help button home button Endocrine Society JCEM
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Journal of Clinical Endocrinology & Metabolism , doi:10.1210/jc.2005-1482
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Damjanovic, S. S.
Right arrow Articles by Djukic, V. B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Damjanovic, S. S.
Right arrow Articles by Djukic, V. B.
Related Collections
Right arrow Metabolism
The Journal of Clinical Endocrinology & Metabolism Vol. 91, No. 7 2574-2581
Copyright © 2006 by The Endocrine Society

Acute Effects of Ghrelin on Insulin Secretion and Glucose Disposal Rate in Gastrectomized Patients

Svetozar S. Damjanovic, Nebojsa M. Lalic, Predrag M. Pesko, Milan S. Petakov, Aleksandra Jotic, Dragana Miljic, Katarina S. Lalic, Ljiljana Lukic, Marina Djurovic and Vojko B. Djukic

Institutes of Endocrinology, Diabetes, and Diseases of Metabolism (S.S.D., N.M.L., M.S.P., A.J., D.M., K.S.L., L.L., M.D.), Digestive Diseases (P.M.P.), and Otorhinolaryngology (V.B.D.), Belgrade University School of Medicine, 11000 Belgrade, Serbia

Address all correspondence and requests for reprints to: Svetozar S. Damjanovic, Institute of Endocrinology, Diabetes, and Diseases of Metabolism, Dr Subotica 13, 11000 Beograd, Serbia. E-mail: sova{at}net.yu.


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Discussion
 References
 
Context: Plasma ghrelin concentration is diminished in gastrectomized patients. Acute ghrelin administration reduces insulin secretion, whereas insulin infusion has been shown to decrease ghrelin levels. Whether ghrelin has any effect on glucose utilization in humans is unknown.

Objective: Our objective was to reveal the effect of ghrelin on insulin-mediated glucose disposal in gastrectomized patients.

Study and Setting: We conducted a double-blind, randomized, placebo-controlled, hospital-based study.

Patients: Seven men and three women who all had a previous total gastrectomy and truncal vagotomy entered and completed the study.

Intervention: Each individual received infusion of saline alone or saline with ghrelin (5.0 pmol/kg·min) during a 5-h hyperinsulinemic (80 mU/m2·min) euglycemic clamp on 2 separate days.

Main Outcome Measures: We assessed glucose disposal rate and concentrations of C-peptide, ghrelin, GH, IGF-I, IGF-binding protein (IGFBP)-3 and -1, cortisol, leptin, and adiponectin.

Results: Glucose disposal rate decreased during ghrelin infusion (control study 8.6 ± 0.2 vs. 7.2 ± 0.1 mg/kg·min P < 0.001). In experiments with saline infusion, levels of ghrelin (P < 0.001), C-peptide (P < 0.001), glucagon (P < 0.001), adiponectin (P = 0.005), cortisol (P = 0.012), IGF-I (P < 0.001), IGFBP-3 (P = 0.038), and IGFBP-1 (P = 0.001) fell in response to euglycemic hyperinsulinemia. GH concentration maintained at baseline, whereas leptin significantly rose (P < 0.001). In the ghrelin infusion study, the plateau level of ghrelin concentration (6963.6 ± 212.9 pg/ml) was maintained from 90 min throughout the experiment. GH (P < 0.001) and cortisol (P = 0.04) concentrations rose, whereas C-peptide levels were more suppressed than in the control study (P < 0.001). Other hormones and IGFBPs changed similarly as in the study with saline infusion.

Conclusion: It appears that ghrelin might be involved in the negative control of insulin secretion and glucose consumption in gastrectomized patients, at least after acute administration.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Discussion
 References
 
GHRELIN IS THE only known peripheral orexigen that reliably evokes feeding through a central action involving primarily the neuropeptide Y signaling pathway in the hypothalamus (1, 2, 3). It is a somatotrophic, orexigenic, and adipogenic hormone that links the regulatory systems for growth and energy balance (4). These effects are mediated through the GH secretagogue receptor, which is widely distributed in the body (5). Discovery of ghrelin confirmed that stomach peptide hormones contribute to the control of pancreatic hormone release (6, 7, 8). Since then, the role of ghrelin in glucose and insulin metabolism has been studied extensively. Oral and iv glucose load and food intake have been shown to decrease ghrelin concentrations (9, 10, 11). In different experimental settings on rat pancreas, both stimulatory and inhibitory effects of ghrelin on ß-cell and insulin secretion have been detected (12, 13, 14). In humans, acute ghrelin administration is associated with reduction of insulin secretion (15, 16), whereas insulin infusion has been shown to decrease ghrelin concentrations (17, 18).

Whether ghrelin influences glucose consumption in humans is unknown. We investigated therefore the effects of iv ghrelin or saline infusion on insulin-mediated glucose disposal in 10 gastrectomized patients during a 5-h exogenous glucose infusion (hyperinsulinemic-euglycemic glucose clamp).


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Discussion
 References
 
Study protocol

Ten patients (seven men) who underwent total gastrectomy and truncal vagotomy because of gastric carcinoma were enrolled in the study, which was approved by the local ethical committee and conducted according to the principles of the Helsinki Declaration. All patients gave their written consent to participate in the study. Patients were in good health as determined by medical history, physical examination, and laboratory and radiological evaluation. Patients entered the study protocol 12–108 months (44.5 ± 9.1, mean ± SE) after operation. Individual characteristics of patients are presented in Table 1Go. Percent body fat mass (FM) was estimated by hand-to-foot impedance.


