Guifen Qiang

Effect of valsartan on the pathological progression of hepatic fibrosis in rats with type 2 diabetes.

Currently there is no effective treatment for nonalcoholic fatty liver disease (NAFLD), especially hepatic fibrosis induced by type 2 diabetes. Valsartan maybe has beneficial effect on the liver disease. The aim of the present study was to investigate the effect of valsartan on the pathological progression of hepatic fibrosis in rats with type 2 diabetes. An animal model of hepatic fibrosis with type 2 diabetes was developed using a high-sucrose, high-fat diet and low-dose streptozotocin. Valsartan (15 mg/kg/day, i.g.) was orally administered for four months. The livers were removed to make hematoxylin-eosin (HE) staining and Picric acid-Sirius red staining, and immunohistochemistry staining of α-smooth-muscle-actin (α-SMA), transforming growth factor β1 (TGF-β1), tumor necrosis factor (TNF-α) and monocyte chemotactic protein-1 (MCP-1). Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining was performed to detect hepatocyte apoptosis. The liver mitochondria were isolated to measure the mitochondrial respiratory function. The results showed that valsartan significantly alleviated the lesion of hepatic steatosis and hepatic fibrosis by HE staining and Picric acid-Sirius red staining. Immunohistochemical staining suggested that the expression of α-SMA, TGF-β1, TNF-α and MCP-1 in liver tissue of diabetic rats was markedly reduced by valsartan. TUNEL staining showed that there were fewer TUNEL-positive apoptotic hepatocytes in valsartan group. In addition, valsartan restored the injured hepatic mitochondrial respiratory function. The findings demonstrated that valsartan prevented the pathological progression of hepatic fibrosis in type 2 diabetic rats, correlated with reducing α-SMA, TGF-β1, TNF-α and MCP-1 expression, also anti-apoptosis and mitochondria-protective potential.

Salvianolic acid A protects against vascular endothelial dysfunction in high-fat diet fed and streptozotocin-induced diabetic rats

Salvianolic acid A (SalA) is one of the main active ingredients of Salvia miltiorrhizae. The objective of this study was to evaluate the effect of SalA on the diabetic vascular endothelial dysfunction (VED). The rats were given a high-fat and high-sucrose diet for 1 month followed by intraperitoneal injection of streptozotocin (30 mg/kg). The diabetic rats were treated with SalA (1 mg/kg, 90% purity) orally for 10 weeks after modeling, and were given a high-fat diet. Contractile and relaxant responses of aorta rings as well as the serum indications were measured. Our results indicated that SalA treatment decreased the level of serum Von Willebrand factor and ameliorated acetylcholine-induced relaxation and KCl-induced contraction in aorta rings of the diabetic rats. SalA treatment also reduced the serum malondialdehyde, the content of aortic advanced glycation end products (AGEs), and the nitric oxide synthase (NOS) activity as well as the expression of endothelial NOS protein in the rat aorta. Exposure of EA.hy926 cells to AGEs decreased the cell viability and changed the cell morphology, whereas SalA had protective effect on AGEs-induced cellular vitality. Our data suggested that SalA could protect against vascular VED in diabetes, which might attribute to its suppressive effect on oxidative stress and AGEs-induced endothelial dysfunction.

Salvianolic Acid A Prevents the Pathological Progression of Hepatic Fibrosis in High-Fat Diet-Fed and Streptozotocin-Induced Diabetic Rats

Type 2 diabetes patients have an increased risk of developing hepatic fibrosis. Salvianolic acid A (SalA) has been reported to be a strong polyphenolic anti-oxidant and free radical scavenger. The aim of the present study was to evaluate the effect of SalA on the pathological progression of hepatic fibrosis in high-fat diet (HFD)-fed and streptozotocin (STZ)-induced diabetic rats and to clarify the underlying mechanisms. Type 2 diabetic animal model with hepatic fibrosis was developed by a high-sucrose, HFD and low-dose STZ injection (i.p.). Diabetic rats were randomly divided into SalA group (0.3 mg/kg/day) and diabetic control groups fed with a HFD. After administration for four months, SalA reversed the hyperlipidemia and reduced hepatic triglyceride (TG). Hematoxylin-Eosin (HE) and Picro acid-Sirius red staining results indicated that SalA significantly alleviated the lesions of hepatic steatosis and fibrosis, with the reduction of type I and III collagens. The expression of α-smooth-muscle-actin (α-SMA) and transforming growth factor β1 (TGF-β1) in the liver were markedly down-regulated by SalA treatment. TUNEL staining showed that SalA reduced apoptosis in hepatocytes. In addition, SalA improved hepatic mitochondrial respiratory function in diabetic rats. Taken together, these findings demonstrated that SalA could prevent the pathological progression of hepatic fibrosis in HFD-fed and STZ-induced diabetic rats. The underlying mechanisms may be involved in reducing oxidative stress, suppressing α-SMA and TGF-β1 expression, as well as exerting anti-apoptotic and mitochondria-protective effects.

