Glucose uptake and insulin sensitivity in rat muscle: changes during 3-96 weeks of age

It has been demonstrated that aging diminishes the rate of glucose utilization by rat skeletal muscle. To determine the basis for this occurrence as well as its temporal sequence, glucose utilization was examined in isolated hindquarters of 3-, 5-, 8-, 16-, 24-, 48-, and 96-wk-old male Sprague-Dawley rats. Glucose utilization diminished progressively during early development (3-5 wk) and adolescence (5-16 wk) in hindquarters perfused in the absence of added insulin. At the same time there was a progressive shift of the insulin dose-response curve to the right, indicating diminished insulin sensitivity and a marked decrease in maximum insulin responsiveness. In contrast, between 24 and 96 wk of age, insulin sensitivity and the rate of glucose utilization in the absence of added insulin did not decrease, and there was only a small decrease in maximum responsiveness. The rate-limiting step in glucose utilization under all conditions was glucose transport. Even at high insulin concentrations, free glucose was not detected in the muscle cells of young or old rats, the uptake of 2-deoxyglucose diminished in parallel with that of glucose, and there was no evidence of a defect in glucose metabolism. These findings indicate that in the Sprague-Dawley rat glucose transport into skeletal muscle and in particular its sensitivity and responsiveness to insulin diminish progressively during early development and adolescence. No further marked changes occurred up to at least 96 wk of age. To what extent these early age-associated changes are due to insulin binding and to what extent to alterations in the glucose transport system per se remains to be determined.

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Muscle alpha-aminoisobutyric acid transport after exercise: enhanced stimulation by insulin

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1985.248.5.e546 ◽

1985 ◽

Vol 248 (5) ◽

pp. E546-E552 ◽

Cited By ~ 9

Author(s):

A. Zorzano ◽

T. W. Balon ◽

L. P. Garetto ◽

M. N. Goodman ◽

N. B. Ruderman

Keyword(s):

Skeletal Muscle ◽

Glucose Transport ◽

Glucose Utilization ◽

Glycogen Synthesis ◽

Common Factor ◽

Insulin Binding ◽

Moderate Intensity ◽

Insulin Effect ◽

Aminoisobutyric Acid ◽

Prior Exercise

After exercise the ability of insulin to stimulate glucose transport and glycogen synthesis in rat skeletal muscle is markedly enhanced (25). The present study was designed to determine whether prior exercise augments the stimulation of other processes by insulin and, if so, whether this can be attributed to an increase in insulin binding to its receptor. Toward this end rats were run on a treadmill for 45 min at moderate intensity and the uptake of alpha-aminoisobutyric acid (AIB) by muscle was then assessed using the isolated perfused hindquarter preparation. Approximately 30 min after the cessation of exercise, both the sensitivity and responsiveness of insulin-stimulated AIB uptake were significantly enhanced in the soleus and the red portion of the gastrocnemius. As previously shown for glucose transport and glycogen synthesis, only small effects were observed in the white portion of the gastrocnemius, which unlike the other muscles was not depleted of glycogen during the run. Insulin-stimulated glucose utilization was also enhanced in the incubated soleus muscle of exercised rats; however, insulin binding to the soleus was not altered. These studies indicate that the ability of insulin to stimulate processes other than glucose transport and glycogen synthesis is enhanced in skeletal muscle after exercise and that this is not due to an alteration in insulin binding. The changes in insulin-stimulated AIB uptake and glucose metabolism after exercise are the reverse of those found in denervated and immobilized muscle and in both situations insulin binding is not altered. This suggests that a common factor(s) modulates the increase in insulin effect after exercise and the insulin resistance of disuse.