View this table:
[in this window]
[in a new window]
  		TABLE 1. Clinical characteristics of gastrectomized patients

 
All subjects were admitted to the Institute of Endocrinology, Diabetes, and Metabolic Disease, Medical School of Belgrade, and studied at random on two occasions, separated by at least 1 wk, in a double-blinded randomized crossover design. Patients received an infusion of either normal saline alone or ghrelin, 5.0 pmol/kg·min, in normal saline in random order (five ghrelin first, five saline first) during hyperinsulinemic-euglycemic glucose clamp. This dose of ghrelin corresponds to approximately half-maximal GH-stimulating dose in healthy persons (19). After overnight fasting, a 22-gauge plastic catheter needle was placed in antecubital vein for the infusions of saline alone or ghrelin in saline, regular human insulin, and a variable 10% glucose solution with 20 mEq KCl by two syringe pumps. A contralateral hand vein was cannulated in a retrograde manner with a 21-gauge butterfly needle and was maintained at 65 C in a thermoregulated Plexiglas box for intermittent sampling of arterialized venous blood. The infusion of regular human insulin started at approximately 0900 h (rate, 80 mU/m2·min) and maintained for 300 min. Plasma glucose concentration was kept at 5 mmol/liter by a variable 10% glucose infusion and adjusted on the basis of immediate measurements of plasma glucose sampled every 5 min. Blood samples for circulating concentrations of insulin, C-peptide, glucagon, and free fatty acids (FFA), leptin, adiponectin, ghrelin, GH, IGF-I, IGF-binding protein (IGFBP)-3, IGFBP-1, and cortisol were taken at –30, 0, 30, 60, 90, 120, 150, 180, 210, 250, 270, and 300 min.

Assays

Plasma glucose was determined by the glucose oxidase method (glucose autoanalyzer from Beckman, Fullerton, CA). Plasma concentration of FFA was measured with an enzymatic colorimetric assay as described before (20).

Insulin and C-peptide levels were determined by RIA (INEP, Zemun, Serbia). Lower limits of sensitivity were 3.0 mU/liter and 0.15 nmol/liter for insulin and C-peptide, respectively. The average intra- and interassay coefficients of variation (CV) were less than 10.0% for both assays. Pancreatic glucagon was measured by RIA (RIAZEN; Zen Tech S.A., Angleur, Belgium). The limit of detection was 15 pg/ml, and the intra- and interassay CV were 8 and 8.2%, respectively. Total leptin, adiponectin, and ghrelin concentrations were measured using commercially available RIAs (human RIA kits from Linco Research, Inc., St. Charles, MO). The lowest levels of leptin, adiponectin, and ghrelin that could be detected by these assays were 0.5 µg/liter, 1.0 ng/ml, and 93.0 pg/ml, respectively. The intra- and interassay CV were less than 10.0% for leptin and adiponectin assays, whereas for the ghrelin RIA kit, intra- and interassay CV were less than 10.0 and 16.0%, respectively. Plasma GH was determined by solid-phase two-site fluorometric assay based on the direct sandwich technique with two monoclonal antibodies directed against two different epitopes of the hGH molecule (Delfia, Wallac Oy, Turku, Finland). The minimal detection limit was 0.011 µg/liter, and intra- and interassay CV were less than 5.0 and 6.3%, respectively. Concentrations of serum IGF-I and IGFBP-3 were determined by solid-phase enzyme-labeled chemiluminescent immunometric assays (Immulite 2000; Diagnostic Products Corp., Los Angeles, CA) with lower detection limits of 20 ng/ml and 0.02 µg/ml, respectively. Intra- and interassay CV for IGF-I were less than 3.9 and 8.1% and for IGFBP-3 less than 4.6 and 7.3%, respectively. We used a commercial test to measure serum IGFBP-1 (IEMA test; Oy Medix Biochemica Ab, Kauniainen, Finland). The detection limit with this assay was 0.4 µg/liter, and intra- and interassay CV were less then 5.5 and 5.9%, respectively. Cortisol concentration was measured with RIA kits (CORT-CT2) supplied by CIS Bio International (Gif-Sur-Yvette, France). The minimum detectable concentration was 4.6 nmol/liter. Intra- and interassay CV were less than 5.4 and 7.3%, respectively.

Calculations and statistical analyses

Data are expressed as means ± SE M values (in milligrams glucose per kilogram per minute) as a measure of insulin-mediated glucose disposal, and the metabolic clearance rate of insulin was calculated as described before (21, 22). Individual differences in M values ({Delta}M) between the control and the ghrelin infusion study were calculated. To calculate the steady-state plasma glucose and insulin concentrations during the insulin infusion, the mean values from 90–300 min were used (22). Individual differences in ghrelin concentrations ({Delta}G) between basal and nadir in control and peak and basal in the ghrelin infusion study were estimated. Within-group comparisons were performed with the two-tailed paired Student’s t test or repeated-measures ANOVA. Linear relationships between variables were tested by correlational analysis (Pearson product moment). A P value of <0.05 was considered as statistically significant.


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Discussion
 References
 
Plasma ghrelin concentrations

Basal levels of ghrelin were similar in the control and the ghrelin infusion study [532.3 ± 85.1 vs. 582.2 ± 69.0 pg/ml; P = not significant (NS)]. Insulin induced a significant decrease of ghrelin levels in the control experiment (P < 0.001) and achieved nadir at 210 min (352.0 ± 92.2 pg/ml; P < 0.001) (Fig. 1Go). Plasma ghrelin levels increased in comparison with basal values during ghrelin infusion (P < 0.001), reaching a mean plateau level of 6963.6 ± 212.9 pg/ml at 90 min that was maintained throughout the experiment (Fig. 1Go).


