Printer Friendly

Hypoglycemic and hypolipidemic effects of oxymatrine in high-fat diet and streptozotocin-induced diabetic rats.

ABSTRACT

Oxymatrine, a quinolizidine alkaloid, has been widely used for the treatment of hepatitis. In this study, we investigated the hypoglycemic and hypolipidemic effects and new pharmacological activities of oxymatrine, in a high-fat diet and streptozotocin (STZ)-induced diabetic rats. The results demonstrated that oxymatrine could significantly decrease fasting blood glucose, glycosylated hemoglobin (GHb), food and water intake, non-esterified fatty acid (NEFA), total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol levels (LDL-c), and increase serum insulin, liver and muscle glycogen, high density lipoprotein cholesterol (HDL-c), glucagon-like peptide-1 (GLP-1) and muscle glucose transporter-4 (GLUT-4) content in diabetic rats. The results of the histological examinations of the pancreas and liver show that oxymatrine protected the islet architecture and prevented disordered structure of the liver. This study displays that oxymatrine can alleviate hyperglycemia and hyperlipemia in a high-fat diet and STZ-induced diabetic rats might by improving insulin secretion and sensitivity.

Keywords:

Oxymatrine

Sophorae flavescentis radix

Diabetes

Insulin resistance

Hypoglycemic

Hypolipidemic

Introduction

Diabetes mellitus (DM) is a complex metabolic disease characterized by high blood glucose levels and a disorder of carbohydrate, fat and protein metabolism. The number of people with diabetes worldwide will rise from over 366 million in 2011-552 million by the year of 2030 and the major part of this increase will occur in developing countries (International Diabetes Federation, 2011). The abnormal increase of blood glucose in diabetes will result in long-term damage and dysfunction of various organs including the eyes, kidneys, nerves and blood vessels (American Diabetes Association, 2010). Consequently, people with diabetes are more likely to have retina damage, nephropathy, amputation and stroke (Prabhakar et al., 2013). Currently, diabetes mellitus is one of the ten leading causes of death and one of the most costly chronic diseases worldwide (American Diabetes Association, 2010). Therefore, it is attractive and urgent to search for more effective and safer antidiabetic drugs.

Various drugs, including biguanide, thiazolidinedione, sulfonylurea, [alpha]-glycosidase inhibitors and insulin were used for treatment of diabetes for many years, however, the usage of these agents were restricted due to several considerable side effects (Prabhakar et al., 2013). A large number of medicinal plants and their bioactive constituents have been used to treat diabetes and its complications for hundreds of years throughout the world, especially in Asian countries (Xie and Du, 2011). Oxymatrine (Fig. 1A, OMT), the major quinolizidine alkaloid in Sophora flavescens (Kushen in Chinese), has various kinds of pharmacological effects, such as antihepatitis, analgesia, antiinflammatory, antioxidation, neuroprotection and antitumor in modern pharmacological research (Hong-Li et al., 2008; Wang et al., 2011 a,b). However, up to the present, few reports have confirmed in detail the effect of oxymatrine on diabetes. In order to obtain more knowledge about oxymatrine, this study was carried out to examine the antidiabetic property of oxymatrine in a high-fat diet combined with a low-dose of streptozotocin (STZ)-induced diabetic rats. In this work, we tested the effect of oxymatrine on blood glucose, lipid profiles, insulin secretion, and insulin sensitivity in diabetic rats.

[FIGURE 1 OMITTED]

Materials and methods

Reagents

STZ was purchased from Sigma-Aldrich Inc., Saint Louis, USA. ELISA kits of insulin and glucagon-like peptide-1 (GLP-1) were obtained from Merck Millipore Inc., Billerica, USA. ELISA kits of glucose transporter 4 (GLUT-4) were obtained from Cusabio Inc., Wuhan, China. The kits of blood glucose, non-esterified fatty acid (NEFA), total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-c), low density lipoprotein cholesterol (LDL-c), glycogen, hemoglobin and glycosylated hemoglobin (GHb) were purchased from Nanjing Jiancheng Bioengineering Institute. Oxymatrine (purity >98%) was supplied by Nanjing Qingze Pharmaceutical Co. Ltd., which was isolated from the Sophorae flavescentis radix. Oxymatrine standards and Sophorae flavescentes radix were purchased from National Institutes for Food and Drug Control, Beijing, China. Metformin hydrochloride (Met) was obtained from Beijing Jingfeng pharmaceutical Co. Ltd.