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Effect of training on insulin binding to rat skeletal muscle sarcolemmal vesicles

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1986.250.5.e570 ◽

1986 ◽

Vol 250 (5) ◽

pp. E570-E575

Author(s):

G. K. Grimditch ◽

R. J. Barnard ◽

S. A. Kaplan ◽

E. Sternlicht

Keyword(s):

Skeletal Muscle ◽

Insulin Sensitivity ◽

Exercise Training ◽

Insulin Binding ◽

Whole Body ◽

Rat Skeletal Muscle ◽

Binding Studies ◽

Muscle Enzyme ◽

Intravenous Glucose ◽

High Affinity

We examined the hypothesis that the exercise training-induced increase in skeletal muscle insulin sensitivity is mediated by adaptations in insulin binding to sarcolemmal (SL) insulin receptors. Insulin binding studies were performed on rat skeletal muscle SL isolated from control and trained rats. No significant differences were noted between groups in body weight or fat. An intravenous glucose tolerance test showed an increase in whole-body insulin sensitivity with training, and specific D-glucose transport studies on isolated SL vesicles indicated that this was due in part to adaptations in skeletal muscle. Enzyme marker analyses revealed no differences in yield, purity, or contamination of SL membranes between the two groups. Scatchard analyses indicated no significant differences in the number of insulin binding sites per milligram SL protein on the high-affinity (15.0 +/- 4.1 vs. 18.1 +/- 6.4 X 10(9)) or on the low-affinity portions (925 +/- 80 vs. 884 +/- 106 X 10(9)) of the curves. The association constants of the high-affinity (0.764 +/- 0.154 vs. 0.685 +/- 0.264 X 10(9) M-1) and of the low affinity sites (0.0096 +/- 0.0012 vs. 0.0102 +/- 0.0012 X 10(9) M-1) also were similar. These results do not support the hypothesis that the increased sensitivity to insulin after exercise training is due to changes in SL insulin receptor binding.

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High glucose and insulin in combination cause insulin receptor substrate-1 and -2 depletion and protein kinase B desensitisation in primary cultured rat adipocytes: possible implications for insulin resistance in type 2 diabetes

Acta Endocrinologica ◽

10.1530/eje.0.1480157 ◽

2003 ◽

Vol 148 (1) ◽

pp. 157-167 ◽

Cited By ~ 43

Author(s):

J Buren ◽

HX Liu ◽

J Lauritz ◽

JW Eriksson

Keyword(s):

Glucose Uptake ◽

High Glucose ◽

Insulin Treatment ◽

Insulin Signalling ◽

Binding Capacity ◽

Insulin Binding ◽

Rat Adipocytes ◽

Glucose Levels ◽

High Insulin ◽

The Right

OBJECTIVE: The purpose of this study was to investigate the cellular effects of long-term exposure to high insulin and glucose levels on glucose transport and insulin signalling proteins. DESIGN AND METHODS: Rat adipocytes were cultured for 24 h in different glucose concentrations with 10(4) microU/ml of insulin or without insulin. After washing, (125)I-insulin binding, basal and acutely insulin-stimulated d-[(14)C]glucose uptake, and insulin signalling proteins and glucose transporter 4 (GLUT4) were assessed. RESULTS: High glucose (15 and 25 mmol/l) for 24 h induced a decrease in basal and insulin-stimulated glucose uptake compared with control cells incubated in low glucose (5 or 10 mmol/l). Twenty-four hours of insulin treatment decreased insulin binding capacity by approximately 40%, and shifted the dose-response curve for insulin's acute effect on glucose uptake 2- to 3-fold to the right. Twenty-four hours of insulin treatment reduced basal and insulin-stimulated glucose uptake only in the presence of high glucose (by approximately 30-50%). At high glucose, insulin receptor substrate-1 (IRS-1) expression was downregulated by approximately 20-50%, whereas IRS-2 was strongly upregulated by glucose levels of 10 mmol/l or more (by 100-400%). Insulin treatment amplified the suppression of IRS-1 when combined with high glucose and also IRS-2 expression was almost abolished. Twenty-four hours of treatment with high glucose or insulin, alone or in combination, shifted the dose-response curve for insulin's effect to acutely phosphorylate protein kinase B (PKB) to the right. Fifteen mmol/l glucose increased GLUT4 in cellular membranes (by approximately 140%) compared with 5 mmol/l but this was prevented by a high insulin concentration. CONCLUSIONS: Long-term exposure to high glucose per se decreases IRS-1 but increases IRS-2 content in rat adipocytes and it impairs glucose transport capacity. Treatment with high insulin downregulates insulin binding capacity and, when combined with high glucose, it produces a marked depletion of IRS-1 and -2 content together with an impaired sensitivity to insulin stimulation of PKB activity. These mechanisms may potentially contribute to insulin resistance in type 2 diabetes.

