• Preventive Nutrition and Food Science
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• 제22권3호
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• pp.172-183
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• 2017

Vitamin A and its metabolites modulate insulin resistance and regulate stearoyl-CoA desaturase 1 (SCD1), which are also known to affect insulin resistance. Here, we tested, whether vitamin A-mediated changes in insulin resistance markers are associated with SCD1 regulation or not. For this purpose, 30-week old male lean and glucose-intolerant obese rats of WNIN/GR-Ob strain were given either a stock or vitamin A-enriched diet, i.e. 2.6 mg or 129 mg vitamin A/kg diet, for 14 weeks. Compared to the stock diet, vitamin A-enriched diet feeding improved hyperglycemia and glucose-clearance rate in obese rats and no such changes were seen in lean rats receiving identical diets. These changes were corroborated with concomitant increase in circulatory insulin and glycogen levels of liver and muscle (whose insulin signaling pathway genes were up-regulated) in obese rats. Further, the observed increase in muscle glycogen content in these obese rats could be explained by increased levels of the active form of glycogen synthase, the key regulator of glycogen synthesis pathway, possibly inactivated through increased phosphorylation of its upstream inhibitor, glycogen synthase kinase. However, the unaltered hepatic SCD1 protein expression (despite decreased mRNA level) and increased muscle-SCD1 expression (both at gene and protein levels) suggest that vitamin A-mediated changes on glucose metabolism are not associated with SCD1 regulation. Chronic consumption of vitamin A-enriched diet improved hyperglycemia and glucose-intolerance, possibly, through the regulation of intracellular signaling and glycogen synthesis pathways of muscle and liver, but not associated with SCD1.

• Asian-Australasian Journal of Animal Sciences
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• 제17권8호
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• pp.1062-1068
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• 2004

Leptin has a major role in the regulation of food intake and energy homeostasis. In addition, leptin participates in many physiological functions including regulation of lipid metabolism. Bovine recombinant leptin protein was produced in E. coli cells in order to understand function of leptin in the regulation of lipid metabolism. The leptin expression vector was constructed in pGEX-4T-3 vector and transformed into E. coli BL21 cells. Expression of the GST-leptin fusion protein was induced with IPTG. The fusion protein was purified using glutathione sepharose 4B batch method, and the recombinant leptin was eluted after thrombin protease digestion. The effect of leptin on glucose transport was examined in the differentiated adipocytes of 3T3-L1 cells. Leptin had no effect on basal and insulin-stimulated glucose transport in 3T3-L1 cells (p>0.05). Effect of recombinant leptin on glucose and acetate transport was examined in adipose tissues of Korean cattle (Hanwoo). Insulin stimulated glucose transport in both intramuscular and subcutaneous adipose tissues (p<0.05), but leptin did not affect glucose transport in both adipose tissues (p>0.05). Insulin stimulated acetate transport in bovine adipose tissues (p<0.05), but leptin did not affect acetate transport (p>0.05). Northern and RT-PCR analyses showed that mRNA levels of uncoupling protein-2 were increased by leptin treatment in 3T3-L1 cells without statistical difference (p>0.05). In conclusion, bovine recombinant leptin did not affect glucose and acetate transport in both 3T3-L1 adipocytes and bovine adipose tissues, while it stimulates UCP-2 mRNA expression in 3T3-L1 cells.

• Nutrition Research and Practice
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• 제2권4호
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• pp.252-258
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• 2008

This study was designed to determine whether acute fructose or sucrose administration at different levels (0.05 g/kg, 0.1 g/kg or 0.4 g/kg body weight) might affect oral glucose tolerance test (OGTT) in normal and type 2 diabetic rats. In OGTT, there were no significant differences in glucose responses between acute fructose- and sucrose-administered groups. However, in normal rats, the AUCs of the blood glucose response for the fructose-administered groups tended to be lower than those of the control and sucrose-administered groups. The AUCs of the lower levels fructose- or sucrose-administered groups tended to be smaller than those of higher levels fructose- or sucrose-administered groups. In type 2 diabetic rats, only the AUC of the lowest level of fructose-administered (0.05 g/kg body weight) group was slightly smaller than that of the control group. The AUCs of fructose-administered groups tended to be smaller than those of the sucrose-administered groups, and the AUCs of lower levels fructose-administered groups tended to be smaller than those fed higher levels of fructose. We concluded from this experiment that fructose has tendency to be more effective in blood glucose regulation than sucrose, and moreover, that smaller amount of fructose is preferred to larger amount. Specifically, our experiments indicated that the fructose level of 0.05 g/kg body weight as dietary supplement was the most effective amount for blood glucose regulation from the pool of 0.05 g/kg, 0.1 g/kg and 0.4 g/kg body weights. Therefore, our results suggest the use of fructose as the substitute sweetener for sucrose, which may be beneficial for blood glucose regulation.