Figure 1
View larger version (27K):
[in this window]
[in a new window]
  		FIG. 1. Ghrelin levels (A), glucose infusion rate (B), plasma concentrations of insulin (C), and glucagon (D) during 5-h hyperinsulinemic-euglycemic clamps (rate, 80 mU insulin/m2·min) in gastrectomized patients with saline alone and saline with ghrelin (5.0 pmol/kg·min). Data are means ± SE. *, P ≤ 0.05, and **, P ≤ 0.01 vs. baseline; ***, P < 0.001 vs. ghrelin infusion study.

 
M values and plasma concentrations of glucose, insulin, glucagon, FFA, and C-peptide

Plasma glucose concentrations were maintained at 5.0 ± 0.16 mmol/liter during steady state of both insulin clamp studies. M values fell significantly during the clamp study with ghrelin infusion in comparison with the control study (7.2 ± 0.1 vs. 8.6 ± 0.2 mg/kg·min; P < 0.001) (Fig. 1Go). There was no difference (P = NS) in basal insulin levels between the studies without and with ghrelin infusion (8.4 ± 0.5 vs. 8.9 ± 0.7 mU/liter). Similar mean steady-state insulin concentrations were achieved during the control experiment and the study with ghrelin infusion (140.1 ± 1.4 and 135.2 ± 0.6 mU/liter; P = NS). The metabolic clearance rate of insulin averaged 574.2 ± 88.1 ml/m2·min during the control study and was unchanged by ghrelin (604.2 ± 56.7 ml/m2·min; P = NS). Plasma glucagon concentrations declined in both the control (P < 0.001) and the ghrelin infusion study (P = 0.05) (Fig. 1Go). Of note, the fall of glucagon from baseline to nadir detected in the control study (137.8 ± 10.2 vs. 100.4 ± 7.8 pg/ml; P < 0.001) was of borderline significance when ghrelin was added with saline (136.9 ± 8.7 vs. 114.3 ± 5.3 pg/ml; P = 0.05). In both experiments, insulin equally suppressed FFA levels (P = NS). Plasma FFA concentration showed a progressive decline from basal values, reaching almost complete suppression after 90 min in both the control (484.9 ± 71.8 vs. 35.5 ± 12.7 µmol/liter; P < 0.001) and the ghrelin infusion study (542.4 ± 40.6 vs. 55.2 ± 14.5 µmol/liter; P < 0.001) (Fig. 2Go). C-peptide levels significantly decreased in both experiments (P < 0.001). However, in comparison with the control study, C-peptide levels were more suppressed during the experiment with ghrelin infusion (P = 0.028); the major differences between the two studies were observed at 120 min (P = 0.021), 150 min (P = 0.018), 180 min (P = 0.01), and 210 min (P = 0.05) (Fig. 2Go).


Figure 2
View larger version (27K):
[in this window]
[in a new window]
  		FIG. 2. Changes in circulating levels of FFA (A), C-peptide (B), total leptin (C), and adiponectin (D) during 5-h hyperinsulinemic-euglycemic clamps (rate, 80 mU insulin/m2·min) with saline alone or saline with ghrelin administration (5.0 pmol/kg·min). Data are means ± SE. *, P < 0.05 vs. study with saline infusion; **, P = 0.01 vs. study with saline infusion.

 
Adipocytokines: serum leptin and adiponectin levels

At baseline, serum leptin (4.0 ± 1.5 vs. 4.0 ± 1.3 µg/liter; P = NS) and adiponectin (37.0 ± 4.9 vs. 35.6 ± 3.9 µg/ml; P = NS) levels were similar in the control and ghrelin infusion experiment. Leptin concentrations increased in both clamp studies (P < 0.001), in a similar way, beginning from 210 min (P = 0.038) (Fig. 2Go). The highest values were achieved at the end of the experiments (P < 0.001). Adiponectin concentrations decreased equally from baseline (P = 0.005) in both experiments, achieving nadir at 150 min (P = 0.001), which was maintained until the end of the experiments. Thus, changes in serum leptin and adiponectin levels were unaffected by ghrelin administration (P = NS) (Fig. 2Go).

GH-IGF-I axis

At baseline, plasma GH (1.7 ± 0.7 vs. 1.4 ± 0.4 µg/liter; P = NS) and serum IGF-I (72.2 ± 4.1 vs. 72.6 ± 4.6 µg/liter; P = NS), IGFBP-3 (2.8 ± 0.19 vs. 2.8 ± 0.18 µg/ml; P = NS), and IGFBP-1 (17.2 ± 4.3 vs. 12.9 ± 2.2 µg/liter; P = NS) levels were similar in the control and ghrelin infusion studies. Plasma GH remained unchanged during the control study. Ghrelin infusion induced a significant rise of GH from baseline (P < 0.001), reaching peak concentration at 90 min (48.3 ± 5.1 µg/liter; P < 0.001) (Fig. 3Go). In comparison with respective baseline values, infusion of insulin alone caused a decrease in concentrations of IGF-I (P < 0.001), IGFBP-3 (P = 0.038), and IGFBP-1 (P = 0.001), and these values were unchanged by ghrelin infusion (P = NS for all) (Fig. 3Go). Nadir levels of IGF-I (68.6 ± 4.3 and 69.3 ± 5.8 µg/liter; P = 0.006 for both) and IGFBP-3 (2.6 ± 0.15 and 2.6 ± 0.18 µg/ml; P = 0.017 for both) were reached between 60 and 90 min in the saline and the ghrelin infusion study, respectively, whereas IGFBP-1 reached the lowest concentrations at the end of the experiments (5.5 ± 0.9 and 4.3 ± 0.8 µg/liter; P < 0.001 for both).


