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Increased Insulin Secretion (increased + insulin_secretion)
Selected AbstractsIslet adaptation to insulin resistance: mechanisms and implications for interventionDIABETES OBESITY & METABOLISM, Issue 1 2005B. Ahrén Abstract:, Insulin sensitivity and insulin secretion are reciprocally related such that insulin resistance is adapted by increased insulin secretion to maintain normal glucose and lipid homeostasis. The relation between insulin sensitivity and secretion is curvilinear and mathematically best described as a hyperbolic relation. Several potential mediators have been suggested to be signals for the beta cells to respond to insulin resistance such as glucose, free fatty acids, autonomic nerves, fat-derived hormones and the gut hormone glucagon-like peptide-1 (GLP-1). Failure of these signals or of the pancreatic beta cells to adequately adapt insulin secretion in relation to insulin sensitivity results in inappropriate insulin levels, impaired glucose intolerance (IGT) and type 2 diabetes. Therefore, treatment of IGT and type 2 diabetes should aim at restoring the normal relation between insulin sensitivity and secretion. Such treatment includes stimulation of insulin secretion (sulphonylureas, repaglinide and nateglinide) and insulin sensitivity (metformin and thiazolidinediones), as well as treatment aimed at supporting the signals mediating the islet adaptation (cholinergic agonists and GLP-1). Both, for correct understanding of diabetes pathophysiology and for development of novel treatment modalities, therefore, the non-linear inverse relation between insulin sensitivity and secretion needs to be acknowledged. [source] Insulin resistance is not coupled with defective insulin secretion in primary hyperparathyroidismDIABETIC MEDICINE, Issue 10 2009F. Tassone Abstract Aims, An increased frequency of both impaired glucose tolerance and Type 2 diabetes mellitus (DM) has been reported in primary hyperparathyroidism (pHPT), thus we sought to investigate insulin sensitivity and insulin secretion in a large series of pHPT patients. Subjects and methods, One hundred and twenty-two consecutive pHPT patients without known DM were investigated [age (mean ± sd) 59.3 ± 13.6 years, body mass index (BMI) 25.7 ± 4.2 kg/m2; serum calcium 2.8 ± 0.25 mmol/l; PTH 203.2 ± 145.4 ng/l]. Sixty-one control subjects were matched, according to the degree of glucose tolerance, in a 2 : 1 patient:control ratio. Fasting- and oral glucose tolerance test-derived estimates of insulin sensitivity and secretion were determined by means of the quantitative insulin sensitivity check index (QUICKI) and the insulin sensitivity index (ISI) composite. Results, Both the QUICKI and ISI composite were lower in pHPT patients than control subjects (P < 0.03 and P < 0.05, respectively) after adjusting for age, systolic blood pressure and BMI. Conversely, all insulin secretion estimates were significantly increased in pHPT patients than in control subjects (P < 0.04 and P < 0.03, respectively) and after adjusting for age, systolic blood pressure and BMI. Log serum calcium levels were negatively associated with the QUICKI and log ISI composite (R = ,0.30, P = 0.001; R = ,0.23, P = 0.020, respectively) in pHPT patients. Serum calcium levels significantly and independently contributed to impaired insulin sensitivity in multivariate analysis (QUICKI as dependent variable: , = ,0.31, P = 0.004, R2 = 0.15; log ISI composite as dependent variable: , = ,0.29, P = 0.005, R2 = 0.16). Conclusions, Our study confirms a reduction in both basal and stimulated insulin sensitivity in primary hyperparathyroidism, in spite of increased insulin secretion. Moreover, our data show for the first time a significant relationship between hypercalcaemia and insulin sensitivity in this condition. [source] Capsaicin-sensitive sensory fibers in the islets of Langerhans contribute to defective insulin secretion in Zucker diabetic rat, an animal model for some aspects of human type 2 diabetesEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2007Dorte X. Gram Abstract The system that regulates insulin secretion from ,-cells in the islet of Langerhans has a capsaicin-sensitive inhibitory component. As calcitonin gene-related peptide (CGRP)-expressing primary sensory fibers innervate the islets, and a major proportion of the CGRP-containing primary sensory neurons is sensitive to capsaicin, the islet-innervating sensory