEGF expression in retina and choroid of rats was of obvious difference between normal group and one-month diabetic group. In two-month diabetic group

VEGF expression in choroid was positive (33.3%)

while VEGF expression in retina was not significantly different with that of normal group. In three-month diabetic group

VEGF expression in choroid was positive (55.6%)

and VEGF expression in inner nuclear layer and ganglion cell layer of retina was positive (33.3%). In four-month diabetic group

VEGF expression in choroid was positive (66.7%)

and VEGF expression in inner limiting membrane

inner nuclear layer

outer nuclear layer and ganglion cell layer of retina was positive (77.8%). In five-month diabetic group

VEGF expression in choroid was positive (88.9%)

and VEGF expression in the whole retina was positive (88.9%). The expression density of VEGF in choroid and retina gradually increased (P0.05).      Conclusion     VEGF expression in choroid and retina of rats is concerned with the pathogenesis of diabetes

and VEGF expression in choroid had precedence over that in retina.