Mechanism of Astragaloside Ⅳ on db/db Mice with Type 2 Diabetes Mellitus and Non-alcoholic Fatty Liver Disease Based on AMPK Signaling Pathway / 中国实验方剂学杂志

ObjectiveTo study the mechanism of astragaloside Ⅳ （AS Ⅳ） on db/db mice with type 2 diabetes mellitus （T2DM） and non-alcoholic fatty liver disease （NAFLD） based on network pharmacology and experimental validation. MethodA total of 24 db/db mice were randomly divided into four groups： model group， metformin group， and low-dose and high-dose AS Ⅳ groups. Six C57 mice were used as the blank group. The low-dose and high-dose AS Ⅳ groups were given AS Ⅳ of 0.015 and 0.030 g·kg-1 by gavage， and the metformin group was given 0.067 g·kg-1 by gavage. The blank and model groups were given equal volumes of distilled water by gavage. After intragastric administration， fasting blood glucose （FBG） was detected， and an oral glucose tolerance test was performed. Serum lipid level and liver histopathology were detected. The target and enrichment pathway of AS Ⅳ for treating T2DM and NAFLD were predicted by network pharmacology， and the main enrichment pathway was verified by molecular biology techniques. The protein expressions of AMPK， p-AMPK， sterol regulatory element-binding protein-1 （SREBP-1）， and fatty acid synthetase （FAS） in liver tissue were detected by Western blot. ResultCompared with the blank group， the levels of body mass， liver weight coefficient， fasting blood glucose， serum total cholesterol， triglyceride， and low-density lipoprotein cholesterol in mice treated with AS Ⅳ were decreased （P<0.05， P<0.01）. The pathology of liver tissue showed significant improvement in lipid accumulation， and imaging results showed that the degree of fatty liver was reduced after AS Ⅳ therapy. Network pharmacological prediction results showed that vascular endothelial growth factor α （VEGFA）， galactoagglutinin 3 （LGALS3）， serine/threonine kinase B2 （Akt2）， RHO-associated coiled-coil protein kinase 1 （ROCK1）， serine/threonine kinase B1 （Akt1）， signaling and transcriptional activator protein （STAT3）， and messtimal epidermal transformation factor （MET） were key targets in "drug-disease" network. The results from the Kyoto encyclopedia of genes and genomes （KEGG） enrichment showed that the AMP-dependent protein kinase （AMPK） signaling pathway was strongly associated with T2DM and NAFLD. Western blot results showed that compared with the blank group， the expression levels of p-AMPK/AMPK in the model group were significantly down-regulated， while those of SREBP-1 and FAS proteins were significantly up-regulated （P<0.01）. Compared with the model group， the expression levels of p-AMPK/AMPK in the metformin group and high-dose AS Ⅳ group were significantly up-regulated， while those of SREBP-1 and FAS proteins were significantly down-regulated （P<0.05， P<0.01）. ConclusionAS Ⅳ regulates the expression of lipid proteins by activating the AMPK signaling pathway， thereby improving lipid metabolism.

An age-dependent alteration of the respiratory exchange ratio in the db/db mouse / 한국실험동물학회지

The leptin receptor-deficient db/db mouse is a rodent model of type 2 diabetes and obesity. Diabetes in db/db mice shows an age-dependent progression, with early insulin resistance followed by an insulin secretory defect resulting in profound hyperglycemia. However, there is insufficient data on agedependent changes of energy metabolism in db/db mice. We demonstrated an age-dependent decrease in the respiratory exchange ratio (RER), calculated by a ratio of VO2/VCO2, in db/db mice. The RER determined by indirect calorimetry, was 1.03 in db/db mice under 6 weeks of age, which were similar to those in heterozygote (db/+) and wild-type (+/+) mice. However, RER decreased from approximately 0.9 to 0.8 by 10 weeks of age and subsequently returned to approximately 0.9 at 22 weeks of age. The changes in RER were concurrent with the alterations in body weight and blood glucose level. However, other metabolic indicators such as glucose tolerance, changes in body fat mass, and urinary glucose levels, did not change with age. The results suggested that the energy source utilized in db/db mice changed with the age-related progression of diabetes.