Figure 3
View larger version (27K):
[in this window]
[in a new window]
  		FIG. 3. Concentrations of GH (A), IGF-I (B), IGFBP-3 (C), and IGFBP-1 (D) during 5-h hyperinsulinemic-euglycemic clamps (rate, 80 mU insulin/m2·min) with saline alone or saline with ghrelin infusion (5.0 pmol/kg·min). Data are means ± SE. *, P < 0.001 vs. study with saline infusion.

 
Serum cortisol

Morning cortisol levels were similar in the control and the ghrelin infusion study (399.3 ± 34.0 and 347.3 ± 25.0 nmol/liter; P = NS). In the control study, a diurnal decrease of cortisol concentrations (P = 0.012) reached nadir at 120 min (P = 0.013) and was completely abolished by ghrelin infusion (P = 0.04). The largest divergence in cortisol levels between the control and the ghrelin infusion study was at 120 min (264.9 ± 27.9 vs. 392.2 ± 29.9 nmol/liter; P = 0.020) (Fig. 4Go).


Figure 4
View larger version (20K):
[in this window]
[in a new window]
  		FIG. 4. Cortisol levels significantly decreased during the control study with saline infusion only during 5-h hyperinsulinemic-euglycemic clamp (rate, 80 mU insulin/m2·min). This decrease was abolished by addition of ghrelin (5.0 pmol/kg·min). Data are means ± SE. *, P < 0.05 vs. study with saline infusion; **, P ≤ 0.01 vs. study with saline infusion.

 
Correlations

M values and GH-IGF-I axis. Individual differences in M value were positively associated with basal IGF-I (r = 0.66; P = 0.039) and IGFBP-3 levels (r = 0.76; P = 0.01) in both the control and the ghrelin infusion study.

Ghrelin and {Delta}M values. Correlation of borderline significance between plasma ghrelin changes ({Delta}G) and {Delta}M (r = 0.62; P = 0.054) was found in the control study and was significant in the ghrelin infusion study (r = 0.70; P = 0.026).

Nutritional factors. Body mass index (BMI) correlated positively with basal C-peptide (r = 0.69; P = 0.03), leptin (r = 0.64; P = 0.048), and percent FM (r = 0.74; P = 0.014) and negatively with basal levels of GH (r = –0.87; P = 0.001) and IGFBP-1 (r = –0.78; P = 0.007). A positive relationship between leptin and percent FM was found (r = 0.82; P = 0.003). Basal glucagon concentrations correlated positively with basal levels of adiponectin (r = 0.75; P = 0.01) and IGFBP-1 (r = 0.65; P = 0.04), whereas it was inversely related to basal C-peptide (r = –0.80; P = 0.005). In the saline study, the percent ghrelin suppression was in negative correlation with BMI (r = –0.79; P = 0.007), and the extent of glucagon and cortisol decline was in negative relationship (r = –0.81; P = 0.008). In the ghrelin infusion experiment, the extent of glucagon decrease was in negative association with basal adiponectin (r = –0.80; P = 0.006) and IGFBP-1 (r = –0.64; P = 0.048). Individual percent changes in plasma ghrelin and adiponectin were in positive association (r = 0.69; P = 0.03). Similarly, individual changes in insulin-mediated glucose disposal index caused by ghrelin were positively associated with basal IGF-I concentrations (r = 0.66; P = 0.004).

Ghrelin and GH-IGF-I axis. The maximal decrease of ghrelin ({Delta}G) in the control study correlated positively with basal IGF-I (r = 0.67; P = 0.034) and IGFBP-3 (r = 0.85; P = 0.002) and inversely with basal GH (r = –0.69; P = 0.03) and IGFBP-1 (r = –0.77; P = 0.009) concentrations. Similarly, the maximal decline of IGFBP-1 was positively correlated with maximal decrease of ghrelin in the control study (r = 0.74; P = 0.015).

Ghrelin and serum cortisol. Individual differences between peak and basal cortisol levels correlated positively with {Delta}G (r = 0.68; P = 0.031) in the ghrelin infusion study.


   Discussion
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Discussion
References
 
This study revealed that ghrelin is involved in negative control of pancreatic ß-cell function and that insulin-mediated glucose disposal rate is reduced after acute ghrelin administration in gastrectomized patients. Supraphysiological ghrelin concentrations (up to 12 times baseline value) were maintained to significantly decrease glucose consumption during hyperinsulinemic euglycemia.

