Short-term infusion of interleukin-6 does not induce insulin resistance in vivo or impair insulin signalling in rats

Abstract Context: It has been demonstrated repeatedly that short-term fasting induces insulin resistance, although the exact mechanism in humans is unknown to date. Intramyocellular sphingolipids (i.e. ceramide) have been suggested to induce insulin resistance by interfering with the insulin signaling cascade in obesity. Objective: Our objective was to study peripheral insulin sensitivity together with muscle ceramide concentrations and protein kinase B/AKT phosphorylation after short-term fasting. Main Outcome Measures and Design: After 14- and 62-h fasting, glucose fluxes were measured before and after a hyperinsulinemic euglycemic clamp. Muscle biopsies were performed in the basal state and during the clamp to assess muscle ceramide and protein kinase B/AKT. Results: Insulin-mediated peripheral glucose uptake was significantly lower after 62-h fasting compared with 14-h fasting. Intramuscular ceramide concentrations tended to increase during fasting. During the clamp the phosphorylation of protein kinase B/AKT at serine473 in proportion to the total amount of protein kinase B/AKT was significantly lower. Muscle ceramide did not correlate with plasma free fatty acids. Conclusions: Fasting for 62 h decreases insulin-mediated peripheral glucose uptake with lower phosphorylation of AKT at serine473. AKT may play a regulatory role in fasting-induced insulin resistance. Whether the decrease in AKT can be attributed to the trend to higher muscle ceramide remains unanswered.

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Short-term K+ deprivation provokes insulin resistance of cellular K+ uptake revealed with the K+ clamp

AJP Renal Physiology ◽

10.1152/ajprenal.2001.280.1.f95 ◽

2001 ◽

Vol 280 (1) ◽

pp. F95-F102 ◽

Cited By ~ 35

Author(s):

Cheol S. Choi ◽

Curtis B. Thompson ◽

Patrick K. K. Leong ◽

Alicia A. McDonough ◽

Jang H. Youn

Keyword(s):

Insulin Resistance ◽

Atpase Activity ◽

Infusion Rate ◽

Insulin Action ◽

Insulin Dose ◽

Short Term ◽

Conscious Rat ◽

Physiological Concentration ◽

Glucose Clearance

We aimed to test the feasibility of quantifying insulin action on cellular K+ uptake in vivo in the conscious rat by measuring the exogenous K+ infusion rate needed to maintain constant plasma K+ concentration ([K+]) during insulin infusion. In this “K+ clamp” the K+ infusion rate required to clamp plasma [K+] is a measure of insulin action to increase net plasma K+ disappearance. K+ infusion rate required to clamp plasma [K+] was insulin dose dependent. Renal K+ excretion was not significantly affected by insulin at a physiological concentration (∼90 μU/ml, P > 0.05), indicating that most of insulin-mediated plasma K+ disappearance was due to K+ uptake by extrarenal tissues. In rats deprived of K+ for 2 days, plasma [K+] fell from 4.2 to 3.8 mM, insulin-mediated plasma glucose clearance was normal, but insulin-mediated plasma K+ disappearance decreased to 20% of control, even though there was no change in muscle Na-K-ATPase activity or expression, which is believed to be the main K+ uptake route. After 10 days K+ deprivation, plasma [K+] fell to 2.9 mM, insulin-mediated K+ disappearance decreased to 6% of control (glucose clearance normal), and there were 50% decreases in Na-K-ATPase activity and α2-subunit levels. In conclusion, the present study proves the feasibility of the K+ clamp technique and demonstrates that short-term K+ deprivation leads to a near complete insulin resistance of cellular K+uptake that precedes changes in muscle sodium pump expression.

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P713Short term treatment of a low dose erythropoietin improves vascular function in a rat model of insulin resistance

European Heart Journal ◽

10.1093/eurheartj/ehz747.0318 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

H Toba ◽

A Yamaoka ◽

S Sakurai ◽

Y Tanaka ◽

A Miyamoto ◽

...

