• Advances in Traditional Medicine
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• v.9 no.4
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• pp.307-314
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• 2009

Oxidative stress plays an important role in the pathogenesis of various diabetic complications and small intestine is vulnerable to damage resulting in morphological and functional changes. In this study, the effects of Asystasia gangetica leaf extract (AGLE) on oxidative stress status in small intestine of diabetic rats were examined. The leaves of Asystasia gangetica was extracted with 70% ethanol. Oral administration of AGLE once daily (100 mg/kg and 200 mg/kg b.w.) for 28 days to diabetic rats significantly (P < 0.05) increased antioxidant levels of catalase, superoxide dismutase, glutathione peroxidase, glutathione, GSSH, carbohydrate metabolizing enzyme, glucose-6-phosphate dehydrogenase. The increased levels of protein carbonyl content, lipid peroxidation and xanthine oxidase/xanthine dehydrogenase in diabetic rats were reverted back to near normal levels on treatment with AGLE. Both doses of AGLE offered significant activity (P < 0.01) against oxidative damage and were comparable with standard, glibenclamide. The results revealed the occurrence of oxidative stress in small intestine during diabetes and suggest the potential of AGLE as an antioxidant in protecting the tissue defense system against oxidative damage in streptozotocin-induced diabetes.

• Journal of Nutrition and Health
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• v.34 no.3
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• pp.253-264
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• 2001

This study was carried out to examine a part of the mechanism for the etiology of diabetic complications. Thirty normal and forty streptozotocin(STZ)-induced diabetic rats were used as the animal models. The animals were sacrificed at the time points of 3 days, 1,2,4 and 6 weeks after STZ-injection and a time course changes in the concentrations of thiobarbituric acid-reactive substances(TBARS) in blood, urine, and tissues, along with the levels of conjugated dienes in tissues were measured as indices of in vivo lipid peroxidation. The activities of antioxidant enzymes, catalase, superoxide dismutase, glutathione peroxidase and the levels of blood retinol and alpha-tocopherol were also measured. The diabetic rats maintained a slightly higher plasma TBARS level throughout the experiment. The urinary TBARS level was significantly higher in diabetic group and gradually increased with time. Concentrations of TBARS in liver, heart, and kidney tissues from diabetic animals were higher than those from the normal group. An increase of conjugated dienes was also observed in the all tissues examined. The kidney tissue of diabetic animals revealed more significant lipid peroxidation state than any other organ tissues. The activities of hepatic antioxidant enzymes such as catalase, superoxide dismutase, glutathione peroxidase were higher in diabetic animals compared to the control ones and increased with the duration of diabetes mellitus. The plasma levels of vitamin A and E were loser in diabetic animals than in normal controls throughout the experimental period. The level of vitamin E in diabetic animals was significantly decreased with the duration of the disease. The results of this study suggest that an effective regimen to suppress the adverse changes in lipid peroxidation and antioxidant defense system is required from the early stage of the disease to prevent the development of diabetic complications. (Korean J Nutrition 34(3) : 253∼264, 2001)

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.5
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• pp.901-907
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• 1997

The purpose of this study was to investigate the effects of green tea catechin o n free radical generation system and peroxidative damage in the liver of streptozotocin(STZ)-induced diabetic rats. Spragu-Dawley male rats weighing 150$\pm$10gm were randomly assigned to one normal and three STZ-induced diabetic groups; diabetic groups were classified to catechin free diet(DM-oC group), 0.5% catechin diet(DM-0.5C group) and 1% catechin diet(DM-1C group) according to the levels of dietary catechin supplementation. Diabetes was experimentally induced by intravenous injection of 55mg/kg of body wt of STZ in citrate buffer(pH 4.3) after feeding of three experimental diet for 4 weeks. Animals were sacrificed at the 6th day of diabetic states. Activities of serum glutamic oxaloacetic transaminase(GPT) in DM-oC groups were higher than those of the normal group, and those in catechin supplementation group were similar to those of the normal group. Liver lipid peroxide values increased by 153%, 49%, and 27% in Dm-oC, DM-0.5C and DM-0C and Dm-1C but was not significantly different in catechin supplementation groups compared with the normal group, and liver cytochrome $P_{450}$ contents was similar to result of XOD activity. In electron microscopic examination of liver, lysosome was relatively scattered in Dm-oC and Dm-0.5C group and preserved normal shapes in DM-1C group. The present results indicate that STZ-induced diabetic rats are more sensitive to oxidative stress, leading to the acceleration of lipid peroxidation process, but this was reduced by anti-oxidative effect of high level of dietary catechin. It is concluded that dietary catechin serves as powerful antioxidant against lipid peroxidation in diabetic rats.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.1
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• pp.39-45
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• 2003

