• The Korean Journal of Physiology and Pharmacology
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• v.11 no.1
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• pp.31-36
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• 2007

To elucidate a potential molecular link between diabetes and atherosclerosis, we investigated the role of Janus tyrosine kinase(JAK) for NAD(P)H oxidase-derived superoxide generation in the enhanced proliferative capacity of vascular smooth muscle cells(VSMC) of Otsuka Long-Evans Tokushima Fatty(OLETF) rat, an animal model of type 2 diabetes. An enhanced proliferative response to 10% fetal bovine serum(FBS) and superoxide generation with an increased NAD(P)H oxidase activity were observed in diabetic(OLETF) VSMC. Both the enhanced proliferation and superoxide generation in diabetic VSMC were significantly attenuated by AG490, JAK2 inhibitor, and PP2, Src kinase inhibitor. Tyrosine phosphorylation of proteins in diabetic VSMC, especially JAK2, was increased compared to control VSMC. Furthermore, the enhanced NAD(P)H oxidase activity in diabetic VSMC was significantly attenuated by AG490 in a dose-dependent manner. Together, these results indicate that the signal pathway which leads to diabetes-associated activation of Src kinase/JAK is critically involved in the diabetic VSMC proliferation through NAD(P)H oxidase activation and superoxide generation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.3
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• pp.521-527
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• 2001

The effects of dietary restriction (DR) on antioxidant enzymes were studied in liver, lung and erythrocytes of diabetic rats. Experimental animals used Sprague-Dawley (SD; body weight 350$\pm$20g) male rats and Otsuka Long Evans Tokushima fatty (OLETE; body weight 5--$\pm$30g) male rats, as a model of type 2 diabetes mellitus. Type I diabetes was induced in SD rats by intramuscular injection of alloxan (80 mg/kg BW). Animals were randomly assigned either to continue the ad libitum diet or 40% DR (60% intake of ad libitum diet) groups. The body weight was measured at every 2 weeks to 4 months following DR. The activities of antioxidant enzymes (superoxide dismutase (SOD), catalase, glutathione peroxidase (GSHPx) were measured in liver, lung and erythrocytes and the concentration of TBARS as a marker of reactive oxygen species-induced tissue injry was also measured in rats after 4 months 40% DR. The body weight 4 months after 40% DR of control SD, alloxian-diabetid SD and OLETE rats were 80%, 98% and 75% of each control groups, respectively. The activities of SOD, catalase and GSHPx in lung and erythrocytes of rats were not change by 40% DR but in 4 month 40% DR rat liver, the activities of SOD and catalase were increased in control SD, alloxan-diabetic SD, and OLETF groups. The concentration of TBARS in lung and erythrocytes was also not changed by 40% DR, while liver TBARS concentration was decreased in OLETF and control SD rats compared to each non-DR control rats. These results suggested that the body weight changes in diabetic rats by DR was more prominent in type 2 diabetes and changes of antioxidant enzymes is most prominent in liver by DR either type 1 and 2 diabetic rats.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.4
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• pp.309-318
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• 2015

Alcohol consumption increases the risk of type 2 diabetes. However, its effects on prediabetes or early diabetes have not been studied. We investigated endoplasmic reticulum (ER) stress in the pancreas and liver resulting from chronic alcohol consumption in the prediabetes and early stages of diabetes. We separated Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a type-2 diabetic animal model, into two groups based on diabetic stage: prediabetes and early diabetes were defined as occurrence between the ages of 11 to 16 weeks and 17 to 22 weeks, respectively. The experimental group received an ethanol-containing liquid diet for 6 weeks. An intraperitoneal glucose tolerance test was conducted after 16 and 22 weeks for the prediabetic and early diabetes groups, respectively. There were no significant differences in body weight between the control and ethanol groups. Fasting and 120-min glucose levels were lower and higher, respectively, in the ethanol group than in the control group. In prediabetes rats, alcohol induced significant expression of ER stress markers in the pancreas; however, alcohol did not affect the liver. In early diabetes rats, alcohol significantly increased most ER stress-marker levels in both the pancreas and liver. These results indicate that chronic alcohol consumption increased the risk of diabetes in prediabetic and early diabetic OLETF rats; the pancreas was more susceptible to damage than was the liver in the early diabetic stages, and the adaptive and proapoptotic pathway of ER stress may play key roles in the development and progression of diabetes affected by chronic alcohol ingestion.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.6
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• pp.449-454
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• 2009