Keyword(s):

Insulin Resistance ◽

Blood Pressure ◽

Vascular Function ◽

Insulin Signalling ◽

Term Treatment ◽

Protective Effects ◽

Insulin Resistant ◽

Induce Insulin Resistance ◽

Group A ◽

Group B

Abstract Background/Introduction Erythropoietin (EPO) exerts haematopoiesis-independent cardiovascular and renal protective effects by binding to EPO receptors expressed in hearts, arteries, and kidneys. We have reported that EPO inhibits vascular and renal injury in rat models of hypertension and type 1 diabetes. Recent studies report that EPO improves glucose tolerance in insulin resistant animals. Purpose This study investigated whether EPO would inhibit vascular and renal dysfunction in the setting of insulin resistance. Methods Rats were treated with sucrose (12% in drinking water) for 10 weeks to induce insulin resistance. EPO (3 times/week, s.c) was administered at the dose of 150U/kg for 10 weeks from the beginning (group A) or at the dose of 75U/kg for the last 4 weeks (group B) of sucrose treatment. Blood pressure was measured every second week by the tail-cuff method. HOMA-IR, haematocrit, and urinary protein excretion were measured. Using isolated aortas, acetylcholine-induced vasorelaxation under phenylephrine-induced pre-contraction was examined. Aortic sections were stained with haematoxylin-eosin. Results Both groups A and B showed higher haematocrit levels compared with the control and sucrose alone-treated groups. Sucrose treatment increased HOMA-IR (7.7±2.0 vs. 24±4.5, p<0.05), which was attenuated in groups A (3.6±0.9) and B (9.7±4.0). EPO treatment (150U/kg) had no effects on blood pressure for the first 4 weeks but caused time-dependent increases in blood pressure from the 6th week. Increased proteinuria and impaired aortic vasorelaxation in sucrose-treated rats were exacerbated by EPO (150U/kg) maybe because of hypertension (Control 122±2mmHg, Sucrose 125±2mmHg, group A 148±5mmHg), one of the major side effects of EPO. According to these results, we treated a half dose of EPO only for the last 4 weeks (group B). A lower dose of EPO treatment for a shorter period did not increase proteinuria (Control 15±2mg/day, Sucrose 25±3mg/day, group B 24±3mg/day) despite a mild increase in blood pressure (132±2mmHg). Impaired endothelium-dependent vasodilation and aortic thickening in the aorta of sucrose alone-treated rats were attenuated by lower and shorter EPO treatment (group B). Conclusions EPO inhibited insulin resistance and vascular injury in sucrose-induced insulin resistant rats. Further investigation into the mechanisms of tissue protective effects of EPO, especially focusing on the effects on insulin signalling in not only hepatic and muscle cell but also vascular and renal cells, will be needed.

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Kupffer cell activation is a causal factor for hepatic insulin resistance

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00391.2009 ◽

2010 ◽

Vol 298 (1) ◽

pp. G107-G116 ◽

Cited By ~ 138

Author(s):

Nicolas Lanthier ◽

Olivier Molendi-Coste ◽

Yves Horsmans ◽

Nico van Rooijen ◽

Patrice D. Cani ◽

...

Keyword(s):

Insulin Resistance ◽

Kupffer Cell ◽

High Fat Diet ◽

Cell Activation ◽

Hepatic Insulin Resistance ◽

High Fat ◽

Short Term ◽

Adipose Tissue Macrophages ◽

Diet Model

Recruited adipose tissue macrophages contribute to chronic and low-grade inflammation causing insulin resistance in obesity. Similarly, we hypothesized here that Kupffer cells, the hepatic resident macrophages, play a pathogenic role in hepatic insulin resistance induced by a high-fat diet. Mice were fed a normal diet or high-fat diet for 3 days. Kupffer cell activation was evaluated by immunohistochemistry and quantitative RT-PCR. Insulin sensitivity was assessed in vivo by hyperinsulinemic-euglycemic clamp and insulin-activated signaling was investigated by Western blot. Liposome-encapsulated clodronate was injected intravenously to deplete macrophages prior to a short-term exposure to high-fat diet. Here, we characterized a short-term high-fat diet model in mice and demonstrated early hepatic insulin resistance and steatosis concurrent with Kupffer cell activation. We demonstrated that selective Kupffer cell depletion obtained by intravenous clodronate, without affecting adipose tissue macrophages, was sufficient to enhance insulin-dependent insulin signaling and significantly improve hepatic insulin sensitivity in vivo in this short-term high-fat diet model. Our study clearly shows that hepatic macrophage response participates to the onset of high-fat diet-induced hepatic insulin resistance and may therefore represent an attractive target for prevention and treatment of diet- and obesity-induced insulin resistance.

