scholarly journals Adipose tissue glycogen synthase activation by in vivo insulin in spontaneously insulin-resistant and Type 2 (non-insulin-dependent) diabetic rhesus monkeys

Diabetologia ◽  
1993 ◽  
Vol 36 (3) ◽  
pp. 200-206 ◽  
Author(s):  
H. K. Ortmeyer ◽  
N. L. Bodkin ◽  
B. C. Hansen
2016 ◽  
Vol 64 (5) ◽  
pp. 989-991 ◽  
Author(s):  
Esben Søndergaard ◽  
Michael D Jensen

In metabolically healthy humans, adipose tissue is exquisitely sensitive to insulin. Similar to muscle and liver, adipose tissue lipolysis is insulin resistant in adults with central obesity and type 2 diabetes. Perhaps uniquely, however, insulin resistance in adipose tissue may directly contribute to development of insulin resistance in muscle and liver because of the increased delivery of free fatty acids to those tissues. It has been hypothesized that insulin adipose tissue resistance may precede other metabolic defects in obesity and type 2 diabetes. Therefore, precise and reproducible quantification of adipose tissue insulin sensitivity, in vivo, in humans, is an important measure. Unfortunately, no consensus exists on how to determine adipose tissue insulin sensitivity. We review the methods available to quantitate adipose tissue insulin sensitivity and will discuss their strengths and weaknesses.


1993 ◽  
Vol 265 (3) ◽  
pp. R552-R558 ◽  
Author(s):  
H. K. Ortmeyer ◽  
N. L. Bodkin ◽  
B. C. Hansen

Altered insulin action on glycogen synthase activity has been well recognized in non-insulin-dependent diabetes, and some prior evidence has suggested this alteration may be one of the earliest disturbances preceding the development of diabetes. The present study, using the spontaneously insulin-resistant and diabetic rhesus monkey, examined insulin's effect on glycogen synthase at the earliest point of identification of developing diabetes. The normal monkeys (n = 11) had a greater insulin-mediated change in glycogen synthase-independent activity compared with the hyperinsulinemic (n = 8) (P < 0.05) and diabetic (n = 8) (P < 0.01) monkeys. Compared with normal monkeys, the diabetic monkeys had lower basal and insulin-stimulated total glycogen synthase activity (P < 0.05). Monkeys with normal beta-cell responsiveness to intravenous glucose had greater insulin-mediated change in glycogen synthase fractional velocity compared with those with exaggerated (P < 0.01) or absent beta-cell responses to glucose (P < 0.05). We conclude that an alteration in insulin action on glycogen synthase is present as early as beta-cell hyperresponsiveness, one of the earliest detected abnormalities in the progression toward diabetes.


Diabetologia ◽  
1984 ◽  
Vol 27 (5) ◽  
pp. 522-526 ◽  
Author(s):  
P. M. Dodson ◽  
P. J. Pacy ◽  
P. Bal ◽  
A. J. Kubicki ◽  
R. F. Fletcher ◽  
...  

1999 ◽  
Vol 277 (4) ◽  
pp. E617-E623 ◽  
Author(s):  
Christophe Broca ◽  
René Gross ◽  
Pierre Petit ◽  
Yves Sauvaire ◽  
Michèle Manteghetti ◽  
...  

We have recently shown in vitro that 4-hydroxyisoleucine (4-OH-Ile), an amino acid extracted from fenugreek seeds, potentiates insulin secretion in a glucose-dependent manner. The present study was designed to investigate whether 4-OH-Ile could exert in vivo insulinotropic and antidiabetic properties. For this purpose, intravenous or oral glucose tolerance tests (IVGTTs and OGTTs, respectively) were performed not only in normal animals but also in a type II diabetes rat model. During IVGTT in normal rats or OGTT in normal dogs, 4-OH-Ile (18 mg/kg) improved glucose tolerance. The lactonic form of 4-OH-Ile was ineffective in normal rats. In non-insulin-dependent diabetic (NIDD) rats, a single intravenous administration of 4-OH-Ile (50 mg/kg) partially restored glucose-induced insulin response without affecting glucose tolerance; a 6-day subchronic administration of 4-OH-Ile (50 mg/kg, daily) reduced basal hyperglycemia, decreased basal insulinemia, and slightly, but significantly, improved glucose tolerance. In vitro, 4-OH-Ile (200 μM) potentiated glucose (16.7 mM)-induced insulin release from NIDD rat-isolated islets. So, the antidiabetic effects of 4-OH-Ile on NIDD rats result, at least in part, from a direct pancreatic B cell stimulation.