• 한방비만학회지
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• 제15권2호
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• pp.131-136
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• 2015

Objectives: The prevalence of obesity and metabolic syndrome is increasing worldwide. Regulation of cellular energy metabolis has the potential to be manipulated therapeutically to serve as a target for obesity and insulin resistance. Skeletal muscle is regarded as a target for regulation of energy metabolism and insulin resistance. In this study, the authors investigated the regulatory effect of (Cinnamomum cassia Blume, CCB), Aconitum carmichaeli Debx (ACD), and Benth (Pueraria lobata Benth, PLB) on energy and glucose metabolism in C2C12 myotubes. Methods: The water extracts of CCB, ACD, and PLB (0.5 mg/ml) were treated in differentiated C2C12 myotubes. The expressions of adenosine monophosphate-activated protein kinase (AMPK) and phosphorylation AMPK were detected with western blotting. Glucose metabolism was investigated with glucose uptake assay and glucose consumption assay, total adenosine triphosphate (ATP) content was also analyzed. Results: CCB, ACD, and PLB activated the phophorylation of AMPK, they also increased the glucose metabolism and total ATP contents in C2C12 myotubes. Conclusions: This study suggests that CCB, ACD, and PLB have the potential to increase energy and glucose metabolism in skeletal muscle.

• Reproductive and Developmental Biology
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• 제39권4호
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• pp.97-104
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• 2015

Glucose is universal and essential fuel of energy metabolism and in the synthesis pathways of all mammalian cells. Glucose is the one of the major precursors of lactose synthesis using glycolysis result in producing milk fat and protein. During the milk fat synthesis, lipoprotein lipase (LPL) and CD36 are required for glucose uptake. Various morecules such as acyl-CoA synthetase 1 (ACSL1) activity of acetyl-CoA synthetase 2 (ACSS2), ACACA, FASN AGPAT6, GPAM, LPIN1 are closely related with milk fat synthesis. Additionally, glucose plays a major role for synthesizing lactose. Activations of lactose synthesize enzymes such as membranebound enzyme, beta-1,4-galactosyl transferase (B4GALT), glucose-6-phosphate dehydrogenase (G6PD) are changed by concentration of glucose in blood resulting change of amount of lactose production. Glucose transporters are a wide group of membrane proteins that facilitate the transport of glucose over a plasma membrane. There are 2 types of glucose transporters which consisted facilitative glucose transporters (GLUT); and sodium-dependent transport, mediated by the Na+/glucose cotransporters (SGLT). Among them, GLUT1, GLUT8, GLUT12, SGLT1, SGLT2 are main glucose transporters which involved in mammary gland development and milk synthesis. However, more studies are required for revealing clear mechanism and function of other unknown genes and transporters. Therefore, understanding of the mechanisms of glucose usage and its regulation in mammary gland is very essential for enhancing the glucose utilization in the mammary gland and improving dairy productivity and efficiency.

• 자연과학논문집
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• 제18권1호
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• pp.29-38
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• 2007

호 알칼리성이며 고온성인 Bacillus cereus TA-11이 세포내로 생성하는 invertase의 생합성 조절 양상을 조사하였다. Bacillus cereus TA-11의 세포내 invertase는 10 mM sucrose의 180분 처리와 25 mM raffinose의 90분 처리에서 각각 효율적으로 유도되었다. 또한 glucose는 sucrose에 의한 invertase의 유도를 억제하였고 cAMP첨가는 catabolite repression을 감소시키지 못하였다.