Analysis of oxymatrine by high-performance liquid chromatography (HPLC)

The oxymatrine in the Sophorae flavescentis radix was characterized by HPLC, according to the Chinese Pharmacopoeia Committee (2010). The samples were analyzed using Hedera N[H..sub.2] column (150mmx5mm, 4.6 |xm) with the detector wavelength set at 220 nm, and the mobile phase consisted of acteonitrile-ethanol-3% phosphoric acid solution (80:10:10, v/v).

Animals

Adult male Sprague-Dawley rats (200-220 g, animal quality certificate number SCKX2008-0010) were purchased from Nantong University laboratory animal center, Jiangsu province, China, and maintained at a constant temperature (23 [+ or -] 2[degrees]C) on a 12 h light/dark cycle with free access to normal laboratory chow and water. All procedures were carried out in accordance with the Principles of Laboratory Animal Care (World Health Organization, 1985).

Experimental induction of diabetes in rats

After 1 week of adaptive feeding, animals were randomly divided into the control and experimental group. The control group rats were given regular diet and the experimental group rats were fed with a high-fat diet (consisting of 70% standard laboratory chow, 15% carbohydrate, 10% lard and 5% yolk powder) (Wu et al., 2012). After 4 weeks of high-fat diet feeding, the experimental group rats were injected with STZ (30 mg/kg, dissolved in 0.01 M sodium citrate buffer, pH 4.4) intraperitoneally, while the control group rats were injected with the vehicle citrate buffer. Fasting blood glucose was measured 1 week after the injection. The rats with blood glucose above 11.1 mmol/1 were considered diabetic and selected for further pharmacological studies. The animals were fed their respective diets until the end of the study (Tahara et al., 2011; Veerapur et al., 2012; Wang et al., 2011a,b; Wu et al., 2012).

Experimental design

The rats (40 diabetic surviving and 8 normal) were randomly divided into 6 groups of 8 rats in each. Normal control (NC) group: normal rats treated with saline in a matched volume; diabetic control (DC) group: diabetic rats treated with saline in a matched volume; Metformin (Met) group: diabetic rats administered with metformin hydrochloride 200mg/kg/day; oxymatrine-50 (OMT-50) group: diabetic rats administered with oxymatrine 50mg/kg/day; oxymatrine-100 (OMT-100) group: diabetic rats administered with oxymatrine 100mg/kg/day; oxymatrine-150 (OMT-150) group: diabetic rats administered with oxymatrine 150 mg/kg. All the drugs were administered orally via an orogastric cannula, continuously for 11 weeks. Body weight, food and water intake were measured every 2 weeks, and fasting blood glucose was monitored periodically. A schematic diagram of the induction and treatment schedule is shown in Fig. 2.

At the end of study, urine samples were collected from the rats housed in individual metabolic cages for 24 h to measure urine volume. The rats were fasted 12 h, anaesthetized and blood was collected via the abdominal aorta with or without heparin for anticoagulant blood or serum, respectively. Livers, gastrocnemius muscle and pancreas were excised. Thereafter, gastrocnemius muscle and left lobe of livers were rinsed with cold isotonic saline and then stored at -70 [degrees]C for biochemical estimations. Pancreas and right lobe of livers were fixed in 4% neutral formaldehyde solution for histological examinations.

[FIGURE 2 OMITTED]

Glucose tolerance

Glucose tolerance was estimated by a simple oral glucose tolerance test (OGTT) at the end of treatment. After a 12 h fasting, the rats were orally administered with 2 g/kg of glucose and blood samples were collected from the caudal vein at 0, 30, 60 and 120 min after glucose administration to measure blood glucose levels. The results were expressed as an integrated area under glucose concentrationtime curve (AUC) (Veerapur et al., 2012).

Analysis of blood biochemical parameters

Hemoglobin and glycosylated hemoglobin (GHb) in whole blood were estimated by diagnostic kits according to the instruction of the kits. GHb was calculated as optical density value per 10g hemoglobin. The levels of blood glucose, NEFA, TG, TC, LDL-c and HDL-c in serum were determined using commercial kits according to the manufacturer's instructions. Serum insulin and GLP-1 were estimated using ELISA kits according to the manufacturer's instructions. Homeostatic model assessment (HOMA), an estimation of insulin resistance, was calculated by the HOMA2 Calculator according to previous reports (Matthews et al., 1985; Wallace et al., 2004).

Histological examination of the rat pancreas and livers

Pancreases and the right lobe of livers from the rats were fixed in 10% neutral formalin, dehydrated through a graded alcohol series, embedded in paraffin and cut into sections. Sections of about 4 [micro]m thickness were stained with hematoxylin and eosin and evaluated the related indicators under light microscope.

[FIGURE 3 OMITTED]

Estimation of liver and muscle glycogen levels

The glycogen levels of the liver and skeletal muscles were measured by the anthrone method as demonstrated in previous studies (Carroll etal., 1956). The concentrations of liver glycogen and muscle glycogen were expressed as mg of glycogen per wet weight.

