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Journal of Clinical Endocrinology & Metabolism, doi:10.1210/jc.2004-2108
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The Journal of Clinical Endocrinology & Metabolism Vol. 90, No. 5 2747-2754
Copyright © 2005 by The Endocrine Society

Enhanced Metabolic Cycling in Subjects after Colonic Resection for Ulcerative Colitis

M. D. Robertson, A. S. T. Bickerton, A. L. Dennis, H. Vidal, D. P. Jewell and K. N. Frayn

Oxford Centre for Diabetes, Endocrinology, and Metabolism (M.D.R., A.S.T.B., A.L.D., K.N.F.) and Nuffield Department of Gastroenterology (D.P.J.), University of Oxford, Oxford OX3 7LJ, United Kingdom; and Institut National de la Santé et de la Recherche Médicale Unité 449/Institut National de la Recherche Agronomique-1235 (H.V.), F-69372 Lyon, France

Address all correspondence and requests for reprints to: Keith N. Frayn, Ph.D., Oxford Centre for Diabetes, Endocrinology, and Metabolism, Churchill Hospital, Oxford OX3 7LJ, United Kingdom. E-mail: keith.frayn{at}oxlip.ox.ac.uk.


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Discussion
 References
 
Colonic resection leads to insulin resistance, but the mechanisms are unknown. We used an integrated approach to examine adipose tissue and skeletal muscle metabolism in patients lacking a colon. Ten healthy colectomized patients having undergone surgery for ulcerative colitis and 10 matched control subjects were studied with a hyperinsulinemic-euglycemic clamp to measure insulin sensitivity, an arteriovenous sampling meal tolerance study to measure postprandial substrate flux across adipose tissue and skeletal muscle, and adipose tissue and skeletal muscle biopsies to quantify the expression of genes involved in glucose and lipid metabolism. Colectomized subjects exhibited lower insulin sensitivity (homeostatic model assessment model, 33% reduction, P = 0.03; minimal model, 29% reduction, P = 0.05), elevated aldosterone (9-fold, P = 0.003), leptin (2.2-fold, P = 0.03), and an increased rate of nonesterified fatty acid and glycerol release from adipose tissue (P = 0.02) especially in the late postprandial period. The uptake of fatty acids into muscle was also significantly increased (P = 0.007), as were muscle CD36 and LPL mRNA expression compared with controls. In adipose tissue, hormone-sensitive lipase mRNA expression was increased (P = 0.015), whereas peroxisome proliferator-activated receptor-{gamma} expression was decreased (P = 0.02), as was that of CD36 (P = 0.001). In this study, alterations in fatty acid metabolism after colonic resection altered may have contributed to the impairment of insulin sensitivity.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Discussion
 References
 
THE GASTROINTESTINAL TRACT plays an important role in glucose tolerance. Modifying upper gut function by reducing gastric emptying (1) and/or delaying digestion or absorption of nutrients (2) are commonly used strategies to improve postprandial glucose metabolism in those with obesity or type 2 diabetes. However, the importance of the distal gut in postprandial glucose handling has received comparatively little attention. Patients lacking a colon (after surgical resection) exhibit a reduction in insulin sensitivity (3, 4), although their metabolism is complex in that the more established functions of the colon in water and electrolyte balance, energy salvage, gut motility, and fermentation of organic material are also compromised.

Ulcerative colitis (UC) is a chronic inflammatory disease of the gastrointestinal tract that currently affects three in 1000 people in the United Kingdom (5) with a similar incidence in both Western Europe and the United States. However, even with effective treatment, approximately 15% of patients with UC will require total colectomy, and so this represents a substantial patient group. After surgery, there is rapid metabolic adaptation of the renin-angiotensin system (6) to prevent electrolyte imbalance (7) and hyperplasia of the upper gut to increase water absorption (8, 9). However, it is not known whether there is further metabolic adaptation in the extraintestinal tissues that would explain the reduction in insulin sensitivity.

It seems possible that the insulin resistance observed in patients lacking a colon reflects alterations in intermediary metabolism. The links between adipose tissue function, fatty acid metabolism, and glucose uptake into insulin-sensitive tissues (primarily muscle) are now well established in healthy, obese, and diabetic subjects. The plasma fatty acid concentration reflects the balance between release (from the lipolysis of adipose tissue stores and intravascular lipolysis of triglyceride-rich lipoproteins) and uptake (predominantly reesterified in adipose tissue and liver and oxidized in muscle, heart, and liver). Abnormalities in fatty acid storage and lipolysis in insulin-sensitive tissues with increased flux from adipose to nonadipose tissues such as skeletal muscle are now believed to be a critical event in the development of insulin resistance (10). Short-chain fatty acids, produced from colonic fermentation, may modulate adipose tissue lipolysis (11). The reduced insulin sensitivity in patients without a colon may also reflect decreased glucagon-like peptide 1 (GLP-1) levels (12). The enteroglucagon-derived peptides are released primarily from the colon and distal ileum. These peptides are among the most important emerging therapies for type 2 diabetes. Lower GLP-1 concentrations are also observed in the insulin-resistant states of obesity (increased activity of dipeptidyl peptidase IV and so increased degradation of the active hormone) (13) and type 2 diabetes (decreased secretion due to impaired L cell function) (14). GLP-1 affects insulin secretion and may also act directly upon peripheral tissues such as adipose tissue to regulate clearance of triglyceride-rich lipoproteins (15).

