Sennoside A induces GLP-1 secretion through activation of the ERK1/2 pathway in L-cells

Abstract Background Glucagon-like peptide-1 (GLP-1) is secreted from the intestinal L-cells to stimulate insulin secretion in the control of blood glucose. Sennoside A (SA), derived from Rhubarb extract of traditional Chinese medicine, is often used to treat constipation and lose weight. Our previous study suggests that SA can increase the plasma GLP-1 level in a mouse model of type 2 diabetes. However, the mechanism of SA activity remains unknown. This issue was addressed in this study. Methods C57bl/6 mice were divided randomly into four groups at n = 12. Group one was used as a control group without drug treatment. The other three groups were treated with (SA) at three dosages: a low dose (15 mg/kg/day), medium dose (30mg/kg/day) or high dose (45 mg/kg/day). SA was delivered into the mice through drinking water. Bodyweight was monitored. After treatment, blood glucose was assayed by OGTT. Plasma GLP-1 and insulin were determined at 15 mins of oral glucose challenge. Colon tissues were collected for mRNA or western blot analysis. Immunofluorescence staining assays was used to evaluate the number of β-cells and L-cells. NCI-H716 cells were employed to investigate the mechanism of SA-induced GLP-1 secretion, and the cells were subjected to western blot analysis. In the study of extracellular signal-regulated kinases 1/2 (ERK1/2) pathway, NCI-H716 cells were pretreated with ERK1/2 inhibitors (PD98059, 50 μM) for 30 min in the presence of SA (100 μM). Results In the current study, SA can reduce body weight during 5 weeks of weight monitoring and improve OGTT in C57BL/6 mice on the Chow diet. Furthermore, plasma GLP-1 was significantly elevated in the mouse treated by SA at the dosage of 45 mg/kg/day. The SA activity was supported by improving glucose-induced insulin secretion. Meanwhile, increased expression of EKR1/2 and prohormone convertase 1/3 (PC1/3) proteins was observed in the large intestine of SA-treated mice. The number of L-cells was not altered in each group. In the NCI-H716 cells, GLP-1 secretion was induced by SA with activation of the ERK1/2 pathway and elevation of PC1/3 protein. The SA effect was blocked by the ERK1/2 inhibitor. These data suggest that SA induced GLP-1 secretion in L-cells through activation of the ERK1/2 pathway in the mouse intestine. Conclusion Our study provides direct evidence that SA interacts with L cells for GLP-1 secretion. The data suggest that the SA effect is dependent on the ERK1/2 signaling pathway. Therefore, SA is a new drug candidate for the treatment of type 2 diabetes by induction of GLP-1 secretion.

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Abstract 1958: MicroRNA Mir-27b Rescues Impaired Angiogenic Function of Endothelial Progenitor Cells and Accelerates Wound Healing in Type 2 Diabetes

Circulation ◽

10.1161/circ.118.suppl_18.s_412 ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Jie-Mei Wang ◽

Jun Tao ◽

Alex F Chen

Keyword(s):

