Hypoglycemic effect of Lentinus strigosus (Schwein.) Fr. crude exopolysaccharide in streptozotocin-induced diabetic rats

ABSTRACT This study reports the hypoglycemic effects of the crude exopolysaccharide (EPS) produced from submerged mycelial culture of Lentinus strigosus (Schwein.) Fr. (Family Polyporaceae) in streptozotocin (STZ)-induced diabetic rats. In a dose-dependent study, diabetic rats were treated with EPS at doses of 50-150 mg/kg of body weight for 7 days. Serum glucose and plasma insulin levels were measured in normal, STZ-induced diabetic, and EPS-treated diabetic rats. Following oral administration of EPS dosages for 7 days, the serum glucose levels in the STZ-induced diabetic rats were reduced up to 21.1% at the dose of 150 mg/kg of body weight. The results revealed that orally administered L. strigosus EPS, at the dose of 150 mg/kg, exhibited a considerable hypoglycemic effect in STZ-induced diabetic rats. Plasma insulin levels of STZ-induced diabetic rats decreased as compared to control group rats (P < .05). Although insulin levels slightly increased in the EPS-treated groups the increase was not statistically significant. The hypoglycemic potential of the EPS was further supported by histological observations of pancreatic islets of Langerhans.     

Anti-diabetic and hypolipidaemic properties of ginger (Zingiber officinale) in streptozotocin-induced diabetic rats

In the present study, the hypoglycaemic potentials of ginger (Zingiber officinale) were studied in rats. An aqueous extract of raw ginger was administered daily (500 mg/kg, intraperitoneally) for a period of 7 weeks to streptozotocin (STZ)-induced diabetic rats. Fasting blood serum was analysed for blood glucose, cholesterol and triacylglycerol levels. The STZ-injected rats exhibited hyperglycaemia accompanied with weight loss, indicating their diabetic condition. At a dose of 500 mg/kg, raw ginger was significantly effective in lowering serum glucose, cholesterol and triacylglycerol levels in the ginger-treated diabetic rats compared with the control diabetic rats. The ginger treatment also resulted in a significant reduction in urine protein levels. In addition, the ginger-treated diabetic rats sustained their initial weights during the treatment period. Moreover, ginger decreased both water intake and urine output in the STZ-induced diabetic rats. The present results indicate that raw ginger possesses hypoglycaemic, hypocholesterolaemic and hypolipidaemic potential. Additionally, raw ginger is effective in reversing the diabetic proteinuria observed in the diabetic rats. Thus, ginger may be of great value in managing the effects of diabetic complications in human subjects.     

Protective effects of gamma-aminobutyric acid in rats with streptozotocin-induced diabetes

The effects of gamma-aminobutyric acid (GABA) in rats with experimental diabetes mellitus were examined. Diabetes mellitus was induced in adult male Wistar rats by streptozotocin (STZ) injection. Oral administration of GABA (100 or 200 mg/kg body weight/d) for 10 d to the diabetic rats resulted in a significant decrease in their serum glucose level. GABA also reduced the level of glycosylated protein in serum, indicating an improvement of hyperglycemic conditions. Rats with STZ-induced diabetes showed arrested body weight gain and an increase in both liver and kidney weight, whereas oral administration of GABA attenuated the organ hypertrophy induced by hyperglycemia. In addition, the degree of serum thiobarbituric acid (TBA)-reactive substance level was significantly lower in the rats treated with 100 mg GABA, and the degree of TBA-reactive substance in the liver and kidney was reduced by GABA in a dose-dependent manner. These results suggest that GABA treatment protects against the development of diabetic complications resulting from impaired glucose metabolism and enhanced oxidative stress.     

Effect of Aegle marmelos fruits on normal and streptozotocin-diabetic Wistar rats

The present study evaluates the antidiabetic effect of an aqueous extract of Aegle marmelos fruits (AMFEt) in diabetes. Female albino Wistar rats were randomly divided into five groups: normal (untreated), normal + AMFEt, streptozotocin (STZ)-treated, STZ-treated + AMFEt, and STZ-treated + glibenclamide. Rats were rendered diabetic by STZ (45 mg/kg) administered intraperitoneally. AMFEt (250 mg/kg) was given twice daily for 1 month. Blood glucose, plasma insulin, glycosylated hemoglobin, liver glycogen, and change in body weight were determined. Food intake and water intake were monitored daily. An oral glucose tolerance test was also performed to determine the effect of this extract. The results show that glucose level and glycosylated hemoglobin were increased and plasma insulin and liver glycogen were decreased in diabetic rats, and that treatment with AMFEt reversed the effects of diabetes on these biochemical parameters to near-normal levels.     

