Resveratrol ameliorates early diabetic nephropathy associated with suppression of augmented TGF-β/smad and ERK1/2 signaling in streptozotocin-induced diabetic rats.

Diabetic nephropathy (DN) is the major cause of end-stage renal disease. The early changes in DN are characterized by an increased in kidney size, glomerular volume, and kidney function, followed by the accumulation of glomerular extracellular matrix, increased urinary albumin excretion (UAE), glomerular sclerosis, and tubular fibrosis. Resveratrol (RSV) has been shown to ameliorate hyperglycemia and hyperlipidemia in streptozotocin-induced diabetic rats. In the present study, we examined the beneficial effects of RSV on DN and explored the possible mechanism of RSV action. Male Sprague-Dawley rats were injected with streptozotocin at 65mg/kg body weight. The induction of diabetes mellitus (DM) was confirmed by a fasting plasma glucose level ≥300mg/dL and symptoms of polyphagia and polydipsia. The DM rats were treated with or without RSV at 0.75mg/kg body weight 3 times a day for 8 weeks. Animals were sacrificed and kidney histology was examined by microscopy. Urinary albumin excretion, glomerular hypertrophy and expressions of fibronectin, collagen IV, and TGF-β in the glomeruli were alleviated in RSV-treated DM rats, but not in untreated DM rats. In addition, RSV treatment reduced the thickness of the glomerular basement membrane (GBM) to the original thickness and increased nephrin expressions to normal levels in DM rats. Moreover, RSV inhibited phosphorylation of smad2, smad3 and ERK1/2 in diabetic rat kidneys. This is the first report showing that RSV alleviates early glomerulosclerosis in DN through TGF-β/smad and ERK1/2 inhibition. In addition, podocyte injuries of diabetic kidneys are lessened by RSV.

Chen KH ，Hung CC ，Hsu HH ，Jing YH ，Yang CW ，Chen JK ... -  《-》

Resveratrol ameliorates vasculopathy in STZ-induced diabetic rats: role of AGE-RAGE signalling.

Resveratrol (RSV) has been shown to ameliorate hyperglycaemia and hyperlipidaemia in streptozotocin-induced diabetic rats. In the present study, we examined the beneficial effects of RSV on diabetes mellitus (DM)-induced vasculopathy and explored its possible mechanism. Male Sprague-Dawley rats were injected with streptozotocin at 65 mg/kg body weight The induction of DM was confirmed by a fasting plasma glucose level > or = 300 mg/dL and symptoms of polyphagia and polydipsia. The DM rats were treated with or without RSV at 0.75 mg/kg body weight three times a day for 4-8 weeks. Animals were sacrificed and vessel wall histology was examined by microscopy. The vascular smooth muscle cell activation was assessed by the medial thickness, collagen deposition, and the expressions receptor for advanced glycation end product, NF-kappaB, proliferation cell nuclear antigen, and the levels of Erk1/2 phosphorylation. In RSV-treated DM rats, the vascular wall thickening, collagen deposition/cross-linking, and vascular permeability were all alleviated compared with that of the untreated DM rats. The vascular smooth muscle cell of the RSV-treated rats was characterized with less proliferation, lower NF-kappaB, and Erk1/2 activation, decreased proliferation cell nuclear antigen and receptor for advanced glycation end product expression. Moreover, the plasma fructosamine was significantly reduced in RSV-treated DM rats. RSV alleviated DM-induced vasculopathy through attenuation of advanced glycation end product-receptor for advanced glycation end product-NF-kappaB signalling pathway.

Jing YH ，Chen KH ，Yang SH ，Kuo PC ，Chen JK ... -  《-》

Preventive effects of rutin on the development of experimental diabetic nephropathy in rats.