Type 2 Diabetes ◽

Wound Healing ◽

Western Blot ◽

Real Time ◽

Blot Analysis ◽

Real Time Pcr ◽

Western Blot Analysis ◽

Type 2 Diabetic

Endothelial progenitor cells (EPCs) play a key role in angiogenesis, which is dysfunctional in diabetes. MicroRNAs (miRNAs) are endogenous non-coding RNAs that regulate gene expression at the post-transcriptional level. However, whether miRNAs regulate EPC-mediated angiogenesis in diabetes is unknown. We tested the hypothesis that mir-27b rescues impaired EPC angiogenesis in vitro and in vivo via suppressing anti-angiogenic molecule thrombospondin-1 (TSP-1) in type 2 diabetes. Bone marrow-derived EPCs from adult male (C57BLKS/J, 9 weeks) type 2 diabetic db/db and their normal littermates db/+ mice (glucose 371.8±37.8 vs. 167.5±21.3 mg/dL, n=38, p<0.05) were used. miRNA processing enzyme Dicer in EPCs was decreased by >40% in db/db vs. db/+ mice (Western blot analysis, n=4 p<0.01), paralleled with >66% reduction of mir-27b expression (real-time PCR, n=4, p<0.05). Both TSP-1 mRNA and protein in EPCs were significantly higher in db/db vs. db/+ mice (real-time PCR, 130.1%, n=4, p<0.05, Western blot analysis, 127.4%, n=4 p<0.05), which were suppressed upon mir-27b mimic transfection (by 75%, real-time PCR and 69%, Western blot analysis, n=4 – 6, p<0.01). EPC-induced angiogenesis was decreased by >70% in db/db vs. db/+ mice (Matrigel tube formation assay, n=4, p<0.05), which was rescued upon mir-27b mimic transfection or silencing TSP-1 expression by its siRNA (both n=4, p<0.05). Furthermore, inhibition of mir-27b in normal EPCs increased their TSP-1 protein by 117.5% (n=6, p<0.05) and impaired their angiogenesis by 81.5% (n=4, p<0.01), both were reversed by silencing TSP-1 expression by its siRNA. Finally, excisional wound closure was markedly delayed in db/db vs. db/+ mice (4-mm punch biopsy, n=4, p<0.05), accompanied by impaired wound angiogenesis (perfusion index by Laser Doppler, n=4, p<0.05). Cell therapy of diabetic EPCs (3×10 5 cells) transfected with mir-27b mimic onto diabetic wounds significantly accelerated their closure rates (n=4, p<0.05 vs. diabetic EPCs alone), with a concomitant augmentation of in vivo wound angiogenesis (n=4, p<0.05). Mir-27b rescues impaired EPC angiogenesis and accelerates wound healing in type 2 diabetic mice, at least in part, via suppressing TSP-1 expression. This research has received full or partial funding support from the American Heart Association, AHA Midwest Affiliate (Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, South Dakota & Wisconsin).

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Comparison of Immunoassays for the Selective Measurement of Human High–Molecular Weight Adiponectin

Clinical Chemistry ◽

10.1373/clinchem.2008.112425 ◽

2009 ◽

Vol 55 (3) ◽

pp. 568-572 ◽

Cited By ~ 8

Author(s):

Dan Liu ◽

Tibor Schuster ◽

Marcus Baumann ◽

Marcel Roos ◽

Daniel Sollinger ◽

...

Keyword(s):

Type 2 Diabetes ◽

Molecular Weight ◽

Western Blot ◽

High Molecular Weight ◽

Western Blotting ◽

Blot Analysis ◽

Western Blot Analysis ◽

Hmw Adiponectin ◽

Deming Regression

Abstract Background: Adiponectin is an adipocyte-derived hormone circulating in different multimer complexes. The high–molecular-weight (HMW) complex is likely the active form of this protein and has been recognized as a risk marker for type 2 diabetes and coronary artery disease (CAD). Because quantification of HMW adiponectin by Western blot analysis is time-consuming, novel ELISAs have been developed to simplify measurements in clinical research. However, these enzyme immunoassays have not been cross-validated in larger patient groups. We evaluated 2 individual ELISA systems by comparison to Western blotting for measurement of the distribution of HMW adiponectin in healthy individuals and patients with CAD and type 2 diabetes. Methods: We measured HMW adiponectin in 204 individuals (83 CAD patients, 81 type 2 diabetes patients, and 40 healthy controls). Correlations, range of agreement, and imprecision of HMW concentrations obtained using 2 commercial ELISAs (#1, ALPCO Diagnostics; #2, Millipore) were evaluated by comparison with quantitative Western blotting. Result: Adiponectin results of the ELISAs were significantly correlated with those obtained by Western blotting (both r > 0.75, P < 0.001). Deming regression and Bland-Altman analyses indicated high agreement among the 3 immunoassays. The median difference between HMW adiponectin concentrations measured by ELISA and by Western blot was +0.4 mg/L for ELISA #1 and −0.4 mg/L for ELISA #2 with 95% of value differences <3 mg/L. Conclusions: Selective measurement of HMW adiponectin by ELISA is feasible; however, individual differences among immunoassays must be considered. The evaluated ELISAs exhibit analytical characteristics that allow their use as equivalent for Western blot analysis in larger clinical and epidemiological groups.

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Interplay of Dinner Timing and MTNR1B Type 2 Diabetes Risk Variant on Glucose Tolerance and Insulin Secretion: A Randomized Crossover Trial

10.2337/figshare.17122142 ◽

2022 ◽

Author(s):

Marta Garaulet ◽

Jesus Lopez-Minguez ◽

Hassan S Dashti ◽

Céline Vetter ◽

Antonio Miguel Hernández-Martínez ◽

...