• 생명과학회지
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• 제27권3호
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• pp.289-294
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• 2017

삼채(Allium species)는 전통적인 약재나 건강 증진 식품으로 사용되어 왔다. 특히, Allium hookeri (A. hookeri)는 제 2형 당뇨병 모델 마우스에서 혈당 감소 효과가 보고되었다. 본 연구에서는 A. hookeri 추출물이 3T3-L1 세포에서 인슐린 민감성을 증진시키는지 시험하였다. 3T3-L1 지방세포분화가 불완전하게 유도되는 저농도의 인슐린 조건에서, A. hookeri 추출물은 세포 내 지방 함량을 증가시키고, 분화 유도 전사인자인 $PPAR{\gamma}$의 발현을 상승시켰다. 또한, A. hookeri 추출물은 포도당 수송체 4(GLUT4)의 발현을 증가시킴으로써 세포 내 포도당 흡수(glucose uptake)를 향상시켰다. 이러한 결과들은 A. hookeri 추출물이 인슐린 민감성을 증진시켜 $PPAR{\gamma}$와 GLUT4를 활성화하고, 세포 내 포도당 흡수를 촉진한다는 사실을 보여준다. 따라서, A. hookeri 추출물은 당뇨병의 예방 및 치료에 임상적으로 응용될 수 있을 것으로 생각된다.

• Journal of Ginseng Research
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• 제41권1호
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• pp.52-59
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• 2017

Background: Korean Red Ginseng extract (KRG, Panax ginseng Meyer) and its constituents have been used for treating diabetes. However, in diet-induced obese mice, it is unclear whether KRG can enhance the glucose-lowering action of rosiglitazone (ROSI), a peroxisome proliferator-activated receptor gamma synthetic activator. Methods: Oral glucose tolerance tests (oGTTs) were performed after 4 days of treatment with a vehicle (CON), KRG [500 mg/kg body weight (b.w.)], ROSI (3.75 mg/kg b.w, 7.5 mg/kg b.w, and 15 mg/kg b.w.), or ROSI and KRG (RK) in obese mice on a high-fat diet. Adipose tissue morphology, crown-like structures (CLSs), and inflammation were compared by hematoxylin-eosin staining or quantitative reverse transcription polymerase chain reaction. Results: The area under the glucose curve (AUC) was significantly lower in the RK group (15 mg/kg b.w. and 500 mg/kg b.w. for ROSI and KRG, respectively) than in the CON group. There was no significant difference in the AUC between the CON and the other groups. Furthermore, the AUC was significantly lower in the RK group than in the ROSI group. The expression of the Ccl2 gene and the number of CLSs were significantly reduced in the RK group than in the CON group. Conclusion: Our results show a potential enhancement of ROSI-induced improvement of glucose regulation by the combined treatment with KRG.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2002년도 Molecular and Cellular Response to Toxic Substances
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• pp.147-147
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• 2002

In this study, a mechanism by which glucose level modulates glucose transport in Jurkat cells was investigated. Glucose uptake was more efficient in the cells cultivated in low glucose (2.5 mM) medium than that grown in high glucose (20 $\mu$M) medium. Vmax (0.74 n㏖/10$^6$ cells$\cdot$min) of glucose uptake measured with the cells grown in the low glucose medium was higher than the one (1.06 n㏖/10$^6$ cells$\cdot$min) in the high glucose medium while Km was almost consistent through the change of glucose levels, indicating the increase of glucose transporter number.

• Molecules and Cells
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• 제23권3호
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• pp.272-279
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• 2007

The maintenance of normal blood glucose levels at rest and during exercise is critical. The maintenance of blood glucose homeostasis depends on the coordination and integration of several physiological systems, including the sympathetic nervous system and the endocrine system. During prolonged exercise increased demand for glucose by contracting muscle causes to increase glucose uptake to working skeletal muscle. Increase in glucose uptake by working skeletal muscle during prolonged exercise is due to an increase in the translocation of insulin and contraction sensitive glucose transporter-4 (GLUT4) proteins to the plasma membrane. However, normal blood glucose level can be maintained by the augmentation of glucose production and release through the stimulation of liver glycogen breakdown, and the stimulation of the synthesis of glucose from other substances, and by the mobilization of other fuels that may serve as alternatives. Both feedback and feedforward mechanisms allow glycemia to be controlled during exercise. This review focuses on factors that control blood glucose homeostasis during prolonged exercise.