Soluble dietary fibre fraction of Trigonella foenum-graecum (fenugreek) seed improves glucose homeostasis in animal models of type 1 and type 2 diabetes by delaying carbohydrate digestion and absorption, and enhancing insulin action

Trigonella foenum-graecum (fenugreek) seeds have been documented as a traditional plant treatment for diabetes. In the present study, the antidiabetic properties of a soluble dietary fibre (SDF) fraction of T. foenum-graecum were evaluated. Administration of SDF fraction (0 x 5 g/kg body weight) to normal, type 1 or type 2 diabetic rats significantly improved oral glucose tolerance. Total remaining unabsorbed sucrose in the gastrointestinal tract of non-diabetic and type 2 diabetic rats, following oral sucrose loading (2 x 5 g/kg body weight) was significantly increased by T. foenum-graecum (0 x 5 g/kg body weight). The SDF fraction suppressed the elevation of blood glucose after oral sucrose ingestion in both non-diabetic and type 2 diabetic rats. Intestinal disaccharidase activity and glucose absorption were decreased and gastrointestinal motility increased by the SDF fraction. Daily oral administration of SDF to type 2 diabetic rats for 28 d decreased serum glucose, increased liver glycogen content and enhanced total antioxidant status. Serum insulin and insulin secretion were not affected by the SDF fraction. Glucose transport in 3T3-L1 adipocytes and insulin action were increased by T. foenum-graecum. The present findings indicate that the SDF fraction of T. foenum-graecum seeds exerts antidiabetic effects mediated through inhibition of carbohydrate digestion and absorption, and enhancement of peripheral insulin action.     

沙棘黄酮对链脲佐菌素致糖尿病大鼠降糖作用

目的:研究沙棘籽渣和果渣中黄酮对链脲佐菌素(STZ)诱导糖尿病大鼠的降糖作用。方法:用STZ成功地制造了1型糖尿病大鼠模型,分别用沙棘籽渣中黄酮(FSH)和沙棘果渣中黄酮(FFH)连续灌胃4w。结果:与模型对照组相比,FSH极显著地降低STZ糖尿病大鼠血糖、果糖胺、血脂水平,提高血清白蛋白、总蛋白含量,增强机体抗氧化能力,对乳酸和肝糖原影响不大,同时可调节糖尿病大鼠的饮食水平;而FFH的作用效果不及FSH。结论:FSH能有效的控制糖尿病大鼠血糖水平,纠正其物质代谢紊乱。     

牛初乳粉预防大鼠高血糖的实验研究

目的: 探讨牛初乳粉(BCP)对大鼠糖尿病的预防作用。方法: 给大鼠灌胃三个不同剂量的BCP(BCP)溶液15 d后,腹腔注射链脲霉素(STZ)55 mg/kg。注射后D7测定体重、血糖;D14除上述指标外,还测定血脂、肝肾组织SOD、GSH-Px、NOS及MDA(饮水量在注射后D 6、13 测量)。结果: 注射STZ后D7、D14 ,中剂量BCP组的血糖均显著低于STZ组(P﹤0.05, P﹤0.01)。D13 中剂量组的饮水量少于STZ组。D14 BCP各组的体重、胸腺指数与 STZ组相比差异均无显著性,5个组之间的血脂、肝MDA、肝肾SOD、GSH-Px、NOS差异均无显著性。 结论: 预防性给与中剂量BCP可缓解STZ所致的高血糖,并使STZ大鼠饮水量减少。     

Effect of Picrorrhiza rhizoma extracts on early diabetic nephropathy in streptozotocin-induced diabetic rats