Established methods such as the euglycemic-hyperinsulinemic clamp may be used to assess insulin sensitivity in the steady state (16). However, loss of the colon is more likely to affect the dynamic metabolic state after a meal. Assessing this is more difficult. The measurement of a metabolite as a concentration indicates the balance between release and uptake into the circulation and information relating to tissue flux is lost. By using an integrative approach incorporating arteriovenous (A-V) sampling techniques and biopsy sampling of both adipose tissue and skeletal muscle, we have now investigated the metabolic adaptations at the whole-body and tissue level that follow total colectomy. Our aim was to clarify the mechanisms leading to insulin resistance in an otherwise healthy group of patients.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Discussion
 References
 
For this study, 10 healthy patients (six female) having undergone total colonic resection after UC [<5 cm bowel resected 4 yr after surgery (range, 1–8 yr)] were recruited from the outpatient stoma clinic at the John Radcliffe Hospital (Oxford, UK). None had reported any postsurgical complications, and they were not currently taking any prescribed medication (with the exception of hormone replacement therapy). Ten healthy control subjects having no history of gastrointestinal disease were matched to the patient group on the basis of age, body mass index, sex, and fasting glucose and lipid levels. These control subjects were also enrolled in a study that investigated the effects of resistant starch intake. The results of that study will be published separately. In view of the importance of dietary preparation for metabolic studies, habitual diet was assessed before enrollment in the study by 7-d food record in both groups (U.S. Department of Agriculture database). Anthropometric measurements are given in Table 1Go.


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  		TABLE 1. Anthropomentric measurements taken in the morning following a 12-h fast and dietary assessments taken from 7-d food records

 
General protocol

Subjects visited the unit for two experimental studies over a period of 2 wk for a hyperinsulinemic-euglycemic clamp and a postprandial test. Subjects were asked to follow their own personal diet diary (completed during the run-in week) during the 2-wk intervention to standardize background diet.

At the end of the first week, subjects attended the metabolic unit, and a hyperinsulinemic-euglycemic clamp was performed in the fasting state. At the end of the second week, subjects attended for a full-day metabolic investigation involving a meal tolerance test (MTT) and A-V sampling across skeletal muscle and abdominal adipose tissue. Vigorous exercise and alcohol were avoided for 48 h before each test, and subjects were provided with a low-fat, low-fiber evening meal (pasta and tomato sauce; 11 g protein, 9 g fat, 34 g carbohydrate, 1 g fiber, 1113 kJ) before each study day to reduce variability (17). This study was approved by the Oxfordshire Clinical Research Ethics Committee, and all subjects gave written informed consent.

Metabolic investigation

Euglycemic-hyperinsulinemic clamp. This was performed as described by DeFronzo et al. (16). Beginning at 0700 h after a 12-h overnight fast, an antecubital vein was cannulated for the infusion of both 20% glucose solution and insulin [Actrapid (Novo Nordisk, Bagsværd, Denmark) in solution of 0.9% saline containing 2 ml subjects’ blood to prevent adhesion of insulin to plastics]. A hand vein was cannulated retrogradely, and the hand was placed in a heated box (55 C) for arterialized sampling. After fasting measurements, the insulin infusion was started at a rate of 35 mU insulin·m–2·min–1. The blood glucose concentration was measured every 5 min by glucose analyzer (HemoCue B-glucose analyzer; HemoCue Ltd., Sheffield UK), and the infusion of 20% glucose was adjusted to maintain blood glucose levels at 5 mmol/liter. Blood was obtained every 10 min during the clamp for the measurement of plasma insulin, nonesterified fatty acid (NEFA), and C-peptide. The insulin infusion was continued for 120 min to obtain a measure of the rate of insulin-stimulated glucose disposal during the last 30 min of the clamp (90- to 120-min period).

Tissue-specific A-V study. To assess the in vivo metabolism of adipose tissue and skeletal muscle in humans, we measured A-V differences across these tissues. Differences between the composition of venous blood draining a particular tissue and arterialized blood reflect that tissue’s metabolic activity. Inclusion of tissue blood flow into the calculations allows quantification of net metabolic flux. On the study day, serial blood samples were taken in the fasting state and for 5 h after a liquid MTT (60 g carbohydrate, 21 g fat, 500 kcal) (18).

Simultaneous sampling from three sites began at 0700 h after a 12-h overnight fast. Arterialized blood was obtained from a vein draining a heated hand. Venous blood from muscle was taken from a vein draining the deep tissues of the forearm. To prevent contamination of the blood from the forearm vein with blood from the hand, a wrist cuff was inflated to 200 mm Hg for 3 min before taking samples. (The local ischemia produced in the hand does not affect the data because venous return from the hand is completely occluded during the period of blood sampling.) Venous blood from adipose tissue was obtained from the superficial epigastric vein (19). This vein drains sc abdominal adipose tissue with negligible contribution from other tissues (20). Oxygen saturation and ultrasound were used to assess correct positioning of the cannulae. Two sets of baseline samples were taken 30 min apart with further blood samples taken for 5 h after the meal.

