HEPARAN-SULFATE PROTEOGLYCAN SYNTHESIS AND ITS EXPRESSION ARE DECREASED IN THE RETINA OF DIABETIC RATS

Purpose. Heparan sulfate proteoglycan (HSPG) is an integral component of all basement membranes and is implicated in the charge-selective pr operties of these basement membranes. Studies have shown a decrease in the number of HSPG anionic sites in the retinal capillary and glomeru lar basement membrane of diabetic animals. This study examined whether a decrease in both HSPG synthesis and its expression as perlecan are reduced in the retina of streptozotocin-diabetic rats. Methods. Diabet es was induced in male Wistar rats by intraperitoneal injection of str eptozotocin and the rats were sacrificed 20 weeks later. Retinas were isolated and HSPG synthesis was assessed by incorporation of S-35-sulf ate into heparan sulfate. The expression of mRNA for perlecan was quan tified by RNase protection assay. Results. Both the synthesis of HSPG and mRNA expression for perlecan were decreased in the retina of diabe tic compared to normal rats. Conclusions. The decrease in HSPG synthes is may account for the reported decrease in retinal basement membrane anionic sites and increased capillary permeability that occurs in diab etes.