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Journal of Clinical Endocrinology & Metabolism , doi:10.1210/jc.2008-0250
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The Journal of Clinical Endocrinology & Metabolism Vol. 93, No. 7 2900-2903
Copyright © 2008 by The Endocrine Society

BRIEF REPORT

Muscle Adaptation to Short-Term Fasting in Healthy Lean Humans

Maarten R. Soeters, Hans P. Sauerwein, Peter F. Dubbelhuis, Johanna E. Groener, Mariëtte T. Ackermans, Eric Fliers, Johannes M. Aerts and Mireille J. Serlie

Departments of Endocrinology and Metabolism (M.R.S., H.P.S., E.F., M.J.S.), of Medical Biochemistry (P.F.D., J.E.G., J.M.A.), and of Clinical Chemistry (M.T.A.), Laboratory of Endocrinology, Academic Medical Center, University of Amsterdam, 1100 DD Amsterdam, The Netherlands

Address all correspondence and requests for reprints to: M. R. Soeters, M.D., Department of Endocrinology and Metabolism, Academic Medical Center, P.O. Box 22660, 1100 DD Amsterdam, The Netherlands. E-mail: m.r.soeters{at}amc.uva.nl.


   Abstract
Top
 Abstract
Introduction
 Subjects and Methods
 Results
 Discussion
 References
 
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.


   Introduction
Top
 Abstract
 Introduction
Subjects and Methods
 Results
 Discussion
 References
 
The incidence of obesity induced insulin resistance and type 2 diabetes mellitus increases. Lipid infusion studies in healthy subjects showed that increased plasma free fatty acids (FFAs) reduce insulin-mediated glucose uptake (1). Plasma FFA levels correlate with intramyocellular triglycerides during lipid infusion (2), and intramyocellular triglycerides correlate negatively with peripheral insulin sensitivity (3).

Various metabolites of FFA, such as ceramide, have been suggested to decrease insulin sensitivity in skeletal muscle (4). Increased muscle ceramide concentrations have correlated negatively with insulin sensitivity in obese insulin-resistant subjects (5). Intracellular ceramide synthesis from palmitate is a mechanism by which FFA decreases insulin-stimulated phosphorylation of protein kinase B/AKT (AKT) (6).

During short-term fasting, plasma FFA (7) as well as intramyocellular lipid stores increase (8). In addition, fasting induces insulin resistance, although the exact mechanism is still unknown (9, 10). Fasting increases intramyocellular ceramide levels in rats (11), but this has not been investigated in lean healthy humans.

Therefore, we studied peripheral glucose metabolism during hyperinsulinemic euglycemic clamp conditions in healthy lean subjects after 14- and 62-h fasting in relation to muscle ceramide and phosphorylation of AKT at serine473 (pAKT-ser473). We hypothesized that fasting increased muscle ceramide and decreased peripheral insulin sensitivity via lower muscle pAKT-ser473 levels.


   Subjects and Methods
Top
 Abstract
 Introduction
 Subjects and Methods
Results
 Discussion
 References
 
Subjects

After informed consent, eight healthy, nonsmoking, male volunteers were included. The study was approved by the Medical Ethical Committee of the Academic Medical Center.

Protocol

Subjects were studied after 14- and 62-h fasting, separated by at least 1 wk. Subjects fasted from 2000 h the evening before the first study day and from 2000 h 3 d before the second study day. Glucose kinetics (tracer: [6,6-2H2]glucose, > 99% enriched; Cambridge Isotopes, Andover, MA; prime, 8.8 µmol/kg; continuous, 0.11 µmol/kg·min), FFA, and glucoregulatory hormones were measured in the basal state and after a 5-h hyperinsulinemic euglycemic clamp (insulin infusion: 60 mU/m2·min; Actrapid 100 IU/ml; Novo Nordisk Farma B.V., Alphen aan den Rijn, The Netherlands), as described earlier (12). Insulin infusion rates were chosen to completely suppress endogenous glucose production (EGP) (13).

Indirect calorimetry (O2 consumption and CO2 production) and muscle biopsies were performed at the end of both basal state and clamp as described previously (12).

Analytical procedures

Plasma glucose and FFA concentrations were measured as reported earlier (12). [6,6-2H2]Glucose enrichment was measured as described previously (12).