Reactive oxygen species (ROS) have been suggested to be contributory factors in complications of diabetes mellitus. In the present study, we investigated the generation of superoxide, the lipid peroxide level measured as thiobarbituric acid reactive substances, the vasorelaxation of isolated thoracic aorta and the iNOS expression in kidney of streptozotocin induced diabetic rats. Sprague Dawley rats were divided into four groups: control, ascorbate (400 mg/kg rat weight daily in drinking water), diabetic (single dose of 50 mg of STZ/kg i.p.) and diabetic simultaneously fed with ascorbate for 12 wk. Rats in groups were studied at tri-weekly intervals (0 to 12 wk). Diabetic rats were evaluated periodically with changes of plasma glucose levels and body weight. The ascorbate supplimentation attenuated the development of hyperglycemia and weight loss induced by STZ injection in rats. In the present experimental condition, the ascorbate supplimentation had no significant effect on plasma glucose levels and changes in body weight of normal rate. The superoxide generation, formation of thiobarbituric acid reactive substance and iNOS expression in kidney were significantly increased in STZ-treated rats that were decreased by ascorbate supplimentation. The ascorbate supplimentation had no effect on vasorelaxation of isolated thoracic aorta. These results indicate that ascorbate supplimentation may exert an inhibitory effect on STZ-induced oxidative tissue damage through protection of pancreatic islet cells by scavanging reactive oxygen species. The ascorbate supplimentation may possibly attenuate the renal complication of diabetes mellitus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.1
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• pp.175-181
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• 1998

The relation between lipid peroxidation and thrombotic reaction were investigated in streptozotocin (STZ)-induced diabetic rats. Sprague-Dawley male rats weighing 100$\pm$10gm were randomly assigned to normal and STZ-induced diabetic group(DM). Diabetes was experimentally induced by intravenous injection of 55mg/kg of body weight of STZ in citrate buffer(pH 4.3) after 4 weeks feeding of basal diet. Animals were sacrificed at the 6th day of diabetic states. Body weight gains were lower in diabetic group after STZ injection. Serum levels of thiobarbituric acid reacting substances(TBARS) that were markedly increased in DM group compared with of normal group. TBARS levels of HDL and LDL were similar patterns to total TBARA of serum. Activities of platelet phospholipase A2(PLA2) were higher in diabetic group than those of normal group. Activities of platelet cyclooxygenase were 106% in DM group than normal group. Platelet thromboxane A2(TXA2) formation was increased in DM group than normal group. Production of aortic prostacyclin(PGI2) was lower in diabetic group than that of normal group. PGI2/TXA2 ratios were decreased by 55% in DM groups than those of normal group. The present results indicate that STZ-induced diabetic rats are more sensitive to oxidative stess which leads to acceleration of lipid peroxidation and platelet aggregability. In conclusion, accelerating effect of lipid peroxidation and thrombogenesis in diabetic state is regareded to be resulted from enhancement of PLA2 activity and arachidonic acid metabolism, inhibition of antiaggrgating agent and aortic PGI2 formation.

• Advances in Traditional Medicine
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• v.10 no.3
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• pp.165-172
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• 2010

The present study investigated the effect of silymarin, a flavonoid, on streptozotocin (STZ) - induced diabetic dyslipidaemia in rats. Experimental diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg). Silymarin (25 mg/kg and 50 mg/kg) was orally administered to diabetic rats for a period of 15 days. Blood glucose levels, serum lipid profile and liver glycogen levels were estimated following the established procedures. Biochemical observations were supplemented with histological examination of liver sections. Oral administration of silymarin to diabetic rats significantly (P < 0.001) decreased the blood glucose levels ($259.99{\pm}23.64$ vs. $99.90{\pm}2.62$ [25 mg] & $89.17{\pm}3.32$ [50 mg]). The most interesting finding was the significant (p < 0.001) increase in HDL-cholesterol levels ($26.99{\pm}0.61$ vs. $40.55{\pm}0.52$ [25 mg] & $41.12{\pm}0.37$ [50 mg]) whereas, there was a significant decrease in serum total cholesterol (TCh), triglycerides (TG), low density lipoprotein (LDL) and very low density lipoprotein (VLDL) cholesterol levels observed in silymarin treated diabetic rats. STZ treatment caused significant degeneration of liver parenchyma, which was normalized to near normal morphology by administration of silymarin. The findings indicate that silymarin effectively improved the overall lipid profile and restored the glycogen stores in the liver of STZ-induced diabetic rats, in a dose dependent manner. The results indicate existence of abnormalities in lipid metabolism in STZ-induced diabetic rats and suggest a protective effect of silymarin in this animal model.

• Korean Journal of Food Science and Technology
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• v.41 no.1
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• pp.77-81
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• 2009

This study examined the effects of black ginseng (9 times-steamed ginseng) on hypoglycemic action in streptozotocininduced diabetic rats as well as changes in ginsenoside composition by the steaming process. As the number of steaming cycles increased, the amounts of crude saponin and most ginsenoside contents decreased, while the amount of ginsenoside- Rg3 and the ratio of PD/PT (=[$Rb_1+Rb_2+Rc+Rd+Rg_3]/[Re+Rb_1+Rh_1]$) increased. This ginsenoside composition is a unique characteristic compared to other types of ginseng products. In order to investigate the hypoglycemic effect of the black ginseng extract, in vivo studies were performed in rats with streptozotocin-induced diabetes. The studies showed that the administration of the black ginseng extract decreased high blood glucose levels (more than 300 mg/dL) to a normal level (102 mg/dL). These results suggest that this black ginseng extract has a significant hypoglycemic effect and can be used as an anti-diabetic substance for dietary supplements or new drugs.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.3
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• pp.257-267
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• 2018

