Effects of KIOM-79 on hyperglycemia and diabetic nephropathy in type 2 diabetic Goto-Kakizaki rats

Associations between local acidosis induced by renal LDHA and renal fibrosis and mitochondrial abnormalities in patients with diabetic kidney disease

During the progression of diabetic kidney disease (DKD), renal lactate metabolism is rewired. The relationship between alterations in renal lactate metabolism and renal fibrosis in patients with diabetes has only been partially established due to a lack of biopsy tissues from patients with DKD and the intricate mechanism of lactate homeostasis. The role of lactate dehydrogenase A (LDHA)-mediated lactate generation in renal fibrosis and dysfunction in human and animal models of DKD was explored in this study. Measures of lactate metabolism (urinary lactate levels and LDHA expression) and measures of DKD progression (estimated glomerular filtration rate and Wilms' tumor-1 expression) were strongly negatively correlated in patients with DKD. Experiments with streptozotocin-induced DKD rat models and the rat renal mesangial cell model confirmed our findings. We found that the pathogenesis of DKD is linked to hypoxia-mediated lactic acidosis, which leads to fibrosis and mitochondrial abnormalities. The pathogenic characteristics of DKD were significantly reduced when aerobic glycolysis or LDHA expression was inhibited. Further studies will aim to investigate whether local acidosis caused by renal LDHA might be exploited as a therapeutic target in patients with DKD.

Effectiveness of Magnolol, a Lignan from Magnolia Bark, in Diabetes, Its Complications and Comorbidities-A Review

Diabetes mellitus is a chronic metabolic disease characterized by disturbances in carbohydrate, protein, and lipid metabolism, often accompanied by oxidative stress. Diabetes treatment is a complicated process in which, in addition to the standard pharmacological action, it is necessary to append a comprehensive approach. Introducing the aspect of non-pharmacological treatment of diabetes allows one to alleviate its many adverse complications. Therefore, it seems important to look for substances that, when included in the daily diet, can improve diabetic parameters. Magnolol, a polyphenolic compound found in magnolia bark, is known for its health-promoting activities and multidirectional beneficial effects on the body. Accordingly, the goal of this review is to systematize the available scientific literature on its beneficial effects on type 2 diabetes and its complications. Taking the above into consideration, the article collects data on the favorable effects of magnolol on parameters related to glycemia, lipid metabolism, or oxidative stress in the course of diabetes. After careful analysis of many scientific articles, it can be concluded that this lignan is a promising agent supporting the conventional therapies with antidiabetic drugs in order to manage diabetes and diabetes-related diseases.

Animal Models of Diabetes-Associated Renal Injury

Diabetic nephropathy (DN) is the main factor leading to end-stage renal disease (ESRD) and subsequent morbidity and mortality. Importantly, the prevalence of DN is continuously increasing in developed countries. Many rodent models of type 1 and type 2 diabetes have been established to elucidate the pathogenesis of diabetes and examine novel therapies against DN. These models are developed by chemical, surgical, genetic, drug, and diet/nutrition interventions or combination of two or more methods. The main characteristics of DN including a decrease in renal function, albuminuria and mesangiolysis, mesangial expansion, and nodular glomerulosclerosis should be exhibited by an animal model of DN. However, a rodent model possessing all of the abovementioned features of human DN has not yet been developed. Furthermore, mice of different genetic backgrounds and strains show different levels of susceptibility to DN with respect to albuminuria and development of glomerular and tubulointerstitial lesions. Therefore, the type of diabetes, development of nephropathy, duration of the study, cost of maintaining and breeding, and animals' mortality rate are important factors that might be affected by the type of DN model. In this review, we discuss the pros and cons of different rodent models of diabetes that are being used to study DN.

Lupinus mutabilis Extract Exerts an Anti-Diabetic Effect by Improving Insulin Release in Type 2 Diabetic Goto-Kakizaki Rats

Lupinus mutabilis (LM) is a legume part of Bolivian traditional diet that has a nutraceutical property reducing blood glucose levels. The prevalence of type 2 diabetes is increasing worldwide thus; the search for novel anti-diabetic drugs is needed. Based on its traditional use, we evaluated the anti-diabetic effect of LM in the spontaneously diabetic Goto-Kakizaki (GK) rat, a model of type 2 diabetes and in Wistar (W) rats as healthy control. LM seeds hydroethanolic extract, analyzed by gas chromatography-mass spectrometry and high-performance liquid chromatography-high resolution mass spectrometry, is a complex mixture of volatile and non-volatile components. A single oral administration of LM extract (2000 mg/kg b.w.) improved glucose tolerance during the oral glucose tolerance test (OGTT) (30–120 min) in GK and W rats (p < 0.0001). The long-term treatment with LM (1000 mg/kg b.w.), for 21 days, improved the area under the curve (AUC) of glucose during OGTT at day 20, in both GK (p < 0.01) and W rats (p < 0.01). The HbA1c (GK rats, p < 0.05 and W rats, p < 0.0001) and the non-fasting glucose (GK rats, p < 0.05) were also reduced. LM increased both serum insulin levels (2.4-fold in GK rats and 2.5-fold W rats), and the glucose-induced (16.7 mM glucose) insulin release in isolated islets from treated animals (6.7-fold in GK rats, and 6.6-fold in W rats). Moreover, LM (10 mg/mL) stimulated in vitro glucose induced (16.7 mM glucose) insulin release in batch incubated GK and W rat islets (p < 0.0001). In perifused GK rat islets, insulin release in 16.7 mM glucose was increased 95.3-fold compared to untreated islets (p < 0.0001), while no significant differences were found in perifused W rat islets. The LM mechanism of action, evaluated using inhibitory compounds of the insulin secretion pathway, showed that LM-dependent insulin secretion was reduced 42% by diazoxide (p < 0.001), 70% by nifedipine (p < 0.001), 86.7% by H89 (p < 0.0001), 70.8% by calphostine-C (p < 0.0001) and 93% by pertussis toxin (p < 0.0001). A similar effect was observed in W rats islets. Our findings provide evidence that LM has an anti-diabetic effect through stimulation of insulin release. The effect is-dependent on L-type calcium channel, protein kinase A and C systems, and G protein-coupled exocytosis and is partially mediated by K-ATP channels.

