• Preventive Nutrition and Food Science
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• 제2권2호
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• pp.144-148
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• 1997

Insulin secretory response to various calcium concentrations was investigated in 10- to 12-week old male lean and obese Zucker rats using an in vitro pancreatic perfusion procedure. There was no significant difference in insulin secretion response to low, medium, and high calcium concentrations in the lean rat. However, the obese rat shows a characteristics of hypersecretion of insulin. The obese rat pancreas perfused with the low calcium concentration released as low insulin as the lean rat. When perfused with the medium calcium concentration, th obese rat pancreas released twice as much insulin as the lean rat. eh hypersecretory phenomenon was also seen in the obese rat pancreas perfused with the high calcium concentration during the first phase of erfusion period, but his phenomenon was gradually diminished during he second phase of perfusion period. These results indicate that there may be a selective insulin secretory response to the extracellular calcium in he obese Zucker rat pancreas.

• Nutritional Sciences
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• 제8권2호
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• pp.83-88
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• 2005

This study was to investigate the effect of psyllium seed husk (PSYL) on postprandial glucose control and insulin secretion dynamics in Sprague-Dawley rats. In experiment 1, the rise in postprandial serum glucose was monitored during a 240-min period using a maltose loading test In normal rats given 16.6 mg/l00 g B.W./ml of PSYL orally, all the blood glucose levels during the 240-min period did not show statistically significant differences from the corresponding levels in normal rats given water. However, in streptozotocin-induced diabetic rats given the same amount of PSYL, the blood glucose level at 30 min was significantly lower than that in diabetic rats given water, and the peak time of the rise in the postprandial glucose was delayed In experiment 2, the normal (N) and diabetic (Db) rats were given PSYL (25 mg/l00 g B.W./ml/day) orally for 5 days. Blood samples were collected in order to measure the s-glucose and s-insulin levels. The final s-glucose level at day 5 in Db-PSYL was significantly lower than that in the corresponding control rats (Db-CONT) and the final s-insulin level in Db-PSYL was significantly greater than that in Db-CONT. In vitro 40-min pancreas perfusion was performed at day 5 in order to examine the insulin secretion dynamics. Results showed that the amounts of insulin secreted during the first phase (11-20 min) and the second phase (21-40 min) in the Db-PSYL were significantly greater than those in Db-CONT. Therefore, it is concluded that psyllium seed husk could be beneficial for controlling postprandial glucose levels in the stretozotocin-induced diabetic rats, and it may be partially mediated by insulin secretion dynamics.

• Clinical and Experimental Pediatrics
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• 제46권8호
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• pp.795-802
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• 2003