Ghrelin induced a marked decrease in circulating C-peptide during euglycemic hyperinsulinemia in our patients. This is consistent with previous reports showing that acute administration of acylated ghrelin in healthy subjects causes a decrease in insulin levels and an increase of plasma glucose concentration (15, 16). Moreover, an inhibitory effect of ghrelin on insulin secretion has been demonstrated in vitro in experiments on isolated rat pancreas (14). On the other hand, gastrectomy and vagotomy are nonphysiological conditions characterized by hypoghrelinemia (9), glucose intolerance as a result of hyperglucagonemia, insulinopenia, and impaired first phase of insulin secretion (6). Reduced parasympathetic tone appears to have a role in the development of impaired insulin secretion in these patients, because glucagon-stimulated C-peptide secretion after gastrectomy is restrained by vagotomy (24). Thus, in vagotomized patients, increased sympathetic nerve tone and glucagon levels might affect insulin response to ghrelin infusion (6, 22). However, involvement of the sympathetic nerve system is unlikely because it has been shown that ghrelin decreases blood pressure (25), inhibits sympathetic activity and thermogenesis (26, 27, 28), and causes vasodilatation (29) in animals and humans. Therefore, a direct effect of ghrelin at the level of the endocrine pancreas seems possible. Whether lowered basal ghrelin levels in gastrectomized and vagotomized patients are also associated with reduced contribution of ghrelin to the control of pancreatic ß-cell function is unknown.

Compared with saline control experiments, ghrelin infusion was associated with a modest (by ~17%) but significant decline in glucose utilization. Theoretically, ghrelin could affect glucose disposal rate in several ways. Because ghrelin enhanced C-peptide suppression, endogenous insulin secretion should be lower in the ghrelin infusion than in the control study. On the other hand, total insulin (exogenous plus endogenous) should be higher in the control than in the ghrelin infusion study. However, this was not the case, and the difference in C-peptide was not translated into a significant difference in insulin concentration, probably because the exogenous insulin by far overweighs endogenous insulin. Thus, we cannot rule out the possibility that diminished glucose utilization after ghrelin administration could result in part from the decrease in endogenous insulin secretion. Furthermore, the observed difference in glucose infusion rate could arise from slightly higher concentrations of glucagon throughout the study with ghrelin infusion. It has already been shown that ghrelin stimulates glucagon secretion from isolated mouse pancreatic islets (30). Liver contribution to observed insulin resistance seems possible, because high levels of ghrelin, even in the face of persistent hyperinsulinemia, could augment hepatic glucose output through glucagon-induced glycogenolysis (31). Besides, ghrelin likely blocks the inhibitory effect of insulin on gluconeogenesis, which was demonstrated in a human hepatoma cell line (32). Ghrelin was shown to stimulate insulin receptor substrate 1 (IRS1) and its downstream molecules including growth factor receptor-bound protein 2 (Grb2) and MAPK, whereas on the other hand, it inhibited serine/threonine kinase (Akt) activation and up-regulated gluconeogenesis by opposing the effect of insulin on phosphoenolpyruvate carboxykinase (32). In line with this, it has been reported that some of the ghrelin analogs might affect insulin-signaling pathways in humans (33).

We showed that ghrelin-induced C-peptide suppression and decline in glucose disposal rate were triggered by mechanisms independent of adiponectin and leptin, because their concentrations changed similarly in both experiments. The observed changes in plasma concentrations of adiponectin and leptin can be explained by insulin action (34, 35, 36, 37, 38). Because ghrelin and adiponectin travel with changes in insulin sensitivity, a high normal concentration of adiponectin and low basal concentration of plasma ghrelin in our gastrectomized patients suggest an insulin-sensitive condition (9, 36, 39, 40, 41, 42). It appears that impairment of the glucose-induced insulin secretion in gastrectomized patients is not in contrast with increased insulin sensitivity in these patients but rather suggests that it can be compensated for by an increase in secretory signals governed by non-glucose-activated transduction mechanisms.

Like other investigators (24, 43), we found a marked increase in serum GH and, to a lower extent, cortisol levels after ghrelin infusion. GH and glucocorticoids have been shown to exhibit insulin antagonistic effect (44, 45, 46, 47, 48, 49, 50, 51). Acute effects of ghrelin on glucose metabolism in our patients might occur via changes in the GH-IGF-I axis (52), cortisol levels, and nutritional status of examined subjects (23, 53). In the ghrelin infusion study, the plasma ghrelin increase was in positive relationship with changes in IGF-I and cortisol concentration and glucose disposal rate. In the saline study, the extent of ghrelin decrease from basal levels correlated positively with basal IGF-I and IGFBP-3 and inversely with BMI, IGFBP-1, and GH levels. However, a similar decrease of IGF-I and IGFBPs observed throughout experiments with euglycemic hyperinsulinemia indicated that there was no change in bioavailability of IGF-I after ghrelin administration. Participation of GH and cortisol in acute deterioration of insulin sensitivity cannot be excluded, but this effect is unlikely to be mediated through enhanced lipolysis, because FFA were fully suppressed during both experiments.

In conclusion, our data suggest that endogenous ghrelin might be involved in the acute regulation of glucose metabolism via negative control of insulin secretion and glucose consumption. However, whether abnormalities in ß-cell function caused by gastrectomy and vagotomy can be improved by ghrelin substitution requires additional investigations.


   Acknowledgments
 
We thank Professor M. A. Ghatei (Hammersmith Hospital, London, UK), for providing ghrelin and D. Topalov for laboratory assistance.


   Footnotes
 
This work was supported by Serbian Ministry of Science (M 1717).

First Published Online April 18, 2006

Abbreviations: BMI, Body mass index; CV, coefficients of variation; FFA, free fatty acids; FM, fat mass; IGFBP, IGF-binding protein; NS, not significant.

Received July 5, 2005.