Measurement of GLUT-4 content

Gastrocnemius muscle was thawed and homogenized with 5 mmol/1 Tris-HCl. Muscle homogenate was centrifuged at 4000 x g for 10 min. The muscle supernatants were immediately measured for GLUT-4 using the ELISA kit.

Statistical analysis

Data were expressed as mean [+ or -] standard deviation (SD) for eight animals in each group. Statistically significant differences between the two groups were ascertained by means of Student's t-test. In all cases probability values of p<0.05 were taken as statistically significant.

Results

HPLC chromatogram of oxymatrine and Sophorae flavescentis radix

The typical HPLC chromatograms of oxymatrine standard, oxymatrine sample and Sophorae flavescentis radix were shown in Fig. 1. By comparing the retention times and the UV spectra to the reference standard, oxymatrine in Sophorae flavescentis radix was well identified.

Effects of oxymatrine on body weight

The body weight of normal control rats increased from 264 [+ or -] 24 g to 560 [+ or -] 51 g during the entire study, however, the body weight of diabetic control rats was significantly less than the normal control group after an injection with STZ (Fig. 3). Oxymatrine did not alter body weight significantly in diabetic rats during the first 8 weeks of treatment. However, during the last 3 weeks, the body weight of the OMT-150 group was significantly higher (p < 0.05) than that of diabetic control group.

Effects of oxymatrine on urine volume, food and water intake

Table 1 shows high-fat diet and STZ-induced diabetic rats had increased urine volume, food and water consumption compared with the normal control rats. After oxymatrine treatment at a 50, 100 and 150mg/kg dose, urine volume and water consumption were decreased significantly (p < 0.01), and at treatment with oxymatrine at the 100 and 150mg/kg dose, food consumption was decreased significantly (p < 0.01).

Effects of oxymatrine on fasting blood glucose, insulin and HOMA-IR

The hypoglycemic effect of oxymatrine was assessed by measuring the fasting blood glucose levels in weeks 0, 4, 8 and 11 of the treatment. As shown in Table 2, the blood glucose levels of diabetic control rats were increased significantly (p<0.01) after the injection of STZ, compared with normal control rats. Before the administration of respective drugs, the fasting plasma glucose levels of the five diabetic groups (DC group, Met group, OMT-50 group, OMT-100 group and OMT-150 group) were almost identical. Compared with the diabetic control group, administration of oxymatrine (50,100 and 150 mg/kg) significantly decreased the fasting blood glucose levels at week 4, 8 and 11 (p < 0.05).

As shown in Table 3, the levels of serum insulin were significantly decreased in diabetic control group. After 11 weeks' treatment with oxymatrine, the levels of serum insulin were significantly increased compared with diabetic control group. Administration of oxymatrine for 11 weeks also significantly reduced (p<0.01) HOMA values compared with diabetic control group. These results suggested that treatment with oxymatrine improves insulin resistance induced by high-fat diet and STZ.

Effects of oxymatrine on GHb

To further evaluate the hypoglycemic effect of oxymatrine in a high-fat diet and STZ-induced diabetic rats, the GHb in rats was determined. In Fig. 4, the levels of GHb in diabetic control rats were significantly increased (p < 0.01), which was 172% of normal control rats. Compared with diabetic control rats, treatment with oxymatrine (50, 100 and 150 mg/kg) for 11 weeks showed a significant reduction (p < 0.01) of GHb levels.

Effects of oxymatrine on OGTT

Compared with the normal control rats, diabetic rats exhibited a significant elevation (p<0.01) of fasting blood glucose at time points 0, 0.5,1 and 2 h and a significant increase (p < 0.01) of AUC. The results suggested that the glucose tolerance of diabetic rats was significantly impaired (Fig. 5). After treatment with different doses of oxymatrine (50, 100 and 150mg/kg) for 11 weeks, the blood glucose levels (at time points 0,0.5,1 and 2 h) and AUC were reduced significantly.

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

Effects of oxymatrine on liver and muscle glycogen content

The effects of oxymatrine on liver and muscle glycogen content are shown in Table 4. Compared with normal control rats, the liver and muscle glycogen content in diabetic control rats decreased significantly (p < 0.01). Treatment with different doses of oxymatrine (50,100 and 150 mg/kg) for 11 weeks resulted in a marked increase (p < 0.05) in the glycogen content in both the liver and muscle when compared with diabetic control rats.

