• Journal of the Korean Wood Science and Technology
• /
• 제47권4호
• /
• pp.498-508
• /
• 2019

This study was carried out to investigate the potential of Korean red pine (Pinus densiflora) inner bark extracts as an antidiabetic agent. The ethyl acetate soluble fraction of the bark extracts was chromatographed on a Sephadex LH-20 column to yield five compounds, which structures were elucidated by NMR spectroscopy. The isolated compounds were (+)-catehin, (-)-epicatechin, taxifolin, taxifolin-3'-O-${\beta}$-D-(+)-glucose and $\tilde{n}$-courmaric acid. The antidiabetic activity of the different fractions, including the crude extracts and isolated compounds, was evaluated by ${\beta}$-cells insulin secretion and glucose uptake in skeletal muscle cells. The insulin secretion was 128% for taxifolin at $25{\mu}g/mL$. However, the other samples had no effect on this test. For the glucose uptake activity assay, $1{\mu}M$ insulin and 2 mM metformin were used as controls. Both the crude extract and taxifolin showed relatively low activity values, but the other samples yielded glucose uptake values over 260%. ${\rho}$-courmaric acid showed the highest uptake (270%). The results confirmed that Korean red pine extracts may be used as a hypoglycemic agent.

• Animal cells and systems
• /
• 제13권1호
• /
• pp.17-23
• /
• 2009

In previous studies, we found that Annexin I (Anx I) was co-secreted with insulin in response to glucose, and that extracellular Anx I stimulated the release of insulin via the Anx I binding site in rat pancreatic islets and the &-cell line. However, the role that Anx I plays in the insulin secretion was not established. Therefore, in this study, we evaluated the insulin secretion pattern in response to Anx I and the involvement of the cytoskeleton or PKC in Anx Istimulated insulin secretion in MIN6N8a cells. The peak time of insulin secretion in response to Anx I treatment corresponded with the second phase insulin secretion by glucose in the perifused pseudoislets. In addition, Anx I-stimulated insulin secretion was not affect by readily releasable pool depletion. Taken together, these findings indicate that Anx I treatment was associated with movement of the reserve pool of insulin. Furthermore, Anx I-stimulated insulin secretion was attenuated by treatment with a microfilament inhibitor, cytochalasin B, as well as by PKC down regulation. These results indicate that Anx I may be a regulator of second phase insulin secretion.

• 동의생리병리학회지
• /
• 제28권5호
• /
• pp.499-505
• /
• 2014

Immunosuppressors cyclosporine A(CsA) and tacrolimus(FK506), the primary cellular target of which is calcineurin/nuclear factor of activated T cells(NFAT) signalling pathways, decrease beta-cell insulin content and mRNA expression. The posttransplantation diabetes mellitus(PTDM) is a frequent complication in immunosuppressive therapy. The present study was to examine the effect of a crude water extracts of medicinal herbs such as Sanguisorba officinalis(SOE) on the immunosuppressive activity with lymphocyte and insulin secretion in insulinoma cell lines with RIN-5mF. It was found that SOE treatment had effect of immunosuppressor on lymphocytes and also significantly increased insulin secretion in RIN-5mF compared to other agents. we might suggest a mechanism on insulin secretion by HNF4a. Taken together, the present study suggested that SOE might serve as immunosuppressive drug in PTDM.

• Nutrition Research and Practice
• /
• 제4권4호
• /
• pp.311-316
• /
• 2010

The purpose of this study was to investigate the relationship between birth weight and appetite related hormones, insulin resistance, and antioxidant status in overweight children aged 9-10 years. Thirty-four healthy overweight children (18 boys, 16 girls) were evaluated with respect to anthropometric measurement, lipid profiles, leptin, ghrelin, glucose, insulin, C-peptide, lipid soluble vitamins, and antioxidant enzyme activities. I found that birth weight was negatively correlated with insulin resistance parameters, ghrelin, and coenzyme Q10 levels. There was a significant positive correlation between present BMI and leptin level, while a negative correlation was noted between the BMI and $\alpha$-tocopherol and lycopene levels. When total subjects were classified into three groups by tertiles of birth weight, the lowest tertile of birth weight (LTB) group showed higher levels of fasting glucose, HOMA-IR, and ghrelin level than the highest tertile of birth weight (HTB) groups. On the other hand, HTB group showed an increased oxidative stress (decreased coenzyme Q10 level and catalase activity) compared to the LTB group. In conclusion, plasma ghrelin level might play an important role in accelerated growth in overweight children with LTB. Increased insulin resistance is present in overweight children with LTB, while decreased coenzyme Q10 and catalase activity in overweight children with HTB. These results suggest that birth weight might be an important factor for determination of treatment for obesity related complications in childhood obesity.