목 적 : 지방조직에 존재하는 OB 유전자에서 전사된 호르몬인 leptin은 여러 가지 생리적 요인이나, 호르몬에 의해서 영향을 받는다. Leptin의 발현에 대한 호르몬에 대한 연구가 많은 동물 실험들을 상대로 시도되고 있으나 사람에서 OB 유전자와 leptin 분비를 조절하는 호르몬의 영향 및 상호작용에 대해서는 아직 명확히 밝혀져 있지 않다. 본 연구는 사람의 복강에서 추출한 조직배양에서 OB 유전자와 leptin 분비를 조절하는 호르몬의 영향 및 상호작용에 대해서 알아보고자 하였다. 방 법 : 복부수술을 위하여 입원한 환자 7명을 대상으로 복강 내 지방조직을 절제하여 배양액에 호르몬을 첨가하지 않은 상태와 배양액에 인슐린, dexamethasone 및, 성장호르몬을 단독으로 첨가하거나, 인슐린과 dexamethasone을 동시에 첨가하거나, 인슐린과 dexamethasone과 성장호르몬을 같이 첨가한 상태에서 48시간 배양한 후 RNA를 추출하여 경쟁적 역전사 중합반응(competitive RT-PCR)을 시행하여 OB 유전자의 발현을 측정하고, human leptin IRMA Kit를 사용하여 지방조직에서 분비되는 배양액 내 leptin 양을 측정하였다. 결 과 : 인슐린은 단독으로는 OB 유전자 발현과 leptin 분비에는 영향을 미치지 못하였다. Dexamethasone은 OB 유전자의 발현과 leptin 분비를 증가시켰는데, 48시간 배양 후에 대조군에 비해 의미있게 증가하였다. 인슐린과 dexamethasone을 같이 배양시에는 OB 유전자 발현에 있어서는 의미있는 차이는 없었으나, leptin 분비는 48시간 배양 후 대조군에 비해 의미있게 증가하였다. 또한 성장호르몬 단독으로는 OB 유전자의 발현에 영향을 미치지는 못하나, 인슐린, dexamethasone, 성장호르몬을 같이 배양시에 인슐린과 dexamethasone의 OB 유전자 발현과 leptin 분비증가 능력을 억제시켰다. 결 론 : 인슐린 단독으로는 leptin 분비를 증가시키지 못하나, dexamethasone에 의해 상승작용이 나타나고, 이는 dexamethasone이 OB 유전자 발현을 증가시킨 후에 인슐린이 세포질내에서의 leptin 분비를 증가시킨다고 추정할 수 있다. 성장호르몬의 억제효과는 성장호르몬이 인슐린이나 dexamethasone에 대한 지방조직의 반응성을 변화시킴으로써 간접적으로 leptin의 발현을 조절할 것으로 추정되며, dexamethasone이 OB 유전자 발현을 증가시킨 후에 인슐린이 세포질 내에서의 leptin 분비를 증가시킨다는 것에 대한 연구가 더 필요하리라 사료된다.

• Preventive Nutrition and Food Science
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• 제9권4호
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• pp.367-373
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• 2004

The prevalence of type-2 diabetes increases remarkably in post-menopausal women, possibly because insulin secretion fails to compensate for the insulin resistance induced in various tissues by estrogen insufficiency. However, this has not been fully defined. Therefore, the present study investigated whether an ovariectomy (OVX) would increase insulin resistance and decrease the $\beta$-cell function and mass in female rats with and without a $90\%$ pancreatectomy (Px). Female rats aged 15 weeks were divided into four groups: 1) OVX + Px, 2) SOVX (sham operation of OVX) + Px, 3) OVX + SPx (sham operation of Px), and 4) SOVX + SPx, and given a $30\%$ fat diet for 8 weeks. At the end of the experimental period, the islet function and insulin resistance were determined using a hyperglycemic clamp and a euglycemic hyperinsulinemic clamp, respectively. The OVX only increased the body weight in the SPx rats, which was partially related to the food intake. Yet, the OVX did increase the peripheral insulin resistance, while the Px increased this resistance further. The OVX and Px both exacerbated the islet function, as measured by the insulin secretion pattern, while delaying and decreasing the first-phase insulin secretion. The OVX only decreased the proliferation of $\beta$-cells in the Px rats, while increasing apoptosis in both the Px and SPx rats. As a result, the OVX decreased the $\beta$-cell mass in the Px rats, but increased the mass in the SPx rats. In conclusion, an OVX was found to accelerate the development and progression of diabetes by increasing the insulin resistance and decreasing the $\beta$-cell mass. Therefore, menopause can be a risk factor for type-2 diabetes, mainly due to a deceased proliferation of $\beta$-cells.

• 대한핵의학회지
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• 제17권1호
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• pp.41-53
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• 1983