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Role of TRIB3 in regulation of insulin sensitivity and nutrient metabolism during short-term fasting and nutrient excess

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00663.2011 ◽

2012 ◽

Vol 303 (7) ◽

pp. E908-E916 ◽

Cited By ~ 14

Author(s):

Jiarong Liu ◽

Wei Zhang ◽

Gin C. Chuang ◽

Helliner S. Hill ◽

Ling Tian ◽

...

Keyword(s):

Skeletal Muscle ◽

Oxygen Consumption ◽

Insulin Sensitivity ◽

Glucose Uptake ◽

Glucose Transport ◽

Oxygen Consumption Rate ◽

Glucose Oxidation ◽

Consumption Rate ◽

Negative Regulator ◽

Short Term

We have suggested previously that Tribbles homolog 3 (TRIB3), a negative regulator of Akt activity in insulin-sensitive tissues, could mediate glucose-induced insulin resistance in muscle under conditions of chronic hyperglycemia (Liu J, Wu X, Franklin JL, Messina JL, Hill HS, Moellering DR, Walton RG, Martin M, Garvey WT. Am J Physiol Endocrinol Metab 298: E565–E576, 2010). In the current study, we have assessed short-term physiological regulation of TRIB3 in skeletal muscle and adipose tissues by nutrient excess and fasting as well as TRIB3's ability to modulate glucose transport and mitochondrial oxidation. In Sprague-Dawley rats, we found that short-term fasting enhanced insulin sensitivity concomitantly with decrements in TRIB3 mRNA (66%, P < 0.05) and protein (81%, P < 0.05) in muscle and increments in TRIB3 mRNA (96%, P < 0.05) and protein (∼10-fold, P < 0.05) in adipose tissue compared with nonfasted controls. On the other hand, rats fed a Western diet for 7 days became insulin resistant concomitantly with increments in TRIB3 mRNA (155%, P < 0.05) and protein (69%, P = 0.0567) in muscle and a decrease in the mRNA (76%, P < 0.05) and protein (70%, P < 0.05) in adipose. In glucose transport and mitochondria oxidation studies using skeletal muscle cells, we found that stable TRIB3 overexpression impaired insulin-stimulated glucose uptake without affecting basal glucose transport and increased both basal glucose oxidation and the maximal uncoupled oxygen consumption rate. With stable knockdown of TRIB3, basal and insulin-stimulated glucose transport rates were increased, whereas basal glucose oxidation and the maximal uncoupled oxygen consumption rate were decreased. In conclusion, TRIB3 impacts glucose uptake and oxidation oppositely in muscle and fat according to levels of nutrient availability. The above data for the first time implicate TRIB3 as a potent physiological regulator of insulin sensitivity and mitochondrial glucose oxidation under conditions of nutrient deprivation and excess.

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Desensitization of beta-adrenergic receptors in adipocytes causes increased insulin sensitivity of glucose transport

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1996.271.2.e271 ◽

1996 ◽

Vol 271 (2) ◽

pp. E271-E276 ◽

Cited By ~ 5

Author(s):

A. Green ◽

R. M. Carroll ◽

S. B. Dobias

Keyword(s):

