Insulin Resistance In KKAy Mice Research Articles

Erucic Acid-Rich Yellow Mustard Oil Improves Insulin Resistance in KK-Ay Mice.

Obesity is a major risk factor for some metabolic disorders including type 2 diabetes. Enhancement of peroxisome proliferator-activated receptor (PPAR) γ, a master regulator of adipocyte differentiation, is known to increase insulin-sensitive small adipocytes. In contrast, decreased PPARγ activity is also reported to improve insulin resistance. We have previously identified erucic acid as a novel natural component suppressing PPARγ transcriptional activity. In this study, we investigated the effect of erucic acid-rich yellow mustard oil (YMO) on obese/diabetic KK-Ay mice. An in vitro luciferase reporter assay and mesenchymal stem cell (MSC) differentiation assay revealed that 25 µg/mL YMO significantly inhibited PPARγ transcriptional activity and differentiation of MSCs into adipocytes but promoted their differentiation into osteoblasts. In KK-Ay mice, dietary intake of 7.0% (w/w) YMO significantly decreased the surrogate indexes for insulin resistance and the infiltration of macrophages into adipose tissue. Furthermore, 7.0% YMO increased bone mineral density. These results suggest that YMO can ameliorate obesity-induced metabolic disorders.

Structure–activity relationship and hypoglycemic activity of tricyclic matrines with advantage of treating diabetic nephropathy

Forty−three tricyclic matrinic derivatives with a unique scaffold were prepared and evaluated for their stimulation effects on glucose consumption in HepG2 cells. The structure−activity relationship was systematically elucidated for the first time. Among them, compound 17a exhibited the most promising potency, and dose-dependently increased glucose consumption in L6 myotubes. It significantly lowered blood glucose, glucosylated haemoglobin and AGE level, and improved glucose tolerance and insulin resistance in KK-Ay mice as well. More importantly, 17a effectively ameliorated diabetic nephropathy (DN), as indicated by the improvement of renal function and pathological changes, and decrease of urinary protein. Furthermore, 17a could induce glycolysis but suppressed aerobic oxidation of glucose, in a similar mechanism to Metform. Our results indicated that in addition to hyperglycemia, 17a may be developed to treat diabetic complication such as DN.

Hypoglycemic activity of CPU2206: A novel peptide from sika (Cervus nippon Temminck) antler.

Previous work had extracted and purified an antidiabetic peptide named CPU2206 with 7,127.6 Da. In this work, the toxicity of CPU2206 was first evaluated by daily administration to ICR mice, and after 28days of administration, the body weight and lipid metabolism of the mice did not change significantly, which proved its safety and reliability. Second, further studies have focused on its hypoglycemic effects by daily intraperitoneal injection to alloxan-induced diabetic mice and KK-Ay mice, showing that CPU2206 effectively decreased the blood glucose and corresponding indicators of diabetic mice. Daily administration of CPU2206 nearly normalized the lipid metabolic parameters in diabetic mice. Histological examination also validated that CPU2206 ameliorated the pancreas injuries induced by alloxan or alleviated islet hypertrophy caused by insulin resistance in KK-Ay mice. To sum up, a totally new bioactive peptide CPU2206 obtained from sika antler showed significantly antidiabetic as well as lipid-lowering effects in diabetic mice. PRACTICAL APPLICATIONS: Antler has been used as a traditional Chinese medicine to invigorate primordial energy, enrich the blood, strengthen bones, and improve both male and female sexual functions for thousands of years. Traditionally, velvet antler can be grinded directly and taken orally, or used in porridge, wine and meat stew. Our experiment enriches the research on the function of edible antlers, provides the basis for developing it into functional health food, and on the other hand, provides an idea for finding new antidiabetic drugs.