As part of the A-V study, sc abdominal adipose tissue blood flow was measured by 133Xe washout (21), and forearm muscle blood flow was assessed by occlusion strain gauge plethysmography (22).

At the end of the study, skeletal muscle and adipose tissue biopsies were taken under local anesthetic (1% lignocaine) from eight of the 10 patients and controls who agreed to undergo the procedure. Subcutaneous abdominal adipose tissue was taken with a 12-gauge needle, and muscle biopsies were taken from the vastus lateralis muscle using a percutaneous needle technique. Samples were snap frozen in liquid nitrogen and stored at –70 C for later mRNA quantification.

Quantitation of messenger mRNAs. The concentrations of the mRNAs corresponding to the genes of interest were measured by reverse transcription followed by real-time PCR using a light cycler (Roche Diagnostics, Meylan, France) as previously reported (23, 24). First-strand cDNAs were first synthesized from 500 ng total RNA in the presence of 100 U SuperScript II (Invitrogen, Eragny, France) using both random hexamers and oligo(dT) primers (Promega, Charbonnières, France). The real-time PCR product was performed in a final volume of 20 µl containing 5 µl of a 60-fold dilution of the RT dilution medium, 15 µl reaction buffer from the FastStart DNA master SYBR Green kit (Roche Diagnostics), and 10.5 pmol of the specific forward and reverse primers (Eurobio, Les Ulis, France). Primers were selected to amplify small fragments (80–200 bp) and to hybridize in different exons of the target sequences. For quantification, a standard curve was systematically generated with six different amounts (150–30,000 molecules/tube) of purified target cDNA cloned in the pGEM plasmid (Promega). Each assay was performed in duplicate. The results are presented in absolute concentrations in attomoles per microgram of total RNA or relative to cyclophilin mRNA level that was measured as internal standard.

Biochemistry. Whole blood for metabolite, insulin, C-peptide, leptin, and aldosterone determination was collected into heparinized syringes (Sarstedt, Leicester, UK). Plasma glucose, triacylglycerol (TG) (Instrumentation Laboratory, Warrington, UK), and NEFA (Alpha Laboratories, Eastleigh, UK) concentrations were measured enzymatically using an IL Monarch automated analyzer. Whole blood for 3-hydroxybutyrate and glycerol determination were deproteinized with 7% (wt/vol) perchloric acid and concentrations were measured enzymatically. Metabolites were batch analyzed and exhibited an intraassay variation of less than 7.2%. Insulin, C-peptide, leptin (Linco Research, St. Charles, MO), and aldosterone (Diagnostic Products, Los Angeles, CA) levels were measured by RIA using commercially available kits. The sensitivity of this assay was 10 pg/ml. The intraassay coefficients of variance for all RIAs were less than 10%.

Statistical analysis and calculations. Adipose tissue blood flow was calculated as described previously (21). A-V and venoarterial differences in metabolite concentrations across both adipose tissue and skeletal muscle were calculated. Concentrations of lipids (measured in plasma) were converted to those in whole blood using the hematocrit values. Absolute flux was calculated as the product of the A-V or venoarterial difference and tissue blood flow. In adipose tissue, the rate of action of lipoprotein lipase (LPL) in vivo was calculated as the absolute rate of net TG extraction. The rate of action of hormone-sensitive lipase (HSL) in adipose tissue in vivo was calculated from the total adipose glycerol release after subtraction of LPL rate of action (19). Transcapillary flux of fatty acids in adipose tissue represents the net flow of fatty acids between adipocytes and capillaries and was calculated from total fatty acid inflow (arterialized NEFA + 3x TG) minus total fatty acid venous outflow, multiplied by blood flow (25). In skeletal muscle, calculations of HSL activity are not valid because of significant reuse of glycerol (26). Instead, we calculated total fatty acid uptake into muscle from the sum of the rates of TG and NEFA removal across the tissue. It should be noted that these A-V difference measurements can only give information on net metabolic exchanges across the tissues unless combined with use of an isotopic tracer, which we did not do in these studies.

Insulin sensitivity and ß-cell function were assessed in various ways that provide complementary data: homeostatic model assessment (HOMA), which give indices of insulin sensitivity and of ß-cell function, respectively, based on fasting glucose and insulin concentrations; hyperinsulinemic-euglycemic clamp [equal to the glucose infusion rate during steady state (final 30 min of clamp)] divided by the systemic insulin concentration, which gives an index of insulin-driven glucose uptake primarily into skeletal muscle; and in the postprandial state from the MTT using a minimal model approach (27). This index is based on the cumulative integrated area under the curve measures of insulin and glucose concentrations, assuming that total glucose disposal from the system after 120 min (or when basal values have been reached) equals the glucose entering the peripheral circulation, allowing for first pass extraction by the liver. Unlike the other measurements, therefore, it involves the role of the gastrointestinal tract in postprandial physiology. The incremental C-peptide to insulin ratio over the first 2 h of the study, an index of hepatic insulin extraction, was calculated as a molar ratio with the trapezoid method.