Insulin Sensitivity ◽

Glucose Transport ◽

Adrenergic Receptors ◽

Plasma Membranes ◽

Insulin Receptors ◽

Insulin Binding ◽

High Dose ◽

Beta Adrenergic Receptors ◽

Beta Adrenergic ◽

Adipocyte Plasma Membranes

To determine the effect of desensitization of adipocyte beta-adrenergic receptors on insulin sensitivity, rats were continuously infused with isoproterenol (50 or 100 micrograms.kg-1.h-1) for 3 days by osmotic minipumps. Epididymal adipocytes were isolated. The cells from treated animals were desensitized to isoproterenol, as determined by response of lipolysis (glycerol release). Binding of [125I]iodocyanopindolol was decreased by approximately 80% in adipocyte plasma membranes isolated from treated rats, indicating that beta-adrenergic receptors were downregulated. Cellular concentrations of Gn alpha and Gi alpha were not altered. Insulin sensitivity was determined by measuring the effect of insulin on glucose transport (2-deoxy-[3H]glucose uptake). Cells from the isoproterenol-infused rats were markedly more sensitive to insulin than those from control rats. This was evidenced by an approximately 50% increase in maximal glucose transport rate in cells from the high-dose isoproterenol-treated rats and by an approximately 40% decrease in the half-maximal effective concentration of insulin in both groups. 125I-labeled insulin binding to adipocytes was not altered by the isoproterenol infusions, indicating that desensitization of beta-adrenergic receptors results in tighter coupling between insulin receptors and stimulation of glucose transport.

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Skeletal Muscle-Selective Knockout of LKB1 Increases Insulin Sensitivity, Improves Glucose Homeostasis, and Decreases TRB3

Molecular and Cellular Biology ◽

10.1128/mcb.00979-06 ◽

2006 ◽

Vol 26 (22) ◽

pp. 8217-8227 ◽

Cited By ~ 155

Author(s):

Ho-Jin Koh ◽

David E. Arnolds ◽

Nobuharu Fujii ◽

Thien T. Tran ◽

Marc J. Rogers ◽

...

Keyword(s):

Skeletal Muscle ◽

Insulin Sensitivity ◽

Glucose Homeostasis ◽

Glucose Utilization ◽

Cell Metabolism ◽

Negative Regulator ◽

Akt Inhibitor ◽

Akt Phosphorylation ◽

Energy Sensing

ABSTRACT LKB1 is a tumor suppressor that may also be fundamental to cell metabolism, since LKB1 phosphorylates and activates the energy sensing enzyme AMPK. We generated muscle-specific LKB1 knockout (MLKB1KO) mice, and surprisingly, found that a lack of LKB1 in skeletal muscle enhanced insulin sensitivity, as evidenced by decreased fasting glucose and insulin concentrations, improved glucose tolerance, increased muscle glucose uptake in vivo, and increased glucose utilization during a hyperinsulinemic-euglycemic clamp. MLKB1KO mice had increased insulin-stimulated Akt phosphorylation and a >80% decrease in muscle expression of TRB3, a recently identified Akt inhibitor. Akt/TRB3 binding was present in skeletal muscle, and overexpression of TRB3 in C2C12 myoblasts significantly reduced Akt phosphorylation. These results demonstrate that skeletal muscle LKB1 is a negative regulator of insulin sensitivity and glucose homeostasis. LKB1-mediated TRB3 expression provides a novel link between LKB1 and Akt, critical kinases involved in both tumor genesis and cell metabolism.

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Characterization of insulin receptor kinase activity and autophosphorylation in different skeletal muscle types

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1991.260.1.e1 ◽

1991 ◽

Vol 260 (1) ◽

pp. E1-E7 ◽

Cited By ~ 1

Author(s):

S. Azhar ◽

J. C. Butte ◽

R. F. Santos ◽

C. E. Mondon ◽

G. M. Reaven

Keyword(s):

Skeletal Muscle ◽

Insulin Sensitivity ◽

Tyrosine Kinase ◽

Insulin Receptor ◽

Kinase Activity ◽

Insulin Binding ◽

Tyrosine Kinase Activity ◽

Fiber Composition ◽

Muscle Types ◽

Skeletal Muscle Types

We have examined insulin binding, autophosphorylation, and tyrosine kinase activity in detergent-solubilized and wheat germ agglutinin-purified insulin receptor preparations from four rat muscles of different fiber composition (i.e., tensor fascia latae, soleus, vastus intermedius, and plantaris). Insulin binding activity was similar in three of the four muscles but lower in tensor fascia latae. No significant differences were noted in the affinity of insulin for its receptor from various muscle types. Insulin receptor tyrosine kinase activity measured in the absence (basal) and presence of insulin (0.3-300 nM) was comparable in all muscle types (normalized to the amount of insulin bound). Insulin sensitivity, measured as the dose of insulin required for half-maximal activation of kinase activity, was also similar in all muscle types. Likewise, incubation of receptor preparations with [gamma-32P]ATP, Mn2+, and insulin (0.25-100 nM) resulted in a dose-dependent autophosphorylation of the beta-subunit (relative molecular weight approximately 95 kDa) with similar kinetics in all muscle types. In conclusion, these results show that the functional behavior of the insulin receptor autophosphorylation-kinase system (in vitro) is not changed by alterations in muscle fiber composition, indicating that differences in insulin sensitivity between different skeletal muscle types is probably not due to modulation of the insulin receptor phosphorylation system.

