ABSTRACT
There is growing evidence suggesting that glomerular endothelial cell proliferation and angiogenesis may be responsible for the pathophysiological events in the early stage of diabetic nephropathy. This study was designed to investigate the factors related to glomerular endothelial cell proliferation and glomerular angiogenesis and assess the effect of propyl gallate on preventing these disorders in diabetic rats. We found that glomerular hypertrophy, glomerular mesangial matrix expansion, and albuminuria were significantly increased in DN rats. CD31+ endothelial cells significantly increased in glomerulus of diabetic rats. Double immunofluorescence staining showed some structurally defective vasculus tubes in glomerulus. Real-time PCR and western blot demonstrated the glomerular eNOS expression remained at the same level, while remarkable decreased NO productions and suppressed eNOS activities were observed in diabetic rats. Treatment with propyl gallate improved glomerular pathological changes, reduced endothelial cell proliferation, decreased albuminuria, and restored eNOS activity, but did not alter eNOS expression. These data suggest that endothelial cell proliferation and immature angiogenesis may be the contributors to progression of DN. Propyl gallate is a potential novel therapeutic agent on prevention of diabetic nephropathy.
Subject(s)
Angiogenesis Inhibitors/therapeutic use , Antioxidants/therapeutic use , Diabetic Nephropathies/prevention & control , Endothelium, Vascular/drug effects , Kidney Glomerulus/drug effects , Neovascularization, Pathologic/prevention & control , Propyl Gallate/therapeutic use , Albuminuria/etiology , Albuminuria/prevention & control , Angiogenesis Inhibitors/administration & dosage , Animals , Antioxidants/administration & dosage , Cell Proliferation/drug effects , Diabetes Mellitus, Type 1/complications , Diabetic Nephropathies/metabolism , Diabetic Nephropathies/pathology , Diabetic Nephropathies/physiopathology , Disease Progression , Endothelium, Vascular/metabolism , Endothelium, Vascular/pathology , Gene Expression Regulation, Enzymologic/drug effects , Glomerular Mesangium/drug effects , Glomerular Mesangium/metabolism , Glomerular Mesangium/pathology , Hypertrophy , Injections, Intraperitoneal , Kidney Glomerulus/metabolism , Kidney Glomerulus/pathology , Male , Molecular Targeted Therapy , Neovascularization, Pathologic/etiology , Nitric Oxide/antagonists & inhibitors , Nitric Oxide/metabolism , Nitric Oxide Synthase Type III/genetics , Nitric Oxide Synthase Type III/metabolism , Platelet Endothelial Cell Adhesion Molecule-1/metabolism , Propyl Gallate/administration & dosage , RatsABSTRACT
BACKGROUND: The uncoupling of the vascular endothelial growth factor-nitric oxide (VEGF-NO) axis may play a vital role in inducing glomerular endothelial dysfunction. We investigate the factors that contribute to the imbalance of the VEGF-NO axis and evaluate the effect of propyl gallate on preventing endothelial dysfunction. METHODS: Streptozotocin (STZ, 60 mg/kg) was administrated to rats to establish an animal diabetic nephropathy model. The diabetic rats were randomly divided into a diabetic model group and a propyl gallate-treated group. Animals were sacrificed 8 weeks after the model was established. Periodic acid-Schiff staining was conducted to observe pathological changes, and reverse transcriptase polymerase chain reaction and Western blot were employed to analyze endothelial nitric oxide synthase (eNOS) and VEGF expressions. Commercial kits were used to detect glomerular eNOS activity and NO production, as well as oxidative stress. RESULTS: Compared with that in the normal control group, glomerular eNOS activity significantly decreased in diabetic rats, but eNOS expression remained at the same level. The expression of VEGF increased at this stage. Levels of glomerular oxidative stress also increased in diabetic rats and were inversely correlated with eNOS activity. Treatment with propyl gallate restored eNOS activity, ameliorated oxidative stress and improved glomerular pathological changes, but did not alter eNOS and VEGF expressions. CONCLUSION: The imbalance of the VEGF-NO axis in the glomeruli of diabetic rats may have resulted from eNOS inactivation, but not from the decrement in eNOS expressions at the early stage of rat diabetic nephropathy. Propyl gallate improved glomerular pathological changes in diabetic rats, possibly through oxidative stress reduction and VEGF-NO axis recovery.