Accepted April 10, 2006.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Discussion
 References
 

  1. Tschop M, Smiley DL, Heiman ML 2000 Ghrelin induces adiposity in rodents. Nature 407:908–913[CrossRef][Medline]
  2. Nakazato M, Murakami N, Date Y, Kojima M, Matsuo H, Kangawa K, Matsukura S 2001 A role for ghrelin in the central regulation of feeding. Nature 409:194–198[CrossRef][Medline]
  3. Horvath TL, Diano S, Sotonyi P, Heiman M, Tschop M 2001 Ghrelin and the regulation of energy balance: a hypothalamic perspective. Endocrinology 142:4163–4169[Abstract/Free Full Text]
  4. Ukkola O, Poykko S 2002 Ghrelin, growth and obesity. Ann Med 34:102–108[CrossRef][Medline]
  5. Gnanapavan S, Kola B, Bustin SA, Morris DG, McGee P, Fairclough P, Bhattacharyia S, Carpenter R, Grossman AB, Kobornits M 2002 The tissue distribution of the mRNA of ghrelin and subtypes of its receptor, GHS-R, in humans. J Clin Endocrinol Metab 87:2988–2991[Abstract/Free Full Text]
  6. Sudo T, Ishiyama K, Takemoto M, Kawamura M, Umemuar H, Shiraha S, Kuyama T, Suzuki T, Tobe T 1982 Pancreatic endocrine function after total gastrectomy and truncal vagotomy. Am J Surg 144:539–544[CrossRef][Medline]
  7. Salehi A, Chen D, Håkanson R, Nordin G, Lundqist I 1999 Gastrectomy induces impaired insulin and glucagon secretion: evidence for a gastro-insular axis in mice. J Physiol 514:579–591[Abstract/Free Full Text]
  8. Kojima M, Hosoda H, Date Y, Nakazato M, Matsuo H, Kangawa K 1999 Ghrelin is a growth-hormone-releasing acylated peptide from stomach. Nature 402:656–660[CrossRef][Medline]
  9. Ariyasu H, Takaya K, Tagami T, Ogawa Y, Hosoda K, Akamizu T, Suda M, Koh T, Natsui K, Toyooka S, Shirakami G, Usui T, Shimatsu A, Doi K, Hosoda H, Kojima M, Kangawa K, Nakao K 2001 Stomach is a major source of circulating ghrelin, and feeding state determines plasma ghrelin-like immunoreactivity levels in humans. J Clin Endocrinol Metab 86:4753–4758[Abstract/Free Full Text]
  10. Shiiya T, Nakazato M, Mizuta M, Date Y, Mondal MS, Tanaka M, Nozoe S-I, Hosoda H, Kangawa K, Matsukura S 2002 Plasma ghrelin levels in lean and obese humans and the effect of glucose on ghrelin secretion. J Clin Endocrinol Metab 87:240–244[Abstract/Free Full Text]
  11. Nakagawa E, Nagaya N, Okumura H, Enomoto M, Oya H, Ono F, Hosoda H, Kojima M, Kangawa K 2002 Hyperglycemia suppresses the secretion of ghrelin, a novel growth-hormone-releasing peptide: responses to the intravenous and oral administration of glucose. Clin Sci (Lond) 103:325–328[Medline]
  12. Date Y, Nakazato M, Hashiguchi S, Dezaki K, Mondal MS, Hosoda H, Mojima M, Kangawa K, Arima T, Matsuo H, Yada T, Matsukura S 2002 Ghrelin is present in pancreatic {alpha}-cells of humans and rats, and stimulates insulin secretion. Diabetes 51:124–129[Abstract/Free Full Text]
  13. Adeghate E, Ponery AS 2002 Ghrelin stimulates insulin secretion from the rat pancreas of normal and diabetic rats. J Neuroendocrinol 14:555–560[CrossRef][Medline]
  14. Egido EM, Rodriguez-Gallardo J, Silvestre RA, Marco J 2002 Inhibitory effect of ghrelin on insulin and pancreatic somatostatin secretion. Eur J Endocrinol 146:241–244[Abstract]
  15. Broglio F, Arvat E, Benso A, Gottero C, Muccioli G, Papotti M, Van Der Lely AJ, Deghenghi R, Ghigo E 2001 Ghrelin, a natural GH secretagogue produced by stomach, induces hyperglycemia and reduces insulin secretion in humans. J Clin Endocrinol Metab 86:5083–5086[Abstract/Free Full Text]
  16. Broglio F, Gottero C, Prodam F, Gauna C, Muccioli G, Papotti M, Abribat AJ, Van Der Lely AJ, Ghigo E 2004 Non-acylated ghrelin counteracts the metabolic but not the neuroendocrine response to acylated ghrelin in humans. J Clin Endocrinol Metab 89:3062–3065[Abstract/Free Full Text]
  17. Flanagan DE, Evans ML, Monsod TP, Rife F, Heptulla RA, Tamborlane WV, Shervin R 2001 The influence of insulin on circulating ghrelin. Am J Physiol Endocrinol Metab 284:E313–E316
  18. Saad MF, Bemaba B, Hwu CM, Jinagouda S, Fahmi S, Kogosov E, Boyadjian R 2002 Insulin regulates plasma ghrelin concentration. J Clin Endocrinol Metab 87:3997–4000[Abstract/Free Full Text]
  19. Wren AM, Seal LJ, Cohen MA, Brynes AE, Frost GS, Murphy KG, Dhillo WS, Ghatei MA, Bloom SR 2001 Ghrelin enhances appetite and increases food intake in humans. J Clin Endocrinol Metab 86:5992–5995[Abstract/Free Full Text]
  20. Itaya K, Michio U 1965 Colorimetric determination of free fatty acids in biological fluids. J Lipid Res 6:16–20[Abstract]
