• Journal of the East Asian Society of Dietary Life
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• v.20 no.1
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• pp.46-53
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• 2010

The study examined the effects of dietary green tea powder supplementation on blood glucose, and plasma and liver lipid concentrations in diabetic rats. Twenty-five male Sprague-Dawley rats (body weight $200{\pm}5\;g$) were divided into two groups (diabetic and non-diabetic), which were each randomly divided into two subgroups that were fed a control and 1% green tea powder-supplemented diet. Serum and liver lipid concentrations were measured by established techniques. Low density lipoprotein-cholesterol (LDL-C) was calculated from an established equation. Body weight gain and feed efficiency ratio were lower in diabetic rats than in non-diabetic rats regardless of diet. There were no differences in weight gain in diabetic and non-diabetic rats consuming the control and green tea powder-supplemented diets. The levels of fasting plasma glucose, serum total cholesterol, triglyceride, LDL-C and atherogenic index of diabetic rats were significantly higher than that of non-diabetic rats. Conversely, the levels of high density lipoprotein-cholesterol (HDL-C) of diabetic rats was significantly lower than that of non-diabetic rats. Fasting plasma glucose, serum total cholesterol, triglyceride, LDL-C and atherogenic index were significantly lower in diabetic rats fed the green tea powder diet than in rats fed the control diet, and HDL-C was significantly higher in rats fed the green tea powder diet than in rats fed the control diet. The content of liver total cholesterol and triglyceride of diabetic rats were significantly higher than that of non-diabetic rats. Liver total cholesterol and triglyceride were significantly lower in diabetic rats fed green tea powder-supplemented diet than in rats fed the control diet. It is concluded that green tea powder supplementation positively influences blood glucose and lipid metabolism in diabetic rats. The present study, although not directly applicable to humans, may have some implications for individuals who habitually consume green tea powder.

• Journal of Community Nutrition
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• v.8 no.4
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• pp.207-213
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• 2006

The present study was conducted to investigate the effect of oolong tea extract on blood glucose level and antioxidant system in diabetic rats. The Sprague-Dawley rats were fed on AIN-76 based experimental diets containing 1 % oolong tea extract for 6 weeks. They were induced to be diabetic by receiving streptozotocin (45mg/kg BW) intramuscularly. Blood glucose, blood and hepatic concentration of vitamins A and E, and antioxidant enzyme activities were measured. Oolong tea extract feeding decreased the plasma glucose in diabetic rats. Dietary supplementation of oolong tea extract did not affect antioxidative enzyme activities such as superoxide dismutase, glutathione peroxidase and catalase in diabetic rats. The plasma level of retinol was increased in diabetic rats by feeding oolong tea extract. Plasma and hepatic levels of ${\alpha}$-tocopherol were higher in diabetic rats fed oolong tea extract. In conclusion, these results suggest that oolong tea extract consumption might reduce the plasma glucose in diabetic rats and protect the oxidative damage from diabetic stress to some extent.

• Preventive Nutrition and Food Science
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• v.3 no.4
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• pp.356-361
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• 1998

An experiment was performed to determine if buckwheat intake would improve insulin sensitivity in in normal healthy ras and steptozoticin-induced diabetic Sprague-Dauley rats. For four weeks, rats were fed either corn starch as a cotnrol diet or buckwheat as an experimental diet. As a result, the insulin sensitivity and plasma glucose levels in normal rats were not significantly affected by buckwheat fedding. The insulin sensitivity was lower in diabetic rats than in normal rats(p<0.05). Buckwheat tends to decrease the final plasma glucose level and increase insulin sensitivity in diabetic rats, but there was no sifnificant difference. Another five-week experiment was conducted to determine protein digestibility and protein utility in normal healty rats ad streptozotocin-induced diabetic rats on a control diet or buckwheat diet. The diet composition in this experiment was the same as the preceeding experiment. In the cotnrol diet groups, the protein digestibility in diabetic rats was significantly lower than that in normal rats(p<0.05). Buckwheat reduced protein digestibility in both normal and disbetic rats(p<0.05). Interestingly, in buckwheat diet groups, protei digestibility in diabetic rats was similar to that in normal rats. Protein utility was significantly lower indiabetic rats than in normal rats. This phenomenon was observed as early as the first week of the feeding period. However, protein utility was not sifnificanlty altered in both normal and diabetic rats by buckwheat feeding. It follows that decreased protein digestibility and utility in diabetic rts are not further aggravated by buckwheat feeding, suggesting that buckwheat can be a feasible supplement food for the diabetic therapeutic diet.