Amaranthus caudatus Stimulates Insulin Secretion in Goto-Kakizaki Rats, a Model of Diabetes Mellitus Type 2

Diabetes Mellitus Type 2 prevalence is increasing worldwide; thus efforts to develop novel therapeutic strategies are required. Amaranthus caudatus (AC) is a pseudo-cereal with reported anti-diabetic effects that is usually consumed in food preparations in Bolivia. This study evaluated the anti-diabetic nutraceutical property of an AC hydroethanolic extract that contains mainly sugars and traces of polyphenols and amino acids (as shown by nalysis with liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR)), in type 2 diabetic Goto-Kakizaki (GK) rats and healthy Wistar (W) rats. A single oral administration of AC extract (2000 mg/kg body weight) improved glucose tolerance during Oral Glucose Tolerance Tests (OGTT) in both GK rats and in W rats. Long-term treatment (21 days) with AC (1000 mg/kg b.w.) improved the glucose tolerance evaluated by the area under the curve (AUC) of glucose levels during the OGTT, in both GK and W rats. The HbA1c levels were reduced in both GK (19.83%) and W rats (10.7%). This effect was secondary to an increase in serum insulin levels in both GK and W rats and confirmed in pancreatic islets, isolated from treated animals, where the chronic AC exposure increased the insulin production 4.1-fold in GK and 3.7-fold in W rat islets. Furthermore, the effect of AC on in vitro glucose-dependent insulin secretion (16.7 mM glucose) was concentration-dependent up to 50 mg/mL, with 8.5-fold increase in GK and 5.7-fold in W rat islets, and the insulin secretion in perifused GK and W rat islets increased 31 and nine times, respectively. The mechanism of action of AC on insulin secretion was shown to involve calcium, PKA and PKC activation, and G-protein coupled-exocytosis since the AC effect was reduced 38% by nifedipine (L-type channel inhibitor), 77% by H89 (PKA inhibitor), 79% by Calphostine-C (PKC inhibitor) and 20% by pertussis toxin (G-protein suppressor).

Metformin ameliorates diabetic nephropathy in a rat model of low-dose streptozotocin-induced diabetes

The present study aimed to explore the renoprotective effect of metformin on diabetic nephropathy in type 2 diabetic rats. A rat model of type 2 diabetic nephropathy (T2DN) was successfully induced via a high-fat diet combined with a single low-dose of streptozotocin. Metformin was administered intragastrically for 13 weeks, and fasting blood glucose (FBG), total cholesterol (TC), triglycerides (TG), HDL-c, LDL-c, urinary and serum creatinine levels were subsequently examined at the end of administration. Renal function was determined after the treatment protocol. Expression levels of transforming growth factor (TGF)-β1 and connective tissue growth factor (CTGF) were assessed via immunohistochemical analysis. Superoxide dismutase activity, malondialdehyde content and glutathione peroxidase levels were assessed in kidney tissues using commercially available kits. The results of the present study demonstrated that metformin administration significantly decreased the levels of serum blood urea nitrogen, serum creatinine, creatinine clearance, urinary albumin excretion and fasting blood glucose in rats with T2DN. Furthermore, TG, TC and LDL-c levels were significantly decreased following metformin treatment, whereas HDL-c was increased. Metformin treatment significantly increased SOD activity and significantly decreased malondialdehyde levels, as compared with the model group. It was also demonstrated that metformin administration significantly decreased the expression levels of TGF-β1 and attenuated the morphological changes associated with T2DN in rats. These data clearly demonstrated the renoprotective effects of metformin against the development and progression of T2DN in rats. The underlying mechanism of this protective effect may be associated with glycemic control, lipid metabolism, and anti-oxidative and anti-inflammatory functions.

Effects of fucoidan on insulin stimulation and pancreatic protection via the cAMP signaling pathway in vivo and in vitro

Diabetes is a global disease, in which pancreatic dysfunction is an important pathological process. In previous years, interest in the biological activities of seaweed has increased. Fucoidan is an extract of the seaweed Fucus vesiculosus, which has been widely investigated. The present study aimed to determine the effects of fucoidan on insulin stimulation and pancreatic protection in vivo and in vitro. Goto‑Kakizaki (GK) rats were provided with free access to standard food, with or without fucoidan, for 13 weeks, following which the body weights, and blood glucose and serum insulin levels of the rats were measured. Wistar rats were used as a control. In addition, the RIN‑5F rat insulin‑secreting cell line was treated with fucoidan in high glucose conditions, following which the dose‑dependent and time‑dependent effects of fucoidan were determined, and the concentration of insulin was measured. Glybenclamide was used as a positive control. In vivo, the body weight and serum insulin levels decreased, whereas blood glucose levels increased significantly in the GK rats, compared with the Wistar control rats. Although, fucoidan did not improve changes in body weight, the increased blood glucose levels were reduced and the decreased serum insulin levels were increased in the GK rats following oral administration of fucoidan. In vitro, fucoidan did not exhibit significant cytotoxicity towards the RIN‑5F cells, and the insulin secretion increased significantly in a dose‑ and time‑dependent manner. Treatment with amylin, an islet amyloid polypeptide and glybenclamide inhibitor, did not inhibit the stimulatory activity of fucoidan. The results of the present study also demonstrated that the concentration of cyclic adenosine monophosphate (cAMP) was significantly increased in the fucoidan‑treated RIN‑5F cells, and this increase was dose‑ and time‑dependent. In addition, treatment with a phosphodiesterase inhibitor, which decreases the degradation of cAMP, significantly increased fucoidan‑induced insulin secretion, whereas treatment with an adenylyl cyclase inhibitor, which decreases the generation of cAMP, significantly decreased fucoidan‑induced insulin secretion. In conclusion, these data indicated that fucoidan may stimulate insulin secretion and provide pancreatic protection via the cAMP signaling pathway, in vivo and in vitro.