db/db mouse and diabetic retinopathy / 中华实验眼科杂志

Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes,the incidence increased year by year,so the research of pathogenesis and interventions of DR is in the ascendant.The mechanism of DR mainly include glucose toxicity products and its effects on cell signaling pathways,leading to vascular disease and neuropathy.Research shows that,DR may occur with actived polyol pathway,increased,oxidative stress,the formation of advanced glycation end products (AGEs),protein kinase C pathway and vascular endothelial growth factor (VEGF)expression.db / db mice as an animal model of spontaneous type 2 diabetes,which is very similar to human type 2 diabetes,is more widely used in studies of DR.This article reviews some progresses of db / db mouse in the DR,and provide clues to further elucidate the pathogenesis of DR and development effective preventive measures.

Black Tea Inhibits Small Intestinal α-Glucosidase Activity in <i>db/db</i> Mouse / 日本補完代替医療学会誌

The inhibitory effects of the freeze-dried powder of the aqueous extract of black tea leaf (JAT) on α-glucosidase activity were investigated. We initially examined the effects of JAT addition on yeast α-glucosidase activity. JAT significantly and dose-dependently inhibited α-glucosidase activity and more strongly inhibited the activity than acarbose, the positive control. Then, we examined the effects of oral administration of JAT on sucrose tolerance in type 2 diabetes mellitus model <i>db/db</i> mice. Both JAT and acarbose administered groups showed a dose-dependent decrease in plasma glucose levels after the sucrose loading compared with the control group. Notable was that the plasma glucose levels of the 500 mg/kg JAT administered group exhibited a significant decrease 30 min or longer after the sucrose loading. On the other hand, no significant difference in plasma insulin levels was seen between the JAT administered group and the control group. We also measured small intestinal sucrase activity in <i>db/db</i> mouse at 30 min after JAT oral administration. Compared to control mice, small intestinal sucrase activity was significantly decreased in the 500 mg/kg JAT administered mice. These findings indicate that JAT may be a useful natural material for the prevention and therapy of type 2 diabetes mellitus.<br>

Silk fibroin hydrolysate exerts an anti-diabetic effect by increasing pancreatic beta cell mass in C57BL/KsJ-db/db mice

Components of silk including silk fibroin have long been used as anti-diabetic remedies in oriental medicine. However, detailed mechanisms underlying these anti-diabetic effects remain unclear. In this study, we examined the anti-diabetic activity of silk fibroin hydrolysate (SFH) in C57BL/KsJ-db/db (db/db) mice, a well-known animal model of non-insulin dependent diabetes mellitus. When the db/db mice were administered SFH in drinking water for 6 weeks, hyperglycemia in the animals gradually disappeared and the level of glycosylated hemoglobin decreased, indicating that SFH plays important role in reducing the symptoms of diabetes. In addition, SFH-treated db/db mice exhibited improved glucose tolerance with increased plasma insulin levels. Immunohistochemical and morphological analyses showed that SFH up-regulated insulin production by increasing pancreatic beta cell mass in the mice. In summary, our results suggest that SFH exerts anti-diabetic effects by increasing pancreatic beta cell mass in a non-insulin dependent diabetes mellitus mouse model.

Quercetin ameliorates hyperglycemia and dyslipidemia and improves antioxidant status in type 2 diabetic db/db mice

This study investigated the hypoglycemic, hypolipidemic, and antioxidant effects of dietary quercetin in an animal model of type 2 diabetes mellitus. Four-week-old C57BL/KsJ-db/db mice (n = 18) were offered an AIN-93G diet or a diet containing quercetin at 0.04% (low quercetin, LQE) or 0.08% of the diet (high quercetin, HQE) for 6 weeks after 1 week of adaptation. Plasma glucose, insulin, adiponectin, and lipid profiles, and lipid peroxidation of the liver were determined. Plasma glucose levels were significantly lower in the LQE group than in the control group, and those in the HQE group were even further reduced compared with the LQE group. The homeostasis model assessment for insulin resistance (HOMA-IR) showed lower values for LQE and HQE than for the control group without significant influence on insulin levels. High quercetin increased plasma adiponectin compared with the control group. Plasma triglycerides in the LQE and HQE groups were lower than those in the control group. Supplementation with high quercetin decreased plasma total cholesterol and increased HDL-cholesterol compared with the control group. Consumption of low and high quercetin reduced thiobarbituric acid reactive substances (TBARS) levels and elevated activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in the liver. Thus, quercetin could be effective in improving hyperglycemia, dyslipidemia, and antioxidant status in type 2 diabetes.