• Nutrition Research and Practice
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• v.3 no.3
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• pp.242-246
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• 2009

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.

• The Korean Journal of Pain
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• v.14 no.1
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• pp.12-18
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• 2001

Background: It is controversial whether the change in nitric oxide (NO) expression in the dorsal root ganglia (DRG) may be responsible for developtment and/or maintenance of painful diabetic neuropathy. The aim of this study was to clarify the role of NO in the pathogenesis of painful diabetic neuropathy. Methods: The effect of L-nitroargine methylester (L-NAME) or sodium nitroprusside (SNP) on allodynia was measured in streptozotocin (STZ)-induced diabetic rats. NO concentration was measured in the cerebrospinal fluid (CSF) and plasma of the diabetic rats. NADPH-diaphorase (NADPH-d) histochemistry was performed on the DRG and spinal cords of the STZ-induced diabetic rats. Results: L-NAME, an inhibitor of nitric oxide synthase, alleviated allodynia, while SNP, a nitric oxide donor, aggravated allodynia in diabetic rats. Plasma NO level in the diabetic rats was significantly decreased compared with control rats. NO level in the CSF of diabetic rats did not differ from that of the control rats. NADPH-d positive cells were decreased in the DRG of diabetic rats. However, NADPH-d histochemistry in the diabetic spinal cord was not different from that of the control rats. Conclusions: Downregulation of NO expression in the diabetic rats may not be causally related to the development and/or maintenance of painful diabetic neuropathy.

• Journal of Nutrition and Health
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• v.36 no.3
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• pp.239-244
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• 2003

This study investigated the in vivo insulin function of Polygonatum odoratum in normal and diabetic male Sprague-Dawley rats. Diabetes mellitus was induced by an i.p. injection of streptozotocin. Normal and diabetic rats were assigned to the diet groups of the control basal diet and Polygonatum odoratum diet. The animals were fed the diet and water ad libitum for 15 days. Initial and final body weights, total food intake and serum glucose and insulin levels were measured. An insulin suppression test was performed to elucidate the insulin function in the peripheral tissues. The results showed that the final serum glucose levels significantly decreased in the diabetic rats on the Polygonatum odoratum diet compared with the diabetic rats on the control diet. The final serum insulin levels were increased in the diabetic rats on the Polygonatum odoratum diet compared with the diabetic rats on the control diet. The in vivo function of the insulin increased in the diabetic rats on the Polygonatum odoratum compared with the diabetic rats on the control diet. These data indicate that Polygonatum odoratum may be beneficial in improving the in vivo insulin function in streptozotocin-induced diabetic rats.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.6
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• pp.704-712
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• 2013

This study was designed to examine the effects of bitter melon (BM) on the plasma blood glucose and cholesterol levels in diabetic rats. Diabetes mellitus was induced in male Sprague-Dawley rats through an injection of streptozotocin (STZ) dissolved in a citrate buffer into the tail vein at a dose of 45 mg/kg of body weight. Sprague-Dawley rats were then fed for four weeks, with the experimental groups receiving a modified diet containing 5% or 10% powder derived from BM. The experimental groups were divided into 4 groups, consisting of the normal control group, STZ-control group and diabetic fed with BM 5% & 10% treated groups. The rats' body weight, blood glucose and cholesterol values were measured along with the hematocrit (Hct) values and aminotransferase activities. Body weight losses were observed in the diabetic groups, whereas the control rats gained weight. There were significant differences in kidney weight between the control group and the diabetic groups. The Hct levels of the diabetic BM-treated group were significantly higher than the STZ-control group. Aspartate aminotransferase activity was lower in the non-diabetic group compared to the diabetic experimental groups. Further, the blood glucose was significantly decreased in the 5% & 10% BM of the diabetic group. There were no significant difference in cholesterol levels among the diabetic groups. These results indicate that the supplementation of bitter melon may have a favorable influence on reducing the blood glucose level in STZ-induced diabetic rats.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.3
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• pp.263-270
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• 2000