The hypoglycemic effect of an aqueous extract of Picrorrhiza Rhizoma (PR) was investigated on diabetic nephropathy. The body weight of each of eight rats per group was measured 7 days after streptozotocin (STZ) treatment. The blood glucose levels 3 days after STZ treatment and the changes in body weight, kidney weight, blood glucose levels, and serum blood urea nitrogen (BUN) were also measured, and the histopathology of the kidney was examined. Body weight decreases and increases of kidney weight, blood glucose levels, and serum BUN and creatinine levels were detected in the diabetic control with histopathological changes related to diabetic nephropathy in the kidney. However, the level of hyperglycemia was significantly lowered in all groups given the PR extract. In addition, the changes related to diabetic nephropathy with the body weight were also significantly lower in the captopril and all PR extract-dosing groups than in the diabetic control. In conclusion, an aqueous extract of PR has relatively good inhibitory effects on STZ-induced diabetes with early diabetic nephropathy with a similar efficacy to an equal dose of captopril.     

Effect of Trigonella foenum-graecum (fenugreek) extract on blood glucose, blood lipid and hemorheological properties in streptozotocin-induced diabetic rats

Trigonella foenum-graecum (fenugreek) seeds have previously been shown to have hypoglycemic and hypocholesterolemic effects on type 1 and type 2 diabetes mellitus patients and experimental diabetic animals. The Trigonella foenum-graecum extract has now been investigated for its effects on general properties, blood glucose and blood lipid, and hemorheological parameters in experimental diabetic rats. Streptozotocin-induced diabetic rats were administrated by oral intragastric intubation separately with low dose (0.44 g/kg.d), middle dose (0.87 g/kg.d), high dose (1.74 g/kg.d) of Trigonella foenum-graecum extract, and Metformin HCl (0.175 g/kg.d) for 6 weeks. Compared with diabetic group, rats treated with Trigonella foenum-graecum extract had an increase in body weight and a decrease in kidney /body weight ratio (p<0.05). Compared with diabetic group, rats treated Trigonella foenum-graecum extract had lower blood glucose, glycated hemoglobin, triglycerides, total cholestrol and higher higher-density-lipoprotein-cholesterol in a dose-dependent manner (p<0.05). The plasma viscosity, whole blood viscosity of high shear rate (200 s-1) and low shear rate (40 s-1), erythrocyte sedimentation rate, whole blood reduction viscosity and platelet conglutination were significantly reduced in diabetic rats treated with high and middle doses of Trigonella foenum-graecum extract, but not in those treated with low dose of Trigonella foenum-graecum extract. It may be concluded that Trigonella foenum-graecum extract can lower kidney /body weight ratio, blood glucose, blood lipid levels and improve hemorheological properties in experimental diabetic rats following repeated treatment for 6 weeks.     

Alterations in the blood glucose, serum lipids and renal oxidative stress in diabetic rats by supplementation of onion (Allium cepa. Linn)

This study examined the anti-diabetic effect of onion (Allium cepa. Linn) in the streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley rats were divided into normal rats fed control diet or supplemented with onion powder (7% w/w) and diabetic rats fed control diet or supplemented with onion powder. Diabetes was induced by a single injection of STZ (60 mg/kg, ip) in citrate buffer. The animals were fed each of the experimental diet for 5 weeks. Blood glucose levels of rats supplemented with onion were lower than those of rats fed control diet in the diabetic rats. Onion also decreased the total serum lipid, triglyceride, and atherogenic index and increased HDL-cholesterol/total cholesterol ratio in the diabetic rats. Glutathione peroxidase, glutathione reductase and glutathione S-transferase activities were high in the diabetic rats compared to normal rats and reverted to near-control values by onion. These results indicate that onion decreased blood glucose, serum lipid levels and reduced renal oxidative stress in STZ-induced diabetic rats and this effect might exert the anti-diabetic effect of onion.     