Effects of oxymatrine on lipid profiles

Table 5 shows the effect of oxymatrine on the NEFA, TG, TC, LDL-c and FIDL-c of diabetic rats. Compared with normal control rats, diabetic control rats exhibited significantly higher (p < 0.01) levels of serum NEFA, TG, TC and LDL-c, and lower levels (p < 0.01) of serum HDL-c. Treatment with different doses of oxymatrine (50, 100 and 150 mg/kg) for 11 weeks resulted in a marked decrease in the levels of serum NEFA, TG, TC and LDL-c and a marked increase in the levels of serum HDL-c when compared with diabetic control rats.

Effects of oxymatrine on liver and pancreas histology Histopathology of normal control rats showed usual hepatic cells and architecture (Fig. 6A) whereas the diabetic control showed disordered liver structure with hepatocellular necrosis and extensive vacuolization (Fig. 6B). Metformin significantly attenuated hepatocellular vacuolization (Fig. 6C). Treatment with oxymatrine for 11 weeks reversed these changes to near normalcy (Fig. 6D-F).

Histopathology of normal control rats showed a normal histological structure of pancreas with normal sized islets (Fig. 7A). However, an injection of STZ partially damaged the pancreatic islets, and decreased the size and number of islets (Fig. 7B). Treatment with metformin for 11 weeks significantly attenuated the damage of the pancreatic islets (Fig. 7C). Treatment with oxymatrine for 11 weeks at 50 and 100mg/kg dose (Fig. 7D-F), significantly increased the size and number of islets in diabetic rats.

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

[FIGURE 8 OMITTED]

Effects of oxymatrine on serum GLP-1 levels

The effects of oxymatrine on serum GLP-1 levels are shown in Fig. 8. Compared with the normal control rats, diabetic rats exhibited a significant reduction (p<0.01) of GLP-1 levels. After treatment with oxymatrine at 50mg/kg dose, the levels of GLP-1 did not significantly changed, but after treatment with oxymatrine at 100 and 150mg/kg dose, rats showed a significant elevation (p< 0.05) in GLP-1 levels.

Effects of oxymatrine on GLUT-4 content in muscle

The effects of oxymatrine on GLUT-4 contents in muscle are shown in Fig. 9. Diabetic rats exhibited a significant reduction (p < 0.01) of GLUT-4 contents in muscle as compared with the normal control rats. Treatment with oxymatrine at 50, 100 and 150mg/kg dose for 11 weeks, rats showed a significant elevation (p < 0.05) in GLUT-4 contents in muscle.

Discussion

Many studies have reported that long term high-fat diet led to insulin resistance and hyperinsulinaemia, under the strain of compensatory hyperinsulinaemia, the [beta]-cells were easily damaged by low doses of STZ (Davidson et al., 2011 ; Tahara et al., 2011). In other words, the high-fat diet combined with low doses of STZ-induced diabetic rats have the characteristics of later-stage T2DM, including hyperglycemia, insulin resistant, moderate impairment of insulin secretion and abnormalities in lipid metabolism (Srinivasan et al., 2005). In the present study, we induced the diabetic rats by feeding them with a high-fat diet for 4 weeks and injecting them with low doses of STZ to mimic the diabetic model, and then investigated the antidiabetic effects and potential mechanisms of oxymatrine in this model.

[FIGURE 9 OMITTED]

In this study, we found the body weight of rats fed with high-fat diet (372 [+ or -] 36g) was higher than normal control rats (350 [+ or -] 33 g); however, the body weight was sustained reduction and significantly less than the normal control rats after injection with STZ. Reduction of body weight may be due to the catabolism of proteins in muscular tissue caused by insulin deficiency (Sundaram et al., 2013). We also found the diabetic rats showed signs of polyphagia, polydipsia and polyuria. However, treatment with oxymatrine attenuated the reduction of body weight and decreased the food intake, water intake and urine volume.

The reduction of the blood glucose level is the primary therapeutic goal of diabetes. In the present study, the blood glucose level of diabetic rats was significantly decreased when treated With oxymatrine, which provided direct evidence for the hypoglycemic effect of oxymatrine. The amount of glycosylated hemoglobin reflects the average blood glucose level (Gabbay, 1976). In this study, treatment with oxymatrine significantly also reduced the glycosylated hemoglobin level in diabetic rats by virtue of its hypoglycemic activity.