Keyword(s):

Type 2 Diabetes ◽

Insulin Secretion ◽

Glucose Tolerance ◽

Area Under The Curve ◽

Serum Levels ◽

Postprandial Glucose ◽

Oral Glucose ◽

Elevated Concentration ◽

Endogenous Melatonin

Objective: We tested whether the concurrence of food intake and elevated concentration of endogenous melatonin, as occurs in late eating, results in impaired glucose control, in particular in carriers of the type 2 diabetes-associated G allele in the melatonin-receptor-1-b gene (MTNR1B). Research Design and Methods: In a Spanish natural late eating population, a randomized, cross-over study design was performed, following an 8-h fast. Each participant (n=845) underwent two evening 2-h 75g oral glucose tolerance tests (OGTT): an early condition scheduled 4 hours prior to habitual bedtime (“early dinner-timing”), and a late condition scheduled 1 hour prior to habitual bedtime (“late dinner-timing”), simulating an early and a late dinner timing, respectively. Differences in postprandial glucose and insulin responses were determined using incremental area under the curve (AUC) calculated by the trapezoidal method between early and late dinner-timing. Results: Melatonin serum levels were 3.5-fold higher in the late vs. early condition, with late dinner-timing resulting in 6.7% lower insulin area-under-the-curve (AUC) and 8.3% higher glucose AUC. In the late condition MTNR1B G-allele carriers had lower glucose tolerance than non-carriers. Genotype differences in glucose tolerance were attributed to reductions in β-cell function (Pint AUCgluc=0.009, Pint CIR=0.022, Pint DI=0.018). Conclusions: Concurrently high endogenous melatonin and carbohydrate intake, as typical for late eating, impair glucose tolerance, especially in MTNR1B G-risk-allele carriers, attributable to insulin secretion defects.

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Transcription factor 7-like 2 (TCF7L2): a culprit gene in Type 2 Diabetes Mellitus

Diabetes Mellitus ◽

10.14341/dm12313 ◽

2021 ◽

Vol 24 (4) ◽

pp. 371-376

Author(s):

A. Jan ◽

H. Jan ◽

Z. Ullah

Keyword(s):

Type 2 Diabetes ◽

Transcription Factor ◽

Insulin Secretion ◽

Blood Glucose ◽

Pancreatic Beta Cell ◽

Genetic Research ◽

Wnt Signaling Pathway ◽

Diabetes Type 2 ◽

Ethnic Population

The genetics of Type 2 diabetes a complex metabolic disorder, characterized by decreased insulin secretion and insulin resistance resulting in impaired blood glucose homeostasis remains enigma for geneticists. In 2006 an important step while finding genetic causes of diabetes type 2 was identification of transcription factor 7-like 2 (TCF7L2) gene an important marker in predisposition of type 2 diabetes in almost all ethnic population. Recent genetic research identifies numerous novel type 2 diabetes susceptible genes among these genes TCF7L2 is considered as gang head and emerged as the most promising types 2 diabetes causing gene. Risk variants in TCF7L2 effects pancreatic beta cell development and insulin secretion by influencing Wnt Signaling pathway. Genetic variants in TCF7L2 confer risk for type 2 diabetes by altering expression of transcription factor (which has key role in blood glucose regulation) in pancreas. The purpose of this paper is to evaluate type 2 diabetes susceptible gene the TCF7L2 and to present a comprehensive review of studies carried out worldwide in different ethnic population on association of TCF7L2 polymorphism with type 2 diabetes.

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9-PAHSA Improves Cardiovascular Complications by Promoting Autophagic Flux and Reducing Myocardial Hypertrophy in Db/Db Mice

Frontiers in Pharmacology ◽

10.3389/fphar.2021.754387 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yan-Mei Wang ◽

Shou-Ling Mi ◽

Hong Jin ◽

Qi-Lin Guo ◽

Zhong-Yu Yu ◽

...