5'-AMP-activated protein kinase (AMPK) is a heterotrimeric complex consisting of a catalytic ($\alpha$) and two regulatory ($\beta$ and $\gamma$) subunits. Two isoforms are known for catalytic subunit (${\alpha}1$, ${\alpha}2$) and are encoded by different genes. To assess the metabolic effects of $AMPK{\alpha}1$, we examined the effects of overexpression of adenoviral-mediated $AMPK{\alpha}1$ in hyperlipidemic type 2 diabetic rats. The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is an established animal model of type 2 diabetes that exhibits chronic and slowly progressive hyperglycemia and hyperlipidemia. Thirty five-week-old overt type 2 diabetic rats (n=10) were administered intravenously with Ad.$AMPK{\alpha}1$. AMPK activity was measured by phosphorylation of acetyl CoA carboxlyase (ACC). To investigate the changes of gene expression related glucose and lipid metabolism, quantitative real-time PCR was performed with liver tissues. Overexpression of $AMPK{\alpha}1$ showed that blood glucose concentration was decreased but that glucose tolerance was not completely recovered on 7th day after treatment. Plasma triglyceride concentration was decreased slightly, and hepatic triglyceride content was markedly reduced by decreasing expression of hepatic lipogenic genes. Overexpression of $AMPK{\alpha}1$ markedly improved hepatic steatosis and it may have effective role for improving hepatic lipid metabolism in hyperlipidemic state.

• Korean Journal of Medicinal Crop Science
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• v.25 no.3
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• pp.165-174
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• 2017

Background: Traditional plant drugs, are less toxic and free from side effects compared to general synthetic drugs. They have been used for the treatment of diabetes and associated renal damage. In this study, we evaluated effect of Hachimi-jio-gan against diabetic renal damage in a rat model of type 1 diabetic nephropathy induced by subtotal nephrectomy plus streptozotocin (STZ) injection, and in Otsuka Long-Evans Tokushima Fatty (OLETF) rats and db/db mice as a model of human type 2 diabetes, and its associated complications. To explore the active components of Hachimi-jio-gan, the antidiabetic effect of corni fructus, a consituent of Hachimi-jio-gan, and 7-O-galloyl-${{\small}D}$-sedoheptulose, a phenolic compound isolated from corni fructus, were investigated. Methods and Results: We conducted an extensive literature search, and all required data were collected and systematically organized. The findings were reviewed and categorized based on relevance to the topic. A summary of all the therapeutic effects were reported as figures and tables. Conclusions: Hachimi-jio-gan serves as a potential therapeutic agent to against the development of type 1 and type 2 diabetic nephropathy. From the results of characterization active components of corni fructus, 7-O-galloyl-${\small}D$-sedoheptulose is considered to play an important role in preventing and/or delaying the onset of diabetic renal damage. 7-O-Galloyl-${\small}D$-sedoheptulose is expected to serve as a novel therapeutic agent against the development of diabetic nephropathy.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.7
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• pp.929-937
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• 2016

The purpose of this study was to investigate the effect of Acanthopanax senticosus extract (ASE) (ethanol : DW=1:1, v/v) on inhibition of type 2 diabetes using an OLETF rat model via regulation of HbA1c and AGEs levels. Supplementation with ASE 0.1% and 0.5% effectively lowered levels of glucose, insulin, oral glucose tolerance test, and Homa-insulin resistance, suggesting reduced insulin resistance. Blood levels of HbA1c and AGEs were significantly reduced in a dose-dependent manner. As oxidative stress plays a key role in accelerating production of HbA1c and AGEs, which worsen symptoms of type 2 diabetes, levels of malonaldehyde and pro-inflammatory cytokines were measured. Lipid peroxidation in both blood and liver tissues was significantly reduced, and induction of pro-inflammatory cytokines interleukin-${\beta}$ and tumor necrosis factor-${\alpha}$, which elevate production of HbA1c and AGEs, was inhibited (P<0.05). To evaluate the possible cellular events after AGEs receptor activation, genetic expression of protein kinase C (PKC)-${\delta}$ and transforming growth factor (TGF)-${\beta}$ was measured by real-time polymerase chain reaction. Supplementation with both ASE 0.1% and 0.5% significantly inhibited mRNA expression of PKC-${\delta}$ and TGF-${\beta}$, indicating that ASE may have beneficial effects on preventing insulin-resistant cells or tissues from progressing to diabetic complications. Taken together, ASE has potential to improve type 2 diabetes by inhibiting insulin resistance and protein glycosylation, including production of HbA1c and AGEs. Anti-oxidative activities of ASE are a main requisite for reducing production of HbA1c and AGEs and are also related to regulation of the PKC signaling pathway, resulting in suppression of TGF-${\beta}$, which increases synthesis of collagen, prostaglandin, and disease-related proteins.