• Molecules and Cells
• /
• 제28권3호
• /
• pp.167-174
• /
• 2009

Genistein has been reported to potentiate glucose-stimulated insulin secretion (GSIS). Inhibitory activity on tyrosine kinase or activation of protein kinase A (PKA) was shown to play a role in the genistein-induced potentiation effect on GSIS. The aim of the present study was to elucidate the mechanism of genistein-induced potentiation of insulin secretion. Genistein augmented insulin secretion in INS-1 cells stimulated by various energygenerating nutrients such as glucose, pyruvate, or leucine/glutamine (Leu/Gln), but not the secretion stimulated by depolarizing agents such as KCl and tolbutamide, or $Ca^{2+}$ channel opener Bay K8644. Genistein at a concentration of $50{\mu}M$ showed a maximum potentiation effect on Leu/Gln-stimulated insulin secretion, but this was not sufficient to inhibit the activity of tyrosine kinase. Inhibitor studies as well as immunoblotting analysis demonstrated that activation of PKA was little involved in genistein-induced potentiation of Leu/Gln-stimulated insulin secretion. On the other hand, all the inhibitors of $Ca^{2+}$/calmodulin kinase II tested, significantly diminished genistein-induced potentiation. Genistein also elevated the levels of $[Ca^{2+}]_i$ and phospho-CaMK II. Furthermore, genistein augmented Leu/Gln-stimulated insulin secretion in CaMK II-overexpressing INS-1 cells. These data suggest that the activation of CaMK II played a role in genistein-induced potentiation of insulin secretion.

• Journal of Periodontal and Implant Science
• /
• 제28권1호
• /
• pp.133-143
• /
• 1998

Diabetes mellitus is a systemic disease with profound effects on oral health and periodontal wound healing. Uncontrolled diabetes adversely affects surgical wound healing and is often associated with abnormal proliferation of fibroblasts. Human gingival fibroblasts and PDL cells were chosen because they are intimately involved in periodontal therapy and are important for the success of surgical procedure such as guided tissue regeneration. The aim of the present study was to elucidate whether cellular activity and collagen synthesis by glucose pre-treated human gingival fibroblasts and PDL cells are influenced by insulin, and whether healthy cells differ from glucose treated cells. Cells were cultured with DMEM at $37^{\circ}C$, 5% $CO_2$, 100% humidified incubator. To evaluate the effect of glucose on gingival fibroblasts and periodontal ligament cells, the cells were seeded at a cell density of $1{\times}10^4\;cells/well$ culture plates and treated with 20 and 50mM of glucose for 5 days. Then MTT assay was carried out. To evaluate the effect of insulin on glucose-pretreated cells, the cells were seeded at a cell density of $1{\times}10^4\;cells/well$ culture plates and treated with 20 and 50mM of glucose for 5 days. After incubation, $10^3$, $10^4$ and $10^5mU/l$ of insulin were also added to the each well and incubated for 2 days, respectively. Then, MTT assay and collagen synthesis assay were carried out. The results indicate that cellular activity of gingival fibroblasts significantly increased by glucose while periodontal ligament cells were unaffected and cellular activity of gingival fibroblasts and periodontal ligament cells were unaffected by insulin. Collagen synthesis of gingival fibroblast with 20mM glucose and insulin unaffected, but 50mM glucose and insulin increased than control. Collagen synthesis of periodontal ligament cell with 20mM glucose and $10^5mU/l$ insulin significantly increased than other groups and 50mM glucose pretreated PDL cells significantly increased at $10^3mU/l$ insulin but decreased at $10^4mU/l$ insulin. Our findings indicated that these cell types differed in their growth response to glucose, and the increase in collagen synthesis was significantly raised at insulin level of $10^3mU/l$ in gingival fibroblasts and periodontal ligament cells except 20mM glucose pretreated periodontal ligament cells.