Time-course data were analyzed by repeated measures ANOVA when normally distributed using SPSS (SPSS Inc., Chicago, IL). Postprandial data are also presented in tables, text, and figures in summary form, i.e. fasting and area under the curve values calculated using the trapezoid rule (28). Summary data are analyzed by paired Student’s t tests. Values of P < 0.05 were taken as significant. Values in text are displayed as mean (range). Gene expression data were analyzed using the nonparametric Mann-Whitney test comparing mRNA levels between control and colectomized patients expressed relative to cyclophilin.


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Discussion
 References
 
The patient and control groups were well matched for age, gender, body composition, and habitual diet (Table 1Go). The energy intake recorded in the 7-d food record was less than expected based on estimates of daily energy requirements (29); however, the degree of underreporting (mean, 14.2 ± 0.8%) did not differ between the groups and was within the range expected for nonobese subjects (30).

Fasting hormones. The fasting plasma aldosterone [163 (10–906) vs. 19 (0–78) pg/ml; P = 0.003] and leptin [15.1 (1.9–77.9) vs. 6.86 (3.19–22.5) ng/ml; P = 0.034] concentrations were significantly elevated in the patient group compared with matched controls. There was no difference in the incremental C-peptide to insulin ratio, an index of hepatic insulin extraction (Table 2Go).


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  		TABLE 2. Indices of insulin sensitivity in a group of healthy colectomized patients and a group of matched controls

 
Insulin sensitivity. The patient group exhibited a significantly lower fasting insulin sensitivity (HOMA; P = 0.03). During the hyperinsulinemic-euglycemic clamp, the insulin sensitivity (reflecting primarily skeletal muscle) did not differ between the groups (Table 2Go). The oral insulin sensitivity index obtained during the MTT was, however, lower in the patient group (P = 0.05), and this was reflected in an elevation in the postprandial insulin concentration (Fig. 1Go) for the first 60 min after the meal.



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  		FIG. 1. Plasma insulin concentration after a MTT in a group of matched patients (•) and control ({circ}) subjects; n = 10, mean (±SEM). Repeated-measures ANOVA showed a significant time effect (P < 0.001) but no effect of subject group.

 
MTT. Both adipose tissue (P = 0.029) and skeletal muscle (P = 0.036) blood flow were significantly higher in the patient group when compared with controls (Fig. 2Go). This was evident in both the fasting and postprandial states.



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  		FIG. 2. Adipose tissue (A) and forearm blood (B) flow after an MTT in a group of matched patients (•) and control ({circ}) subjects; n = 10, mean (±SEM). Both adipose tissue (P = 0.029) and forearm (P = 0.036) blood flow were significantly elevated in the patient group. Only forearm blood flow showed a significant time effect after MTT (P = 0.01).

 
The circulating concentrations of NEFA and TG were higher in the patient group, although these differences failed to reach statistical significance (Fig. 3Go). Despite this, in the late postprandial period, there was a significant increase in the output of both NEFA and glycerol from adipose tissue in the patient group (Fig. 4Go). There was no difference in the calculated rate of action of HSL in adipose tissue (170 ± 90 vs. 128 ± 48 nmol·100 g tissue–1·min–1); however, there was an increase in the calculated rate of action of adipose tissue LPL (326 ± 51 vs. 188 ± 39 nmol·100 g tissue–1·min–1; P = 0.05) in the patient group compared with controls. This higher efflux of fatty acids from adipose tissue was matched with a higher uptake of total fatty acids (TG and NEFA) by skeletal muscle in the patient group (Fig. 5AGo), again concentrated in the late postprandial period. The transcapillary flux of fatty acids in adipose tissue reflects the dynamic flow of fatty acids in and out of adipocytes with changing nutritional state (25) (Fig. 5BGo). There was a greater uptake of fatty acids into adipose tissue in the mid-postprandial state in the patients (P = 0.046), with increased outflow of fatty acids later as the patients re-entered a postabsorptive state.



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  		FIG. 3. Plasma NEFA (A) and plasma TG (B) concentrations after an MTT in a group of matched patients (•) and control ({circ}) subjects; n = 10, median values. Both NEFA and TG showed a significant time effect after the MTT (P < 0.01); however, neither showed a significant difference between the groups.

 


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  		FIG. 4. NEFA (A) and glycerol release (B) from sc adipose tissue after an MTT in a group of matched patients (•) and control ({circ}) subjects; n = 10, mean (±SEM). The release of both NEFA (P = 0.019) and glycerol (P = 0.02) from adipose tissue was significantly higher in the patient group (repeated-measures ANOVA).

 


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  		FIG. 5. A, Total fatty acid uptake into skeletal muscle; B, transcapillary flux of fatty acids across adipose tissue after an MTT in a group of matched patients (•) and control ({circ}) subjects; n = 10, mean (±SEM). A, Uptake of fatty acids by muscle was significantly (P = 0.007) higher in the patients compared with controls (repeated measures ANOVA). B, Pattern of fatty acid flux differed significantly between groups (P = 0.05, group x time interaction, repeated-measures ANOVA). Post hoc Student’s t tests (with Bonferroni correction) showed an increased fatty acid uptake into adipose tissue in the postprandial period (0–180 min) in the patient group (P = 0.046), whereas flux during the postabsorptive period (180–300 min) was not significantly different.