The effects of emodin on insulin resistance in KKAy mice with diabetes mellitus

Background: Emodin can ameliorate insulin resistance in diabetes mellitus (DM), but the molecular mechanisms are still uncertain. Objective: The objective of this study is to identify the potential molecular mechanisms of emodin-mediated type 2 DM treatment. Methods: We treated the type 2 diabetic KKAy mice with emodin in different doses. Biochemistry data were collected, and the expression of peroxisome proliferator activated receptor γ (PPARγ) and Glucose transporter (GLUT)-2/4 were examined in liver, muscle, and adipose tissues using immunohistochemistry and reverse transcriptase polymerase chain reaction. The expression of IRS-1, PI3K, pAkt-ser473, and FoxO1 were also tested in these tissues. Results: Our data demonstrated that the levels of cholesterol, higher fasting plasma glucose, total cholesterol, total triacylglycerol, low-density lipoprotein cholesterol, free fatty acid, C creative protein, and tumor necrosis factor-α (P < 0.05), lower high-density lipoprotein, and insulin sensitivity index (P < 0.05) were ameliorated by emodin in a dose-dependent manner (P < 0.05). In addition, emodin was also identified to improve insulin sensitivity in KKAy diabetic mice (P < 0.05). In DM, the expression of PPARγ and GLUT-2 was down-regulated in liver (P < 0.05) as well as in muscle and adipose tissues (P < 0.05) when compared with the controls. However, the decreased levels were subject to emodin treatment in a dose-dependent manner. Meantime, emodin was identified to up-regulate the expression of IRS-1, PI3K, Akt-ser473 (P < 0.05), while FoxO1 (P < 0.05) was down-regulated. Conclusion: These results suggest that emodin represents a promising target to improve insulin sensitivity by enhancing liver glucose utilization, glucose uptake of muscle, and fat through IRS/PI3K/Akt/FoxO1 pathway. Abbreviations used: DM: Diabetes mellitus; PPARγ: Peroxisome proliferator activated receptor γ; GLUT: Glucose transporter; IRS: Insulin receptor substrate; PI3K: Phosphatidylinositide 3 kinase; Akt(PKB): Protein kinase; FoXO1: Fork head box protein O1.

10-Hydroxy-2-decenoic acid, a natural product, improves hyperglycemia and insulin resistance in obese/diabetic KK-Ay mice, but does not prevent obesity.

10-Hydroxy-2-decenoic acid (10H2DA) is a fatty acid found in royal jelly (RJ). In healthy mice, it activates 5’-AMP-activated protein kinase (AMPK) and increases glucose transporter 4 (GLUT4) translocation. Therefore, we examined whether 10H2DA has a potential therapeutic effect against type 2 diabetes in obese/diabetic KK-Ay mice. 10H2DA (3 mg/kg body weight) was administered to female KK-Ay mice for 4 weeks by oral gavage. Phenotypes for body weight, plasma glucose by oral glucose tolerance test and insulin levels were measured. mRNA and protein levels were determined using qRT-PCR and Western blot analyses, respectively. Long-term administration of 10H2DA significantly improved hyperglycemia and insulin resistance in KK-Ay mice, but did not prevent obesity. 10H2DA increased the expression of phosphorylated AMPK (pAMPK) protein in skeletal muscles; however, this expression did not correlate with increased GLUT4 translocation. Furthermore, 10H2DA neither enhanced the expression of adiponectin receptor mRNA nor activated the insulin signaling cascade, such as GSK-3β phosphorylation, in the liver. We found that 10H2DA-treated mice had a significant increase in the expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (Pgc-1α) mRNA in skeletal muscles compared with non-treated group (P=0.0024). These findings suggest that 10H2DA is involved in the improvement of type 2 diabetes, at least in part via activation of Pgc-1α expression, but does not prevent obesity.

A novel formula Sang-Tong-Jian improves glycometabolism and ameliorates insulin resistance by activating PI3K/AKT pathway in type 2 diabetic KKAy mice.

