Spontaneously Diabetic Torii Fatty Rat Shows Early Stage of Diabetic Retinopathy Characterized by Capillary Changes and Inflammation.

Purpose: The Spontaneously Diabetic Torii (SDT) fatty rat is an animal model of obese Type 2 diabetes. We previously reported that the SDT fatty rats develop diabetic cataracts. This study aimed to elucidate early diabetic changes in the retina of the SDT fatty rats. Materials and Methods: The retinal thickness, capillary diameter, and pericyte/endothelial cell (P/E) ratio were assessed in the male SDT fatty rats and Sprague-Dawley (SD) rats at 24 weeks of age. Immunostaining was performed to assess the intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) levels in the retinal capillaries. DNA microarray analysis was performed to detect inflammation-associated molecules in the retina of the SDT fatty rats. Real-time PCR and Magnetic Luminex Assay were performed to validate the results. Results: The retinal thickness in the SDT fatty rats was significantly greater than that in SD rats. The capillary diameter in the retina of the SDT fatty rats was significantly higher than that of SD rats. The P/E ratio in the SDT fatty rats was significantly lower than that in SD rats. ICAM-1 and VCAM-1 were observed in the retinal vessels of the SDT fatty rats. The levels of mRNA and protein of Mcp1, Il1b, Icam1, and Tnf were upregulated in the retinal tissues of the 24-week-old SDT fatty rats. Conclusions: Our study demonstrated that the SDT fatty rats exhibited early diabetic retinal changes, suggesting that the SDT fatty rats may be useful in research on the pathogenesis of early human diabetic retinopathy.