Administration of beta-carotene suppresses lipid peroxidation in tissues and improves the glucose tolerance ability of streptozotocin-induced diabetic rats

The present study attempted to examine the antioxidative effect of dietary beta-carotene (BC) on lipid peroxidation (LPO) in the streptozotocin (STZ)-induced diabetic rats. Male Sprague-Dawley (SD) rats were fed on the AIN76 standard diet with or without 0.1% BC. On the 21st day after introduction of these diets, STZ was intraperitoneally injected in half the subjects of both groups. All animals were sacrificed seven days after the STZ injection. Glucose tolerance and thiobarbituric acid reactive substance (TBARS) in the tissues or serum were measured. Body weight gain in the BC + STZ group was significantly higher than that in the STZ group (p < 0.05). Blood glucose and TBARS concentrations of the liver, pancreas, and serum in the BC + STZ group were significantly lower than those in the STZ group. The blood insulin concentration in the BC + STZ group was significantly higher than that in the STZ group. The hepatic and serum beta-carotene concentrations in the BC + STZ group were significantly lower than those in the BC group. Moreover, the synthesis and oxidation of glutathione (GSH) in the BC + STZ group were reduced when compared to the STZ group. These results suggest that the administration of beta-carotene suppresses the elevation of LPO and reduces the symptoms of diabetes mellitus (DM) in the STZ-induced diabetic rats.     

Therapeutic effects of Teucrium polium extract on oxidative stress in pancreas of streptozotocin-induced diabetic rats

Increased oxidative stress is a widely accepted factor in the development and progression of diabetes and its complications. In this study, we evaluated the antioxidative potential of Teucrium polium (Family Lamiaceae) aqueous extract for protecting rat pancreatic tissue against streptozotocin (STZ)-induced oxidative stress. Diabetes was induced in rats by intraperitoneal injections of at a single dose of STZ at 40 mg/kg. The crude extract (equivalent to 0.5 g of plant powder/kg of body weight) was administered orally (intragastrically) to a group of STZ diabetic rats for 30 consecutive days. Changes in antioxidant status were evaluated by determining catalase (CAT) and superoxide dismutase (SOD) activities and the level of reduced glutathione (GSH) in pancreatic tissue. In addition, serum nitric oxide (NO) concentration, pancreatic tissue malondialdehyde (MDA) (an index of lipid peroxidation) level, and reliable markers of protein oxidation such as protein carbonyl content (PCO) and advanced oxidation protein products (AOPP) were also determined. Under diabetic conditions, blood glucose level, serum NO concentration, and pancreatic MDA, PCO, and AOPP levels were all increased. The diabetic rats also exhibited pancreatic GSH depletion along with significant reductions in activities of CAT and SOD. Rats treated with T. polium extract had significantly higher GSH levels along with enhanced CAT and SOD activities in pancreatic tissue. In addition to suppressed blood glucose levels, serum NO, pancreatic MDA, PCO, and AOPP levels were all lower than in the diabetic group. Our results strongly support the proposal that antioxidative activity of T. polium occurs by quenching the extent of lipid and protein oxidation. Based on these observations, it is concluded that T. polium may have protective effect(s) on pancreatic tissue in STZ-induced oxidative stress due to its high antioxidative potential.     

Antihyperglycemic effect of Fomitopsis pinicola extracts in streptozotocin-induced diabetic rats

The antihyperglycemic effect of a water extract (WE) and an alkali extract (AE) of the Fomitopsis pinicola fruit body was studied in streptozotocin (STZ)-induced diabetic rats. The STZ-induced diabetes mellitus (DM) control group lost a significant amount of body weight, whereas the normal control group (NC) gained weight; however, the DM-AE group gained a significant amount of weight, with weight gain approaching normal. Feed intake by the DM-AE group was also similar to the NC group. The liver and kidney weights per body weight increased with the STZ treatment; however, the weights were lower in the F. pinicola-treated groups and nearly normalized in the DM-AE group. The weights of the heart, lungs, and spleen were not influenced by the STZ treatment. Blood glucose levels of F. pinicola-treated DM groups were significantly lower than that of the DM group. In particular, STZ-induced hyperglycemia was remarkably inhibited by the AE-supplemented diet. Serum insulin levels were decreased with STZ injection; however, the decreased levels were almost restored to the NC level with F. pinicola supplementation. The increased serum fructosamine levels associated with hyperglycemia were decreased with the F. pinicola treatment. Cells of the pericentral regions were found to have significant swelling, and some necrotic cells were observed in the pancreas of DM animals; however, pancreatic tissue damage by STZ in the F. pinicola-supplemented diet groups was ameliorated. In this study, the AE from F. pinicola showed the highest antidiabetic effect among the treatments. These results indicate that constituents of F. pinicola may regulate hyperglycemia via either increased insulin secretion during recovery or the prevention of STZ-induced pancreatic damage. This is the first report of antihyperglycemic effects of F. pinicola in STZ-induced DM rats.     