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Reversal of enhanced muscle glucose transport after exercise: roles of insulin and glucose

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1990.259.5.e685 ◽

1990 ◽

Vol 259 (5) ◽

pp. E685-E691 ◽

Cited By ~ 22

Author(s):

E. A. Gulve ◽

G. D. Cartee ◽

J. R. Zierath ◽

V. M. Corpus ◽

J. O. Holloszy

Keyword(s):

Skeletal Muscle ◽

Insulin Sensitivity ◽

Glucose Transport ◽

Transport Process ◽

Sugar Transport ◽

Transport Activity ◽

High Concentration ◽

Exercise Induced ◽

Muscle Glucose Transport

Exercise stimulates insulin-independent glucose transport in skeletal muscle and also increases the sensitivity of the glucose transport process in muscle to insulin. A previous study [D. A. Young, H. Wallberg-Henriksson, M. D. Sleeper, and J. O. Holloszy. Am. J. Physiol. 253 (Endocrinol. Metab. 16): E331–E335, 1987] showed that the exercise-induced increase in glucose transport activity disappears rapidly when rat epitrochlearis muscles are incubated for 3 h in vitro in the absence of insulin and that 7.5 microU/ml insulin in the incubation medium apparently slowed the loss of enhanced sugar transport. We examined whether addition of insulin several hours after exercise increases glucose transport to the same extent as continuous insulin exposure. Addition of 7.5 microU/ml insulin 2.5 h after exercise (when glucose transport has returned to basal levels) increased sugar transport to the same level as that which resulted from continuous insulin exposure. This finding provides evidence for an increase in insulin sensitivity rather than a slowing of reversal of the exercise-induced increase in insulin-independent glucose transport activity. Glucose transport was enhanced only at submaximal, not at maximal, insulin concentrations. Exposure to a high concentration of glucose and a low insulin concentration reduced the exercise-induced increase in insulin-sensitive glucose transport. Incubation with a high concentration of 2-deoxy-D-glucose (2-DG) did not alter the increase in insulin sensitivity, even though a large amount of 2-DG entered the muscle and was phosphorylated.(ABSTRACT TRUNCATED AT 250 WORDS)

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Furosemide decreases the sensitivity of glucose transport to insulin in skeletal muscle in vitro

Acta Endocrinologica ◽

10.1530/eje.0.1390118 ◽

1998 ◽

Vol 139 (1) ◽

pp. 118-122 ◽

Cited By ~ 3

Author(s):

G Dimitriadis ◽

B Leighton ◽

M Parry-Billings ◽

C Tountas ◽

S Raptis ◽

...

Keyword(s):

Skeletal Muscle ◽

Glucose Transport ◽

Soleus Muscle ◽

Transport Process ◽

Glucose Utilization ◽

Glucose Disposal ◽

Rat Soleus Muscle ◽

Lactate Formation

The effects of the diuretic furosemide on the sensitivity of glucose disposal to insulin were investigated in rat soleus muscle in vitro. At basal levels of insulin, the rates of 3-O-methylglucose transport, 2-deoxyglucose phosphorylation and lactate formation were not affected significantly by furosemide (0.5 mmol/l). However, furosemide significantly decreased these rates at physiological and maximal levels of insulin. The contents of 2-deoxyglucose and glucose 6-phosphate in the presence of furosemide were not significantly different from those in control muscles at all levels of insulin studied. It is concluded that furosemide decreases the sensitivity of glucose utilization to insulin in skeletal muscle by directly inhibiting the glucose transport process.

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