[Effects of vascular endothelial growth factor and basic fibroblast growth factor in early stage diabetic retinopathy and their molecular pathological mechanism].

OBJECTIVE

To study the effects of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in early stage diabetic retinopathy and their mechanisms, so as to guide the clinical work theoretically.

METHODS

Fifty-five Wistar rats were randomly divided into four groups. Ten rats were used as controls (M group). Streptozocin was injected intraperitoneally to induce diabetes for I month (M(1) group, n = 15), 3 months (M(3) group, n = 15), and 5 months (M(5) group, n = 15). At the experimental ends of each group, the rats were over-anesthetized and their eyeballs were extracted to make digest preparation. In situ hybridization and immunohistochemistry were used to investigate the expression of bFGF and VEGF on retinal vascular. Transmission electron microscopy was used to observe the histology of the retinal vessels.

RESULTS

There was no difference in the number of pericytes between M(1) group and M group (P > 0.05), but the number of pericytes was significantly lower in M(3) and M(5) groups than in the M and M(1) groups (P < 0.001). VEGF in situ hybridization showed an expression rate of 34% in the M(5) group. VEGF immunohistochemistry showed an expression rate of 56% in M(5) group. bFGF in situ hybridization showed an expression rate of 78% in M(3) group and an expression rate of 89% in M(5) group. Transmission electron microscopy showed no change in M group. However, it showed swelling of endothelial cells, finger-like process into the capillary cavity, and uneven distribution of heterochromatin in pericytes in M(1) group. Obvious fragmental thickening and splitting of basement membrane, swelling and deformation, finger like process to the capillary cavity, and concentration and margination of heterochromatin in endothelial cells and swelling and deformation of rough surfaced endoplasmic reticulum and mitochondrion in pericytes were seen in the M(3) and M(5) groups, especially the latter.

CONCLUSION

During the course of diabetic retinopathy, morphologic changes of vessels occurs prior to the expression of growth factors, in which the expression of VEGF follows the expression of bFGF.