Supplementation of fenugreek leaves reduces oxidative stress in streptozotocin-induced diabetic rats

Trigonella foenum-graecum, commonly known as fenugreek, is a traditional medicinal plant of the Leguminoseae family in India. The antioxidant effect of fenugreek leaves was evaluated in the streptozotocin-induced diabetic rat model. The antioxidant effect was evaluated by estimating thiobarbituric acid-reactive substances and reduced glutathione and measuring the activities of catalase and superoxide dismutase in liver, heart, and kidney in diabetic rats. Fenugreek leaf powder supplementation significantly lowered lipid peroxidation and significantly increased the antioxidant system in diabetic rats. The effect at a dose of 1 g/kg of body weight of fenugreek leaf powder was similar to that of glibenclamide. Insulin restores all the parameters to near normal values. Thus, fenugreek leaf powder reduces oxidative stress in experimental diabetes.     

Oral administration of insulin-like growth factor-I from colostral whey reduces blood glucose in streptozotocin-induced diabetic mice

The aim of the present study was to investigate the effects of oral administration of the insulin-like growth factor-I-rich fraction (IGF-I-RF) from bovine colostral whey on the regulation of blood glucose levels in streptozotocin (STZ)-induced diabetic mice. We obtained a peptide fraction containing IGF-I (10 ng/mg protein) from Holstein colostrum within 24 h after parturition by using ultrafiltration. The blood glucose levels of STZ-induced diabetic mice fed with IGF-I-RF (50 μg/kg per d) were significantly reduced by 11 and 33 % at weeks 2 and 4, respectively (P < 0·05). The body weights of STZ-induced diabetic mice increased following the oral administration of the IGF-I-RF. The kidney weights of STZ-induced diabetic mice decreased significantly (P < 0·05) following the administration of the IGF-I-RF, and the liver weights of STZ-induced diabetic mice decreased significantly (P < 0·05) following the administration of 50 μg/kg per d of the IGF-I-RF. The present results indicate that the IGF-I-RF obtained from Holstein colostrum could be a useful component for an alternative therapeutic modality for the treatment of diabetes in insulin-resistant patients.     

Hypoglycaemic and antioxidant effects of onion,Allium cepa: dietary onion addition,antioxidant activity and hypoglycaemic effects on diabetic rats

The purpose of the present study was to discover the relative potency of onion, Allium cepa, with respect to its hypoglycaemic and hypolipidaemic effects on the diabetic situation, and the association of these effects with the potential against oxidative stress. Male Wistar rats were divided into four groups. A normal control (group A), and a non-diabetic group (group B) were treated daily with 1 ml A. cepa solution (0.4 g A. cepa/rat). Groups C and D were made diabetic by an intraperitoneal injection of streptozotocin (STZ) (60 mg/kg body weight) in citrate buffer (pH 6.3). These animals (groups C and D) were the STZ diabetic control and STZ diabetic rats with onion intake, respectively. Onion increased the fasting serum high-density lipoprotein levels, and demonstrated alleviation of hyperglycaemia in STZ diabetic rats. The hypoglycaemic and hypolipidaemic actions of A. cepa were associated with antioxidant activity, since onion decreased superoxide dismutase activities while no increased lipid hydroperoxide and lipoperoxide concentrations were observed in diabetic rats treated with A. cepa.     

Extract of green tea leaves partially attenuates streptozotocin-induced changes in antioxidant status and gastrointestinal functioning in rats