Sang-Tong-Jian (STJ), a novel formula composed of flavonoids and alkaloids derived from mulberry leaf, has been found to reduce blood glucose levels in rats with type 2 diabetes mellitus (T2DM) in our previous studies. However, the precise mechanisms remain unknown. Insulin resistance is the main characteristic of T2DM, which may be due to impairment of the PI3K/AKT signaling pathway. In this study, we investigated the effects of STJ on glycometabolism and insulin resistance in KKAy mice. A total of 50 KKAy male mice were randomly divided into five groups: model, metformin at 260mg/kg, and STJ at 105, 210 and 420mg/kg. C57BL/6J mice were used as the control group. Random blood glucose levels in KKAy mice were determined every 10days after treatments. At the 10th and 13th week, oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were conducted after a 12h overnight fast, respectively. After 13-week treatments, glycosylated hemoglobin (GHb) and serum insulin were measured using a colorimetric method and ELISA kits. Liver glycogen and muscle glycogen levels were analyzed using a colorimetric method. The morphology of pancreas, liver, skeletal muscle and epididymal fat were visualized by haematoxylin and eosin staining. The gene level of GLUT2 (liver) and GLUT4 (skeletal muscle, epididymal fat) were detected by real-time PCR. The proteins of GLUT2, GLUT4, IRS1, PI3K, AKT and their phosphorylation were assayed by Western blot analyses. STJ significantly decreased the random blood glucose and GHb levels, and increased liver and muscle glycogen levels. The results of OGTT and ITT and measurement of serum insulin indicated that STJ ameliorated insulin resistance in KKAy mice. STJ treatments also ameliorated the histopathological alterations in pancreas, liver, skeletal muscle and epididymal fat in KKAy mice. Furthermore, STJ upregulated the gene and protein expression of GLUT2 (liver) and GLUT4 (skeletal muscle, epididymal fat). Meanwhile, GLUT4 translocation and phosphorylation of IRS1, p85-PI3K and AKT were significantly increased by STJ treatments. Our results indicated that STJ ameliorated glycometabolism and insulin resistance in KKAy mice, which might be due to activation of PI3K/AKT pathway.

Effect of metformin on global gene expression in liver of KKAy mice.

Metformin is a first-line drug for treating type 2 diabetes mellitus, yet its mechanism remains only partially understood and controversial. In this study we assessed a global gene expression profiling in liver of KKAy mice affected by metformin. This study aimed to identify the novel anti-diabetic mechanisms of metformin. After KKAy mice were administered metformin for 5 weeks, the gene changes profile in the livers of KKAy mice were assessed by using the Agilent whole mice genome oligo microarray. Metformin altered the gene expression profiles in liver of KKAy mice. To our best knowledge, some genes have not been reported until now, such as Anxa2, Atf6, and so on. These genes were involved in many pathways, such as peroxisome proliferator activated receptor signaling pathway. Gene expression changes induced by metformin were in support of the improvement of glucolipid metabolism and insulin resistance in KKAy mice. These findings expanded our knowledge of pharmacological action of metformin, and provided the potential novel insights and interesting information about the molecules involved in the antidiabetic effects of metformin.

Evaluating the antidiabetic effects of Chinese herbal medicine: Xiao-Ke-An in 3T3-L1 cells and KKAy mice using both conventional and holistic omics approaches.