 
There was no difference in the arterialized plasma concentration of glucose. Glucose clearance by skeletal muscle was higher in the patient group, but when this was expressed per picomole insulin (to adjust for the hyperinsulinemia in the patient group), the difference became nonsignificant. A similar pattern was observed for glucose uptake across adipose tissue.

Gene expression. Gene expression data for patients and controls are shown in Tables 3Go and 4Go. There was decreased expression of both CD36 (63% of control level) and peroxisome proliferator-activated receptor (PPAR)-{gamma} (63% of control level) and enhanced expression of HSL (161% of control level) in the sc adipose tissue biopsies from the patient group. In skeletal muscle samples, the expression of both CD36 (182% of control level) and LPL (322% of control level) were higher in the patient group.


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  		TABLE 3. mRNA levels (attomoles per microgram of total RNA) of target genes involved with glucose and lipid metabolism from adipose tissue biopsies in a group of healthy colectomized patients and a group of matched controls

 

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  		TABLE 4. mRNA levels (percent expression relative to cyclophilin) of target genes involved with glucose and lipid metabolism from skeletal muscle biopsies in a group of healthy colectomized patients and a group of matched controls

 

   Discussion
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Discussion
References
 
In this study, we have demonstrated clear metabolic changes in otherwise healthy patients having previously undergone total proctocolectomy after severe UC. Alteration in metabolic cycling, primarily of fatty acids in both muscle and adipose tissue, is an unreported phenomenon in healthy individuals and is more commonly associated with conditions such as obesity (25). In contrast with obesity, however, in our ileostomy patients the increased rate of adipose tissue lipolysis did not lead to significant elevations in the systemic concentration of either NEFA or TG because this was apparently balanced by the increased uptake of fatty acids into both skeletal muscle and, in the postprandial state, into adipose tissue. The long-term consequences of this alteration in the postprandial handling of nutrients require further evaluation in terms of diabetic and cardiovascular risk.

It could be stated that the uptake and efflux of substrate by a tissue is mediated primarily by the rate of blood flowing through that tissue. Blood flow, especially adipose tissue blood flow, has been found to be correlated to insulin sensitivity (31), i.e. the highest blood flow is found in the individuals with the highest degree of insulin sensitivity. Our data cannot be explained by such a relationship because we found a lower insulin sensitivity in the patient group. However, this significant change in vascular physiology could potentially be explained by adaptations in other systemically released hormones. Recent data suggest that elevated plasma aldosterone increases forearm blood flow by increasing NO release in the vascular endothelium (32), which may account for the significant increase in skeletal muscle blood flow in our patients. Postsurgical water and sodium loss leads to activation of the renin-angiotensin system, leading to stimulation of the adrenal cortex resulting in functional hyperaldosteronism (33). In this study, we found an 8-fold elevation in fasting aldosterone levels in patients up to 8 yr postsurgery, indicating a more long-term metabolic change.

The documented effects of increased renin-angiotensin system activity on adipose tissue vascular function are less clear-cut with angiotensin II infusion actually inhibiting blood flow in healthy subjects (34). An explanation for this apparent contradiction comes from work in sodium depleted subjects (35). Under conditions of sodium depletion (as experienced after ileostomy and indicated by raised aldosterone), there is an enhanced blood flow response to both doxazosin ({alpha}1) and yohimbine ({alpha}2) adrenoceptor antagonists compared with sodium-replete conditions. The hyperleptinemia we found in our subjects may also be an adaptation to enhance sodium retention and plasma volume expansion. Leptin increases sympathetic outflow to many tissue including adipose tissue (36) with leptin-induced NO release in the vascular endothelium (37). Therefore, it may be the increased sympathetic neural activity associated with elevated leptin, combined with the enhanced role of both classes of {alpha}-adrenoceptors, which results in increased adipose tissue blood flow in our patient group.

Enhanced tissue blood flow could not be solely responsible for the enhanced metabolic cycling we observed; enzyme efficiency and uptake of substrate would also need to be increased. In adipose tissue, the calculated efficiency of LPL was significantly increased as was the HSL mRNA content found in adipose tissue from the patient group. The increase in LPL is perhaps as we would expect as both insulin (38) and gastric inhibitory polypeptide (15) have been shown to increase adipose tissue LPL, and both of these hormones are elevated after ileostomy (3, 4). Uptake of fatty acids by adipose tissue requires transfer across the membrane by proteins such as FAT/CD36. The uptake of fatty acids by adipose tissue was also increased in the patient group during the early postprandial period, which may have led to the observed down-regulation of CD36 gene expression in adipose tissue. HSL, however, is normally suppressed by insulin, and so the increased HSL gene expression noted in adipose tissue could be due instead to the increased uptake of glucose into adipose tissue in the patient group (driven by increased blood flow) and binding to the glucose-responsive region of the HSL gene (39). Increased HSL phosphorylation and lipase activity could also partly explain the increased levels of adipose tissue lipolysis in these ileostomists. It is likely, therefore, that changes in adipose tissue metabolism are driven by both changes in vascular function and lipase efficiency, both indirect adaptations to the loss of colonic tissue.