Rats with severe streptozotocin (STZ)-induced diabetes were subjected to dietary green tea extract supplementation at 2 doses (0.01% and 0.2%; GTL and GTH groups, respectively) to evaluate their effects on antioxidant, gastrointestinal, and renal parameters of experimental animals. The lower dietary supplementation reflects daily consumption of 3 cups of green tea for an average adult weighing 70 kg. Supplementation of a diet with green tea extract had no influence on elevated food intake, body weight loss, increased glucose concentration, or declined antioxidant capacity of water-soluble substances in plasma in the diabetic rats. In cases of intestinal maltase activity, attenuation of liver and kidney hypertrophy, triacylglycerol concentration, and aspartate aminotransferase activity in the serum, both dietary treatments normalized metabolic disorders caused by STZ injection to a similar extent. Unlike the GTL group, the GTH treatment significantly ameliorated development of diabetes-induced abnormal values for small intestinal saccharase and lactase activities, renal microalbuminuria, thiobarbituric acid-reactive substance content in kidney tissue, as well as total antioxidant status in the serum of rats. The GTH group was also characterized by higher antioxidant capacity of lipid-soluble substances in plasma and superoxide dismutase activity in the serum. Although the higher dose of green tea extract did not completely protect against STZ-induced hyperglycemia and oxidative stress in experimental rats, this study suggests that green tea extract ingested at high amounts may prove to be a useful therapeutic option in the reversal of diabetic dysfunction.     

Hypoglycaemic and antioxidant effects of onion,Allium cepa: dietary onion addition,antioxidant activity and hypoglycaemic effects on diabetic rats

The purpose of the present study was to discover the relative potency of onion, Allium cepa, with respect to its hypoglycaemic and hypolipidaemic effects on the diabetic situation, and the association of these effects with the potential against oxidative stress. Male Wistar rats were divided into four groups. A normal control (group A), and a non-diabetic group (group B) were treated daily with 1 ml A. cepa solution (0.4 g A. cepa/rat). Groups C and D were made diabetic by an intraperitoneal injection of streptozotocin (STZ) (60 mg/kg body weight) in citrate buffer (pH 6.3). These animals (groups C and D) were the STZ diabetic control and STZ diabetic rats with onion intake, respectively. Onion increased the fasting serum high-density lipoprotein levels, and demonstrated alleviation of hyperglycaemia in STZ diabetic rats. The hypoglycaemic and hypolipidaemic actions of A. cepa were associated with antioxidant activity, since onion decreased superoxide dismutase activities while no increased lipid hydroperoxide and lipoperoxide concentrations were observed in diabetic rats treated with A. cepa.     

链脲佐菌素诱导糖尿病大鼠肾病模型的建立

目的评价链脲佐菌素(STZ)糖尿病大鼠肾病动物模型。方法用STZ 65 mg/kg一次性腹腔内注射方式制作糖尿病大鼠模型,60只SD大鼠随机分为正常对照组(M),糖尿病1个月组(M1)、3个月组(M2),每组20只。期间观察大鼠血糖、尿糖及一般情况变化,实验结束时,测定血肌酐、尿素氮、尿蛋白、尿白蛋白排泄率,取肾作病理及超微病理检查。结果M未见异常改变,从M1开始出现异常改变,以M2最明显。M2模型组大鼠的血肌酐、尿素氮、尿蛋白、尿白蛋白明显升高,出现肾脏肥大,病理显示明显的肾小球、肾小管病变。结论STZ诱导的糖尿病大鼠肾脏病变表现为肾小球及小管间质损害,可用作糖尿病肾病研究的动物模型。     

Antihyperglycemic activity of Piper betle leaf on streptozotocin-induced diabetic rats

Piper betle, an indigenous medicinal plant, has a folk (Siddha and Ayurvedha) reputation in the rural southern India. The present study was carried out to evaluate the effect of P. betle on glucose metabolism since it is consumed as betel-quid after meals. Plasma levels of glucose and glycosylated hemoglobin and activities of liver hexokinase and gluconeogenic enzymes such as glucose-6-phosphatase and fructose-1,6-bisphosphatase in control and streptozotocin (STZ) diabetic rats were assayed. Oral administration of leaf suspension of P. betle (75 and 150 mg/kg of body weight) for 30 days resulted in significant reduction in blood glucose (from 205.00 +/- 10.80 mg/dL to 151.30 +/- 6.53 mg/dL) and glycosylated hemoglobin and decreased activities of liver glucose-6-phosphatase and fructose-1,6-bisphosphatase, while liver hexokinase increased (P < .05), in STZ diabetic rats when compared with untreated diabetic rats. P. betle at a dose of 75 mg/kg of body weight exhibited better sugar reduction than 150 mg/kg of body weight. In addition, protection against body weight loss of diabetic animals was also observed. The effects produced by P. betle were compared with the standard drug glibenclamide. Thus, the present study clearly shows that P. betle intake influences glucose metabolism beneficially.