Insulin, cortisol, glucagon, and catecholamines were determined as described previously (12). Soluble TNF receptors (sTNF-Rs) I and II were determined with an EASIA kit (Biosource Europe S.A., Nivelles, Belgium).

Ceramide in muscle biopsies was measured as described previously (12).

Muscle immunoblots were visualized by enhanced chemiluminescence. Chemicals for enhanced chemiluminescence were from Sigma-Aldrich (St. Louis, MO). Phosphospecific anti-AKT-ser473, phosphospecific anti-glycogen synthase kinase (GSK)-3-ser9, total anti-AKT, and total anti-eIF4E (loading control) were from Cell Signaling (Boston, MA). Phosphospecific anti-AS160-thr642 was from GeneTex Inc. (San Antonio, TX). Twenty milligrams of muscle tissue was taken up in 300 µl ice-cold lysis buffer [20 mM Tris (pH 7.5), 50 mM NaCl, 250 mM sucrose, 50 mM NaF, 5 mM Na4P2O7, 1 mM dithiothreitol, and 1.0% Triton X-100] supplemented with cocktail protease inhibitor tablets. Cell lysate was cleared by centrifugation for 15 min at 4 C. Cell protein was determined and separated by SDS-PAGE. A standard Western blotting procedure was performed, and polyvinylidene fluoride blots were incubated with appropriate antibodies. Results are presented as fold increase compared with control after 14-h fasting.

Calculations and statistics

EGP and peripheral glucose uptake rate of disappearance (Rd) were calculated with modified forms of the Steele Equations as described (12). Glucose oxidation was calculated as reported previously (12).

Comparisons and correlations were performed with the Wilcoxon signed rank test and Spearman’s rank correlation analysis ({rho}), respectively. The statistical software program version 12.0.1 (SPSS, Inc., Chicago, IL) was used for statistical analysis. Data are presented as median (minimum-maximum).


   Results
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
Discussion
 References
 
Anthropometric characteristics

Subject characteristics were: age, 23 yr (20–26); weight, 70.1 kg (62.5–75.5) after 14-h and 69.0 kg (60.0–72.8) after 62-h fasting (P = 0.012); body mass index 20.9 kg/m2 (19.2–23.3) after 14-h and 20.3 kg/m2 (18.3–22.6) after 62-h fasting (P = 0.011).

Glucose kinetics, FFAs, and glucoregulatory hormones (Table 1Go)

Basal plasma glucose concentrations, glucose oxidation, and EGP were significantly lower after 62-h fasting, whereas basal plasma FFAs increased significantly.


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  		TABLE 1. Glucose kinetics, FFAs, and glucoregulatory hormones

 
No differences were found in plasma glucose concentrations between clamps. Rd was significantly lower after 62-h fasting. Nonoxidative glucose disposal (NOGD) and oxidative glucose disposal during the clamp was lower after 62 h. Glucose oxidation and NOGD expressed as percentage of Rd did not differ between clamps. Plasma FFAs were equally suppressed during both clamps.

Insulin levels were lower after 62-h fasting in the basal state and during the clamp. Glucagon levels were higher in the basal state and tended to be higher during the clamp after 62-h fasting. Fasting did not influence plasma cortisol and norepinephrine levels. However, plasma epinephrine concentrations were higher after 62-h fasting in the basal state, but not during the clamp. sTNF-RI and II did not change.

Muscle measurements

Muscle ceramide concentrations in the basal state tended to be higher after 62-h fasting: 38.0 pmol/mg wet weight (25.2–54.9) vs. 29.5 pmol/mg wet weight (14.0–58.9), respectively (P = 0.069). During the clamp no differences were found between 62- and 14-h fasting: 35.3 pmol/mg wet weight (26.2–84.6) vs. 32.2 pmol/mg wet weight (25.9–54.3), respectively (P = 0.5).

Insulin-mediated peripheral glucose uptake and muscle ceramide levels did not correlate after 62-h fasting ({rho} = –0.12; P = 0.78). Muscle ceramide and plasma FFA levels showed no correlation ({rho} = –0.30; P = 0.47).

pAKT-ser473 increased significantly during both clamps (Fig. 1Go). A significant lower ratio of pAKT-ser473 to total AKT (pAKT-ser473/tAKT) was observed during the clamp after 62-h fasting vs. 14 h, but not in the basal state. The increase of pAKT-ser473/tAKT was lower after 62-h fasting.