The present study aimed to evaluate the cinnamic acid effect on memory impairment, oxidative stress, and cholinergic dysfunction in streptozotocin (STZ)-induced diabetic model in mice. In this experimental study, 48 male Naval Medical Research Institute (NMRI) mice (30-35 g) were chosen and were randomly divided into six groups: control, cinnamic acid (20 mg/kg day, i.p.), diabetic, and cinnamic acid-treated diabetic (10, 20 and 40 mg/kg day, i.p.). Memory was impaired by administering an intraperitoneal STZ injection of 50 mg/kg. Cinnamic acid was injected for 40 days starting from the 21st day after confirming STZ-induced dementia to observe its therapeutic effect. Memory function was assessed using cross-arm maze, morris water maze and passive avoidance test. After the administration, biochemical parameters of oxidative stress and cholinergic function were estimated in the brain. Present data indicated that inducing STZ caused significant memory impairment, whereas administration of cinnamic acid caused significant and dose-dependent memory improvement. Assessment of brain homogenates indicated cholinergic dysfunction, increase in lipid peroxidation and reactive oxygen species (ROS) levels, and decrease in glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) activities in the diabetic group compared to the control animals, whereas cinnamic acid administration ameliorated these indices in the diabetic mice. The present study demonstrated that cinnamic acid improves memory by reducing the oxidative stress and cholinergic dysfunction in the brain of diabetic mice.

• Nutritional Sciences
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• v.5 no.1
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• pp.3-8
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• 2002

The purpose of this study was to investigate the effects of L-carnitine administration on lipid metabolism in streptozotocin-induced diabetes. Diabetes was induced by a single intraperitoneal injection of streptozotocin (50 mg/kg b.w.) and was confirmed by determination of urinary glucose secretion. Diabetic rats in the three L-carnitine treated groups were given L-carnitine, 50(D5O), 100(D100) and 200 (D200) mg/kg body weight, by subcutaneously every other day for four weeks, while animals in normal (N) and diabetic (DM) groups for control received saline by the same method. The daily weight gain was not different between normal and diabetic rats, but daily dietary intake was significantly higher in diabetic rats than in normal rat. Diabetic rats had a significantly lower carnitine concentration in both serum and liver compared to normal rats. Total carnitine concentration in serum was increased dose dependently upon carnitine administration, but statistic significance was shown only in D200 group. Diabetic rats had significantly higher serum triglyceride and cholesterol concentrations compared to normal rats. However there were no significant differences in liver L-carnitine administration to diabetic rats significantly decreased serum triglyceride but not cholesterol concentrations. In liver, triglyceride and cholesterol concentrations were not attired by L-carnitine administration. These results indicated that streptozotocin induced-diabetic rats have decreased carnitine and increased lipid concentrations compared with normal rats. Also it indicated that L-carnitine administration has an effect on the normalization of serum triglyceride concentrations in diabetic rats.

• Journal of Nutrition and Health
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• v.38 no.8
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• pp.663-671
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• 2005

The purpose of this study was to investigate not only quality characteristics such as overrun, meltdown and sensory evaluation of oligosaccharide-supplemented soy ice cream but also physiological effects of ice cream with soy and/or oligosaccharide on blood sugar and lipid profile in streptozotocin-induced diabetic rats. Powder of parched soybean was added at $7.6\%$ replacing skimmed milk and cream, soybean oil at $7.6\%$ replacing milk oil in cream, and fructooli-gosaccharide at $9.5\%$ replacing sucrose on weight basis. Five kinds of ice cream were prepared: MMS (skimmed milk, milk oil, sucrose), MMO (skimmed milk, milk oil, oligosaccharide), SSS (soybean, soybean oil, sucrose), SSO (soybean, soybean oil, oligosaccharide), and BSO (black soybean, soybean oil, oligosaccharide). Overrun and meltdown of soy ice cream were significantly lower than those of milk ice cream. Scores of sensory evaluation especially in mouth feel and melting feel in mouth were lower in soy ice cream. Freeze-dried ice cream was supplemented to AIN93-based diets at $30\%$(w/w). Sprague-Dawley male rats with diabetes induced by injecting streptozotocin were fed experimental diets for 4 weeks. Plasma glucose level was significantly lowered in SSO group compared with MMS group. Plasma insulin levels of MMO and SSO groups were not significantly different from that of normal group, while those of MMS and SSO group were significantly lower than normal group. Plasma cholesterol was decreased in groups fed ice cream supplemented either soybean or fructooligosaccharide compared to MMS group. HDL-cholesterol level was elevated and triglyceride was decreased significantly in MMO group compared to MMS group. LDL-cholesterol levels of SSS and BSO groups and liver triglyceride level of SSO group were significantly lower compared to MMS group. In conclusion, oligosaccharide-supplemented soy ice cream lowered blood sugar, and ice cream supplemented with soybean and/or oligosaccharide improved lipid profile in diabetic rats.