Immunohistochemical characterization of glomerular PDGF B-chain and PDGF beta-receptor expression in diabetic rats

Platelet-derived growth factor (PDGF) was found to contribute to the pathop hysiological process in the development and progression of glomeruloscleros is characterized by mesangial cell proliferation and accumulation of extrac ellular matrix. To examine the role of PDGF in the development of diabetic nephropathy, we conducted immunohistochemical analysis for PDGF B-chain (PD GF-B) and PDGF beta-receptor (PDGFR-beta) in the glomeruli of streptozotoci n-induced diabetic rats. At 2, 4, and 12 weeks after the onset of diabetes, the expression of PDGF-B ill glomeruli of diabetic rats was increased sign ificantly as compared to control or diabetic rats treated with insulin. Sim ilar changes were observed on PDGFR-beta immunostaining. The immunostaining of mirror sections revealed the existence of PDGF-B or PDGFR-beta not only in mesangial cells but also in visceral epithelial cells. Glomerular volum e was significantly increased ill diabetes. This early glomerular abnormali ty was prevented by an inhibition of PDGF system with trapidil as well as b y the treatment of insulin. Our results suggest that the activation of the PDGF system in glomerular cells might play an important role in the develop ment of early glomerular lesion in diabetes. (C) 2000 Elsevier Science irel and Ltd. All rights reserved.