Figure 1
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  		FIG. 1. A, pAKT-Ser473 during the basal state (P = 0.3) and the hyperinsulinemic euglycemic clamp (**P = 0.069) after 14-h (open box plots) and 62-h (gray box blots) fasting. *P = 0.012 and 0.017 for the increase in pAKT-Ser473 during the clamps after 14- and 62-h fasting, respectively. B, pAKT-Ser473 in proportion to total AKT (pAKT-ser473/tAKT) (n = 6) during the basal state (P = 0.3) and the hyperinsulinemic euglycemic clamp (***P = 0.028) after 14-h (open box plots) and 62-h (gray box blots) fasting. *P = 0.028 and 0.028 for the increase in pAKT-ser473/tAKT during the clamps after 14- and 62-h fasting, respectively. C, pGSK-3-ser9 (n = 6) during the basal state (P = 0.3) and the hyperinsulinemic euglycemic clamp (P = 0.3) after 14-h (open box plots) and 62-h (gray box blots) fasting. *P = 0.028 and 0.028 for the increase in pGSK-3-ser9 during the clamps after 14 - and 62-h fasting, respectively. D, pAS160-Thr642 during the basal state (P = 0.7) and the hyperinsulinemic euglycemic clamp (***P = 0.017) after 14-h (open box plots) and 62-h (gray box blots) fasting. *P = 0.012 and 0.012 for the increase in pAS160-Thr642 during the clamps after 14 and 62-h fasting, respectively.

 
pAS160-thr642 increased significantly during both clamps, but lower pAS160-thr642 was observed during the clamp after 62-h fasting.

pGSK-3-ser9 was not different between basal states or clamps but increased significantly during the clamps.


   Discussion
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
References
 
We studied the adaptation to 62-h fasting in healthy lean men to explore the mechanism underlying the fasting-induced decrease in peripheral insulin sensitivity.

Our study confirms reports on lower glucose concentrations, EGP, and peripheral insulin sensitivity after fasting (9, 10). The lower NOGD after fasting supports data by Bergman et al. (9). However, not all studies detected changes in NOGD during fasting (14). If glucose oxidation and NOGD were expressed as percentage of Rd, no differences were found, suggesting that the intracellular fate of glucose remains intact, despite decreased peripheral glucose uptake.

To explore further the fasting-induced insulin resistance, we examined muscle ceramide. The trend toward increased muscle ceramide levels in the basal state after 62-h fasting suggests a fasting effect but hinders a definite assumption. Muscle ceramide is mainly derived from de novo synthesis from serine and palmitate (6). We found no correlation of muscle ceramide with plasma FFA levels, suggesting that de novo synthesis is not the denominator of muscle ceramide during short-term fasting (12).

Sphingomyelin hydrolysis, another pathway resulting in ceramide generation, occurs under stress stimuli like TNF{alpha} (6). However, we found no changes in plasma sTNF-RI and II. In addition, we earlier reported no changes in inflammatory parameters during fasting (10). Therefore, the trend for higher muscle ceramide levels within skeletal muscle after fasting remains unexplained.

AKT is a 56-kDa serine/threonine kinase and a mediator of many insulin effects, and its regulation is complex (15). To be activated, AKT is translocated to the plasma membrane via its PH domain that binds PI3,4,5P3, the product of phosphoinositol-3-kinase. Here, phosphorylation of serine473 by 3-phosphoinositide dependent kinase 2 (16) and threonine308 by phosphoinositide dependent kinase 1 occurs (15). We found a significant lower ratio pAKT-ser473/tAKT after 62-h fasting during the clamp, but not in the basal state. Bergman et al. (9) reported no difference in pAKT-ser473 and the ratio pAKT-ser473/tAKT between 12- and 48-h fasting. This may be explained by differences in fasting duration. Remarkably, Bergman et al. (9) showed no increase of pAKT-ser473 during hyperinsulinemia, as reported earlier (17, 18). Intriguingly, lipid infusion in healthy men induces peripheral insulin resistance without effect on pAKT-ser473 (17). Another study found no differences in pAKT-ser473 between patients with type 2 diabetes and healthy matched controls (18). This indicates that the impairment in insulin signaling during fasting differs from the impairment during elevation of plasma FFAs by lipid infusion or obesity. Whether the lower pAKT-ser473/tAKT during hyperinsulinemia is attributed to the trend to higher muscle ceramide levels in the basal state remains unanswered because we found no correlation of ceramide levels with peripheral insulin sensitivity, which is in line with previous observations (12, 19). Other lipid mediators such as diacylglycerol or ganglioside GM3 may interfere with the insulin signaling cascade (4). Fasting increases muscle diacylglycerol in animals (11).