We infer that there are two potential mechanisms of the hypoglycemic action of oxymatrine: firstly, it may stimulate insulin release or regenerate [beta]-cells; secondly, it may enhance the sensitivity of target tissues to insulin. Therefore, we determined the serum insulin level and the histology of the pancreas. Our results show that the serum insulin level and the number and size of islets were significantly decreased, in line with previous reports (Prabhakar et al., 2013), whereas, treatment with oxymatrine significantly increased the number of islets (in 30 random fields of pathological sections, the number of oxymatrine-150 group is 21 [+ or -] 3, but the number of diabetic group is 15 [+ or -] 3) and promoted the secretion of insulin in the diabetic rats. We believe that GLP-1 played an important role in this progress. GLP-1, an incretin hormones secreted by the intestinal L cells, can be rapidly released after a meal's ingestion, and then stimulates insulin secretion and inhibits glucagon secretion in a glucose-dependent manner. Furthermore, GLP-1 can increase P-cell mass by stimulating proliferation and inhibiting apoptosis. Therefore, GLP-1 has been explored as a new pharmacological therapy for type 2 diabetes (Ahren, 2011). In the present study, GLP-1 secretion was significantly reduced in diabetic rats, in agreement with previous reports. Treatment with oxymatrine for 11 weeks significantly increased the serum GLP-1 level, which may be its mechanism for increasing insulin secretion and amelioration of impaired pancreatic [beta]-cells.

The amelioration of insulin sensitivity is an important therapeutic approach for type 2 diabetes. The HOMA value reflects the extent of insulin resistance in diabetes (Matthews et al" 1985). OGTT reflects the efficiency of the body to dispose of glucose and it is a simple test for an indirect assessment of insulin resistance in animals. In this study, treatment with oxymatrine reduced the increase of HOMA value as well as the damage of OGTT. It is suggested that oxymatrine could ameliorate the insulin sensitivity of high-fat diet and STZ-induced diabetic rats.

Raised plasma NEFA level and hypertriglyceridemia are the important inductor of both peripheral and hepatic insulin resistance. TG and NEFA oxidation competitively inhibits glucose oxidation, so high levels of TG and NEFA reduce glucose uptake and utilization in skeletal muscle and lead to insulin resistance. On the other hand, insulin deficiency leads to abnormalities in lipid metabolism, including accumulation of lipids in animals (Moree et al., 2013; Rajalingam et al., 1993). In the present study, treatment with oxymatrine markedly reduced the hypertriglyceridaemia and hypercholesterolaemia. The potential mechanism is oxymatrine decrease the absorption and endogenous production of triglycerides and cholesterol, at the same time increase uptake in peripheral tissues.

The liver is the vital organ of metabolism and plays an important role in maintaining normal blood glucose levels via its ability to store glucose as glycogen and hydrolyze glycogen to glucose. Histopathological study of liver revealed that oxymatrine reduced hypertrophy of hepatocytes. It indicated that the oxymatrine may have the capacity to prevent liver injury and increase its ability to maintain normal blood glucose levels in high-fat diet and STZinduced rats (Atsuo et al., 2011).

GLUT-4, present in adipose tissue, skeletal and cardiac muscles, plays a critical role in the regulation of glucose homeostasis through the translocation and activation triggered by insulin (Charron et al., 1999). Intracellular GLUT-4 translocates to the plasma membrane and facilitates glucose uptake stimulated by insulin. Under the diabetic condition, GLUT-4 expression and translocation are reduced due to the impairment of insulin signaling. These alterations lead to a decrease in the consumption of glucose in adipose tissue and skeletal muscles (Gandhi et al., 2013) and elevation of the blood glucose level. In the present study, we demonstrate for the first time that oxymatrine increased the content of GLUT-4 in skeletal muscles. The results indicate that oxymatrine could improve glucose transport, which is a rate-limiting step of glucose uptake in the tissue.

Conclusion

According to the studies on high fat-diet and streptozotocin-induced diabetic rats, the administration of oxymatrine attenuated the blood glucose, GHb and blood lipoid levels as well as decreased the urine volume, water and food consumption. The cause of these effects might be due to oxymatrine improve insulin secretion and sensitivity, at least in part. Further studies will be in progress to elicit the exact mechanism(s) of oxymatrine for its antidiabetogenic effect.

ARTICLE INFO

Article history:

Received 26 September 2013

Received in revised form

12 December 2013

Accepted 22 February 2014

Conflict of interest

The authors have declared that there is no conflict of interest.

Acknowledgements

This work was supported by a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions. The assistance of the staff is gratefully acknowledged.

References

Ahren, B., 2011.GLP-1 for type 2 diabetes. Exp. Cell Res. 317,1239-1245.

American Diabetes Association, 2010. Diagnosis and classification of diabetes meliitus. Diabetes Care 33, s62-s69.

Atsuo, T.. Akiko. M.Y., Masayuki, S., 2011. Effects of antidiabetic drugs in high-fat diet and streptozotocin-nicotinamide-induced type 2 diabetic mice. Eur. J. Pharmacol. 655,108-116.

Carroll, N.V., Longley, R.W., Roe, J.H., 1956. The determination of glycogen in liver and muscle by use of anthrone reagent. J. Biol. Chem., 583-593.