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The Role of TGFβ Ligands and Signalling on Insulin Resistance in Skeletal Muscle in Women With PCOS

Journal of the Endocrine Society ◽

10.1210/jendso/bvab048.906 ◽

2021 ◽

Vol 5 (Supplement_1) ◽

pp. A443-A444

Author(s):

Alba Moreno-Asso ◽

Luke C McIlvenna ◽

Rhiannon K Patten ◽

Andrew J McAinch ◽

Raymond J Rodgers ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Glucose Uptake ◽

Insulin Signalling ◽

Signalling Pathway ◽

Whole Body ◽

Insulin Signalling Pathway ◽

Cultured Myotubes ◽

Tgfβ Superfamily

Abstract Polycystic ovary syndrome (PCOS) is the most common female endocrinopathy affecting metabolic and reproductive health of 8–13% of reproductive-age women. Insulin resistance (IR) appears to underpin the pathophysiology of PCOS and is present in approximately 38–95% of women with PCOS. This underlying IR has been identified as unique from, but synergistic with, obesity-induced IR (1). Skeletal muscle accounts for up to 85% of whole-body insulin-stimulated glucose uptake; however, in PCOS this is reduced by about 27% when assessed by a euglycaemic-hyperinsulinaemic clamp (2). Interestingly, this reduced insulin-stimulated glucose uptake observed in skeletal muscle tissue is not retained in cultured myotubes (3), suggesting that in vivo environmental factors may play a role in this PCOS-specific IR. Yet, the molecular mechanisms regulating IR remain unclear (4). A potential environmental mechanism contributing to the development of peripheral IR may be the extracellular matrix remodelling and aberrant transforming growth factor beta (TGFβ) signalling. Previous work demonstrated that TGFβ superfamily ligands are involved in the increased collagen deposition and fibrotic tissue in the ovaries, and suggested that these ligands may be involved in the metabolic morbidity associated with PCOS (5). In this study, we investigated the effects of TGFβ1 (1, 5 ng/ml), and the Anti-Müllerian hormone (AMH; 5, 10, 30 ng/ml), a TGFβ superfamily ligand elevated in women with PCOS, as causal factors of IR in cultured myotubes from women with PCOS (n=5) and healthy controls (n=5). TGFβ1 did not have a significant effect on insulin signalling but induced expression of some ECM related genes and proteins, and increased glucose uptake via Smad2/3 signalling in myotubes from both groups. Conversely, AMH did not appear to activate the TGFβ/Smad signalling pathway and had no significant impact on insulin signalling or glucose uptake in any of the groups. In conclusion, these findings suggest that TGFβ1, but not AMH, may play a role in skeletal muscle ECM remodelling/fibrosis and glucose metabolism in PCOS but does not have a direct effect on insulin signalling pathway. Further research is required to elucidate its contribution to the development of in vivo skeletal muscle IR and broader impact in this syndrome. References: (1) Stepto et al., Hum Reprod 2013 Mar;28(3):777–784. (2) Cassar et al., Hum Reprod 2016 Nov;31(11):2619–2631. (3) Corbould et al., Am J Physiol-Endoc 2005 May;88(5):E1047-54. (4) Stepto et al., J Clin Endocrinol Metab, 2019 Nov 1;104(11):5372–5381. (5) Raja-Khan et al., Reprod Sci 2014 Jan;21(1):20–31.

