ABSTRACT
BACKGROUND: Vascular endothelial growth factor (VEGF) is constitutively expressed in the glomerulus where it may have a role in the maintenance of capillary endothelial cell integrity. The present study sought to examine changes in VEGF expression in a model of progressive renal disease and to assess the effects of angiotensin converting enzyme (ACE) inhibition. METHODS: Subtotal nephrectomized (STNx) rats were randomly assigned to receive vehicle (n=10) or the ACE inhibitor perindopril (8 mg/l drinking water) for 12 weeks duration (n=10). Sham-operated rats were used as controls (n=10). Glomerular capillary endothelial cell density was evaluated by immunostaining for the pan-endothelial cell marker RECA-1 and VEGF expression was assessed by quantitative in situ hybridization. RESULTS: In STNx rats glomerular capillary endothelial cell density was reduced to 19% that of sham rats (P<0.01) with a concomitant reduction in glomerular VEGF expression, also to 19% of sham rats (P<0.01). Perindopril treatment was associated with normalization of both capillary endothelial cell density and glomerular VEGF mRNA. CONCLUSIONS: Reduction in glomerular VEGF expression is a feature of the renal pathology that follows subtotal nephrectomy. In the context of the known functions of this growth factor, these findings suggest that diminution in VEGF may contribute to the demonstrated loss of glomerular endothelium that develops in this model of progressive renal disease.
Subject(s)
Angiotensin-Converting Enzyme Inhibitors/therapeutic use , Endothelial Growth Factors/analysis , Endothelial Growth Factors/genetics , Endothelium, Vascular/drug effects , Endothelium, Vascular/physiopathology , Gene Expression/drug effects , Gene Expression/genetics , Kidney Diseases/drug therapy , Kidney Diseases/physiopathology , Kidney Glomerulus/chemistry , Kidney Glomerulus/drug effects , Perindopril/therapeutic use , Vascular Endothelial Growth Factor A/analysis , Vascular Endothelial Growth Factor A/genetics , Animals , Cell Count , Disease Models, Animal , Endothelium, Vascular/pathology , In Situ Hybridization , Kidney Diseases/pathology , Kidney Glomerulus/pathology , Male , Rats , Rats, Sprague-Dawley , Vascular Endothelial Growth Factor A/drug effectsABSTRACT
In addition to hyperglycemia, hypertension and the renin-angiotensin system have been consistently implicated in the pathogenesis of diabetic nephropathy. Each of these pathogenetic factors may induce changes in cellular function by a common intracellular signaling pathway, the activation of protein kinase C (PKC) beta. The present study thus sought to determine the in vivo effect of PKC beta inhibition in experimental diabetic nephropathy in the setting of continued hyperglycemia, hypertension, and activation of the RAS. Studies were conducted in the (mRen-2)27 rat, a rodent that is transgenic for the entire mouse renin gene (Ren-2) and develops many of the structural, functional, and molecular characteristics of human diabetic nephropathy when experimental diabetes is induced with streptozotocin (STZ). Six-week-old female Ren-2 rats received an injection of STZ or vehicle and were maintained for 6 months. Within 24 h, diabetic rats were further randomized to receive treatment with the specific PKC beta inhibitor, LY333531, admixed in diet (10 mg x kg(-1) x d(-1)) or no treatment (n = 8/group). Diabetic rats developed albuminuria, glomerulosclerosis, and tubulointerstitial fibrosis with a concomitant increase in transforming growth factor-beta (TGF-beta). Western blot analysis demonstrated increased PKC beta in diabetic animals, localized by immunofluorescence to the glomerular mesangium. In vivo inhibition of PKC beta with LY333531 led to a reduction in albuminuria, structural injury, and TGF-beta expression, despite continued hypertension and hyperglycemia.