Charron, M.J.. Katz, E.B., Olson, A.L., 1999. GLUT4 gene regulation and manipulation. J. Biol. Chem. 6,3253-3256.

China Pharmacopoeia Committee, 2010. Pharmacopoeia of the People's Republic of China (Edition of 2010). China Medical Science Press, Beijing, pp. 188-189.

Davidson, E.P., Coppey, L.J., Holmes, A., Dake, B., Yorek, M.A., 2011. Effect of treatment of high fat fed/low dose streptozotocin-diabetic rats with Ilepatril on vascular and neural complications. Eur. J. Pharmacol. 668,497-506.

Gabbay, K.H., 1976. Glycosylated haemoglobin and diabetic control. N. Engl. J. Med., 443-444.

Gandhi, G.R., Stalin, A., Balakrishna, K., Ignacimuthu, S., Paulraj, M.G., Vishal, R., 2013. Insulin sensitization via partial agonism of PPARy and glucose uptake through translocation and activation of GLUT4 in PI3K/p-Akt signaling pathway by embelin in type 2 diabetic rats. Biochim. Biophys. Acta (BBA)--Gen. Subj. 1830, 2243-2255.

Hong-Li, S., Lei, L, Lei, S., Dan, Z.. De-Li, D., Guo-Fen, Q., Yan, L, Wen-Feng, C., Bao-Feng, Y., 2008. Cardioprotective effects and underlying mechanisms of oxymatrine against ischemic myocardial injuries of rats. Phytother. Res. 22, 985-989.

International Diabetes Federation, 2011. Global Diabetes Plan 2011-2012., pp. 4.

Matthews, D.R., Hosker, J.R., Rudenski, A.S., Naylor, B.A., Treacher, D.F., Turner, R.C., 1985. Homeostasis model assessment: insulin resistance and ([beta]-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia, 412-419.

Moree, S.S., Kavishankar, G.B., Rajesha, J., 2013. Antidiabetic effect of secoisolariciresinol diglucoside in streptozotocin-induced diabetic rats. Phytomedicine 20, 237-245.

Prabhakar, P.K., Prasad, R., Ali, S., Doble, M., 2013. Synergistic interaction of ferulic add with commercial hypoglycemic drugs in streptozotocin induced diabetic rats. Phytomedicine 20,488-494.

Rajalingam, R., Srinivasan, N., Govindarajulu, P., 1993. Effects of alloxan induced diabetes on lipid profiles in renal cortex and medulla of mature albino rats. Indian J. Exp. Biol. 31,577-579.

Srinivasan, K., Viswanad, B., Asrat, L, Kaul, C.L., Ramarao, P., 2005. Combination of high-fat diet-fed and low-dose streptozotocin-treated rat: a model for type 2 diabetes and pharmacological screening. Pharmacol. Res. 52,313-320.

Sundaram. R., Naresh, R., Shanthi, P., Sachdanandam, P., 2013. Modulatory effect of green tea extract on hepatic key enzymes of glucose metabolism in streptozotocin and high fat diet induced diabetic rats. Phytomedicine 20,577-584.

Tahara, A., Matsuyama-Yokono, A., Shibasaki, M., 2011. Effects of antidiabetic drugs in high-fat diet and streptozotocin-nicotinamide-induced type 2 diabetic mice. Eur.J. Pharmacol. 655,108-116.

Veerapur, V.P., Prabhakar, K.R., Thippeswamy, B.S., Bansal, P., Srinivasan, K.K., Unnikrishnan, M.K., 2012. Antidiabetic effect of Ficus racemosa Linn, stem bark in high-fat diet and low-dose streptozotocin-induced type 2 diabetic rats: a mechanistic study. Food Chem. 132.186-193.

Wallace, T.M., Levy, J.C., Matthews, D.R., 2004. Use and abuse of HOMA modeling. Diabetes Care 27,1487-1495.

Wang, Y., Campbell. T.. Perry, B., Beaurepaire, C, Qin, L., 2011a. Hypoglycemic and insulin sensitizing effects of berberine in high-fat diet- and streptozotocin-induced diabetic rats. Metabolism 60, 298-305.

Wang, Y., Zhao, W., Xue, R., Zhou, Z., Liu, F., Han, Y., Ren, G., Peng, Z., Cen, S., Chen, H., Li, Y., Jiang, J., 2011b. Oxymatrine inhibits hepatitis B infection with an advantage of overcoming drug-resistance. Antiviral Res. 89,227-231.

World Health Organization, 1985. World Health Organization Chronicle., pp. 51-56.