BackgroundXiao-Ke-An (XKA) is a Chinese medicine widely used for treating type 2 diabetes mellitus (T2D). It is composed of eight herbal medicines traditionally used for T2D, including Rehmannia glutinosa Libosch, Anemarrhena asphodeloides Bunge, Coptis chinensis Franch, etc. The aim of the present study was to investigate the antidiabetic effects of XKA with both conventional and holistic omics approaches.MethodsThe antidiabetic effect of XKA was first investigated in 3T3-L1 cells to study the effect of XKA on adipogenesis in vitro. Oil Red O staining was performed to determine the lipid accumulation. The intracellular total cholesterol (TC) and triglyceride (TG) contents in XKA treated 3T3-L1 cells were also evaluated. The therapeutic effects of XKA was further evaluated in KKAy mice with both conventional and holistic omics approaches. Body weight, fasting and non-fasting blood glucose, and oral glucose tolerance were measured during the experiment. At the time of sacrifice, serum was collected for the measurement of TG, TC, high-density lipoprotein cholesterol (HDL-c) and low-density lipoprotein cholesterol (LDL-c). The liver, kidney, spleen, pancreas, heart and adipose tissues were harvested and weighted. The liver was used for further microarray experiment. Omics approaches were adopted to evaluate the holistic rebalancing effect of XKA at molecular network level.ResultsXKA significantly inhibited adipogenic differentiation, lowered the intracellular TC and TG contents in 3T3-L1 cells. XKA improved the glucose homeostasis and lipid metabolism, ameliorated insulin resistance in KKAy mice. Futhermore, XKA also exhibited effective therapeutic effects by reversing the molecualr T2D disease network from an unbalanced state.ConclusionsThis study investigated the antidiabetic effects of XKA with both conventional and holistic omics approaches, providing both phenotypic evidence and underlying action mechanisms for the clinical use of XKA treating T2D.Electronic supplementary materialThe online version of this article (doi:10.1186/s12906-015-0785-2) contains supplementary material, which is available to authorized users.

Study of effect of Humifuse Euphorbia Herb on alleviating insulin resistance in type 2 diabetic model KK-Ay mice

[To explore the effect of Humifuse Euphorbia Herb ( HEH) on alleviating insulin resistance in type 2 diabetic KK-Ay mice. Totally 40 KK-Ay mice fed with high-fat diet were divided into four groups: the metformin group, the model group, the HEH low-dose group and the HEH high-dose group, and orally administrated with metformin hydrochloride (250 mg x kg(-1)), distilled water, humifuse euphorbia herb 1 g x kg(-1) and 2 g x kg(-1). Besides, C57BL/6J mice with ordinary feed were taken as the normal control group and orally administrated with equal distilled water. The oral administration for the five groups lasted for eight weeks. Before and after the experiment, weight, fasting glucose and insulin tolerance were determined. The morphological changes in pancreas were observed through hematoxylin-eosin (HE) staining on pancreatic tissue sections. The serum insulin, TNF-α, IL-6, adiponectin (ADPN) and leptin (LEP) were detected by ELISA. The results showed that HEH could reduce weight and fasting glucose in KK-Ay mice, alleviate hyperinsulinemia, reduce blood glucose-time AUC, increase 30-min blood glucose decline rate, relieve insulin resistance, significantly ameliorate the pathomorphological changes in pancreas in each group, decrease serum TNF-α, IL-6 and leptin levels in KK-Ay mice and rise serum ADPN level. This study proved that humifuse euphorbia herb can ameliorate the insulin resistance in KK-Ay mice, and its mechanism may be related to the effect on inflammatory factors and adipocytokines.

PP001-SUN: Outstanding abstract: Ingestion of Panaxatriol Ameliorates Insulin Resistance in KK-AY Mice by Promoting Insulin Dependent Glucose Uptake in Skeletal Muscle

PP001-SUN: Outstanding abstract: Ingestion of Panaxatriol Ameliorates Insulin Resistance in KK-AY Mice by Promoting Insulin Dependent Glucose Uptake in Skeletal Muscle

Hypoglycaemic and hypolipidaemic activities of sesamin from sesame meal and its ability to ameliorate insulin resistance in KK‐Ay mice

The ability of sesamin from sesame meal to ameliorate insulin resistance in KK-Ay mice (an animal model of type 2 diabetes) was evaluated. Treatment with sesamin (100 or 50 mg kg(-1)) significantly decreased the level of fasting plasma glucose, glycosylated serum protein, serum insulin, triglycerides, cholesterol, free fatty acid and malondialdehyde content of livers. Treatment with sesamin significantly increased the content of hepatic glycogen, reduced glutathione and the activity of superoxide dismutase and glutathione peroxidase. Moreover, the insulin-binding capacity to liver crude plasma membranes increased and histopathological changes of the pancreas were ameliorated in the treatment group. Sesamin has hypoglycaemic, hypolipidaemic and the ability to ameliorate insulin resistance in KK-Ay mice, which might be related to its effect on insulin receptors, and thus increases insulin sensitivity.