Fucoidan exerts protective effects against diabetic nephropathy related to spontaneous diabetes through the NF-κB signaling pathway in vivo and in vitro

Fucoidan, an extract of the seaweed, Fucus vesiculosus, has been widely investigated for its antioxidant effects. However, to date and to the best of our knowledge, pathological studies on the effects of fucoidan against diabetic nephropathy (DN) related to spontaneous diabetes have not been carried out. DN is one of the most serious microvascular complications of diabetes. Therefore, in the present study, the effects of fucoidan against DN related to spontaneous diabetes were investigated in vitro and in vivo. Goto-Kakizaki (GK) rats were allowed free access to standard rat food with or without fucoidan for 13 weeks, and Wistar rats were used as controls. Fucoidan did not show any cytotoxicity on glomerular mesangial cells (GMCs) which were separated from rat kidneys. Fasting blood glucose levels were measured using a blood glucose meter, blood urea nitrogen (BUN) and serum creatinine (Cr) levels were measured using an automatic biochemistry analyzer and urine protein levels were measured using an ELISA kit. Collagen Ⅳ levels in the renal cortex were measured using an ELISA kit, and the expression levels of transforming growth factor-β1 (TGF-β1) and fibronectin (FN) in the renal cortex and GMCs, and nuclear factor-κB (NF-κB) in GMCs were determined by western blot analysis. Fasting blood glucose, BUN, serum Cr, urine protein and collagen Ⅳ levels, and the expression of TGF-β1 and FN, as well as NF-κB p65 nuclear translocation all significantly increased in the GK rats compared with the control Wistar rats. The increase in the fasting blood glucose, BUN, serum Cr, urine protein and collagen Ⅳ levels in the renal cortex was reversed in the GK rats which were orally administered fucoidan. The oral administration of fucoidan also decreased the expression of TGF-β1 and FN in the renal cortex and GMCs, as well as the nuclear translocation of NF-κB p65 in the GMCs. Taken together, the data from our in vitro and in vivo experiments indicate that fucoidan attenuates hyperglycemia and prevents or impedes the development of DN related to spontaneous diabetes by attenuating the activation of the NF-κB signaling pathway.

Root of Polygonum cuspidatum extract reduces progression of diabetes-induced mesangial cell dysfunction via inhibition of platelet-derived growth factor-BB (PDGF-BB) and interaction with its receptor in streptozotocin-induced diabetic rats

Background

Platelet-derived growth factor–BB (PDGF-BB) is highly expressed in the renal tissues of patients with diabetic nephropathy, and it plays an important role in the initiation and progression of diabetic nephropathy. The aim of this study was to evaluate the protective effects of root of Polygonum cuspidatum extract (PCE) on early renal glomerular proliferation in streptozotocin (STZ)-induced diabetic rats.

Methods

PCE (100, 350 mg/kg/day) was administered to diabetic rats for 16 weeks. Blood glucose and albuminuria were measured. Renal histology, α-smooth muscle actin (α-SMA), and proliferating cell nuclear antigen (PCNA) expression levels were also examined.

Results

After 16 weeks of treatment with PCE, severe hyperglycemia and albuminuria were observed in the diabetic rats. The expressions levels of α-SMA and PCNA proteins were significantly increased in the glomeruli of the diabetic rats. The expression levels of PDGF-BB and its receptor expressions were greatly increased in the glomeruli of the diabetic rats. However, PCE markedly reduced albuminuria in the diabetic rats. PCE inhibited α-SMA and PCNA up-regulation and ameliorated PDGF-BB and PEGFR-ß protein expression in the diabetic rats. In addition, the binding of PDGF-BB/PDGFR-ß was inhibited by PCE as shown by an in vitro assay.

Conclusions

These results suggest that PCE has an inhibitory effect on mesangial proliferation in diabetic renal tissues via the inhibition of the interaction of PDGF-BB with its receptor. PCE may have beneficial effects in preventing the progression of diabetic nephropathy.

Electronic supplementary material

The online version of this article (doi:10.1186/1472-6882-14-477) contains supplementary material, which is available to authorized users.

Extract of Cassiae semen attenuates diabetic nephropathy via inhibition of advanced glycation end products accumulation in streptozotocin-induced diabetic rats

Chronic hyperglycemia leads to the formation of advanced glycation end products (AGEs), which accelerates the development of diabetic complications. Previous studies have shown that extract of Cassiae semen (CS), the seed of Cassia tora, has inhibitory activity on AGEs formation in vitro and reduces transforming growth factor-beta1 (TGF-β1) and extracellular matrix protein expression via inhibition of AGEs-mediated signaling in glomerular mesangial cells. In this study, to examine the preventive effects of CS extract on the development of diabetic nephropathy in vivo, streptozotocin (STZ)-injected diabetic rats were orally administered CS extract (200 mg/kg body weight/day) for 12 weeks. Serum glucose, triglycerides, and total cholesterol in diabetic rats were significantly higher compared to control rats. CS or aminoguanidine (AG) treatment significantly reduced these factors. Proteinuria and creatinine clearance were also significantly decreased in the CS-treated group compared with the untreated diabetic group. The CS-treated group had significantly inhibited COX-2 mRNA and protein, which mediates the symptoms of inflammation in the renal cortex of diabetic rats. Furthermore, histopathological studies of kidney tissue showed that in diabetic rats, AGEs, the receptor for AGEs, TGF-β1, and collagen IV were suppressed by CS treatment. Our data suggest that oral treatment of CS can inhibit the development of diabetic nephropathy via inhibition of AGEs accumulation in STZ-induced diabetic rats.