Wu, D., Wen, W., Qi, C, Zhao, R., Lii, J., Zhong, C, Chen, Y., 2012. Ameliorative effect of berberine on renal damage in rats with diabetes induced by high-fat diet and streptozotocin. Phytomedicine 19,712-718.

Xie, W., Du, L, 2011. Diabetes is an inflammatory disease: evidence from traditional Chinese medicines. Diabetes Obes. Metab. 13,289-301.

Changrun Guo (a,1), Chunfeng Zhang (a,1), Lu Li (a), Zhenzhong Wang (b), Wei Xiao (b,*), Zhonglin Yang (a,*)

(a) State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing 210009, PR China

(b) Jiangsu Kanion Pharmaceutical Co. Ltd., Lianyungang 222001, PR China

Abbreviations: AUC, area under glucose concentration-time curve; DC, diabetic control; DM, diabetes mellitus; GHb, glycosylated hemoglobin; GLP-1, glucagonlike peptide-1; GLUT-4, glucose transporter-4; HDL-c, high density lipoprotein cholesterol; HOMA, homeostatic model assessment; LDL-c, low density lipoprotein cholesterol; Met, metformin hydrochloride; NC, normal control; NEFA, nonesterified fatty acid; OGTT, oral glucose tolerance test; OMT, oxymatrine; STZ, streptozotocin; T2DM, type 2 diabetes mellitus; TC, total cholesterol; TG, triglyceride.

* Corresponding authors at: State Key Laboratory of Natural Medicines, China Pharmaceutical University, No. 24Tongjia Lane, Nanjing City 210009, PR China. Tel.: +86 25 83271426; fax: +86 25 83271426.

E-mail addresses: wzhzh-nj@163.net (W. Xiao), YZLH950@126.com (Z. Yang).

(1) These two authors contributed equally to this work.

http://dx.doi.org/10.1016/j.phymed.2014.02.007
Table 1
Effects of different treatments on food intake, water intake and urine
volume in diabetic rats.

Groups     Food intake (g/kg BW)      Water intake (ml/kg BW)

NC          79.7 [+ or -] 10.4         84.8 [+ or -] 11.3
DC         185.1 [+ or -] 24.1 (##)   588.9 [+ or -] 76.6 (##)
Met        130.7 [+ or -] 16.9 **     266.9 [+ or -] 34.7 **
OMT-50     161.9 [+ or -] 21.1        272.3 [+ or -] 35.4 **
OMT-100    137.7 [+ or -] 17.9 *      246.7 [+ or -] 35.1 **
OMT-150    113.5 [+ or -] 14.7 **     224.2 [+ or -] 29.1 **

Groups     Urine volume (ml/kg BW)

NC          89.7 [+ or -] 17.5
DC         500.2 [+ or -] 64.0 (##)
Met        234.1 [+ or -] 36.9 **
OMT-50     246.7 [+ or -] 21.5 **
OMT-100    228.7 [+ or -] 24.2 **
OMT-150    207.1 [+ or -] 34.6 **

Values are mean [+ or -] SD for 8 rats in each group.

(##) p < 0.01 as compared with the normal control group.

* p < 0.05 as compared with the diabetic control group.

** p < 0.01 as compared with the diabetic control group.

Table 2
Effects of different treatments on feasting blood glucose in diabetic
rats.

Groups     Feasting blood glucose (mmol/1)

           Before treatment            4 weeks after treatment

NC          5.31 [+ or -] 0.78          6.55 [+ or -] 1.37
DC         26.64 [+ or -] 3.22 **      31.92 [+ or -] 2.89 (##)
Met        24.94 [+ or -] 2.06         20.83 [+ or -] 3.77 **
OMT-50     25.69 [+ or -] 3.45         21.27 [+ or -] 4.13 **
OMT-100    25.53 [+ or -] 3.69         20.44 [+ or -] 4.52 **
OMT-150    25.36 [+ or -] 2.45         17.62 [+ or -] 3.94 **

Groups     Feasting blood glucose (mmol/1)

           8 weeks after treatment     11 weeks after treatment

NC         5.81 [+ or -] 0.47           5.57 [+ or -] 1.11
DC         25.95 [+ or -] 3.64 (##)    21.19 [+ or -] 3.82 (##)
Met        15.24 [+ or -] 5.59 *       15.55 [+ or -] 4.81 *
OMT-50     15.48 [+ or -] 4.38 *       14.53 [+ or -] 3.33 *
OMT-100    17.76 [+ or -] 4.72 *       13.24 [+ or -] 3.59 **
OMT-150    16.05 [+ or -] 3.46 **      12.96 [+ or -] 3.09 **

Values are mean [+ or -] SD for 8 rats in each group.

** p<0.01 as compared with the normal control group.

* p < 0.05 as compared with the diabetic control group.