Direct Angiotensin II Type 2 Receptor Stimulation Ameliorates Insulin Resistance in Type 2 Diabetes Mice with PPARγ Activation

ObjectivesThe role of angiotensin II type 2 (AT2) receptor stimulation in the pathogenesis of insulin resistance is still unclear. Therefore we examined the possibility that direct AT2 receptor stimulation by compound 21 (C21) might contribute to possible insulin-sensitizing/anti-diabetic effects in type 2 diabetes (T2DM) with PPARγ activation, mainly focusing on adipose tissue.MethodsT2DM mice, KK-Ay, were subjected to intraperitoneal injection of C21 and/or a PPARγ antagonist, GW9662 in drinking water for 2 weeks. Insulin resistance was evaluated by oral glucose tolerance test, insulin tolerance test, and uptake of 2-[3H] deoxy-D-glucose in white adipose tissue. Morphological changes of adipose tissues as well as adipocyte differentiation and inflammatory response were examined.ResultsTreatment with C21 ameliorated insulin resistance in KK-Ay mice without influencing blood pressure, at least partially through effects on the PPARγ pathway. C21 treatment increased serum adiponectin concentration and decreased TNF-α concentration; however, these effects were attenuated by PPARγ blockade by co-treatment with GW9662. Moreover, we observed that administration of C21 enhanced adipocyte differentiation and PPARγ DNA-binding activity, with a decrease in inflammation in white adipose tissue, whereas these effects of C21 were attenuated by co-treatment with GW9662. We also observed that administration of C21 restored β cell damage in diabetic pancreatic tissue.ConclusionThe present study demonstrated that direct AT2 receptor stimulation by C21 accompanied with PPARγ activation ameliorated insulin resistance in T2DM mice, at least partially due to improvement of adipocyte dysfunction and protection of pancreatic β cells.

Retinoids as Promising Treatment for Non-alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is frequently associated with insulin resistance, suggesting its crucial role in the development and progression of NAFLD. We used a mouse model of high-fat, high-fructose (HFHFr) diet-induced NAFLD to examine the effects of retinoids on insulin resistance. Dietary administration of all-trans-retinoic acid (ATRA) significantly improved insulin sensitivity in C57BL/6J mice fed the HFHFr diet, and in KK-Ay mice but not in the leptin-deficient ob/ob mice. ATRA treatment significantly upregulated hepatic leptin receptor (LEPR) expression. In agreement with these observations, in vitro experiments showed ATRA directly induced LEPR gene expression through RARα. In the livers of C57BL/6J mice administered ATRA, insulin receptor substrate-1 (IRS1) was activated concomitantly with the phosphorylation of Janus kinase-2 and signal transducer and activator of transcription-3 (STAT3). STAT3 phosphorylation was also observed in KK-Ay but not in ob/ob mice. In in vitro experiments, ATRA significantly enhanced insulin-induced IRS1 tyrosine phosphorylation solely in the presence of leptin. A selective RARα/β agonist, tamibarotene, also enhanced hepatic LEPR expression, STAT3 phosphorylation, and ameliorated insulin resistance in KK-Ay mice. We discovered an unrecognized mechanism of retinoid action for the activation of hepatic leptin signaling, which resulted in enhancing insulin sensitivity in two mouse models of insulin resistance. Moreover, we also found that retinoids attenuate hepatic iron overload and iron-induced oxidative stress, which have recently emerged as an important factor for the development and progression of insulin resistance. Our data suggest that retinoids might have potential for treating NAFLD associated with insulin resistance.