Effect of KIOM-79 on Diabetes-Induced Myocardial Fibrosis in Zucker Diabetic Fatty Rats

KIOM-79, a herbal mixture of parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix, and Euphorbiae radix, has a strong inhibitory effect on advanced glycation end products (AGEs) formation. We investigated the beneficial effects of KIOM-79 on cardiac fibrosis in Zucker diabetic fatty (ZDF) rats. KIOM-79 (50 or 500 mg/kg/day) was orally administered for 13 weeks. AGEs formation and collagen expression in the myocardium were assessed by immunohistochemistry. The expression levels of the receptor for AGEs (RAGE), transforming growth factor- β 1 (TGF- β 1), collagen IV, fibronectin, urotensin II, and urotensin II receptor were examined in the myocardial tissue of ZDF rats. KIOM-79 treatment at 500 mg/kg inhibited the accumulation of AGEs, reduced RAGE mRNA and protein expression, and reduced the upregulation of cardiac fibrogenic factors, such as fibronectin and collagen IV, in heart of ZDF rats. Additionally, KIOM-79 ameliorated urotensin II/receptor gene expression in the cardiac tissue of ZDF rats. Our findings indicate that KIOM-79 diminishes cardiac fibrosis in ZDF rats by preventing AGEs accumulation and RAGE overexpression and by modulating the cardiac urotensin II/receptor pathway, which decreases the amount of profibrotic factors, such as TGF- β 1, fibronectin, and collagen in cardiac tissue.

Smoking in diabetic nephropathy: sparks in the fuel tank?

Diabetic nephropathy is associated with high morbidity and mortality and the prevalence of this disease is continuously increasing worldwide. Long-term diabetes increases the likelihood of developing secondary complications like nephropathy, the most common cause of end stage renal disease. Usually, other factors like hypertension, alcoholism and smoking also partly contribute to the progression of diabetic nephropathy. Among this, cigarette smoking in diabetes has been repeatedly confirmed as an independent risk factor for the onset and progression of diabetic nephropathy. Various studies suggest that smoking is a major fuel in the development of high oxidative stress and subsequently hyperlipidemia, accumulation of advanced glycation end products, activation of the renin angiotensin system and Rho-kinase, which are observed to play a pathogenic role in the progression of diabetic nephropathy. Furthermore, cigarette smoking in diabetic patients with vascular complications produces a variety of pathological changes in the kidney, such as thickening of the glomerular basement membrane and mesangial expansion with progression in glomerulosclerosis and interstitial fibrosis, which ultimately results in end stage renal failure. Strong associations are consistently found between chronic cigarette smoking and diabetic microvascular complications. A diverse group of studies unveil potential mechanisms that may explain the role of cigarette smoking in the progression of diabetic nephropathy. Tremendous efforts are being made to control smoking mediated progression of diabetic nephropathy, but no promising therapy is yet available. The present review critically discusses the possible detrimental role of chronic cigarette smoking in the progression of diabetic nephropathy and various possible pharmacological interventions to attenuate the exacerbation of diabetic nephropathy.

An aqueous extract of Portulaca oleracea ameliorates diabetic nephropathy through suppression of renal fibrosis and inflammation in diabetic db/db mice

Diabetic nephropathy is one of the most common microvascular complications of diabetes and the leading cause of end-stage renal disease. In the present study, we investigated the renoprotective effect of the aqueous extract of Portulaca oleracea (AP) on diabetic nephropathy accelerated by renal fibrosis and inflammation in type 2 diabetic db/db mice. The mice were treated with AP (300 mg/kg/day, p.o.) for ten weeks to examine the long-term effects on diabetic nephropathy and renal dysfunction. We found that AP treatment markedly lowered blood glucose to 412 ± 11.4 mg/dl and plasma creatinine level to 2.3 ± 0.8 mg/dl compared to db/db mice (p < 0.05, p < 0.01, respectively). This study also showed that treatment with AP significantly decreased water intake and urine volume in diabetic db/db mice (p < 0.05). In immunohistological study, the renal expression of transforming growth factor-β1 (TGF-β1), advanced glycation end products (AGE), and intercellular adhesion molecule (ICAM)-1 markedly increased in the renal cortex of untreated db/db mice (p < 0.01). In contrast, AP treatment significantly reduced these expressions to 50 ± 2.1%, 48 ± 2.8%, 61 ± 1.1%, respectively (p < 0.01). Furthermore, NF-κB p65 activation in renal tissues markedly increased in untreated db/db mice, which was significantly suppressed by AP treatment. Taken together, these findings suggest that AP attenuates diabetic nephropathy through inhibition of renal fibrosis and inflammation in db/db mice.

KIOM-79 protects AGE-induced retinal pericyte apoptosis via inhibition of NF-kappaB activation in vitro and in vivo

KIOM-79 is an herbal mixture of parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix and Euphorbiae radix. In the present study, we determined the efficacy and possible mechanism of KIOM-79 on the advanced glycation end product (AGE)-modified bovine serum albumin (BSA)-induced apoptosis of cultured bovine retinal pericytes and rat retinal pericytes in Zucker diabetic fatty (ZDF) rats. Seven-week-old male ZDF rats were treated with KIOM-79 (50 mg/kg body weight) once a day orally for 13 weeks. KIOM-79 significantly inhibited pericyte apoptosis which were induced by the AGE-BSA treatment. The KIOM-79 treatment markedly suppressed the activation of nuclear factor-kappaB (NF-κB) through the inhibition of inhibitory κB kinase complex. In addition, the oral administration of KIOM-79 inhibited the changes in retinal vasculature (vascular hyperpermeability, acellular capillary). KIOM-79 strongly inhibited pericyte apoptosis, NF-κB activation and the expression of pro-apoptotic Bax and tumor necrosis factor-α. Our results suggest that KIOM-79 may exert inhibitory effects on AGE-induced pericyte apoptosis by blocking NF-κB activation, thereby ameliorating retinal microvascular dysfunction.

Chinese medicine for treating diabetic nephropathy

Diabetic nephropathy is one of the main causes of renal end-stage disease. The pathogenesis of diabetic nephropathy is complex. The current treatment is only for a particular cause without multi-target therapeutic drugs. Chinese medicine is a great treasure with multi-component complex drugs interacting with multiple targets and functions. This paper reviewed the protective effect of Chinese medicine for treating diabetic nephropathy in clinical studies, in vivo studies, and in vitro studies. The possible mechanisms, the major compounds and active crude drugs were also summarized. It was shown that Chinese medicine could not only relieve several symptoms and improve the quality of life, but also reduce the levels of proteinuria and kidney damage, and further improve renal function via multiple pathways based on the whole human system. Moreover, there were no reports of severe adverse reactions during the treatment.

KIOM-79 inhibits aldose reductase activity and cataractogenesis in Zucker diabetic fatty rats

Objectives

KIOM-79, a combination of four plant extracts, has a preventive effect on diabetic nephropathy and retinopathy in diabetic animal models. In this study, we have investigated the inhibitory effects of KIOM-79 on diabetic cataractogenesis.

Methods

We evaluated aldose reductase activity during cataractogenesis using Zucker diabetic fatty (ZDF) rat, an animal model of type 2 diabetes. ZDF rats were treated orally with KIOM-79 (50 mg/kg body weight) once a day for 13 weeks.

Key findings

In vehicle-treated ZDF rats, lens opacity was increased, and lens fibre swelling and membrane rupture were observed. In addition, aldose reductase activity and aldose reductase protein expression in diabetic lens were markedly enhanced. However, the administration of KIOM-79 inhibited the development of diabetic cataract through the inhibition of aldose reductase activity and protein expression in diabetic lenses.

Conclusions

These observations suggested that KIOM-79 was useful against the treatment of diabetic cataractogenesis.

Whole grain consumption has a modest effect on the development of diabetes in the Goto-Kakisaki rat

Epidemiological evidence suggests that whole grain intake is associated with reduced risk of type 2 diabetes. However, studies of individual whole grains on the prevention of type 2 diabetes are lacking. The objective of the present study was to examine the effect of different whole grains on type 2 diabetes in an animal model of type 2 diabetes, the Goto-Kakisaki (GK) rat. GK rats were fed either a basal diet or a whole grain-containing diet for 5 months. Whole grain diets contained 65 % whole grain flours of wheat, barley, oats or maize. After 2 months of feeding, fasting plasma glucose concentrations were lower in the wheat, barley and oats groups, compared with the basal group, whereas glycated Hb was significantly greater in the wheat group compared with other groups. Feeding of whole barley and maize increased plasma C-peptide concentrations compared with whole wheat at 2 months. There was a trend in the improvement of insulin resistance with a consumption of barley and oats diets at 2 months (P = 0·06) compared with the basal diet. Oxidative stress markers, urinary thiobarbituric acid-reactive substances and 8-isoprostane, did not improve with whole grain intake at 2 months. At 5 months, whole grain diets did not differ from the basal diet in glycaemic control, insulin secretion, oxidative stress and preservation of pancreatic β-cell mass. These results suggest that the consumption of whole grains may offer modest benefit early in the development of type 2 diabetes, but this benefit is lost with further development of the disease.

KIOM-79, an Inhibitor of AGEs-Protein Cross-linking, Prevents Progression of Nephropathy in Zucker Diabetic Fatty Rats

Advanced glycation end products (AGEs) have been implicated in the development of diabetic complications, including diabetic nephropathy. KIOM-79, an 80% ethanolic extract obtained from parched Puerariae Radix, gingered Magnolia Cortex, Glycyrrhiza Radix and Euphorbia Radix, was investigated for its effects on the development of renal disease in Zucker diabetic fatty rats, an animal model of type 2 diabetes. In vitro inhibitory effect of KIOM-79 on AGEs cross-linking was examined by enzyme-linked immunosorbent assay (ELISA). KIOM-79 (50 mg/kg/day) was given to Zucker diabetic fatty rats for 13 weeks. Body and kidney weight, blood glucose, glycated hemoglobin, urinary albumin and creatinine excretions were monitored. Kidney histopathology, collagen accumulation, fibrinogen and transforming growth factor-beta 1 (TGF-β1) expression were also examined. KIOM-79 reduced blood glucose, kidney weight, histologic renal damage and albuminuria in Zucker diabetic fatty rats. KIOM-79 prevented glomerulosclerosis, tubular degeneration, collagen deposition and podocyte apoptosis. In the renal cortex, TGF-β1, fibronectin mRNA and protein were significantly reduced by KIOM-79 treatment. KIOM-79 reduces AGEs accumulation in vivo, AGE-protein cross-linking and protein oxidation. KIOM-79 could be beneficial in preventing the progression of diabetic glomerularsclerosis in type 2 diabetic rats by attenuating AGEs deposition in the glomeruli.

Protection against advanced glycation end products and oxidative stress during the development of diabetic keratopathy by KIOM-79

OBJECTIVES

KIOM-79 is a mixture of 80% ethanol extracts of parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix and Euphorbiae radix. The preventive effect of KIOM-79 on the development of diabetic keratopathy has been investigated.

METHODS

Seven-week-old male Zucker diabetic fatty (ZDF) rats were treated with KIOM-79 (50 mg/kg body weight) once a day orally for 13 weeks. The thickness of the cornea was measured and the extent of corneal cell death was detected by a terminal deoxynucleotidyl transferase dUTP nick-end labelling assay. The expression of advanced glycation end products (AGEs), 8-hydroxydeoxyguanosine, nuclear factor-kappaB (NF-κB), Bax and Bcl-2 were evaluated in corneal tissues.

KEY FINDINGS

The administration of KIOM-79 prevented corneal oedema and apoptotic cell death of corneal cells. The accumulation of AGE in corneal tissues was reduced in ZDF rats treated with KIOM-79. Moreover, KIOM-79 attenuated oxidative DNA damage, NF-κB activation and Bax overexpression in the cornea.

CONCLUSIONS

The results suggested that KIOM-79 exhibited corneal protective properties by not only reducing oxidative stress but inhibiting the AGEs/NF-κB downstream signal pathway during the development of diabetic keratopathy.

Combination of Medicinal Herbs KIOM-79 Reduces Advanced Glycation End Product Accumulation and the Expression of Inflammatory Factors in the Aorta of Zucker Diabetic Fatty Rats

Previous studies have reported that KIOM-79 shows a strong inhibitory effect on AGE formation and inhibited a proinflammatory state in a murine macrophage cell line. In the present study, we investigated the effect of KIOM-79 on AGE accumulation and vascular inflammation in the aorta of Zucker diabetic fatty (ZDF) rats, a commonly used model of type 2 diabetes. Seven-week-old male ZDF rats were treated with KIOM-79 (50 mg/kg) once a day orally for 13 weeks. We examined the dissected aortas for AGE accumulation, expression of the receptor for AGEs (RAGE), and the expression of proinflammatory factors, including monocyte chemoattractant protein-1 (MCP-1), vascular endothelial growth factor (VEGF), and vascular adhesion molecule-1 (VCAM-1). Nuclear factor-kappaB (NF-κB) and inducible nitric oxide synthase (iNOS) were also measured by Southwestern histochemistry, electrophoretic mobility shift assay (EMSA), and immunohistochemistry, respectively. KIOM-79 markedly reduced the accumulation of AGEs and the expression of RAGE in the aorta. We also found that KIOM-79 attenuated the expression of inflammatory factors including NF-κB, MCP-1, VEGF, VCAM-1, and iNOS in the aortas of ZDF rats. These data suggest that KIOM-79 may prevent or retard the development of inflammation in diabetic vascular disease.

Effects of heat-processed ginseng and its active component ginsenoside 20(S)-Rg3 on the progression of renal damage and dysfunction in type 2 diabetic Otsuka Long-Evans Tokushima Fatty rats

The effects of heat-processed ginseng (HPG) and ginsenoside 20(S)-Rg(3) on the progression of renal damage in type 2 diabetic rats were investigated. Twenty-two-week-old male Otsuka Long-Evans Tokushima Fatty (OLETF) rats were divided into 4 orally administered groups: vehicle (diabetic control), HPG water extract (100 mg/kg) and 20(S)-Rg(3) (5, 10 mg/kg). Non-diabetic Long-Evans Tokushima Otsuka (LETO) rats were used as a normal group. OLETF rats showed markedly higher blood glucose, triglyceride, and total cholesterol levels than those of LETO rats. The elevated blood glucose level of OLETF rats was significantly lowered by 20(S)-Rg(3) administration. The elevated serum triglyceride and total cholesterol levels were significantly reduced by the administrations of HPG and 20(S)-Rg(3). The serum levels of thiobarbituric acid-reactive substance, an index of lipid peroxidation, were markedly increased in OLETF compared to LETO rats, but it was significantly reduced by HPG and 20(S)-Rg(3) administrations. The urinary protein level, an indicator of advanced diabetic nephropathy, of OLETF rats was 4.4 times higher than in LETO rats, but it was reduced significantly by the administrations of HPG and 20(S)-Rg(3). Creatinine clearance of OLETF rats was significantly increased after HPG and 20(S)-Rg(3) administrations. The elevation of inducible nitric oxide synthase and N(epsilon)-(carboxymethyl)lysine protein expressions in renal tissues of OLETF rats was prevented by 20(S)-Rg(3) administration. This study provides scientific evidence that 20(S)-Rg(3) prevents the progression of renal damage and dysfunction in type 2 diabetic rats via inhibiting oxidative stress and advanced glycation endproduct formation.

KIOM-79 Prevents Lens Epithelial Cell Apoptosis and Lens Opacification in Zucker Diabetic Fatty Rats

Damage of lens epithelial cells (LECs) has been implicated in cataract formation. The aim of this study was to investigate the protective effect of KIOM-79, a combination of four plant extracts, on LECs. We examined the levels of advanced glycation end products (AGEs), nuclear factor-kappaB (NF-κB) activation and inducible nitric oxide synthase (iNOS) expression in LECs during cataract development using the Zucker diabetic fatty (ZDF) rat, an animal model of type 2 diabetes. KIOM-79 was orally administered by gavage to ZDF rats once a day for 13 weeks. Apoptosis was detected by TUNEL assay, and NF-κB activation and iNOS expression were studied by southwestern histochemistry and immunohistochemistry, respectively. In diabetic cataractous lenses, TUNEL-positive LECs were markedly increased 20-fold, and AGEs were highly accumulated (2.7-fold) in LECs. In addition, both NF-κB activation, and iNOS expression were significantly enhanced 3- to 5-fold, respectively, compared to levels found in normal ZL rats. However, the administration of KIOM-79 delayed the development of diabetic cataracts and prevented LEC apoptosis (70%) through the inhibition of AGEs, NF-κB-activation and iNOS expression. These observations suggest that KIOM-79 is useful in inhibiting diabetic cataractogenesis and acts through an antiapoptotic mechanism to protect LECs from injury.

KIOM-79 prevents xylose-induced lens opacity and inhibits TGF-beta2 in human lens epithelial cells cultured under high glucose

AIM OF THE STUDY

To investigate the effects of KIOM-79 in preventing the development of diabetic complications, such as cataracts.

MATERIALS AND METHODS

The inhibitory effects of KIOM-79 were assessed in a model of xylose-induced lens opacity and on changes mediated by high levels of glucose in human lens epithelial (HLE-B3) cells.

RESULTS

In lenses treated with KIOM-79, opacity was significantly improved and glutathione (GSH) was increased compared to controls. In HLE-B3 cells treated with KIOM-79, high glucose-mediated increases in TGF-beta2, alphaB-crystallin, and fibronectin were significantly inhibited in a dose-dependent manner. KIOM-79 decreased the phosphorylation of p-Smad2/3, pp38MAPK, pp44/42, and NF-kappaB signaling in cells grown under high glucose conditions.

CONCLUSION

KIOM-79 is protective against lens opacity and protects HLE-B3 cells from the toxic effects of high glucose. Therefore, KIOM-79 may provide a potential therapeutic approach for preventing diabetic complications, such as cataracts.

KIOM-79 prevents methyglyoxal-induced retinal pericyte apoptosis in vitro and in vivo

AIMS OF STUDY

The purpose of this study was to investigate the protective effects of KIOM-79, a combination of four plant extracts, on retinal pericytes loss, which is one of the histopathological hallmarks of early diabetic retinopathy.

MATERIALS AND METHODS

To investigate the protective effect of KIOM-79 on pericyte apoptosis, we have used methylglyoxal (MGO)-treated primary rat retinal pericytes and retinal vessels from intravitreally MGO-injected eyes. Primary rat retinal pericytes were exposed to 400 microM MGO for 6h with or without KIOM-79. 400 microM final intravitreal concentration of MGO with or without KIOM-79 (10 microg/ml final intravitreal concentration) were intravitreally injected into the right eyes of rats for 2 days. The left eyes were received 3mul of saline only. Retinal vessels were then isolated. We examined apoptosis, ROS productions, 8-OHdG in cultured rat retinal pericytes and retinal vessels.