** p < 0.01 as compared with the diabetic control group.

Table 3
Effects of different treatments on serum insulin and HOMA value in
diabetic rats.

Groups     Serum insulin (mU/l)       HOMA value

NC         20.42 [+ or -] 1.67        2.29 [+ or -] 0.11
DC         13.72 [+ or -] 1.27 (##)   5.15 [+ or -] 2.79 (#)
Met        14.81 [+ or -] 2.01        2.76 [+ or -] 0.54 *
OMT-50     15.76 [+ or -] 1.33 *      2.64 [+ or -] 1.11 *
OMT-100    15.43 [+ or -] 1.21 *      2.49 [+ or -] 0.49 *
OMT-150    16.48 [+ or -] 1.60 *      2.41 [+ or -] 0.47 *

Values are mean [+ or -] SD for 8 rats In each group.

(#) p < 0.05 as compared with the normal control group.

(##) p < 0.01 as compared with the normal control group.

* p < 0.05 as compared with the diabetic control group.

Table 4
Effects of different treatments on liver glycogen and muscle glycogen
in diabetic rats.

Groups     Liver glycogen             Muscle glycogen
           (mg/g liver)               (mg/g muscle)

NC         12.52 [+ or -] 2.72        1.81 [+ or -] 0.25
DC          8.55 [+ or -] 0.90 (##)   1.29 [+ or -] 0.15 (##)
Met        11.83 [+ or -] 2.55 **     1.66 [+ or -] 0.43 *
OMT-50     10.27 [+ or -] 1.94 *      1.51 [+ or -] 0.31
OMT-100    10.74 [+ or -] 1.35 **     1.52 [+ or -] 0.17 *
OMT-150    11.17 [+ or -] 1.96 **     1.71 [+ or -] 0.44 *

Values are mean [+ or -] SD for 8 rats in each group.

(##) p<0.01 as compared with the normal control group.

* p < 0.05 as compared with the diabetic control group.

** p <0.01 as compared with the diabetic control group.

Table 5
Effects of different treatments on NEFA, TG, TC, LDL-C and HDL-C in
diabetic rats.

Groups     NEFA ([micro]mol/1)          TG (mmol/l)

NC         347.1 [+ or -] 50.0          0.691 [+ or -] 0.256
DC         463.1 [+ or -] 52.8 (##)     2.266 [+ or -] 0.372 (##)
Met        386.9 [+ or -] 65.5 *        1.371 [+ or -] 0.318 **
OMT-50     379.6 [+ or -] 69.4 *        1.452 [+ or -] 0.317 **
OMT-100    387.6 [+ or -] 54.2 *        1.338 [+ or -] 0.349 **
OMT-150    352.9 [+ or -] 41.6 **       1.192 [+ or -] 0.278 **

Groups     TC (mmol/l)                  LDL-C (mmol/l)

NC         3.043 [+ or -] 0.363         1.418 [+ or -] 0.133
DC         5.657 [+ or -] 0.735 (##)    2.536 [+ or -] 0.548 (##)
Met        4.596 [+ or -] 0.909 *       1.684 [+ or -] 0.396 *
OMT-50     3.718 [+ or -] 0.713 **      1.476 [+ or -] 0.366 **
OMT-100    3.684 [+ or -] 0.580 **      1.377 [+ or -] 0.410 **
OMT-150    3.383 [+ or -] 0.772 **      1.228 [+ or -] 0.366 **

Groups     HDL-C (mmol/l)

NC         1.431 [+ or -]0.373
DC         0.778 [+ or -] 0.092 (##)
Met        0.993 [+ or -] 0.251
OMT-50     1.123 [+ or -] 0.266 **
OMT-100    1.144 [+ or -] 0.379 *
OMT-150    1.215 [+ or -] 0.306 **

Values are mean [+ or -] SD for 8 rats in each group.

(##) p <0.01 as compared with the normal control group.

* p < 0.05 as compared with the diabetic control group.

** p < 0.01 as compared with the diabetic control group.
COPYRIGHT 2014 Urban & Fischer Verlag
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2014 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Guo, Changrun; Zhang, Chunfeng; Li, Lu; Wang, Zhenzhong; Xiao, Wei; Yang, Zhonglin
Publication:Phytomedicine: International Journal of Phytotherapy & Phytopharmacology
Article Type:Report
Date:May 15, 2014
Words:5405
Previous Article:Suppression of adipocyte hypertrophy by polymethoxyflavonoids isolated from Kaempferia parviflora.
Next Article:Effects of total glucosides of paeony on immune regulatory toll-like receptors TLR2 and 4 in the kidney from diabetic rats.
Topics:

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters