Lilly Lecture 1980: Insulin Resistance and Insulin Action: An In Vitro and In Vivo Perspective

Decreased cellular GSH content is a common finding in experimental and human diabetes, in which increased oxidative stress appears to occur. Oxidative stress has been suggested to play a causative role in the development of impaired insulin action on adipose tissue and skeletal muscle. In this study we undertook to investigate the potential of GSH depletion to induce insulin resistance, by utilizing the GSH synthesis inhibitor, L-buthionine-[S,R]-sulfoximine (BSO). GSH depletion (20-80% in various tissues), was achieved in vivo by treating rats for 20 days with BSO, and in vitro (80%) by treating 3T3-L1 adipocytes with BSO for 18 h. No demonstrable change in the GSH/GSSG ratio was observed following BSO treatment. GSH depletion was progressively associated with abnormal glucose tolerance test, which could not be attributed to impaired insulin secretion. Skeletal muscle insulin responsiveness was unaffected by GSH depletion, based on normal glucose response to exogenous insulin, 2-deoxyglucose uptake measurements in isolated soleus muscle, and on normal skeletal muscle expression of GLUT4 protein. Adipocyte insulin responsiveness in vitro was assessed in 3T3-L1 adipocytes, which displayed decreased insulin-stimulated tyrosine phosphorylation of insulin-receptor-substrate proteins and of the insulin receptor, but exaggerated protein kinase B phosphorylation. However, insulin-stimulated glucose uptake was unaffected by GSH depletion. In accordance, normal adipose tissue insulin sensitivity was observed in BSO-treated rats in vivo, as demonstrated by normal inhibition of circulating non-esterified fatty acid levels by endogenous insulin secretion. In conclusion, GSH depletion by BSO results in impaired glucose tolerance, but preserved adipocyte and skeletal muscle insulin responsiveness. This suggests that alternative oxidation-borne factors mediate the induction of peripheral insulin resistance by oxidative stress.

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Antidiabetic Properties of Naringenin: A Citrus Fruit Polyphenol

Biomolecules ◽

10.3390/biom9030099 ◽

2019 ◽

Vol 9 (3) ◽

pp. 99 ◽

Cited By ~ 16

Author(s):

Danja J. Den Hartogh ◽

Evangelia Tsiani

Keyword(s):

Insulin Resistance ◽

Animal Studies ◽

Citrus Fruit ◽

Epidemiological Studies ◽

Personal Health ◽

Current Review ◽

Vegetables And Fruits

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by insulin resistance and hyperglycemia and is associated with personal health and global economic burdens. Current strategies/approaches of insulin resistance and T2DM prevention and treatment are lacking in efficacy resulting in the need for new preventative and targeted therapies. In recent years, epidemiological studies have suggested that diets rich in vegetables and fruits are associated with health benefits including protection against insulin resistance and T2DM. Naringenin, a citrus flavanone, has been reported to have antioxidant, anti-inflammatory, hepatoprotective, nephroprotective, immunomodulatory and antidiabetic properties. The current review summarizes the existing in vitro and in vivo animal studies examining the anti-diabetic effects of naringenin.

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Leprechaunism: In Vitro Insulin Action Despite Genetic Insulin Resistance

Pediatric Research ◽

10.1203/00006450-198709000-00010 ◽

1987 ◽

Vol 22 (3) ◽

pp. 286-291 ◽

Cited By ~ 22

Author(s):

Mitchell E Geffner ◽

Solomon A Kaplan ◽

Noelle Bersch ◽

Barbara M Lippe ◽

Wesley G Smith ◽

...

Keyword(s):

Insulin Resistance ◽

Insulin Action

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Effects of Hyperglycemia on Vascular Smooth Muscle Ca2+Signaling

BioMed Research International ◽

10.1155/2017/3691349 ◽

2017 ◽

Vol 2017 ◽

pp. 1-16 ◽

Cited By ~ 6

Author(s):

Nahed El-Najjar ◽

Rashmi P. Kulkarni ◽

Nancy Nader ◽

Rawad Hodeify ◽

Khaled Machaca

Keyword(s):

Insulin Resistance ◽

Smooth Muscle ◽

Sarcoplasmic Reticulum ◽

Vascular Smooth Muscle ◽

Complex Disease ◽

Prolonged Exposure ◽

In Vitro System ◽

A7r5 Cells

Diabetes is a complex disease that is characterized with hyperglycemia, dyslipidemia, and insulin resistance. These pathologies are associated with significant cardiovascular implications that affect both the macro- and microvasculature. It is therefore important to understand the effects of various pathologies associated with diabetes on the vasculature. Here we directly test the effects of hyperglycemia on vascular smooth muscle (VSM) Ca2+signaling in an isolated in vitro system using the A7r5 rat aortic cell line as a model. We find that prolonged exposure of A7r5 cells to hyperglycemia (weeks) is associated with changes to Ca2+signaling, including most prominently an inhibition of the passive ER Ca2+leak and the sarcoplasmic reticulum Ca2+-ATPase (SERCA). To translate these findings to the in vivo condition, we used primary VSM cells from normal and diabetic subjects and find that only the inhibition of the ER Ca2+leaks replicates in cells from diabetic donors. These results show that prolonged hyperglycemia in isolation alters the Ca2+signaling machinery in VSM cells. However, these alterations are not readily translatable to the whole organism situation where alterations to the Ca2+signaling machinery are different.

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Endothelial insulin receptors differentially control insulin signaling kinetics in peripheral tissues and brain of mice

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1710625114 ◽

2017 ◽

Vol 114 (40) ◽

pp. E8478-E8487 ◽

Cited By ~ 37

Author(s):

Masahiro Konishi ◽

Masaji Sakaguchi ◽

Samuel M. Lockhart ◽

Weikang Cai ◽

Mengyao Ella Li ◽

...