  21. DeFronzo RA, Tobin JD, Andres R 1979 Glucose clamp technique: a method for quantifying insulin secretion and sensitivity. Am J Physiol Endocrinol Metab Gastrointest Physiol 237:E214–E223
  22. Deibert DC, DeFronzo RA 1980 Epinephrine-induced resistance in man. J Clin Invest 65:717–721[Medline]
  23. Engström BE, Burman P, Holdstock C, Karlsson FA 2003 Effects of growth hormone (GH) on ghrelin, leptin and adiponectin in GH-deficient patients. J Clin Endocrinol Metab 88:5193–5198[Abstract/Free Full Text]
  24. Nordback I, Harju E 1991 Immediate effect of vagotomy on pancreatic insulin secretion. Gut 32:303–305[Abstract/Free Full Text]
  25. Nagaya N, Kojima M, Uematsu M, Yamagishi M, Hosoda H, Oya H, Hayashi Y, Kangawa K 2001 Hemodynamic and hormonal effects of human ghrelin in healthy volunteers. Am J Physiol Integr Comp Physiol 280:R1483–R1487
  26. Matsumura K, Tsuchihashi T, Fujii K, Abe I, Iida M 2002 Central ghrelin modulates sympathetic activity in conscious rabbits. Hypertension 40:694–699[Abstract/Free Full Text]
  27. Matsumura K, Tsuchihashi T, Fujii K, Iida M 2003 Neural regulation of blood pressure by leptin and related peptides. Regul Pept 114:79–86[CrossRef][Medline]
  28. Yasuda T, Masaki T, Kakuma H, Yoshimatsu H 2003 Centrally administered ghrelin suppresses sympathetic nerve activity in brown adipose tissue of rats. Neurosci Lett 349:75–78[CrossRef][Medline]
  29. Okumura H, Nagaya N, Enomoto M, Nakagawa E, Oya H, Kangawa K 2002 Vasodilatory effect of ghrelin, an endogenous peptide from stomach. J Cardiovasc Pharmacol 39:779–783[CrossRef][Medline]
  30. Salehi A, de la Cour CD, Håkanson R, Lundquist I 2004 Effects of ghrelin on insulin and glucagon secretion: a study of isolated pancreatic islets and intact mice. Regul Pept 118:143–150[CrossRef][Medline]
  31. Gustavson SM, Chu CA, Nishizawa M, Farmer B, Neal D, Yang Y, Donahue P, Flakoll P, Cherrington AD 2003 Interaction of glucagon and epinephrine in the control of hepatic glucose production in the conscious dog. Am J Physiol Endocrinol Metab 284:E695–E707
  32. Murata M, Okimura Y, Iida K, Matsumoto M, Sowa H, Kaji H, Kojima M, Kangawa K, Chihara K 2002 Ghrelin modulates the downstream of insulin signaling in hepatoma cells. J Biol Chem 277:5667–5674[Abstract/Free Full Text]
  33. Muller AF, Janssen JA, Hofland LJ, Lamberts SW, Bidlingmaier M, Strasburger CJ, van der Lely AJ 2001 Blockade of the growth hormone (GH) receptor unmasks rapid GH-releasing peptide-6-mediated tissue-specific insulin resistance. J Clin Endocrinol Metab 86:590–593[Abstract/Free Full Text]
  34. Hotta K, Funahashi T, Bodkin NL, Ortmeyer HK, Arita Y, Hansen BC, Matsuzawa Y 2001 Circulating concentrations of the adipocyte protein adiponectin are decreased in parallel with reduced insulin sensitivity during the progression to type 2 diabetes in rhesus monkeys. Diabetes 50:1126–1133[Abstract/Free Full Text]
  35. Stefan N, Vozarova B, Funahashi T, Matsuzawa Y, Weyer C, Lindsay RS, Youngren JF, Havel PJ, Pratley RE, Bogardus C, Tataranni PA 2002 Plasma adiponectin concentration is associated with skeletal muscle insulin receptor tyrosine phosphorylation, and low plasma concentration precedes a decrease in whole-body insulin sensitivity in humans. Diabetes 51:1884–1888[Abstract/Free Full Text]
  36. Tschritter O, Fritsche A, Thamer C, Haap M, Shirkavand F, Rahe S, Staiger H, Maerker A, Häring H, Stumvoll M 2003 Plasma adiponectin concentrations predict insulin sensitivity of both glucose and lipid metabolism. Diabetes 52:239–249[Abstract/Free Full Text]
  37. Kolaczynski JW, Nyce MR, Considine RV, Boden G, Nolan JJ, Henry R, Mudaliar SR, Olefsky J, Caro JF 1996 Acute and chronic effects of insulin on leptin production in humans: studies in vivo and in vitro. Diabetes 45:699–701[Abstract]
  38. Saad MF, Khan A, Sharma A, Michael R, Riad-Gabriel M, Boyadjian R, Jinagouda SD, Steil GM, Kamdar V 1998 Physiological insulinemia acutely modulates plasma leptin. Diabetes 47:544–549[Abstract]
  39. Pöykkö SM, Kellokoski E, Hörkkö S, Kauma H, Kesäniemi YA, Ukkola O 2003 Low plasma ghrelin is associated with insulin resistance, hypertension, and the prevalence of type 2 diabetes. Diabetes 52:2546–2553[Abstract/Free Full Text]
  40. Purnell JQ, Wiegle DS, Breen P, Cummings DE 2003 Ghrelin correlate with insulin levels, insulin resistance, and high-density lipoprotein cholesterol, but not with gender, menopausal status, or cortisol levels in humans. J Clin Endocrinol Metab 88:5747–5752[Abstract/Free Full Text]