Effects of ursolic acid in ameliorating insulin resistance in liver of KKAy mice via peroxisome proliferator-activated receptors α and γ

To explore the effects and mechanism of ursolic acid in improving hepatic insulin resistance in KKAy mice with spontaneous type 2 diabetes. Thirty-five KKAy mice were divided into five groups according to the randomized block design, namely, control, rosiglitazone, fenofibrate, and high- and low-dose ursolic acid groups with seven mice in each group. C57BL/6J mice were used as the normal control group. At the end of the 4th week, free fatty acid (FFA), tumor necrosis factor-α (TNF-α) and adiponectin contents in serum were detected by enzyme-linked immunosorbent assay; the protein expressions of phosphoenolpyruvate carboxykinase (PEPCK), insulin receptor substrate-2 (IRS-2) and glucose transport factor-2 (GLUT-2) were detected by Western blot method; the mRNA expressions of PEPCK, IRS-2 and GLUT-2 were detected by real-time polymerase chain reaction; the expressions of peroxisome proliferator-activated receptor α (PPARα) and peroxisome proliferator-activated receptor γ (PPARγ) in liver tissue were detected by immunohistochemical method. After four weeks of intervention, the contents of FFA, TNF-α and adiponectin in serum of the high-dose ursolic acid group had changed, showing statistically significant difference compared to those of the control group (P<0.01); high dose of ursolic acid had depressant effect on the expressions of PEPCK protein and PEPCK mRNA (P<0.01); low dose of ursolic acid depressed the expression of PEPCK mRNA and induced phosphorylation of IRS-2 in the liver (P<0.05); both high and low dose of ursolic acid improved the expression of PPARα in the liver (P<0.01). The effects of ursolic acid in improving hepatic insulin resistance in KKAy mice with spontaneous type 2 diabetes may be closely related to affecting the contents of FFA, TNF-α and adiponectin, improving the expression of PPARα protein, regulating transcription of PEPCK protein and inducing phosphorylation of IRS-2.

MDG-1, a polysaccharide from Ophiopogon japonicus exerts hypoglycemic effects through the PI3K/Akt pathway in a diabetic KKAy mouse model

Ethnopharmacological relevanceOphiopogon japonicus is a traditional Chinese medicine that might be helpful for the treatment of type 2 diabetes. Recent studies have confirmed its beneficial properties, but not the mechanism of action. Aim of studyIn this study, we examined the effects of a water-soluble β-d-fructan (MDG-1) from O. japonicus on type 2 diabetes through the PI3K/Akt pathway in a diabetic KKAy mouse model. Materials and methodsMDG-1 was extracted from the tube root of O. japonicus and purified as described previously (Xu et al., 2005). The KKAy mice were gavaged once daily with either distilled water, MDG-1or rosiglitazonefor 8 weeks. Blood glucose levels were tested regularly for the fed and fasted mice. In order to evaluate the effect of MDG-1 on disease progression, the proteins of InsR/IRS-1/PI3K/Akt/GSK-3/Glut-4 were detected by Western blotting and serum TG, TC, HDL-C, LDL-C were also dertermined. ResultsMDG-1 reduced the hyperglycemia, hyperinsulinemia and hyperlipidemia in the KKAy mice. The oral glucose tolerance test (OGTT) and the level of insulin in the serun showed that insulin resistance in KKAy mice was ameliorated after MDG-1 treated. After 8 weeks treatment with 300mg/kg MDG-1, the content of triglycerides (TG) and low density lipoprotein cholesterol (LDL-C) the serum decreased significantly. Meanwhile high density lipoprotein cholesterol (HDL-C) content increased notably. MDG-1 did not have any effect on total cholesterol (TC) content in the serum, whereas rosiglitazone significantly decreased the TC content. In addition, MDG-1 upregulates the phosphoinositide 3-kinase p85 subunit, Akt, insulin receptor (InsR), insulin receptor substrate-1 (IRS-1) and Glut-4 expression, but downregulates glycogen synthase kinase 3β expression. ConclusionsThese data indicate that MDG-1 has remarkable anti-diabetic activity through the InsR/IRS-1/PI3K/Akt/GSK-3/Glut-4 signaling pathway. We believe that MDG-1 is a promising anti-diabetic compound that will be helpful for the treatment of T2DM.