It is already well known that many factors are involved in maintaining normal blood glucose level. The amount and components of meal are also thought to be some of the factors which affect the blood glucose and insulin levels. It is reported that as for Koreans sugar takes up over 75% out of 2,098 kcal, the average daily calorie intake per adult. It implies that Koreans take a high-sugar diet compared with Westerners who take $40\sim50%$ of sugar out of their total average daily calorie. For the purpose of studying diurnal variations in serum glucose, insulin and C-peptide of normal Korean adults based on ordinary Korean diet, we selceted 13 normal Korean male adults and divided them into two groups, Group I (7 persons) and Group II (6 persons). We put Group I on 3,100kcal and 75% sugar diet, and Group II on 2,100 kcal and 69% sugar diet per day for over 4 days. Serum glucose, insulin and C-peptide were checked every 30 minutes or every hour throughout 24 hours. Results are as follows: 1. As for serum glucose level, in the prep ran dial fasting state in the morning, $mean{\pm}S.D.$ of Group I was $91.1{\pm}8.2mg%$, while that of Group II is $82.5{\pm}4.4mg%$. Both groups showed peaks of increased glucose level at postprandial 1 hour after each meal. The peak returned to the level shown during the fasting state at postprandial 1 hour after breakfast while the relatively high glucose levels were maintained respectively even for 2 or 3 hours.after lunch and dinner. 2. As for serum insulin level, Group showed $mean{\pm}S.D.$ of $14.7{\pm}3.0{\mu}U/ml$ while Group II shows that of $7.0{\pm}2.6{\mu}U/ml$ in the fasting state. Group I particularly showed the largest peak from preprandial a half or one and half an hour to postprandial one hour of lunch, and made relatively small peaks $(47.7{\pm}10.8{\mu}U/ml)$ at postorandial 1 hour after breakfast and dinner. No such large peak was marked in Group II, though it showed relatively similar patterns of peak after each meal. 3. As for C-peptide, in the fasting state, Group I and Group II showed $3.50{\pm}1.85$ and $1.66{\pm}0.53ng/ml$ of $mean{\pm}S.D.$, respectively. Group II showed peaks parallel to those for insulin level. None out of seven in Group I showed expected increase in C-peptide based insulin secretion at a half or one and half an hour before lunch. On the contrary, C-peptide increased in 5 subjects out of seven in Group I at 11:00 p.m. when insulin did not increase. 4. According to the integrated concentration method for a measurement of 24-hour total. insulin secretion rate, the $mean{\pm}S.D.$ of Group I was $76.4{\pm}15.2$ U and that of Group II was $58.6{\pm}21.1$ U. The above results confirm that Koreans, when given ordinary diet of 2,100 kcal and 69%, sugar, show insulin secretion pattern essentially similar to that of Westerners. On the contrary, when they are put on a high-calorie diet of 3,100 kcal a day, 75% of which is sugar, insulin secretion can be increased before lunch without increase in blood glucose. These results implies that insulin secretion can be affected by some other factors. The observation that an increase in C-peptide after 11 : 00 p.m. independent of insulin level supports an assertion that insulin secretion and C-peptide secretion can be thought as being physiologically dissociable, and these changes of diurnal patterns in the levels of serum insulin and C-peptide are thought to be resulted from the large meal and high-carbohydrate diet.

• Journal of Ginseng Research
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• 제47권4호
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• pp.572-582
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• 2023

Background: Free fatty acid-induced lipotoxicity is considered to play an important role in pancreatic β-cell dysfunction. The effect of ginsenosides on palmitic acid-induced pancreatic beta-cells cell death and failure of glucose-stimulated secretion of insulin (GSIS) was evaluated in this study. Methods: Enzyme-linked immunosorbent assay kit for a rat insulin was used to quantify glucose-stimulated insulin secretion. Protein expression was examined by western blotting analysis. Nuclear condensation was measured by staining with Hoechst 33342 stain. Apoptotic cell death was assessed by staining with Annexin V. Oil Red O staining was used to measure lipid accumulation. Results: We screened ginsenosides to prevent palmitic acid-induced cell death and impairment of GSIS in INS-1 pancreatic β-cells and identified protopanaxadiol (PPD) as a potential therapeutic agent. The protection effect of PPD was likely due to a reduction in apoptosis and lipid accumulation. PPD attenuated the palmitic acid-induced increase in the levels of B-cell lymphoma-2-associated X/B-cell lymphoma 2, poly (ADP-ribose) polymerase and cleaved caspase-3. Moreover, PPD prevented palmitic acid-induced impairment of insulin secretion, which was accompanied by an increase in the activation of phosphatidylinositol 3-kinase, peroxisome proliferator-activated receptor γ, insulin receptor substrate-2, serine-threonine kinase, and pancreatic and duodenal homeobox-1. Conclusion: Our results suggest that the protective effect of PPD on lipotoxicity and lipid accumulation induced by palmitic acid in pancreatic β-cells.