Keyword(s):

Cardiovascular Disease ◽

Blood Glucose ◽

Western Blot ◽

Vascular Calcification ◽

Blot Analysis ◽

Western Blot Analysis ◽

Myocardial Hypertrophy ◽

Autophagic Flux ◽

Glucose Levels ◽

Blood Glucose Levels

Atherosclerotic cardiovascular disease is a common and severe complication of diabetes. There is a large need to identify the effective and safety strategies on diabetic cardiovascular disease (DCVD). 9-PAHSA is a novel endogenous fatty acid, and has been reported to reduce blood glucose levels and attenuate inflammation. We aim to evaluate the effects of 9-PAHSA on DCVD and investigate the possible mechanisms underlying it. Firstly, serum 9-PAHSA levels in human were detected by HPLC-MS/MS analysis. Then 9-PAHSA was synthesized and purified. The synthesized 9-PAHSA was gavaged to db/db mice with 50 mg/kg for 4 weeks. The carotid arterial plaque and cardiac structure was assessed by ultrasound. Cardiac autophagy was tested by western blot analysis, electron microscope and iTRAQ. The results showed that 9-PAHSA, in patients with type 2 diabetes mellitus (T2DM), was significantly lower than that in non-diabetic subjects. Administration of 9-PAHSA for 2 weeks reduced blood glucose levels. Ultrasound observed that continue administration of 9-PAHSA for 4 weeks ameliorated carotid vascular calcification, and attenuated myocardial hypertrophy and dysfunction in db/db mice. Electron microscopy showed continue 9-PAHSA treatment significantly increased autolysosomes, while dramatically decreased greases in the myocardial cells of the db/db mice. Moreover, iTRAQ analysis exhibited that continue 9-PAHSA treatment upregulated BAG3 and HSPB8. Furthermore, western blot analysis confirmed that 9-PAHSA down-regulated Akt/mTOR and activated PI3KIII/BECN1 complex in diabetic myocardium. Thus, 9-PAHSA benefits DCVD in diabetic mice by ameliorating carotid vascular calcification, promoting autophagic flux and reducing myocardial hypertrophy.

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Mechanisms of Action of Liraglutide in Patients With Type 2 Diabetes Treated With High-Dose Insulin

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2015-3906 ◽

2016 ◽

Vol 101 (4) ◽

pp. 1798-1806 ◽

Cited By ~ 12

Author(s):

Anna Vanderheiden ◽

Lindsay B. Harrison ◽

Jeremy T. Warshauer ◽

Beverley Adams-Huet ◽

Xilong Li ◽

...

Keyword(s):

Type 2 Diabetes ◽

Insulin Secretion ◽

Insulin Treatment ◽

Glycosylated Hemoglobin ◽

Challenge Test ◽

Glucagon Secretion ◽

Mechanisms Of Action ◽

High Dose ◽

C Peptide

Abstract Context: The mechanisms of action of incretin mimetics in patients with long-standing type 2 diabetes (T2D) and high insulin requirements have not been studied. Objective: To evaluate changes in β-cell function, glucagon secretion, and fat distribution after addition of liraglutide to high-dose insulin. Design: A single-center, randomized, double-blind, placebo-controlled trial. Setting: University of Texas Southwestern and Parkland Memorial Hospital clinics. Patients: Seventy-one patients with long-standing (median, 17 years) T2D requiring high-dose insulin treatment (>1.5 U/kg/d; average, 2.2 ± 0.9 U/kg/d). Intervention: Patients were randomized to liraglutide 1.8 mg/d or matching placebo for 6 months. Main Outcome Measures: We measured changes in insulin and glucagon secretion using a 4-hour mixed-meal challenge test. Magnetic resonance-based techniques were used to estimate sc and visceral fat in the abdomen and ectopic fat in the liver and pancreas. Results: Glycosylated hemoglobin improved significantly with liraglutide treatment, with an end-of-trial estimated treatment difference between groups of −0.9% (95% confidence interval, −1.5, −0.4%) (P = .002). Insulin secretion improved in the liraglutide group vs placebo, as measured by the area under the curve of C-peptide (P = .002) and the area under the curves ratio of C-peptide to glucose (P = .003). Insulin sensitivity (Matsuda index) and glucagon secretion did not change significantly between groups. Liver fat and sc fat decreased in the liraglutide group vs placebo (P = .0006 and P = .01, respectively), whereas neither visceral nor pancreatic fat changed significantly. Conclusions: Treatment with liraglutide significantly improved insulin secretion, even in patients with long-standing T2D requiring high-dose insulin treatment. Liraglutide also decreased liver and sc fat, but it did not alter glucagon secretion.