Keyword(s):

Insulin Resistance ◽

Endothelial Cells ◽

Food Intake ◽

Insulin Signaling ◽

Insulin Action ◽

Insulin Receptors ◽

Brain Regions ◽

Peripheral Tissues ◽

Systemic Insulin Resistance

Insulin receptors (IRs) on endothelial cells may have a role in the regulation of transport of circulating insulin to its target tissues; however, how this impacts on insulin action in vivo is unclear. Using mice with endothelial-specific inactivation of the IR gene (EndoIRKO), we find that in response to systemic insulin stimulation, loss of endothelial IRs caused delayed onset of insulin signaling in skeletal muscle, brown fat, hypothalamus, hippocampus, and prefrontal cortex but not in liver or olfactory bulb. At the level of the brain, the delay of insulin signaling was associated with decreased levels of hypothalamic proopiomelanocortin, leading to increased food intake and obesity accompanied with hyperinsulinemia and hyperleptinemia. The loss of endothelial IRs also resulted in a delay in the acute hypoglycemic effect of systemic insulin administration and impaired glucose tolerance. In high-fat diet-treated mice, knockout of the endothelial IRs accelerated development of systemic insulin resistance but not food intake and obesity. Thus, IRs on endothelial cells have an important role in transendothelial insulin delivery in vivo which differentially regulates the kinetics of insulin signaling and insulin action in peripheral target tissues and different brain regions. Loss of this function predisposes animals to systemic insulin resistance, overeating, and obesity.

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Studies of insulin resistance in patients with clinical and subclinical hypothyroidism

Acta Endocrinologica ◽

10.1530/eje-08-0797 ◽

2009 ◽

Vol 160 (5) ◽

pp. 785-790 ◽

Cited By ~ 165

Author(s):

Eirini Maratou ◽

Dimitrios J Hadjidakis ◽

Anastasios Kollias ◽

Katerina Tsegka ◽

Melpomeni Peppa ◽

...

Keyword(s):

Insulin Resistance ◽

Plasma Membrane ◽

Glucose Transport ◽

Subclinical Hypothyroidism ◽

Tolerance Test ◽

Oral Glucose ◽

Model Assessment ◽

Increased Risk

ObjectiveAlthough clinical hypothyroidism (HO) is associated with insulin resistance, there is no information on insulin action in subclinical hypothyroidism (SHO).Design and methodsTo investigate this, we assessed the sensitivity of glucose metabolism to insulin both in vivo (by an oral glucose tolerance test) and in vitro (by measuring insulin-stimulated rates of glucose transport in isolated monocytes with flow cytometry) in 21 euthyroid subjects (EU), 12 patients with HO, and 13 patients with SHO.ResultsAll three groups had comparable plasma glucose levels, with the HO and SHO having higher plasma insulin than the EU (P<0.05). Homeostasis model assessment index was increased in HO (1.97±0.22) and SHO (1.99±0.13) versus EU (1.27±0.16, P<0.05), while Matsuda index was decreased in HO (3.89±0.36) and SHO (4.26±0.48) versus EU (7.76±0.87, P<0.001), suggesting insulin resistance in both fasting and post-glucose state. At 100 μU/ml insulin: i) GLUT4 levels on the monocyte plasma membrane were decreased in both HO (215±19 mean fluorescence intensity, MFI) and SHO (218±24 MFI) versus EU (270±25 MFI, P=0.03 and 0.04 respectively), and ii) glucose transport rates in monocytes from HO (481±30 MFI) and SHO (462±19 MFI) were decreased versus EU (571±15 MFI, P=0.04 and 0.004 respectively).ConclusionsIn patients with HO and SHO: i) insulin resistance was comparable; ii) insulin-stimulated rates of glucose transport in isolated monocytes were decreased due to impaired translocation of GLUT4 glucose transporters on the plasma membrane; iii) these findings could justify the increased risk for insulin resistance-associated disorders, such as cardiovascular disease, observed in patients with HO or SHO.

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Exposure to the Widely Used Pyrethroid Pesticide Deltamethrin, Does Not Exacerbate High Fat Diet Induced Obesity or Insulin Resistance in C57BL/6J Mice

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.090 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A45-A46

Author(s):

Evangelia Evelyn Tsakiridis ◽

Marisa Morrow ◽

Andrea Llanos ◽

Bo Wang ◽

Alison Holloway ◽

...

Keyword(s):

Insulin Resistance ◽

Glycemic Control ◽

Metabolic Diseases ◽

Uncoupling Protein ◽

Diet Induced Obesity ◽

Brown Adipose ◽

Pyrethroid Pesticide ◽

First Time

Abstract Deltamethrin is a commonly used pesticide for the control of mosquito populations. Despite widespread use, the effects of deltamethrin on adiposity and glucose homeostasis have been equivocal with some studies showing increased, decreased and no effect on adiposity and glycemic control. However, no study to date has investigated the effect of deltamethrin in mice housed at thermoneutral temperatures, which is important for modelling metabolic diseases in rodents due to reduced thermal stress and constitutive activation of brown adipose tissue. In the current study we demonstrate for the first time that deltamethrin reduces uncoupling protein-1 expression in brown adipocytes cultured in vitro at concentrations as low as 1pm. Meanwhile, in-vivo deltamethrin does not appear to alter glycemic control or promote adiposity at exposures equivalent to 0.01, 0.1 or 1.0 mg/kg/day. Together, our study demonstrates environmentally relevant exposure to deltamethrin does not exacerbate diet induced obesity or insulin resistance.

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