• Environmental Analysis Health and Toxicology
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• v.22 no.2 s.57
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• pp.165-170
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• 2007

Elevation of homocysteine levels is a risk factor for cardiovascular diseases and liver diseases. It has been reported that both streptozotocin-induced type I diabetic rats and obese type II diabetic rats have plasma total homocysteine lower than each control rats. We determined the effects of lean type II diabetes on homocysteine levels using type 2 diabetic Goto-Kakizaki rats. The concentrations of serum glucose were increased to ${\sim}two-fold$ of control levels and the total cholesterol levels were also increased in GK rats. Hepatic aspartate, histidine, threonine, alanine and methionine levels were significantly increased in GK rats. Plasma aspartate and glutamate levels were elevated, but threonine and arginine levels were decreased in GK rats. Plasma total homocysteine levels were not changed in GK rats, but hepatic total homocysteine levels were increased to ${\sim}three-fold$ of control levels. These results suggest that hepatic metabolism of sulfur-amino acid may be altered in diabetic condition.

• Nutrition Research and Practice
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• v.3 no.1
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• pp.23-30
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• 2009

The aim of this study was to examine the hypoglycemic effect of chlorella in 6 week-old type 2 diabetic Goto-Kakizaki (GK, n=30) rats and 6 week-old normal Wistar (n=30) rats. Animals were randomly assigned to 3 groups respectively, and were fed three different experimental diets containing 0%, 3% or 5% (w/w) chlorella for 8 weeks. In diabetic GK rats, the insulinogenic-indices were not significantly different among the groups. The concentrations of fasting plasma glucagon and hepatic triglyceride, and the insulin/glucagon ratios of the GK-3% chlorella and GK-5% chlorella groups were significantly lower than those of the GK-control group. The HOMA-index and the concentrations of fasting blood glucose and plasma insulin of the GK-3% chlorella and GK-5% chlorella groups were slightly lower than those of the GK-control group. In normal Wistar rats, the insulinogenic-indices were not significantly different among the normal groups, but that of the Wistar-5% chlorella group was slightly higher than the other groups. The concentrations of fasting blood glucose and plasma insulin, and the HOMA-index of the Wistar-5% chlorella group were a little higher, and the fasting plasma glucagon concentration and the insulin/glucagon ratio of the Wistar-5% chlorella group were significantly higher than those of the Wistar-control and Wistar-3% chlorella groups. In conclusion, this study shows that the glucose-stimulated insulin secretion was not affected by the intake of chlorella, which could be beneficial, however, in improving insulin sensitivity in type 2 diabetic GK and normal Wistar rats.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.3
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• pp.355-359
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• 2014

The objective of this study was to determine the hyperglycemic effects of mineral-rich salt in type 2 diabetic Goto-Kakizaki (GK) rats and normal Wistar rats. Animals were divided into five groups, including a normal group, fed three different experimental salts [purified salt (PS), mineral-rich salt (WS1 and WS2), and bamboo salt (BS)] in the form of 1% salt solution for 12 weeks. Liver, kidney, and spleen weights were significantly increased in GK rats of salt groups as compared to Wistar normal group without salt. However, there was no difference among the salt groups. For serum lipids, total cholesterol level in the BS group and triglyceride level in the WS group were significantly reduced compared to those of the PS group. The concentration of blood glucose in the GK-PS group increased continuously during the experimental period, whereas that in the GK-WS group was significantly reduced at 12 weeks. In GK rats, glucose levels among the salt groups in OGTT by glucose were not significantly different compared to normal rats. Insulin and glucagon levels in blood were not significantly different among the groups, and no such association was observed for insulin. Pancreatic lslets of Langerhans in the PS group showed irregular formation compared to those of the normal, WS, and BS groups.

• Nutrition Research and Practice
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• v.3 no.4
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• pp.272-278
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• 2009

Postprandial hypoglycemic effect of mulberry leaf (Morus alba L.) was compared in two animal models: Goto-Kakizaki (GK) rats, a spontaneous non-obese animal model for type II diabetes, and their counterpart control Wistar rats. First, the effect of a single oral administration of mulberry leaf aqueous extract (MLE) on postprandial glucose responses was determined using maltose or glucose as substrate. With maltose-loading, MLE reduced peak responses of blood glucose significantly in both GK and Wistar rats (P < 0.05), supporting the inhibition of $\alpha$-glucosidase by MLE in the small intestine. With glucose-loading, MLE also significantly reduced blood glucose concentrations, measured at 30 min, in both animal models (P < 0.01), proposing the inhibition of glucose transport by MLE. Next, dried mulberry leaf powder (MLP) was administered for 8 weeks by inclusion in the diet. By MLP administration, fasting blood glucose was significantly reduced at weeks 4 and 5 (P < 0.05), but then returned to values that were similar to those of the control at the end of experimental period in GK rats. Insulin, HOMA-IR, C-reactive protein, and triglycerides tended to be decreased by MLP treatment in GK rats. All other biochemical parameters were not changed by MLP administration in GK rats. Collectively, these findings support that MLE has significant postprandial hypoglycemic effect in both non-obese diabetic and healthy animals, which may be beneficial as food supplement to manage postprandial blood glucose. Inhibitions of glucose transport as well as $\alpha$-glucosidase in the small intestine were suggested as possible mechanisms related with the postprandial hypoglycemic effect of MLE.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.11
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• pp.1537-1543
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• 2011