AKT phosphorylates both AS160 and GSK. AS160 is involved in the insulin-induced translocation of glucose transporter 4; moreover, insulin-mediated phosphorylation of AS160 was decreased in patients with type 2 diabetes (18). Phosphorylation of GSK by AKT stimulates glycogen synthesis (20). The equal pGSK-3-ser9 during the clamps is in line with the NOGD (as percentage of Rd), and suggests differential regulation of downstream events by AKT because pAS160-thr642 and peripheral insulin sensitivity were lower after 62-h fasting.

A remarkable finding in our study was the lower insulin levels during the clamp after 62-h fasting. Insulin infusions were almost identical during both clamps. It is unlikely that endogenous insulin secretion was stimulated at these euglycemic conditions. Plasma clearance of infused insulin is mainly renal in contrast to the first pass effect of endogenous insulin by the liver (21). Earlier studies showed equal insulin levels and lower Rd after fasting, making fasting-induced insulin resistance widely accepted (9). The insulin dose-response curve negates that the different plasma insulin levels account for differences in Rd (13).

In conclusion, short-term fasting induces peripheral insulin resistance of glucose uptake, whereas the muscle fate of glucose stays intact. Muscle ceramide tends to increase during fasting. The decreased peripheral glucose uptake is explained by a decrease in pAKT-ser473/tAKT and pAS160-thr642 during the clamp.

Because studies in obesity induced insulin resistance and type 2 diabetes mellitus have not shown effects on pAKT-ser473-, it is possible that pAKT-ser473 is involved in the physiological adaptation to fasting, inducing a reduction in peripheral glucose uptake and protecting the body from hypoglycemia.


   Acknowledgments
 
We thank A. F. C. Ruiter and A. Poppema for excellent assistance on laboratory analyses.


   Footnotes
 
Disclosure Statement: The authors have nothing to disclose.

First Published Online April 8, 2008

Abbreviations: EGP, Endogenous glucose production; FFA, free fatty acid; GSK, glycogen synthase kinase; NOGD, nonoxidative glucose disposal; pAKT-ser473, phosphorylation of AKT at serine473; sTNF-R, soluble TNF receptor.

Received February 4, 2008.

Accepted April 2, 2008.


   References
Top
 Abstract
 Introduction
 Subjects and Methods
 Results
 Discussion
 References
 