Diabetic nephropathy (DN) is an important microvascular complication and one of the main causes of end-stage renal disease. In this study, the preventive effect and mechanism of rutin on the development of DN in streptozotocin (STZ)-induced diabetic rats were investigated. After an early DN model was induced by STZ, rats were orally administered rutin at 3 doses for 10 weeks. Fasting blood glucose, creatinine (Cr), blood urea nitrogen (BUN), urine protein, kidney index, antioxidase, advanced glycosylation end products (AGEs), extracellular matrix (ECM) including collagen IV and laminin, connective tissue growth factor (CTGF), phosphorylated Smad 2/3 (p-Smad 2/3) and Smad 7 (p-Smad 7), and transforming growth factor-β(1) (TGF-β(1)) were determined by different methods, respectively. The ultrastructural morphology was observed by a transmission electron microscope. Compared with the DN group, rutin decreased the levels of fasting blood glucose, Cr, BUN, urine protein, the intensity of oxidative stress and p-Smad 7 significantly. The expression of AGEs, collagen IV and laminin, TGF-β(1), p-Smad 2/3 and CTGF was inhibited by rutin significantly. Moreover, rutin was observed to inhibit proliferation of mesangial cells and decrease thickness of glomerular basement membrane (GBM) by electron microscopy. The preventive effect of rutin on the development of DN is closely related to oxidative stress and the TGF-β(1)/Smad/ECM and TGF-β(1)/CTGF/ECM signaling pathways. Those results suggest that rutin can prevent the development of experimental DN in rats.

Hao HH ，Shao ZM ，Tang DQ ，Lu Q ，Chen X ，Yin XX ，Wu J ，Chen H ... -  《-》

Extracellular superoxide dismutase ameliorates streptozotocin-induced rat diabetic nephropathy via inhibiting the ROS/ERK1/2 signaling.

Diabetic nephropathy is the leading cause of end stage renal disease in developed countries throughout the world. The imbalance between the production of reactive oxygen species (ROS) and the antioxidant defense system is the main problem that is responsible for the progression of diabetic kidney disease. In this study, we investigated whether human extracellular superoxide dismutase (hEC-SOD) can prevent diabetic nephropathy in the rat model. Diabetic nephropathy symptoms were induced by intraperitoneal injection with 60 mg/kg streptozotocin (STZ) in male Sprague-Dawley (SD) rats. After daily supplement of rhEC-SOD (3200 U/kg/day) for 4 weeks, the serum or urine biochemical markers (glucose, creatinine, blood urea nitrogen, triglyceride, hemoglobin A1c, and microalbuminuria), histological changes, gene expressions (phox47, opn, and gapdh), and protein levels (TGF-β, AT1-R, phospho-p42/p44 MAPK, and p42/p44 MAPK) were determined. Results showed that rhEC-SOD administration could reverse SOD activity measured in kidney and diabetic-associated changes, including the fibrosis change, expression of collagen I, transforming growth factor-beta (TGF-β) and angiotensin II type I receptor (AT1-R), as well as the activation of the intracellular mitogen-activated protein kinase (MAPK) signaling pathway, associating with its inhibition of p42(MAPK)/p44(MAPK) (ERK1/2) phosphorylation. Additionally, diabetic nephropathy up-regulated the expression of the phox47 and opn genes, and these changes could also be suppressed. Though the proteinuria did not significantly reduce. Treatment with rhEC-SOD ameliorates STZ-induced diabetic nephropathy, leading to reduced death rates, kidney weight/body weight ratio, fibrosis change, and TGF-β1 expression through the down-regulation of ROS/ERK1/2 signaling pathway. We conclude that rhEC-SOD can act as a therapeutic agent to protect the progression of diabetic nephropathy.

Kuo CW ，Shen CJ ，Tung YT ，Chen HL ，Chen YH ，Chang WH ，Cheng KC ，Yang SH ，Chen CM ... -  《-》

Sitagliptin ameliorates diabetic nephropathy by blocking TGF-β1/Smad signaling pathway.

Wang D ，Zhang G ，Chen X ，Wei T ，Liu C ，Chen C ，Gong Y ，Wei Q ... -  《-》