RESULTS

In CCK-8 assay and TUNEL staining, MGO-induced apoptosis of rat retinal pericytes was markedly inhibited by KIOM-79. KIOM-79 significantly reduced intracellular ROS productions and oxidative damage induced by MGO. In addition, the intravitreal injection of KIOM-79 prevented apoptosis of retinal microvascular cells, MGO accumulation and oxidative DNA damage in intravitreally MGO-injected eye.

CONCLUSION

These observations suggest that KIOM-79 acts through an antioxidant mechanism to protect against oxidative stress-induced apoptosis in retinal pericytes.

KIOM-79 prevents S100b-induced TGF-beta1 and fibronectin expression in mouse mesangial cells

AIM OF THE STUDY

In this study, we investigated whether KIOM-79 inhibits transforming growth factor-beta 1 (TGF-beta1) and fibronectin expression in mouse mesangial cells cultured under S100b, a specific ligand of the receptor for advanced glycation end products (RAGE).

MATERIALS AND METHODS

Cell counting kit (CCK-8) assay was employed to evaluate the viability of KIOM-79-treated mesangial cells. The effect of KIOM-79 on S100b-induced TGF-beta1 and fibronectin expression was investigated using RT-PCR, ELISA, and Western blot on mesangial cells.

RESULTS

KIOM-79 (up to 50 microg/ml) appeared to have no effect on cell viability. S100b induced an increase in the expression TGF-beta1 and fibronectin. Expression of TGF-beta1 and fibronectin was inhibited significantly by KIOM-79 treatment in mesangial cells. KIOM-79 also inhibited the expression of NF-kB and inactivated p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) 1/2 in mesangial cells. KIOM-79 pretreatment inhibited increased malondialdehyde (a product of lipid peroxidation and a marker for oxidative stress) levels in S100b-induced mesangial cells.

CONCLUSIONS

These data demonstrate that KIOM-79 inhibits expression of TGF-beta1 and fibronectin through inactivation of MAPK/ERK1/2 signaling, reduction in malondiadehyde levels, and inhibition of NF-kB in mesangial cells cultured under diabetic conditions. KIOM-79 could be beneficial for preventing of the development of diabetic complications such as nephropathy.

Effects of mixed herbal extracts from parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix and Euphorbiae radix (KIOM-79) on cardiac ion channels and action potentials

KIOM-79, a mixture of ethanol extracts from four herbs (parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix and Euphorbiae radix), has been developed for the potential therapeutic application to diabetic symptoms. Because screening of unexpected cardiac arrhythmia is compulsory for the new drug development, we investigated the effects of KIOM-79 on the action potential (AP) and various ion channel currents in cardiac myocytes. KIOM-79 decreased the upstroke velocity (V(max)) and plateau potential while slightly increased the duration of action potential (APD). Consistent with the decreased V(max) and plateau potential, the peak amplitude of Na+ current (I(Na)) and Ca2+ current (I(Ca,L)) were decreased by KIOM-79. KIOM-79 showed dual effects on hERG K+ current; increase of depolarization phase current (I(depol)) and decreased tail current at repolarization phase (I(tail)). The increase of APD was suspected due to the decreased I(tail). In computer simulation, the change of cardiac action potential could be well simulated based on the effects of KIOM-79 on various membrane currents. As a whole, the influence of KIOM-79 on cardiac ion channels are minor at concentrations effective for the diabetic models (0.1-10 microg/mL). The results suggest safety in terms of the risk of cardiac arrhythmia. Also, our study demonstrates the usefulness of the cardiac computer simulation in screening drug-induced long-QT syndrome.

Administration of a substituted adamantyl urea inhibitor of soluble epoxide hydrolase protects the kidney from damage in hypertensive Goto-Kakizaki rats

Hypertension and Type 2 diabetes are co-morbid diseases that lead to the development of nephropathy. sEH (soluble epoxide hydrolase) inhibitors are reported to provide protection from renal injury. We hypothesized that the sEH inhibitor AUDA [12-(3-adamantan-1-yl-ureido)-dodecanoic acid] protects the kidney from the development of nephropathy associated with hypertension and Type 2 diabetes. Hypertension was induced in spontaneously diabetic GK (Goto-Kakizaki) rats using AngII (angiotensin II) and a high-salt diet. Hypertensive GK rats were treated for 2 weeks with either AUDA or its vehicle added to drinking water. MAP (mean arterial pressure) increased from 118+/-2 mmHg to 182+/-20 and 187+/-6 mmHg for vehicle and AUDA-treated hypertensive GK rats respectively. AUDA treatment did not alter blood glucose. Hypertension in GK rats resulted in a 17-fold increase in urinary albumin excretion, which was decreased with AUDA treatment. Renal histological evaluation determined that AUDA treatment decreased glomerular and tubular damage. In addition, AUDA treatment attenuated macrophage infiltration and inhibited urinary excretion of MCP-1 (monocyte chemoattractant protein-1) and kidney cortex MCP-1 gene expression. Taken together, these results provide evidence that sEH inhibition with AUDA attenuates the progression of renal damage associated with hypertension and Type 2 diabetes.

KIOM-79 prevents apoptotic cell death and AGEs accumulation in retinas of diabetic db/db mice

AIM OF THE STUDY

KIOM-79 retards the development of diabetic nephropathy in animal models of type 1 and type 2 diabetes. In this study, we evaluated whether KIOM-79 could prevent apoptotic cell death and advanced glycation end products (AGEs) accumulation in the retinas of diabetic db/db mice.

MATERIAL AND METHODS

Mice were treated orally with KIOM-79 (150 mg/kg body weight) once daily for 12 weeks. Levels of retinal ganglion cell death were measured by terminal dUTP nick-end labeling (TUNEL) assay. In the retina, the activity of caspase-3 (a marker of apoptosis) and the formation of AGEs were measured by immunohistochemical staining.