A reduction in insulin sensitivity after ileostomy has been reported previously, although the exact mechanism has yet to be described. This observation has been explained in many ways: reduced short-chain fatty acid (SCFA) production (40), low GLP-1 levels (12), and even as a consequence of inflammatory cytokines or prior steroid use during active bowel disease (41). Patients with quiescent UC, however, do not exhibit characteristics of insulin resistance (42), and so we can be more confident that metabolic changes observed in such studies are indeed as a result of the lack of a colon. In elucidating the mechanism of reduced insulin sensitivity, we were able to demonstrate directly an increased uptake of fatty acids into skeletal muscle compared with controls. This increased uptake of fatty acids may again be driven by increased blood flow, although in this case, the effect seems to be substrate specific. There was a significant increase in both CD36 and LPL mRNA in muscle samples indicating metabolic adaptation to increase fatty acid metabolism in muscle; however, the glucose clearance (when adjusted for insulin) across skeletal muscle and GLUT-4 mRNA level were not increased. Under resting conditions, the delivery of fatty acids to the mitochondria for ß-oxidation is regulated by the rate of tissue uptake, and so we could predict that fatty acid oxidation was increased in these patients. Although indirect calorimetry was not performed in this study, our previous work has shown that rates of whole-body fat oxidation are increased at the expense of glucose after ileostomy (3). Historically, increased fatty acid oxidation has been shown to reduce glucose transport/phosphorylation and oxidation in isolated muscle (43), and so the reduced insulin sensitivity in our ileostomy patients may indeed be directly linked to increased muscle fatty acid uptake. Another related possibility is that the release of adipokines such as adiponectin, with potentially insulin-sensitizing effects, might have been altered in the patients. We did not attempt to assess this because any such measurements would have been entirely speculative.

The gene expression aspect of this study has been a novel addition to the metabolic characterization of this patient group. A reduced PPAR{gamma} expression in adipose tissue from our patients fits in with what we know about the relationship with insulin sensitivity. Low PPAR{gamma} in adipose tissue has been linked to increased fat uptake by muscle, although the data from human studies have made the mechanism difficult to interpret (44). In other tissues, colonic cell PPAR{gamma} expression has been shown to be reduced in UC (45) due potentially to changes in SCFA metabolism (46). Whether the lack of bacterial fermentation and subsequent SCFA metabolism after ileostomy could lead to changes in PPAR regulation in extra-intestinal tissues is potentially an important question and could be answered simply by studying gene expression in germ-free animals. Despite a significantly increased plasma leptin concentration, leptin mRNA in sc adipose tissue was not increased. This is perhaps not surprising with what we know about the differences in responsiveness in the regional fat depots (47).

We acknowledge that metabolic studies of the type performed in this paper are dependent upon prior nutritional status. A concern might be that we did not adequately standardize nutritional intake of the two groups. We tried to make diets consistent during the period of the physiological tests by using diet diaries, although we acknowledge that these provide only imperfect information. These diet diaries also suggest that the two groups did not differ in habitual dietary intake. Bingham et al. (48) found no difference in energy and macronutrient intake between ileostomists and controls, although a slightly lower fiber intake in the patients. In the end, however, we have reported on metabolic differences between patients and controls, and if these differences reflect in part the dietary habits of the participants, that is at least a reflection of their normal metabolic state.

In summary, proctocolectomy for UC results in many long-term metabolic adaptations resulting in a reduction in insulin sensitivity. There was no change in any of the measured genes directly relating to insulin action (IRS-1, P85{alpha}PI3 K, HK II, and Glut-4), whereas genes relating to lipid metabolism were affected in both skeletal muscle and adipose tissue. These individuals may, therefore, be at an increased risk of developing symptoms of the metabolic syndrome by a mechanism specific to fatty acid metabolism.


   Acknowledgments
 
We thank Jenny Currie and Nathalie Vega for technical assistance and all patients and volunteers for giving their time so freely.


   Footnotes
 
This work was supported by Supported by a grant from the Biotechnology and Biological Sciences Research Council (United Kingdom).

First Published Online February 15, 2005

Abbreviations: A-V, Arteriovenous; GLP-1, glucagon-like peptide 1; HOMA, homeostatic model assessment; HSL, hormone-sensitive lipase; LPL, lipoprotein lipase; MTT, meal tolerance test; NEFA, nonesterified fatty acid; PPAR, peroxisome proliferator-activated receptor; SCFA, short-chain fatty acid; TG, triacylglycerol; UC, ulcerative colitis.

Received October 26, 2004.