Effects of resveratrol on the amelioration of insulin resistance in KKAy mice

Resveratrol (Res) has attracted great interest regarding its effects related to metabolic syndrome, especially for lipid metabolic disorder or insulin resistance; however, the underlying mechanisms remain elusive. To explore the effects of Res on insulin sensitivity and the underlying mechanism, insulin-resistant KKA(y) mice were treated with 2and 4g/kg diets of Res for 12weeks. After the treatment, blood glucose, serum insulin, glucose tolerance, and insulin tolerance, as well as other indices such as adiponectin mRNA in epididymal adipose tissues, silent information regulator 1 (Sirt1), AMP-activated protein kinase (AMPK), insulin receptor substrate 1 (IRS1), and phosphorylated protein kinase B (PKB/AKT) proteins in liver and soleus muscles, were investigated. The results indicate that Res intervention reduces blood glucose and serum insulin levels, improves insulin and glucose tolerance, increases serum adiponectin and adiponectin mRNA levels in epididymal adipose tissues, and more importantly, elevates Sirt1, p-AMPK, p-IRS1, and p-AKT levels in liver and soleus muscles. In conclusion, Res could improve insulin sensitivity and ameliorate insulin resistance in KKA(y) mice, which may be associated with the upregulation of Sirt1 protein in liver and soleus muscles and consequent AMPK activation, as well as insulin-signaling related proteins.

Lessons From the KK-Ay Mouse, a Spontaneous Animal Model for the Treatment of human Type 2 Diabetic Nephropathy

Diabetic nephropathy is a major cause of end-stage kidney disease (ESKD) in patients with type 1 and type 2 diabetes throughout the world. In human glomeruli, expansion of diffuse mesangial matrices, exudative lesions and/or segmental nodular sclerosis are pathological features of diabetic nephropathy. There have been many reports on the pathogenesis and treatment of type 2 diabetes using various animal models.It appears that KK-Ay mice, especially in terms of their immunohistological findings, are a suitable animal model for human type 2 diabetic nephropathy. Many compounds have been reported to be advanced glycation end product (AGE) inhibitors such as aminoguanidine, angiotensin II receptor inhibitors and pyridoxamine, and these are useful in therapeutic interventions for reducing AGEs. Pyridoxamine ameliorates lipid peroxidation and insulin resistance in KK-Ay mice. Combination therapy with angiotensin converting inhibitors (ACE-I) and angiotensin II type 1 receptor blockers (ARB), including an ARB and 1,25-dihydroxyvitamin D3, i.e. anti-hypertensive and anti-reactive oxygen species effects, or with eicosapentaenoic acid (EPA), i.e. anti-microinflammation effect, have shown efficacy in the treatment of diabetic nephropathy in KK-Ay mice. It appears that KK-Ay mice are a useful spontaneous animal model for the evaluation of pathogenesis and treatment in patients with type 2 diabetic nephropathy.

Repeated ingestion of the leaf extract from Morus alba reduces insulin resistance in KK-Ay mice