Quercetin attenuates fasting and postprandial hyperglycemia in animal models of diabetes mellitus

The objective of this study was to investigate the hypoglycemic effects of quercetin (QE) in animal models of diabetes mellitus (DM). A starch solution (1 g/kg) with and without QE (100 mg/kg) or acarbose (40 mg/kg) was orally administered to streptozotocin (STZ)-induced diabetic rats after an overnight fast. Postprandial plasma glucose levels were measured and incremental areas under the response curve were calculated. To study the effects of chronic feeding of QE, five-week-old db/db mice were fed an AIN-93G diet, a diet containing QE at 0.08%, or a diet containing acarbose at 0.03% for 7 weeks after 1 week of adaptation. Plasma glucose and insulin, blood glycated hemoglobin, and maltase activity of the small intestine were measured. Oral administration of QE (100 mg/kg) or acarbose (40 mg/kg) to STZ-treated rats significantly decreased incremental plasma glucose levels 30-180 min after a single oral dose of starch and the area under the postprandial glucose response, compared with the control group. QE (0.08% of diet) or acarbose (0.03% of diet) offered to db/db mice significantly reduced both plasma glucose and blood glycated hemoglobin compared to controls without significant influence on plasma insulin. Small intestine maltase activities were significantly reduced by consumption of QE or acarbose. Thus, QE could be effective in controlling fasting and postprandial blood glucose levels in animal models of DM.

Hypolipidemic effect of Salicornia herbacea in animal model of type 2 diabetes mellitus

To control blood glucose level as close to normal is a major goal of treatment of diabetes mellitus. Hyperglycemia and hyperlipidemia are the major risk factors for cardiovascular complications, the major cause of immature death among the patients with type 2 diabetes. The purpose of this study is to determine the hypoglycemic and hypolipidemic effects of Salicornia herbacea in animal model of type 2 diabetes and to investigate the possible mechanisms for the beneficial effects of S. herbacea. S. herbacea was extracted with 70% ethanol and desalted with 100% ethanol. Three week-old db/db mice (C57BL/KsJ, n=16) were fed AIN-93G semipurified diet or diet containing 1% desalted ethanol extract of S. herbacea for 6 weeks after 1 week of adaptation. Fasting plasma glucose, triglyceride, and total cholesterol were measured by enzymatic methods and blood glycated hemoglobin (HbA1C) by the chromatographic method. Body weight and food intake of S. herbacea group were not significantly different from those of the control group. Fasting plasma glucose and blood glycated hemoglobin levels tended to be lowered by S. herbacea treatment. Consumption of S. herbacea extract significantly decreased plasma triglyceride and cholesterol levels (p<0.05). The inhibition of S. herbacea extract against yeast alpha-glucosidase was 31.9% of that of acarbose at the concentration of 0.5 mg/mL in vitro. The inhibitory activity of ethanol extract of S. herbacea against porcine pancreatic lipase was 59.0% of that of orlistat at the concentration of 0.25 mg/mL in vitro. Thus, these results suggest that S. herbacea could be effective in controlling hyperlipidemia by inhibition of pancreatic lipase in animal model of type 2 diabetes.

Study on amelioration of aminoguanidine on diabetic neuropathy and its mechanism / 中国药理学通报

Aim: To determine whether aminoguanidine increases the motor neve conduction velocity of db/db mice and why. Mothods: Motor neve conduction velocity was assayed by Powerlab/8s multipurpose physiological recorder. Advanced glycosylation end products of db/db mice kidney were determined by fluorometer. Results Motor neve conduction velocity of 6 months db/db mice treated with Aminoguanidine for 5 months increased significantly. Conclusion: Aminoguanidine can prevent the decrease of the motor neve conduction velocity of db/db mouse by decreasing the advanced glycosylation end products.