fibers may represent the capsaicin-sensitive inhibitory component. Here, we examined the expression of the capsaicin receptor, vanilloid type 1 transient receptor potential receptor (TRPV1) in CGRP-expressing fibers in the pancreatic islets, and the effect of selective elimination of capsaicin-sensitive primary afferents on the decline of glucose homeostasis and insulin secretion in Zucker diabetic fatty (ZDF) rats, which are used to study various aspects of human type 2 diabetes mellitus. We found that CGRP-expressing fibers in the pancreatic islets also express TRPV1. Furthermore, we also found that systemic capsaicin application before the development of hyperglycemia prevents the increase of fasting, non-fasting, and mean 24-h plasma glucose levels, and the deterioration of glucose tolerance assessed on the fifth week following the injection. These effects were accompanied by enhanced insulin secretion and a virtually complete loss of CGRP- and TRPV1-coexpressing islet-innervating fibers. These data indicate that CGRP-containing fibers in the islets are capsaicin sensitive, and that elimination of these fibers contributes to the prevention of the deterioration of glucose homeostasis through increased insulin secretion in ZDF rats. Based on these data we propose that the activity of islet-innervating capsaicin-sensitive fibers may have a role in the development of reduced insulin secretion in human type 2 diabetes mellitus. [source] The effect of weight loss by energy restriction on metabolic profile and glucose tolerance in poniesJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 5 2008S. Van Weyenberg Summary In nine initially obese ponies, a weekly weight loss according to 1% of their ideal body weight was evaluated for its impact on insulin sensitivity and metabolic profile. Weight loss was obtained solely through energy restriction, initially at 70% of maintenance energy requirements, but to maintain constant weight loss, feed amount had to be decreased to 50% and 35% of maintenance energy requirement during the course of the trial. An oral glucose tolerance test (OGTT) was performed at weeks 0, 10 and 17. Fasted blood samples were taken on weeks 0, 3, 10, 17 for analysis of triglycerides (TG), non-esterified fatty acids (NEFA), creatine phosphokinase (CPK), lactate dehydrogenase (LDH), T3, T4 and leptin. Total average weight loss was 18.2%. When the OGTT was performed at weeks 0, 10 and 17, ponies had lost 0.22%, 9.9% and 16.3% of their initial weight respectively. Weight loss was associated with a decreased AUC for glucose and insulin. Moreover, greater % weight loss was associated with a significantly lower glucose peak and a lower area under the curve (AUC glucose). The lower glucose response after an OGTT in lean ponies was not the result of an increased insulin secretion, but an improved insulin sensitivity. Restricted feeding led to mobilization of TG and NEFA and to a reduced basal metabolism, with lower LDH, CPK, T3 and leptin. In conclusion: in obese Shetland ponies, weight loss at a rate of 1% of ideal body weight per week through restricted energy intake, ameliorated insulin sensitivity. [source] Antidiabetic activity of Croton klozchianus in rats and direct stimulation of insulin secretion in-vitroJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 3 2008R. Govindarajan Croton klozchianus is a relatively uninvestigated species with no pharmacological or phytochemical reports available, although it has been used clinically by Ayurvedic physicians to treat diabetes. We have investigated this use by studying the insulin secretion and antidiabetic activity of C. klozchianus. Treatment of diabetic rats with aerial parts of C. klozchianus extract (CK, 100 and 300 mg kg,1 body weight) for three weeks showed significant reduction in blood glucose (45.8% after 14 days for 300 mg kg,1). C. klozchianus extract caused a significant concentration-dependent increase in insulin secretion (8-fold at 2 mg mL,1 for cells challenged with 20 mm glucose) from MIN6 cells grown as monolayers and as pseudoislets, indicating that the antidiabetic activity may have been as a result of increased insulin secretion. It also had a role on the lipid profile of the rats by causing reduction in cholesterol and triglycerides and increasing high density lipoprotein significantly. The results obtained gave some scientific support to the traditional use of the plant as a treatment for diabetes. [source] | |||||||||||||