Accepted February 3, 2005.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Discussion
 References
 

  1. Holt S, Heading RC, Carter DC, Prescott LF, Tothill P 1979 Effect of gel fibre on gastric emptying and absorption of glucose and paracetamol. Lancet 8117:636–639
  2. Jenkins DJ, Taylor RH, Goff DV, Fielden H, Misiewicz JJ, Sarson DL, Bloom SR, Alberti KG 1981 Scope and specificity of acarbose in slowing carbohydrate absorption in man. Diabetes 30:951–954[Abstract]
  3. Robertson MD, Livesey G, Hampton SM, Mathers JC 2000 Evidence for altered control of glucose disposal after total colectomy. Br J Nutr 86:813–819
  4. Nauck MA, Siemsgluss J, Orskov C, Holst JJ 1996 Release of glucagon-like peptide 1 (GLP-1 [7-36 amide]), gastric inhibitory polypeptide (GIP) and insulin in response to oral glucose after upper and lower intestinal resections. Z Gastroenterol 34:159–166[Medline]
  5. Stone MA, Mayberry JF, Baker R 2003 Prevalence and management of inflammatory bowel disease: a cross sectional study from central England. Eur J Gastoroenterol Hepatol 15:1275–1280
  6. Kennedy HJ, Al-Dujaili EA, Edwards CR, Truelove SC 1983 Water and electrolyte imbalance in subjects with a permanent ileostomy. Gut 24:702–705[Abstract/Free Full Text]
  7. Christl SU, Sceppach W 1997 Metabolic consequences of total colectomy. Scand J Gastroenterol Suppl 222:20–24[Medline]
  8. Wright HK, Cleveland JC, Tilson MD, Herskovic T 1969 Morphology and absorptive capacity of the ileum after ileostomy in man. Am J Surg 117:242–245[Medline]
  9. Woo ZH, Nygaard K 1978 Small-bowel adaptation after colectomy in rats. Scand J Gastroenterol 13:903–910[Medline]
  10. McGarry JD 2002 Banting lecture 2001: dysregulation of fatty acid metabolism in the etiology of type 2 diabetes. Diabetes 51:7–18[Free Full Text]
  11. Crouse JR, Gerson CD, DeCarli LM, Lieber CS 1968 Role of acetate in the reduction of plasma free fatty acids produced by ethanol in man. J Lipid Res 9:509–512[Abstract]
  12. Robertson MD, Livesey G, Morgan LM, Hampton SM, Mathers JC 1999 The influence of the colon on postprandial glucagon-like peptide 1 (7–36) amide concentration in man. J Endocrinol 161:25–31[Abstract]
  13. Lugari R, Dei Cas A, Ugolotti D, Barilli AL, Camellini C, Ganzerla GC, Luciani A, Salerni B, Mittenperger F, Nadari S, Gnudi A, Zandomeneghi R 2004 Glucagon-like peptide 1 secretion and plasma dipeptidyl peptidase IV (DPP-IV) activity in morbidly obese patients undergoing biliopancreatic diversion. Horm Metab Res 36:111–115[CrossRef][Medline]
  14. Vilsboll T, Holst JJ 2004 Incretins, insulin secretion and type 2 diabetes mellitus. Diabetologia 47:357–366[CrossRef][Medline]
  15. Beck B 1989 Gastric inhibitory polypeptide: a gut hormone with anabolic functions. J Mol Endocrinol 169–174
  16. DeFronzo RA, Tobin J, Andres R 1979 Glucose clamp technique: a method for quantifying insulin secretion and resistance. Am J Physiol 237:E214–E223
  17. Robertson MD, Henderson RA, Vist GE, Rumsey RDE 2002 Extended effect of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism. Am J Clin Nutr 75:505–510[Abstract/Free Full Text]
  18. Robertson MD, Currie JM, Morgan LM, Jewell DP, Frayn KN 2003 Prior short-term consumption of resistant starch enhances postprandial insulin sensitivity in healthy subjects. Diabetologia 46:659–665[Medline]
  19. Frayn KN, Coppack SW 2001 Assessment of white adipose tissue metabolism by measurement of arteriovenous differences. Methods Mol Biol 155:269–279[Medline]
  20. Frayn KN, Coppack SW, Humphreys SM, Whyte PL 1989 Metabolic characteristics of human adipose tissue in vivo. Clin Sci 76:509–516[Medline]
  21. Larsen OA, Lassen NA, Quaade F 1966 Blood flow through human adipose tissue determined with radioactive xenon. Acta Physiol Scand 66:337–345[Medline]
  22. Rådegran G 1999 Limb and skeletal muscle blood flow measurements at rest and during exercise in human subjects. Proc Nutr Soc 58:887–898[Medline]
  23. Debard C, Lavelli M, Berbe V, Loizon E, Guillet C, Morio-Liondore B, Boirie Y, Vidal H 2004 Expression of key genes of fatty acid oxidation including adiponectin receptors, in skeletal muscle of type 2 diabetic patients. Diabetologia 47:917–925[CrossRef][Medline]
  24. Tan GD, Goossens GH, Humphreys SM, Vidal H, Karpe F 2004 Upper and lower adipose tissue function: a direct comparison of fat mobilization in humans. Obes Res 12:114–118[Medline]
  25. Frayn KN 2002 Adipose tissue as a buffer for daily lipid flux. Diabetologia 45:1201–1210[CrossRef][Medline]