We investigated the anti-diabetic effects of Hemicentrotus pulcherrimus (sea urchin, SU) shells on non-obese type 2 diabetic Goto-Kakizaki (GK) rats. We measured body weight, blood glucose, and plasma insulin levels and conducted an oral glucose tolerance test (OGTT). The SU shells (100 and 200 mg/kg) significantly reduced the blood glucose of GK rats from 203.8${\pm}$29.8 mg/dL to 138.5${\pm}$21.2 mg/dL at after 4 weeks of daily oral administration. However, plasma insulin levels at the same time were not changed by treatment with SU. During the OGTT, the SU-treated GK rats maintained a lower blood glucose level than the control group for 15 to 120 min. Based on these results, SU shells are considered to be effective in improving glucose tolerance. These results suggest that SU shells have unique properties to lower blood glucose, raise insulin sensitivity, and improve insulin resistance in GK rats.

• Development and Reproduction
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• v.14 no.2
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• pp.75-82
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• 2010

The objective of this study is to identify the effects of endurance exercise and selenium on mitochondrial transcription factor in old Goto-Kakizaki (GK) rats. In this experiments, endurance exercise were treadmill-run at 24 m/min, 30 min/day, 5 days/week, 6 weeks and 5 umol/kg of sodium selenite was injected intraperitoneally. In exercise group, selenium group, and combination group, the mitohondrial biogenesis-related genes, including PGC-$1{\alpha}$, NRF-1, and Tfam expression level were significantly increased compared to control group. Consistent with the increased biogenesis-related genes, the cytochrome C in the treated groups, which was the indicator of mitochondrial content, was significantly increased compared to control group. Especially, combination of exercise and selenium may be effective in the increase of mitochondrial biogenesis, activity and insulin sensitivity. Therefore, exercise and selenium treatment is likely to promote diabeticmitochondrial malfunction and then improve diabetes.

• Nutrition Research and Practice
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• v.5 no.3
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• pp.205-213
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• 2011

Exercise training (ET) and selenium (SEL) were evaluated either individually or in combination (COMBI) for their effects on expression of glucose (AMPK, PGC- $1{\alpha}$, GLUT-4) and lactate metabolic proteins (LDH, MCT-1, MCT-4, COX-IV) in heart and skeletal muscles in a rodent model (Goto-Kakisaki, GK) of diabetes. Forty GK rats either remained sedentary (SED), performed ET, received SEL, ($5\;{\mu}mol{\cdot}kg$ body $wt^{-1}{\cdot}day^{-1}$) or underwent both ET and SEL treatment for 6 wk. ET alone, SEL alone, or COMBI resulted in a significant lowering of lactate, glucose, and insulin levels as well as a reduction in HOMA-IR and AUC for glucose relative to SED. Additionally, ET alone, SEL alone, or COMBI increased glycogen content and citrate synthase (CS) activities in liver and muscles. However, their effects on glycogen content and CS activity were tissue-specific. In particular, ET alone, SEL alone, or COMBI induced upregulation of glucose (AMPK, PGC-la, GLUT-4) and lactate (LDH, MCT-1, MCT-4, COX-IV) metabolic proteins relative to SED. However, their effects on glucose and lactate metabolic proteins also appeared to be tissue-specific. It seemed that glucose and lactate metabolic protein expression was not further enhanced with COMBI compared to that of ET alone or SEL alone. These data suggest that ET alone or SEL alone or COMBI represent a practical strategy for ameliorating aberrant expression of glucose and lactate metabolic proteins in diabetic GK rats.

• Journal of the Korean Society of Food Culture
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• v.22 no.1
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• pp.157-165
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• 2007

This study was designed to evaluate the effects of fructose(F) or sucrose(S) and guar gum intake on carbohydrate and lipid metabolism in 15-week-old male Goto-Kakizaki(GK) rats. Fifty rats were randomly assigned to 5 groups which were different in carbohydrate(25% of carbohydrate) and fiber(5% w/w) sources. The carbohydrate(CHO) sources of each group were comstarch(control group, 100% of CHO), fructose with cellulose(F), fructose with guar gum(FG), sucrose with cellulose(S), and sucrose with guar gum(SG). Each group was fed exterimental diet for 4 weeks. We measured food intake, body weight gain, adipose tissues weight and organs weight. We conducted oral glucose tolerance test(OGTT) and measured plasma insulin concentration to examine carbohydrate metabolism. To evaluate lipid metabolism, we measured the lipid profile of plasma, liver and feces. Food intake and weight gain of FG or SG groups tended to be less than those of F or S groups. Perirenal and epididymal fat pad weights of SG group were significantly lower than those of S group and those of FG group tended to be lower than those of F group. In OGTT, blood glucose values of F or S groups were significantly higher than those of C group, and FG or SG groups tended to be lower than those of F or S groups during the experimental time. The area under the curve(AUC) of C group was significantly highest among the groups, AUC and plasma insulin concentration of FG or SG groups tended to be lower than those of F or S groups. Plasma and hepatic triglyceride (TG) of FG and SG groups were significantly lower than those of F and S groups, plasma and hepatic total lipid(TL) and total cholesterol(TC) of FG and SG groups tended to be lower than those of F and S groups. Fecal TL, TG and TC of FG or SG groups tended to be higher than those of F and S groups. In conclusion, intake of guar gum should improve carbohydrate and lipid metabolism in partial substitution of fructose or sucrose for cornstarch in GK rats.