Effects of salvianolic scid A on plantar microcirculation and peripheral nerve function in diabetic rats

Salvianolic acid A (SalA) is the main efficacious, water-soluble constituent of Salvia miltiorrhiza Bunge. This study evaluated the effects of SalA on plantar microcirculation and peripheral nerve dysfunction in streptozotocin (STZ )-induced type 2 diabetic rats. The rats were given a high-fat and high-sucrose diet for a month followed by intraperitoneal injection of STZ (30 mg/kg). Oral administration of SalA (1 and 3mg/kg, respectively) was performed daily for 10 weeks after modeling. Diabetic rats were given a high-fat diet, while age-matched healthy rats were given a standard chow. Plantar microcirculation was measured by Laser Doppler flowmetry, and peripheral nerve function was measured with regard to pain withdrawal latency and motor nerve conduction velocity. The results show that the plantar blood perfusion and vasodilation reactivities decreased significantly, and latency of pain withdrawal and motor nerve conduction velocity rose in diabetic rats compared with the normal control group. SalA increased peripheral blood perfusion and vascular activities; improved peripheral nerve function; and decreased AGEs levels, vascular eNOS expression, and blood glucose, lipid, vWF and malondialdehyde levels in diabetic rats. The beneficial effects of SalA on plantar microcirculation and peripheral nerve function in diabetic rats might be attributed to improvements in lipid and glucose metabolism in diabetic rats, the inhibition of AGEs formation and the development of oxidative stress-related nervous and vascular damage. Based on these findings, we proposed that therapeutic use of SalA to prevent the development of diabetic foot problems.

Salvianolic Acid A Protects Against Diabetic Nephropathy through Ameliorating Glomerular Endothelial Dysfunction via Inhibiting AGE-RAGE Signaling

Background/Aims: Glomerular endothelium dysfunction leads to the progression of renal architectonic and functional abnormalities in early-stage diabetic nephropathy (DN). Advanced glycation end products (AGEs) and receptor for AGEs (RAGE) are proved to play important roles in diabetic nephropathy. This study investigated the role of Salvianolic acid A (SalA) on early-stage DN and its possible underlying mechanism. Methods: In vitro AGEs formation and breaking rate were measured to illustrate the effect of SalA on AGEs. Type 2 diabetic nephropathy rats were induced by high-fat diet and low-dose streptozocin (STZ). After eight-week treatment with SalA 1 mg/kg/day, 24h-urine protein, creatinine clearance was tested and renal structural injury was assessed by PAS and PASM staining. Primary glomerular endothelial cell permeability was evaluated after exposed to AGEs. AGEs-induced RhoA/ROCK and subsequently activated disarrange of cytoskeleton were assessed by western blot and immunofluorescence. Results: Biochemical assay and histological examination demonstrated that SalA markedly reduced endothelium loss and glomerular hyperfiltration, suppressed glomerular hypertrophy and mesangial matrix expansion, eventually reduced urinary albumin and ameliorated renal function. Further investigation suggested that SalA exerted its renoprotective effects through inhibiting AGE-RAGE signaling. It not only inhibited formation of AGEs and increased its breaking in vitro, but also reduced AGEs accumulation in vivo and downregulated RAGE expression. SalA restored glomerular endothelial permeability through suppressing AGEs-induced rearrangement of actin cytoskeleton via AGE-RAGE-RhoA/ ROCK pathway. Moreover, SalA attenuated oxidative stress induced by AGEs, subsequently alleviated inflammation and restored the disturbed autophagy in glomerular endothelial cell and diabetic rats via AGE-RAGE-Nox4 axis. Conclusion: Our study indicated that SalA restored glomerular endothelial function and alleviated renal structural deterioration through inhibiting AGE-RAGE, thus effectively ameliorated early-stage diabetic nephropathy. SalA might be a promising therapeutic agent for the treatment of diabetic nephropathy.

Unusual cadinane-type sesquiterpene glycosides with α-glucosidase inhibitory activities from the fruit of Cornus officinalis Sieb. et Zuuc

Five novel and rare cadinane-type sesquiterpene glycosides, cornucadinoside A-E (1-5) were isolated from water extract of the fruit of Cornus officinalis Sieb. et Zuuc.. The new chemical structures, together with their absolute configurations, were elucidated on the basis of extensive spectroscopic analysis, including a comparison of their experimental and calculated electronic circular dichroism (ECD) spectra. Their structures, which possess a naphthalene skeleton, are the first report on the occurrence of cadinane sesquiterpene glycosides in Cornus. Additionally, all the compounds exhibited marked α-glucosidase inhibitory activity except for 3in vitro.

Puerarin Mitigates Diabetic Hepatic Steatosis and Fibrosis by Inhibiting TGF-β Signaling Pathway Activation in Type 2 Diabetic Rats

Lipid metabolism disorder and inflammation are essential promoters in pathogenesis of liver injury in type 2 diabetes. Puerarin (PUR) has been reported to exert beneficial effects on many diabetic cardiovascular diseases and chemical-induced liver injuries, but its effects on diabetic liver injury and its mechanism are still unclear. The current study was designed to explore the therapeutic effect and mechanism of PUR on liver injury in a type 2 diabetic rat model induced by a high-fat diet combined with low-dose streptozotocin. The diabetic rats were treated with or without PUR (100 mg/kg/day) by gavaging for 8 weeks, and biochemical and histological changes in liver were examined. Results showed that treatment with PUR significantly attenuated hepatic steatosis by regulating blood glucose and ameliorating lipid metabolism disorder. Liver fibrosis was relieved by PUR treatment. PUR inhibited oxidative stress and inflammation which was associated with inactivation of NF-κB signaling, thereby blocking the upregulation of proinflammatory cytokines (IL-1β, TNF-α) and chemokine (MCP-1). This protection of PUR on diabetic liver injury is possibly related with inhibition on TGF-β/Smad signaling. In conclusion, the present study provides evidence that PUR attenuated type 2 diabetic liver injury by inhibiting NF-κB-driven liver inflammation and the TGF-β/Smad signaling pathway.