To evaluate the involvement of nitric oxide production on the endothelium-dependent relaxation in diabetes, we have measured vascular and endothelial function and nitric oxide concentration, and the expression level of endothelial nitric oxide synthase in the streptozotocin-induced diabetic rats. Diabetic rats were induced by the injection of streptozotocin (50 mg/kg i.v.) in the Sprague-Dawley rats. Vasoconstrictor responses to norepinephrine (NE) showed that maximal contraction to norepinephrine $(10^{-5}\;M)$ was significantly enhanced in the aorta of diabetic rats. Endothelium-dependent relaxation induced by acetylcholine was markedly impaired in the aorta of diabetic rats, these responses were little improved by the pretreatment with indomethacin. However, endothelium-independent relaxation induced by nitroprusside was not altered in the diabetic rats. Plasma nitrite and nitrate $(NO_2/_3)$ levels in diabetic rats were significantly lower than in non-diabetic rats. Western blot analysis using a monoclonal antibody against endothelial cell nitric oxide synthase (eNOS) revealed that the protein level was lower in the aorta of diabetic rats than in non-diabetic rats. These data indicate that nitric oxide formation and eNOS expression is reduced in diabetes, and this would, in part, account for the impaired endothelium-dependent relaxation in the aorta of streptozotocin-induced diabetic rats.

• Nutrition Research and Practice
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• v.2 no.4
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• pp.240-246
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• 2008

Cassia tora L. seeds have previously been reported to reduce blood glucose level in human and animals with diabetes. In the present study, the effects of Cassia tora L. seed butanol fraction (CATO) were studied on postprandial glucose control and insulin secretion from the pancreas of the normal and diabetic rats. Diabetes was induced by an i.p. injection of Streptozotocin (55 mg/kg BW) into the male Sprague-Dawley rats. The postprandial glucose control was monitored during a 240 min-period using a maltose loading test. In normal rats, rats fed CATO (20 mg/l00 g BW/d) showed lower postprandial glucose levels in all the levels from 30 min up to 180 min than those in the control rats without CATO (p<0.05). In diabetic rats, those levels in the CATO group seemed to be lower during the $30{\sim}180$ min, but only glucose level at 30 min showed significant difference compared to that in the control group. Moreover, CATO delayed the peak time of the glucose rise in both normal and diabetic rats in the glucose curves. On the other hand, when CATO was administered orally to the diabetic rats for 5 days, 12 hr fasting serum glucose level was decreased in the diabetic rats (p<0.05). Degree of a decrease in 12 hr fasting serum insulin levels was significantly less in the diabetic CATO rats as compared to diabetic control rats. On the last day of feeding, P cells of the pancreas were stimulated by 200 mg/dL glucose through a 40 min-pancreas perfusion. Amounts of the insulin secreted from the pancreas during the first phase ($11{\sim}20$ min) and the second phase ($21{\sim}40$ min) in the CATO fed diabetic rats were significantly greater than those in the diabetic control group (p<0.05). These findings indicated that constituents of Cassia tora L. seeds have beneficial effect on postprandial blood glucose control which may be partially mediated by stimulated insulin secretion from the pancreas of the diabetic rats.

• Food Science of Animal Resources
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• v.35 no.6
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• pp.847-858
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• 2015

The study aimed to evaluate the effect of kefir combination from goat milk and soy milk on lipid profile, plasma glucose, glutathione peroxidase (GPx) activity and the improvement of pancreatic β-cell in diabetic rats. Male rats were divided into five treatments: normal control, diabetic control, goat milk kefir, combination of goat milk-soy milk kefir and soy milk kefir. All rats were induced by streptooztocin-nicotinamide (STZ-NA), except for normal control. After 35 d experiment, the rats were sampled for blood, sacrificed and sampled for pancreatic tissues. Results showed that diabetic rats fed kefir combination had higher (p<0.05) triglyceride than the rats fed goat milk or soy milk kefir. Decreasing of plasma glucose in diabetic rats fed kefir combination was higher (p<0.05) than rats fed goat millk kefir. The activity of GPx in diabetic rats fed three kinds of kefir were higher (p<0.01) than untreated diabetic rats. The average number of Langerhans and β-cells in diabetic rats fed kefir combination was the same as the normal control, but it was higher than diabetic control. It was concluded that kefir combination can be used as antidiabetic through maintaining in serum triglyceride, decreasing in plasma glucose, increasing in GPx activity and improving in pancreatic β-cells.