  1. Belfort R, Mandarino L, Kashyap S, Wirfel K, Pratipanawatr T, Berria R, DeFronzo RA, Cusi K 2005 Dose-response effect of elevated plasma free fatty acid on insulin signaling. Diabetes 54:1640–1648[Abstract/Free Full Text]
  2. Boden G, Lebed B, Schatz M, Homko C, Lemieux S 2001 Effects of acute changes of plasma free fatty acids on intramyocellular fat content and insulin resistance in healthy subjects. Diabetes 50:1612–1617[Abstract/Free Full Text]
  3. Krssak M, Falk Petersen K, Dresner A, DiPietro L, Vogel SM, Rothman DL, Roden M, Shulman GI 1999 Intramyocellular lipid concentrations are correlated with insulin sensitivity in humans: a 1H NMR spectroscopy study. Diabetologia [Errata (1999) 42:386 and (1999) 42:1269] 42:113–116[CrossRef]
  4. Holland WL, Knotts TA, Chavez JA, Wang LP, Hoehn KL, Summers SA 2007 Lipid mediators of insulin resistance. Nutr Rev 65(6 Pt 2):S39–S46
  5. Straczkowski M, Kowalska I, Nikolajuk A, Dzienis-Straczkowska S, Kinalska I, Baranowski M, Zendzian-Piotrowska M, Brzezinska Z, Gorski J 2004 Relationship between insulin sensitivity and sphingomyelin signaling pathway in human skeletal muscle. Diabetes 53:1215–1221[Abstract/Free Full Text]
  6. Summers SA 2006 Ceramides in insulin resistance and lipotoxicity. Prog Lipid Res 45:42–72[CrossRef][Medline]
  7. Klein S, Sakurai Y, Romijn JA, Carroll RM 1993 Progressive alterations in lipid and glucose metabolism during short-term fasting in young adult men. Am J Physiol 265(5 Pt 1):E801–E806
  8. Stannard SR, Thompson MW, Fairbairn K, Huard B, Sachinwalla T, Thompson CH 2002 Fasting for 72 h increases intramyocellular lipid content in nondiabetic, physically fit men. Am J Physiol Endocrinol Metab 283:E1185–E1191
  9. Bergman BC, Cornier MA, Horton TJ, Bessesen DH 2007 Effects of fasting on insulin action and glucose kinetics in lean and obese men and women. Am J Physiol Endocrinol Metab 293:E1103–E1111
  10. van der Crabben SN, Allick G, Ackermans MT, Endert E, Romijn JA, Sauerwein HP 2008 Prolonged fasting induces peripheral insulin resistance, which is not ameliorated by high-dose salicylate. J Clin Endocrinol Metab 93:638–641[Abstract/Free Full Text]
  11. Turinsky J, Bayly BP, O’Sullivan DM 1991 1,2-Diacylglycerol and ceramide levels in rat liver and skeletal muscle in vivo. Am J Physiol 261(5 Pt 1):E620–E627
  12. Soeters MR, Sauerwein HP, Groener JE, Aerts, JM, Ackermans MT, Glatz JF, Fliers E, Serlie MJ 2007 Gender-related differences in the metabolic response to fasting. J Clin Endocrinol Metab 92:3646–3652[Abstract/Free Full Text]
  13. Rizza RA, Mandarino LJ, Gerich JE 1981 Dose-response characteristics for effects of insulin on production and utilization of glucose in man. Am J Physiol 240:E630–E639
  14. Webber J, Taylor J, Greathead H, Dawson J, Buttery PJ, Macdonald IA 1994 Effects of fasting on fatty acid kinetics and on the cardiovascular, thermogenic and metabolic responses to the glucose clamp. Clin Sci (Lond) 87:697–706[Medline]
  15. Scheid MP, Woodgett JR 2003 Unravelling the activation mechanisms of protein kinase B/Akt. FEBS Lett 546:108–112[CrossRef][Medline]
  16. Dong LQ, Liu F 2005 PDK2: the missing piece in the receptor tyrosine kinase signaling pathway puzzle. Am J Physiol Endocrinol Metab 289:E187–E196
  17. Tsintzas K, Chokkalingam K, Jewell K, Norton L, Macdonald IA, Constantin-Teodosiu D 2007 Elevated free fatty acids attenuate the insulin-induced suppression of PDK4 gene expression in human skeletal muscle: potential role of intramuscular long-chain acyl-coenzyme A. J Clin Endocrinol Metab 92:3967–3972[Abstract/Free Full Text]
  18. Karlsson HKR, Zierath JR, Kane S, Krook A, Lienhard GE, Wallberg-Henriksson H 2005 Insulin-stimulated phosphorylation of the Akt substrate AS160 is impaired in skeletal muscle of type 2 diabetic subjects. Diabetes 54:1692–1697[Abstract/Free Full Text]
  19. Serlie MJ, Meijer AJ, Groener JE, Duran M, Endert E, Fliers E, Aerts JM, Sauerwein HP 2007 Short-term manipulation of plasma free fatty acids does not change skeletal muscle concentrations of ceramide and glucosylceramide in lean and overweight subjects. J Clin Endocrinol Metab 92:1524–1529[Abstract/Free Full Text]
  20. Doble BW, Woodgett JR 2003 GSK-3: tricks of the trade for a multi-tasking kinase. J Cell Sci 116(Pt 7):1175–1186
  21. Duckworth WC, Bennett RG, Hamel FG 1998 Insulin degradation: progress and potential. Endocr Rev 19:608–624[Abstract/Free Full Text]



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