• 대한한의학회지
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• 제31권4호
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• pp.79-100
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• 2010

Objective: Production of ROS from glucose toxicity results in injury of pancreatic $\beta$-cells in diabetes models. This study was undertaken to examine the influence of Lespedeza Cuneata extract (LCE) on cytoprotective effects on glucose toxicity, insulin secretion and gene expression in RIN-m5F cells. Methods: First, we measured LCE's antioxidant activity by DPPH free radical-scavenging activity and SOD activity. After the various concentrations of LCE were added to the RIN-m5F cells, we measured cell viability with glucose stimulation by MTT assay and glucose-stimulated insulin secretion. We analyzed gene expression with Agilent whole mouse genome 44K oligo DNA microarray and searched for related pathways in KEGG (Kyoto Encyclopedia of Genes and Genomes). Lastly we measured INS-1, INS-2, INS-R, IRS-1, IRS-2, IRS-3, GLP-1R, and GLP-2R mRNA expression by real time RT-PCR. Results: Free radical-scavenging activity, SOD activity and insulin secretion increased dependent on LCE concentration, but LCE did not show considerable cytoprotective effect on RIN-m5F cells. More than twice expressed gene was 6362 in Oligo DNA chip. In KEGG, the most related pathway was the metabolic pathway. In the insulin signaling pathway, up expressed genes were Irs1, Mapk8, Akt1, and Lipe and down expressed genes were Rhoq, Fbp2, Prkar2b, Gck, and Prkag1. In real time RT-PCR, IRS-2, and IRS-3 expression increased significantly compared to the control group on LCE $12{\mu}g/m{\ell}$ concentration and GCK expression decreased significantly compared to the control group. Conclusions: These results show that LCE encourages insulin secretion and insulin metabolism by complicated gene mechanisms. Further mechanism study and clinical study seem to be necessary about Lespedeza Cuneata.

• Nutrition Research and Practice
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• 제2권4호
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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.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 2001년도 학술 발표회 진행표 및 논문초록
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• pp.47-47
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• 2001

Opening of $Ca^{2＋}$ -channels represents the final common pathway for insulin secretion in pancreatic beta-cells and related cell lines. We investigated voltage-sensitive calcium channels (VSCCs) and insulin secretion in RINm5F, an insulinoma cell line derived from rat pancreatic beta-cells. Several types of VSCCs were identified in RINm5f cells： dihydropyridine-sensitive L-type, $\omega$-conotoxin GVIA-sensitive N-type, $\omega$-agatoxin IVA-sensitive P-type channels, and $\omega$-conotoxin MVIIC sensitive Q-type channels.(omitted)

• 대한한방내과학회지
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• 제30권3호
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• pp.481-494
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• 2009

Background : Radix Sophora Flavescentis (SF) is used for the treatment of diabetes mellitus in Traditional Korean Medicine. However, little is known about the effects of Radix Sophora Flavescentis extract (SFE) on the hypoglycemic mechanism. Objective : We performed a series of experiments to verify the effects of SFE on the proliferation of RIN-m5F, the secretion and synthetic processes of insulin with glucose stimulation and inhibition of $\alpha$-glucosidase. Methods : Various amounts of SFE were added to the RIN-m5F cell culture to identify the effects on the cell proliferation, total amounts of insulin secretion, and related gene expression at the molecular level. Also to identify the inhibitory effect on the $\alpha$-glucosidase activities, ${\rho}NPG$ assay was done with various SFE concentrations followed by comparison with control. Results : SFE did not show considerable effects on RIN-m5F cells proliferation, insulin secretion or insulin mRNA expression, whichever phenomena did not depend on the glucose concentration. However, SFE significantly inhibited $\alpha$-glucosidase activity in a dose dependent manner compared to control. Conclusions : This study showed that SFE has potent $\alpha$-glucosidase inhibitory activity. Thus, SF may by used for the improvement of overall glycemic control. Further mechanism studies on the lipid toxicity and oxidation stress of SF seem to be necessary.