The objective of this study was to test the hypothesis that repeated ingestion of diet containing the leaf extract from a Morus alba (LEM) maintains the postprandial hypoglycemic response and suppresses the progression of insulin resistance in high-sucrose diet-fed KK-Ay mice with spontaneous type 2 diabetes mellitus (DM). This hypothesis is based on our previous studies where LEM competitively inhibited intestinal disaccharidases and suppressed the elevation of postprandial plasma glucose and insulin levels. Ten KK-Ay mice in each group were raised on 0%, 3%, or 6% LEM powder-containing high-sucrose diets for 8 weeks. Blood samples were collected to measure fasting plasma glucose and insulin levels at weeks 2, 4, and 7 after the start of feeding. Urinary glucose excretion was monitored as a parameter of insulin resistance in 3-day intervals. Fasting plasma glucose level and urinary glucose excretion were significantly lower in both 3% and 6% LEM groups compared with the control group throughout the experiment. The plasma insulin of the 6% LEM group was significantly lower compared with the 3% LEM and control groups. Maintenance of low blood glucose and insulin delayed the onset time of urinary glucose excretion and were reflected by the ratio of additional LEM to sucrose in the diet. We observed the suppressive effects on the progression of hyperglycemia and hyperinsulinemia in the repeated ingestion of the LEM-containing diet. Namely, repeated ingestion of the LEM-containing diet reduces insulin resistance and may delay the appearance of DM, especially type 2 DM. Therefore, daily intake of LEM may be suitable for the prevention of obesity and DM.

Hydroxypropylated Tapioca Starch Retards the Development of Insulin Resistance in KKAy Mice, a Type 2 Diabetes Model, Fed a High‐Fat Diet

The hypoglycemic and antidiabetic effect of hydroxypropyl tapioca starch (HPTS, degree of substitution = 0.180) was investigated in male KKAy mice. Mice were fed a purified high-fat (20%) diet without or with HPTS (5% or 10%) for 33 d. Gelatinized tapioca starch (TS) was used as a reference. Fasting blood glucose concentrations, days 14 and 28, were significantly lower in the 10% HPTS group compared with the reference. In an oral glucose tolerance test (OGTT), day 28, blood glucose concentrations in the 5% HPTS group, at 60, 90, and 120 min, and in the 10% HPTS group, at 30, 60, and 90 min after oral administration of glucose, were significantly lower compared with the reference. The area under the glucose curve (AUC) for glucose in both HPTS groups was significantly lower compared with the reference. Energy intake was significantly lower in the 10% HPTS group compared with the reference. At the end of the experiment, adiponectin concentrations were significantly higher in the 10% HPTS group compared with the reference. A homeostasis model assessment of insulin resistance (HOMA-IR) tended to be lower in the 10% HPTS group compared with the reference, whereas a quantitative insulin sensitivity check index (QUICKI) was significantly higher in both HPTS groups compared with the reference. These results show that HPTS retards the development of insulin resistance in KKAy mice fed a high-fat diet.

High‐Hydroxypropylated Tapioca Starch Improves Insulin Resistance in Genetically Diabetic KKAy Mice

The hypoglycemic and antidiabetic effect of hydroxypropyl tapioca starch (HPTS) with a varying degree of substitution (DS: 0.058, 0.091, and 0.180) was investigated in rats and KKAy mice, an animal model of type 2 diabetes. The positive incremental area under the curve (IAUC) for glucose significantly decreased as the DS of HPTS increased. The IAUC after intragastric intubation of the highest HPTS (HPTS-III, DS = 0.180) was 55% of the IAUC of tapioca starch (TS). After 28 d, fasting blood glucose and insulin concentrations were significantly lower in rats fed HPTS-III (50 g/kg diet) than in those fed TS (P < 0.05). In KKAy mice fed HPTS-III (50 or 100 g/kg diet) for 33 d, as compared with TS, there was a delay in the detection of glucose in urine and also a decreased incidence of finding glucose in urine on days 7, 21, and 28; in addition, the AUCs for glucose in the oral glucose tolerance test on days 14 and 28 were significantly lower (P < 0.05 and P < 0.05, respectively). The plasma adiponectin concentration and the quantitative insulin sensitivity check index (QUICKI) were significantly higher in mice fed HPTS-III than in those fed TS (P < 0.01), whereas the homeostasis model assessment of insulin resistance (HOMA-IR) was lower (P < 0.01). Energy intake was significantly lower in mice fed HPTS-III than in those fed TS. These findings show that HPTS with a high DS resists digestion by alpha-amylase and improves insulin resistance in KKAy mice by decreasing energy intake. However, the potential mechanism by which HPTS-III decreases energy intake is unclear at present.