  26. Coppack SW, Persson M, Judd RL, Miles JM 1999 Glycerol and nonesterified fatty acid metabolism in human muscle and adipose tissue in vivo. Am J Physiol 276:E233–E240
  27. Caumo A, Bergman RN, Cobelli C 2000 Insulin sensitivity from meal tolerance tests in normal subjects: a minimal model index. J Clin Endocrinol Metab 85:4396–4402[Abstract/Free Full Text]
  28. Matthews JNS, Altman DG, Campbell MJ, Royston P 1990 Analysis of serial measurements in medical research. Br Med J 300:230–235
  29. 1995 MAFF manual of nutrition. 10th ed. London: HMSO; 1995
  30. Livingstone MB, Black AE 2003 Markers of the validity of reported energy intake. J Nutr 133(Suppl 3):895S–920S
  31. Karpe F, Fielding BA, Ardilouze JL, Ilic V, Macdonald IA, Frayn KN 2002 Effects of insulin on adipose tissue blood flow in man. J Physiol 540:1087–1093[Abstract/Free Full Text]
  32. Schmidt BMW, Oehmer S, Delles C, Bratke R, Schneider MP, Klingbeil A, Fleischmann EH, Schmieder RE 2003 Rapid nongenomic effects of aldosterone on human forearm vasculature. Hypertension 42:156–160[Abstract/Free Full Text]
  33. Huber FX, Lucas M, Stern J, Hinz U, Haack D, Heuschen U, Herfarth C 2001 Changes in glucocorticoid and mineralocorticoid hormone levels due to compensation for ileostomy levels. Int J Surg Invest 2:369–375
  34. Goossens GH, Blaak EE, Saris WH, Van Baak MA 2004 Angiotensin II-induced effects on adipose and skeletal muscle tissue blood flow and lipolysis in normal weight and obese subjects. J Clin Endocrinol Metab 89:2690–2696[Abstract/Free Full Text]
  35. Baan J, Chang PC, Vermeij P, Pfaffendorf M, Van Zweiten PA 1999 Effects of sodium depletion on the role of ATI - and {alpha} adrenergic receptors in the regulation of forearm vascular tone in humans. J Hypertens 17:229–235[Medline]
  36. Satoh N, Ogawa Y, Katsuura G, Numata Y, Tsuji T, Hayase M, Ebihara K, Masuzaki H, Hosoda K, Yoshimasa Y, Nakao K 1999 Sympathetic activation of leptin via the ventromedial hypothalamus: leptin-induced increase in catecholamine secretion. Diabetes 48:1787–1793[Abstract]
  37. Kimura K, Tsuda K, Baba A, Kawabe T, Boh-oka S, Ibata M, Moriwaki C, Hano T, Nishio I 2000 Involvement of nitric oxide in endothelium-dependent arterial relaxation by leptin. Biochem Biophys Res Commun 273:745–749[CrossRef][Medline]
  38. Fielding BA, Frayn KN 1998 Lipoprotein lipase and the disposition of dietary fatty acids. Br J Nutr 80:495–502[CrossRef][Medline]
  39. Smih F, Rouet P, Lucas S, Mairal A, Sengenes C, Lafontan M, Vaulont S, Casado M, Langin D 2002 Transcriptional regulation of adipocyte hormone-sensitive lipase by glucose. Diabetes 51:293–300[Abstract/Free Full Text]
  40. Thorburn A, Muir J, Proitto J 1993 Carbohydrate fermentation lowers hepatic glucose output in healthy subjects. Metabolism 42:780–785[CrossRef][Medline]
  41. Miles PDG, Romeo OM, Higo K, Cohen A, Rafaat K, Olefsky JM 1997 TNF-{alpha} induced insulin resistance in vivo and its prevention by troglitazone. Diabetes 46:1678–1683[Abstract]
  42. Capristo E, Mingrone G, Addolorato G, Greco AV, Gasbarrini G 1999 Glucose metabolism and insulin sensitivity in inactive inflammatory bowel disease. Aliment Pharmacol Ther 13:209–217[Medline]
  43. Randle PJ, Garland PB, Hales CN, Newsholme EA 1963 The glucose fatty-acid cycle. Its role in insulin sensitivity and the metabolic disturbances of diabetes mellitus. Lancet 1:785–789[Medline]
  44. Tan GD, Debard C, Tiraby C, Humphreys SM, Frayn KN, Langin D, Vidal H, Karpe F 2003 A futile cycle induced by thiazolidinediones in human adipose tissue. Nat Med 9:811–812[CrossRef][Medline]
  45. Dubuquoy L, Jansson EA, Deeb S, Rakotobe S, Karoui M, Colombel JF, Auwerx J 2003 Impaired expression of peroxisome proliferator activated receptor {gamma} in ulcerative colitis. Gastroenterology 124:1265–1276[CrossRef][Medline]
  46. Kinoshita M, Suzuki Y, Saito Y 2002 Butyrate reduces colonic paracellular permeability by enhancing PPAR {gamma} activation. Biochem Biophys Res Commun 293:827–831[CrossRef][Medline]
  47. Li Y, Bujo H, Takahashi K, Shibasaki M, Zhu Y, Yoshida Y, Otsuka Y, Hashimoto N, Saito Y 2003 Visceral fat: higher responsiveness of fat mass and gene expression to calorie restriction than subcutaneous fat. Exp Biol Med 228:1118–1123[Abstract/Free Full Text]
  48. Bingham S, Cummings JH, McNeil NI 1982 Diet and health of people with an ileostomy: I. Dietary assessment. Br J Nutr 47:399–406[Medline]




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