Mìžnarodnij Endokrinologìčnij Žurnal (Nov 2019)
The reno-protective effect of metformin against type 2 diabetic rats via up-regulating renal tissue pigment epithelium-derived factor expression
Abstract
Background. Diabetic nephropathy has become the primary cause of end-stage renal disease worldwide. Pigment epithelium-derived factor (PEDF) is an endogenous anti-inflammatory factor in vivo, which can inhibit the expression of pathogenic factors — transforming growth factor β1 and connective tissue growth factor, and suppresses extracellular matrix protein production in diabetic kidney, suggesting an antifibrogenic activity. The aim of this study was to investigate the effect of metformin on renal tissue PEDF expression in type 2 diabetic rats and explore its possible underlying protective mechanisms in renal injury. Materials and methods. Ten clean male Sprague-Dawley rats were randomly selected as the normal control group. Type 2 diabetes model were induced by a high-fat diet and intraperitoneal injection of 30 mg/kg streptozotocin. A total of 30 type 2 diabetic rats were divided into 3 groups, which were treated with metformin 300 mg/kg/day (MET group, n = 10), glibenclamide 5 mg/kg/day (GLY group, n = 10), or saline (DM group, n = 10) by gavage for 8 weeks. Various biochemical parameters, kidney histopathology and renal tissue PEDF expression levels were examined. Results. At the 8th week, fasting blood glucose, glycated hemoglobin, triglyceride levels, urinary albumin and PEDF excretion, serum creatinine and blood urea nitrogen in MET group and GLY group decreased significantly compared to DM group, there were no significant differences in fasting blood glucose and glycated hemoglobin between MET group and GLY group. The histological examinations revealed amelioration of diabetes-induced glomerular pathological changes following treatment with MET and GLY when compared to DM group. In addition, urinary albumin and PEDF excretion were decreased, glomerular pathological changes was lightened and protein and mRNA expression of renal tissue PEDF were increased more in MET group compared with GLY group. Conclusions. Metformin reduced urinary albumin excretion in diabetic rats, and improved podocyte morphology and structural damage. The mechanism may be partly related to its role in restoring PEDF expression and inhibiting urinary excretion of PEDF.
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