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TIMING OF ACUTE PASSIVE HEATING ON GLUCOSE TOLERANCE AND BLOOD PRESSURE IN PEOPLE WITH TYPE 2 DIABETES: A RANDOMIZED, BALANCED CROSSOVER, CONTROL TRIAL

Journal of Applied Physiology ◽

10.1152/japplphysiol.00747.2020 ◽

2021 ◽

Author(s):

Thomas Joseph James ◽

Jo Corbett ◽

Michael H. Cummings ◽

Sharon Allard ◽

John S. Young ◽

...

Keyword(s):

Blood Pressure ◽

Type 2 Diabetes ◽

Blood Glucose ◽

Insulin Sensitivity ◽

Glucose Tolerance ◽

Microvascular Dysfunction ◽

Oral Glucose ◽

Passive Heating ◽

Chronic Hyperglycemia

Type 2 diabetes mellitus (T2DM) is characterized by chronic hyperglycemia and progressive insulin resistance, leading to macro and microvascular dysfunction. Passive heating has potential to improve glucose homeostasis and act as an exercise mimetic. We assessed the effect of acute passive heating before or during an oral glucose tolerance test (OGTT) in people with T2DM. Twelve people with T2DM were randomly assigned to 3 conditions:1) 3 h OGTT (CON); 2) 1 h passive heating (40 °C water) 30 min before an OGTT (HOT-OGTT); and 3) 1 h passive heating (40 °C water) 30 min after commencing an OGTT (OGTT-HOT). Blood [glucose], insulin sensitivity, extracellular heat shock protein 70 (eHSP70), total energy expenditure (TEE), heart rate (HR), systolic (SBP) and diastolic blood pressure (DBP) were recorded. Passive heating did not alter blood [glucose] (CON, 1,677 (386) a.u.; HOT-OGTT, 1,797 (340) a.u.; OGTT-HOT, 1,662 (364) a.u.; P = 0.28), insulin sensitivity (P = 0.15), or SBP (P = 0.18), but did increase [eHSP70] in both heating conditions (CON, 203.48 (110.81) pg·mL-1; HOT-OGTT, 402.47 (79.02) pg·mL-1; OGTT-HOT, 310.00 (60.53) pg·mL-1; P < 0.001), increased TEE (via fat oxidation) in the OGTT-HOT condition (CON, 263 (33) kcal; HOT-OGTT, 278 (40) kcal; OGTT-HOT, 304 (38) kcal; P = 0.001), increased HR in both heating conditions (P < 0.001) and reduced DBP in OGTT-HOT condition (P < 0.01). Passive heating in close proximity to a glucose challenge does not alter glucose tolerance but does increase [eHSP70] and TEE, and reduce blood pressure in people with T2DM.

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Prevalence and risk factors of Type 2 diabetes in an urbanizing rural community of Bangladesh

Bangladesh Medical Research Council Bulletin ◽

10.3329/bmrcb.v33i2.1204 ◽

1970 ◽

Vol 33 (2) ◽

pp. 48-54 ◽

Cited By ~ 16

Author(s):

Md. Mafuzar Rahman ◽

Md. Abdur Rahim ◽

Quamrun Nahar

Keyword(s):

Risk Factors ◽

Type 2 Diabetes ◽

Blood Glucose ◽

Rural Community ◽

Rural Areas ◽

Fasting Blood Glucose ◽

Significant Risk ◽

Oral Glucose ◽

Total Prevalence

This cross-sectional study was carried out to estimate the prevalence of type 2 diabetes mellitus and itsâ risk factors in an urbanizing rural community of Bangladesh. Two villages were randomly selected from the rural areas of Gazipur district and total 975 subjects (>20 years), were included following simple random procedure. Capillary blood glucose levels, fasting blood glucose (FBG) levels and 2-hour after 75 g oral glucose load (OGTT) were measured. Height, weight, waist and hip circumferences and blood pressure were measured. The study population was lean with mean body mass index (BMI) of 20.48. The total prevalence of type 2 diabetes was 8.5%, men showed higher prevalence (9.4%) compare to women (8.0%). Increasing age and higher BMI were found to be significant risk factors following both FBG and OGTT. The study has shown that prevalence of diabetes has increased in the populations who are in transitional stage of urbanization, and may indicate an epidemiological transition due to fast expanding urbanization. Keywords: Bangladesh; Diabetes; RuralDOI: 10.3329/bmrcb.v33i2.1204Bangladesh Med Res Counc Bull 2007; 33: 48-54

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