RESULTS

KIOM-79 reduced the number of TUNEL-immunoreactive retinal cells. KIOM-79 attenuated caspase-3 expression and AGEs accumulation in the retina.

CONCLUSIONS

These data show that KIOM-79 can prevent apoptosis in neuronal cells, AGEs accumulation in the retina, and retard the development of diabetic retinopathy.

Effect of KIOM-79 against mitochondrial damage induced by streptozotocin in pancreatic beta-cells

The present study examined the effects of KIOM-79 on streptozotocin (STZ)-induced mitochondrial oxidative stress in rat pancreatic beta-cells (RINm5F). KIOM-79 is a mixture of plant extracts from parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix, and Euphorbiae radix. A marked increase in mitochondrial reactive oxygen species (ROS) was observed in STZ induced diabetic cells, which returned to control conditions after KIOM-79 treatment. Mitochondrial manganese superoxide dismutase (Mn SOD) activity and its protein expression were downregulated by STZ treatment but upregulated by KIOM-79 treatment. In addition, KIOM-79 treatment restored the loss of the mitochondrial membrane potential (Deltapsi) produced by STZ treatment. KIOM-79 induced an increase in Bcl-2 and a decrease in phospho Bcl-2 and Bax, which are related to permeability of the mitochondrial membrane. Further, KIOM-79 inhibited the translocation of cytochrome c from the mitochondria to the cytosol and elevated the ATP level, which was reduced by STZ treatment. These results suggest that KIOM-79 exhibits a protective effect through activation of antioxidant defense mechanisms and by attenuation of mitochondrial dysfunction in STZ-induced diabetic cells.

Interaction between COX-2 and iNOS aggravates vascular lesion and antagonistic effect of ginsenoside

AIM OF THE STUDY

Ginseng, the root of Panax ginseng C.A.Meyer (Araliaceae), is one of the most widely used Chinese herbs with hypotensive and cardiotonic actions for thousands of years, but the underlying mechanisms have not been well determined. Ginsenoside, the effective components of ginseng, has anti-inflammatory and anti-oxidative effects. Cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) are key enzymes in inflammation and oxidative stress, respectively, which have close interaction, aggravating their damaging effects. This study investigated whether COX-2 interacted with iNOS in vascular endothelial lesion and the protective effect of ginsenoside.

MATERIALS AND METHODS

SD male rats were fed with high l-methionine (3%, w/w) to induce vascular endothelial lesion, and the rats in ginsenoside group were fed ginsenoside solution (0.8 mg kg(-1)d(-1)). The mRNA expression and protein contents of COX-2 and iNOS were detected by RT-PCR and Western blotting, respectively. The interaction between COX-2 and iNOS was analyzed by co-immunoprecipitation and laser confocal microscopy. The content of NT, a specific marker of peroxynitrite, was evaluated by Western blotting. The morphological changes of vascular endothelium were observed.

RESULTS

Compared with control group, the transcription and protein levels of both COX-2 and iNOS increased obviously and their interaction enhanced significantly in model group, in accord with the increased NT content and the pathological alterations of aorta. In ginsenoside group, all these alterations were attenuated significantly (P < 0.01 or P < 0.05).

CONCLUSIONS

It is proved that there exists interaction between COX-2 and iNOS, aggravating endothelial lesion through peroxynitrite and ginsenoside might antagonize their interaction, playing a protective role.

Induction of heme oxygenase-1 by plant extract KIOM-79 via Akt pathway and NF-E2 related factor 2 in pancreatic beta-cells

The objective of the present study was to determine the mechanism by which KIOM-79 induced heme oxygenase-1 (HO-1) in rat pancreatic beta-cells (RINm5F). A mixture of plant extracts (KIOM-79) was obtained from Magnolia officinalis, Pueraria lobata, Glycyrrhiza uralensis, and Euphorbia pekinensis. HO-1, an antioxidant phase 2 enzyme, was previously reported to possess cytoprotective properties in pancreatic beta-cells. KIOM-79 induced heme oxygenase-1 (HO-1) expression at the mRNA and protein levels, leading to increased HO-1 activity. The transcription factor, NF-E2 related factor 2 (Nrf2), regulates the antioxidant response element (ARE) of the phase 2 detoxifying and antioxidant enzymes, resulting in modulation of HO-1 expression. KIOM-79 increased nuclear translocation, ARE binding, and transcriptional activity of Nrf2. Furthermore, KIOM-79 also elicited activation of Akt (protein kinase B) and LY294004 (inhibitor of Akt)-suppressed KIOM-79-induced activation of Nrf2, which subsequently decreased HO-1 protein levels. Taken together, these data suggest that KIOM-79 augments the cellular antioxidant defense capacity through induction of HO-1 via the Akt-Nrf2-ARE signaling pathway, thereby protecting cells from streptozotocin-induced oxidative stress.

KIOM-79 inhibits high glucose or AGEs-induced VEGF expression in human retinal pigment epithelial cells

We evaluated whether KIOM-79, a mixture of extracts obtained from Puerariae lobata, Magnolia officinalis, Glycyrrhiza uralensis and Euphorbia pekinensis, could inhibit vascular endothelial growth factor (VEGF) expression in human retinal pigment epithelial (RPE) cells cultured under high glucose (HG, 25mM) or S100b (a specific ligand of the receptor for advance glycation end products (RAGE), 5microg/ml). In this study, the effect of KIOM-79 on HG or S100b-induced VEGF expression was investigated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, RT-PCR, ELISA, and Western blot on human RPE cells. The MTT assay (p<0.01) revealed that KIOM-79 (up to 1mg/ml) had no effect on cell growth. HG or S100b induced an increase in expression of VEGF at both mRNA and protein levels (p<0.05; p<0.01 versus control). The increase in VEGF expression by HG or S100b was dose- and time-dependently prevented by KIOM-79 (p<0.05 versus 25mM glucose; p<0.01 versus S100b). Also, KIOM-79 inhibited protein kinase C (PKC)-alpha/beta(alpha) and p38 mitogen-activated protein kinase (MAPK) activation. Our results demonstrate that KIOM-79 can inhibit VEGF expression via inhibition of the MAPK and PKC pathway.