• Biomolecules & Therapeutics
• /
• 제17권4호
• /
• pp.395-402
• /
• 2009

Insulin appears to play a role in brain physiology, and disturbances of cerebral insulin signalling and glucose homeostasis are implicated in brain pathology. The objective of the present study was to investigate the protective effects of insulin under conditions of oxidative stress induced by hydrogen peroxide ($H_2O_2$) in C6 glial cells. Insulin at concentration of $10^{-7}$ M could prevent 12 h $H_2O_2$-induced cell death. The formation of reactive oxygen species (ROS), nitric oxide (NO) and 2-thiobarbituric acid-reactive substances (TBARS) were significantly scavenged by insulin pre-treatment in C6 glial cells after $H_2O_2$-induced oxidative stress. Insulin significantly stimulated the phosphorylation of Akt in the cells and the activation of Akt was maintained in response to insulin under $H_2O_2$ incubation for 12 h. In conclusion, these results provide evidence that insulin acts as a free radical scavenger and stimulating Akt activity. These data suggest that insulin may be effective in degenerative diseases with oxidative stress.

• Molecules and Cells
• /
• 제20권2호
• /
• pp.280-287
• /
• 2005

The insulin-mediated Ras/mitogen-activated protein (MAP) kinase cascade was examined in SK-N-BE(2) and PC12 cells, which can and cannot produce reactive oxygen species (ROS), respectively. Tyrosine phosphorylation of the insulin receptor and insulin receptor substrate 1 (IRS-1) was much lower in SK-N-BE(2) cells than in PC12 cells when the cells were treated with insulin. The insulin-mediated interaction of IRS-1 with Grb2 was observed in PC12 but not in SK-N-BE(2) cells. Moreover, the activity of extracellular-signal-related kinase (ERK) was much lower in SK-N-BE(2) than in PC12 cells when the cells were treated with insulin. Application of exogenous $H_2O_2$ caused increased tyrosine phosphorylation and Grb2 binding to IRS-1 in SK-N-BE(2) cells, while exposure to an $H_2O_2$ scavenger (N-acetylcysteine) or to a phophatidylinositol-3 kinase inhibitor (wortmannin), and expression of a dominant negative Rac1, decreased the activation of ERK in insulin-stimulated PC12 cells. These results indicate that the transient increase of ROS is needed to activate ERK in insulin-mediated signaling and that an inability to generate ROS is the reason for the insulin insensitivity of SK-N-BE(2) cells.

• 한국잠사곤충학회지
• /
• 제39권1호
• /
• pp.86-92
• /
• 1997

The effects of silkworm extract on body weight, blood glucose and insulin levels, and an intestinal glycosidase activity were studied in high carbohydrate diet administered mice. Hyperglycemia and hyperinsulinemia represented in high carbohydrate diet administered mice disappeared when silkworm extract(50 mg) was added to 100 g diet for 10 week period. These results suggest that silkworm extract may resolve the insulin resistance by lowering serum insulin level resulting from inhibition of intestinal glycosidase activity. Silkworm extract coadministered with high carbohydrate diet to mice for 10 weeks significantly induced maltase, sucrase and lactase acivities, especially middle and distal portion. Further studies about regulatory mechanisms of glycosidase by silkworm extract are needed.

• The Korean Journal of Physiology
• /
• 제6권1호
• /
• pp.19-26
• /
• 1972

Physiological changes in hibernating animals (Manchurian Chipmunk and Hamster) were studied during various phases of the hibernation. The results obtained are summarized as follows. 1. Rectal temperature was declined markedly during hibernation, whereas it remained constant even in exposure of the animals to 0 C environment if the animals were not prepared for hibernation. As body temperature was lowered, heart rate was also markedly reduced as well as respiration and blood pressure. 2. The electrical activity recorded from cortical structure was characterized by replacement of fast wave activity by slow wave activity as body temperature was lowered and became flat at body temperature below 20C. 3. Blood glucose level showed no clear seasonal variations. However, the glycogen contents of the liver were markedly greater during the cold seasons than during the warm seasons. 4. Blood levels of insulin showed no clear seasonal variations.