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257-OR: Short-Term Hyperglucagonemia Induces Adipose Tissue Insulin Resistance and Inflammation In Vivo

Diabetes ◽

10.2337/db21-257-or ◽

2021 ◽

Vol 70 (Supplement 1) ◽

pp. 257-OR

Author(s):

XI CHEN ◽

MARCEL FOURCAUDOT ◽

LUKE NORTON ◽

RALPH A. DEFRONZO ◽

DEVJIT TRIPATHY

Keyword(s):

Insulin Resistance ◽

Adipose Tissue ◽

Short Term

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Insulin resistance in polycystic ovary syndrome is associated with defective regulation of ERK1/2 by insulin in skeletal muscle in vivo

Biochemical Journal ◽

10.1042/bj20082176 ◽

2009 ◽

Vol 418 (3) ◽

pp. 665-671 ◽

Cited By ~ 23

Author(s):

Madhurima Rajkhowa ◽

Sandra Brett ◽

Daniel J. Cuthbertson ◽

Christopher Lipina ◽

Antonio J. Ruiz-Alcaraz ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Insulin Sensitivity ◽

Polycystic Ovary Syndrome ◽

Insulin Signalling ◽

Polycystic Ovary ◽

Insulin Stimulation ◽

Ovary Syndrome ◽

Stimulation Of

Insulin resistance is a recognized feature of PCOS (polycystic ovary syndrome). However, the molecular reason(s) underlying this reduced cellular insulin sensitivity is not clear. The present study compares the major insulin signalling pathways in skeletal muscle isolated from PCOS and controls. We measured whole-body insulin sensitivity and insulin signalling in skeletal muscle biopsies taken before and after acute exposure to hyperinsulinaemia in nine women diagnosed with PCOS and seven controls. We examined the expression, basal activity and response to in vivo insulin stimulation of three signalling molecules within these human muscle samples, namely IRS-1 (insulin receptor substrate-1), PKB (protein kinase B) and ERK (extracellular-signal-regulated kinase) 1/2. There was no significant difference in the expression, basal activity or activation of IRS-1 or PKB between PCOS and control subjects. However, there was a severe attenuation of insulin stimulation of the ERK pathway in muscle from all but two of the women with PCOS (the two most obese), and an accompanying trend towards higher basal phosphorylation of ERK1/2 in PCOS. These results are striking in that the metabolic actions of insulin are widely believed to require the IRS-1/PKB pathway rather than ERK, and the former has been reported as defective in some previous PCOS studies. Most importantly, the molecular defect identified was independent of adiposity. The altered response of ERK to insulin in PCOS was the most obvious signalling defect associated with insulin resistance in muscle from these patients.

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Uncoupling insulin signalling by serine/threonine phosphorylation: a molecular basis for insulin resistance

Biochemical Society Transactions ◽

10.1042/bst0320812 ◽

2004 ◽

Vol 32 (5) ◽

pp. 812-816 ◽

Cited By ~ 72

Author(s):

Y. Zick

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Insulin Signalling ◽

Control Mechanisms ◽

Nutrient Metabolism ◽

Insulin Signal Transduction ◽

Induce Insulin Resistance ◽

Downstream Effectors ◽

Insulin Receptor Substrates ◽

Resistance State

Insulin resistance refers to a decreased capacity of circulating insulin to regulate nutrient metabolism. Recent studies reveal that agents that induce insulin resistance exploit phosphorylation-based negative feedback control mechanisms otherwise utilized by insulin itself to uncouple the insulin receptor from its downstream effectors and thereby terminate insulin signal transduction. This article focuses on the Ser/Thr protein kinases which phosphorylate insulin receptor substrates and the major Ser sites that are phosphorylated, as key elements in the uncoupling of insulin signalling and the induction of an insulin resistance state.

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Transforming Growth Factor Beta 1 Alters Glucose Uptake but Not Insulin Signalling in Human Primary Myotubes From Women With and Without Polycystic Ovary Syndrome

Frontiers in Endocrinology ◽

10.3389/fendo.2021.732338 ◽

2021 ◽

Vol 12 ◽

Author(s):

Luke C. McIlvenna ◽

Rhiannon K. Patten ◽

Andrew J. McAinch ◽

Raymond J. Rodgers ◽

Nigel K. Stepto ◽

...

