Abstract
Abstract: :
Purpose: A new spontaneously diabetic strain of the Sprague–Dawlay (SD) rats has been established and named the SDT (Spontaneously diabetic torii) rat. Hyperglycemia and glucosuria appears at approximately 20 week–old in male rats. Cataract, massive hemorrhage in anterior chamber, and tractional detachment with fibrous have been reported as eye complications in SDT rats. In this study, we investigated the expression of pigment epithelium–derived factor (PEDF) in eyes of SDT rats and compared it to the expression of vascular endothelial growth factor (VEGF). Methods: The eyes were obtained from 10–, 20–, and 40–week–old male SDT rats and control SD rats. Specimens of eyes were processed for paraffin–embedded sections, and enrolled into immunoperoxidase analysis to detect the expression of PEDF with a LSAB kit (DAKO, Glostrup, Denmark). The expression levels of PEDF and VEGF were also detected by Western blotting analysis. The signals were digitized using a scanner and analyzed by NIH Image software. Results: Immunoperoxidase analysis showed that expression of PEDF was strongly detected in the cornea and weakly detected in the retina of both SDT rats and control SD rats. The expression of PEDF in the cornea did not change significantly with age, whereas the expression of PEDF in the retina seemed to increase with age in SDT rats, but not in SD rats. Western blotting analysis showed PEDF and VEGF was strongly detected in the cornea of SDT rats and SD rats in all ages. On the other hands, PEDF and VEGF expression was weak in the retina of SDT rats at 10–week–old, but both PEDF and VEGF expression increased with age and strongly observed at 20– and 40–week–old. In the control SD rats, both PEDF and VEGF expression was weak in the retina and did not alter with age. Conclusions: Tractional detachment with fibrous has been reported in SDT rats as a retinopathy with diabetes. A recent study reported decreased levels of PEDF and increased levels of VEGF in eye with diabetic retinopathy in human eyes. In contrast to the previous study, we found that PEDF and VEGF, both expression increased in the retina with progressing diabetes mellitus in SDT rats. These results suggested that the underlying mechanism of diabetic retinopathy in SDT rats is different from that observed in human eyes.
Keywords: diabetic retinopathy • retinal neovascularization • pathology: experimental