2008 ◽  
Vol 295 (5) ◽  
pp. E1142-E1151 ◽  
Author(s):  
Helen Cho ◽  
Shawn C. Black ◽  
David Looper ◽  
Manli Shi ◽  
Dawn Kelly-Sullivan ◽  
...  

c-Jun NH2-terminal kinase (JNK) plays an important role in insulin resistance; however, identification of pharmacologically potent and selective small molecule JNK inhibitors has been limited. Compound A has a cell IC50 of 102 nM and is at least 100-fold selective against related kinases and 27-fold selective against glycogen synthase kinase-3β and cyclin-dependent kinase-2. In C57BL/6 mice, compound A reduced LPS-mediated increases in both plasma cytokine levels and phosphorylated c-Jun in adipose tissue. Treatment of mice fed a high-fat diet with compound A for 3 wk resulted in a 13.1 ± 1% decrease in body weight and a 9.3 ± 1.5% decrease in body fat, compared with a 6.6 ± 2.1% increase in body weight and a 6.7 ± 2.1% increase in body fat in vehicle-treated mice. Mice pair fed to those that received compound A exhibited a body weight decrease of 7 ± 1% and a decrease in body fat of 1.6 ± 1.3%, suggesting that reductions in food intake could not account solely for the reductions in adiposity observed. Compound A dosed at 30 mg/kg for 13 days in high-fat fed mice resulted in a significant decrease in phosphorylated c-Jun in adipose tissue accompanied by a decrease in weight and reductions in glucose and triglycerides and increases in insulin sensitivity to levels comparable with those in lean control mice. The ability of compound A to reduce the insulin-stimulated phosphorylation of insulin receptor substrate-1 (IRS-1) von Ser307 and partially reverse the free fatty acid inhibition of glucose uptake in 3T3L1 adipocytes, suggests that enhancement of insulin signaling in addition to weight loss may contribute to the effects of compound A on insulin sensitization in vivo. Pharmacological inhibition of JNK using compound A may therefore offer an effective therapy for type 2 diabetes mediated at least in part via weight reduction.


2000 ◽  
Vol 167 (1) ◽  
pp. 107-115 ◽  
Author(s):  
J Shao ◽  
H Yamashita ◽  
L Qiao ◽  
JE Friedman

Recent studies suggest that the serine/threonine kinase protein kinase B (PKB or Akt) is involved in the pathway for insulin-stimulated glucose transporter 4 (GLUT4) translocation and glucose uptake. In this study we examined the components of the Akt signaling pathway in skeletal muscle and adipose tissue in vivo from C57BL/KsJ-Lepr(db/db) mice (db/db), a model of obesity, insulin resistance, and type II diabetes. There were no changes in the protein levels of GLUT4, p85alpha, or Akt in tissues from db/db mice compared with non-diabetic littermate controls (+/+). In response to acute insulin administration, GLUT4 recruitment to the plasma membrane increased twofold in muscle and adipose tissue from +/+ mice, but was significantly reduced by 42-43% (P<0.05) in both tissues from db/db mice. Insulin increased Akt-Ser(473) phosphorylation by two- to fivefold in muscle and adipose tissue from all mice. However, in db/db mice, maximal Akt-Ser(473) phosphorylation was decreased by 32% (P<0.05) and 69% (P<0.05) in muscle and adipose tissue respectively. This decreased phosphorylation in db/db mice corresponded with a significant decrease in maximal Akt kinase activity using a glycogen synthase kinase-3 fusion protein as a substrate (P<0.05). The level of insulin-stimulated tyrosine phosphorylation of p85alpha from phosphatidylinositol 3 (PI 3)-kinase, which is upstream of Akt, was also reduced in muscle and adipose tissue from db/db mice (P<0.05); however, there was no change in extracellular signal-regulated kinase-1 or -2 phosphorylation. These data implicate decreased insulin-stimulated Akt kinase activity as an important component underlying impaired GLUT4 translocation and insulin resistance in tissues from db/db mice. However, impaired insulin signal transduction appears to be specific for the PI 3-kinase pathway of insulin signaling, while the MAP kinase pathway remained intact.


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