Keyword(s):

Insulin Resistance ◽

Skeletal Muscle ◽

Growth Factor ◽

Glucose Uptake ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Insulin Signalling ◽

Polycystic Ovary ◽

Short Term ◽

Tgfβ Signalling

Women with polycystic ovary syndrome (PCOS), commonly have profound skeletal muscle insulin resistance which can worsen other clinical features. The heterogeneity of the condition has made it challenging to identify the precise mechanisms that cause this insulin resistance. A possible explanation for the underlying insulin resistance may be the dysregulation of Transforming Growth Factor-beta (TGFβ) signalling. TGFβ signalling contributes to the remodelling of reproductive and hepatic tissues in women with PCOS. Given the systemic nature of TGFβ signalling and its role in skeletal muscle homeostasis, it may be possible that these adverse effects extend to other peripheral tissues. We aimed to determine if TGFβ1 could negatively regulate glucose uptake and insulin signalling in skeletal muscle of women with PCOS. We show that both myotubes from women with PCOS and healthy women displayed an increase in glucose uptake, independent of changes in insulin signalling, following short term (16 hr) TGFβ1 treatment. This increase occurred despite pro-fibrotic signalling increasing via SMAD3 and connective tissue growth factor in both groups following treatment with TGFβ1. Collectively, our findings show that short-term treatment with TGFβ1 does not appear to influence insulin signalling or promote insulin resistance in myotubes. These findings suggest that aberrant TGFβ signalling is unlikely to directly contribute to skeletal muscle insulin resistance in women with PCOS in the short term but does not rule out indirect or longer-term effects.

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Resveratrol prevents insulin resistance caused by short-term elevation of free fatty acids in vivo

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2015-0075 ◽

2015 ◽

Vol 40 (11) ◽

pp. 1129-1136 ◽

Cited By ~ 12

Author(s):

Sandra Pereira ◽

Edward Park ◽

Jessy Moore ◽

Brandon Faubert ◽

Danna M. Breen ◽

...

Keyword(s):

Insulin Resistance ◽

Fatty Acids ◽

Free Fatty Acids ◽

Glucose Utilization ◽

Glucose Production ◽

Endogenous Glucose Production ◽

Serine Phosphorylation ◽

Peripheral Insulin Resistance ◽

Induce Insulin Resistance

Elevated levels of plasma free fatty acids (FFA), which are commonly found in obesity, induce insulin resistance. FFA activate protein kinases including the proinflammatory IκBα kinase β (IKKβ), leading to serine phosphorylation of insulin receptor substrate 1 (IRS-1) and impaired insulin signaling. To test whether resveratrol, a polyphenol found in red wine, prevents FFA-induced insulin resistance, we used a hyperinsulinemic-euglycemic clamp with a tracer to assess hepatic and peripheral insulin sensitivity in overnight-fasted Wistar rats infused for 7 h with saline, Intralipid plus 20 U·mL−1 heparin (IH; triglyceride emulsion that elevates FFA levels in vivo; 5.5 μL·min−1) with or without resveratrol (3 mg·kg−1·h−1), or resveratrol alone. Infusion of IH significantly decreased glucose infusion rate (GIR; P < 0.05) and peripheral glucose utilization (P < 0.05) and increased endogenous glucose production (EGP; P < 0.05) during the clamp compared with saline infusion. Resveratrol co-infusion, however, completely prevented the effects induced by IH infusion: it prevented the decreases in GIR (P < 0.05 vs. IH), peripheral glucose utilization (P < 0.05 vs. IH), and insulin-induced suppression of EGP (P < 0.05 vs. IH). Resveratrol alone had no effect. Furthermore, IH infusion increased serine (307) phosphorylation of IRS-1 in soleus muscle (∼30-fold, P < 0.001), decreased total IRS-1 levels, and decreased IκBα content, consistent with activation of IKKβ. Importantly, all of these effects were abolished by resveratrol (P < 0.05 vs. IH). These results suggest that resveratrol prevents FFA-induced hepatic and peripheral insulin resistance and, therefore, may help mitigate the health consequences of obesity.

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