  41. Weyer C, Funahashi T, Tanaka S, Hotta K, Matsuzawa Y, Pratley RE, Tataranni PA 2001 Hypoadiponectinemia in obesity and type 2 diabetes: close association with insulin resistance and hyperinsulinemia. J Clin Endocrinol Metab 86:1930–1935[Abstract/Free Full Text]
  42. Kern PA, Di Gregorio GB, Lu T, Rassuoli N, Ranganathan G 2003 Adiponectin expression from human adipose tissue: relation to obesity, insulin resistance, and tumor necrosis factor-{alpha} expression. Diabetes 52:1779–1785[Abstract/Free Full Text]
  43. Takaya K, Ariyasu H, Kanamoto N, Iwakura H, Yoshimoto A, Harada M, Mori K, Komatsu Y, Usui T, Shimatsu A, Ogawa Y, Hosoda K, Akamizu T, Kojima M, Kangawa K, Nakao K 2000 Ghrelin strongly stimulates growth hormone release in humans. J Clin Endocrinol Metab 85:4908–4911[Abstract/Free Full Text]
  44. Fineberg SE, Merimee TJ 1974 Acute effects of human growth hormone. Diabetes 23:499–504[Medline]
  45. Bratush-Marrian PR, Smith D, DeFronzo RA 1992 The effect of growth hormone on glucose metabolism and insulin secretion in man. Diabetologia 21:387–393
  46. O’Neal DN, Kalfas A, Dunning PL, Christopher MJ, Sawyer SD, Ward GM, Alford FP 1994 The effect of 3 months of recombinant human growth hormone (GH) on insulin and glucose-mediated glucose disposal and insulin secretion in GH-deficient adults: a minimal model analysis. J Clin Endocrinol Metab 79:975–983[Abstract]
  47. Foss MC, Saad MJA, Paccola GM, Paula FJ, Piccinato CE, Moriera AC 1991 Peripheral glucose metabolism in acromegaly. J Clin Endocrinol Metab 72:1048–1053[Abstract/Free Full Text]
  48. Hansen I, Tsalikian E, Beaufrere B, Gerich J, Haymond M, Rizza R 1986 Insulin resistance in acromegaly: defects in both hepatic and extrahepatic insulin action. Am J Physiol 250:E269–E273
  49. Beard JC, Halter JB, Best JD, Pfeiffer MA, Porte Jr D 1984 Dexamethasone-induced insulin resistance enhances B cell responsiveness to glucose level in normal men. Am J Physiol 247:E592–E596
  50. Rebuffe-Scrive M, Krotkiewski M, Elfverson J, Björntorp P 1988 Muscle and adipose tissue morphology and metabolism in Cushing’s syndrome. J Clin Endocrinol Metab 67:1122–1128[Abstract/Free Full Text]
  51. Widjaja A, Schürmeyer TH, Von Zur Mühlen A, Brabant G 1998 Determinants of serum leptin levels in Cushing’s syndrome. J Clin Endocrinol Metab 83:600–603[Abstract/Free Full Text]
  52. Popovic V, Miljic D, Pekic S, Pesko P, Djurovic M, Doknic M, Damjanovic S, Micic D, Cvijovic G, Glodic J, Dieguez C, Casanueva FF 2005 Low plasma ghrelin level in gastrectomized patients is accompanied by enhanced sensitivity to the ghrelin-induced growth hormone release. J Clin Endocrinol Metab 90:2187–2191[Abstract/Free Full Text]
  53. Grinspoon S, Miller KK, Herzog DB, Grieco KA, Klibanski A 2004 Effects of estrogen and recombinant human insulin-like growth factor-I on ghrelin secretion in severe undernutrition. J Clin Endocrinol Metab 89:3988–3993[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 DiabetesHome page
E. T. Vestergaard, L. C. Gormsen, N. Jessen, S. Lund, T. K. Hansen, N. Moller, and J. O. L. Jorgensen
Ghrelin Infusion in Humans Induces Acute Insulin Resistance and Lipolysis Independent of Growth Hormone Signaling
Diabetes, December 1, 2008; 57(12): 3205 - 3210.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
R. C. Paulo, R. Brundage, M. Cosma, K. L. Mielke, C. Y. Bowers, and J. D. Veldhuis
Estrogen Elevates the Peak Overnight Production Rate of Acylated Ghrelin
J. Clin. Endocrinol. Metab., November 1, 2008; 93(11): 4440 - 4447.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
S. Gjedde, E. T. Vestergaard, L. C. Gormsen, A. L. D. Riis, J. Rungby, N. Moller, J. Weeke, and J. O. L. Jorgensen
Serum Ghrelin Levels Are Increased in Hypothyroid Patients and Become Normalized by L-Thyroxine Treatment
J. Clin. Endocrinol. Metab., June 1, 2008; 93(6): 2277 - 2280.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
E. T. Vestergaard, C. B. Djurhuus, J. Gjedsted, S. Nielsen, N. Moller, J. J. Holst, J. O. L. Jorgensen, and O. Schmitz
Acute Effects of Ghrelin Administration on Glucose and Lipid Metabolism
J. Clin. Endocrinol. Metab., February 1, 2008; 93(2): 438 - 444.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
M. Anderwald-Stadler, M. Krebs, M. Promintzer, M. Mandl, M. G. Bischof, P. Nowotny, T. Kastenbauer, A. Luger, R. Prager, and C. Anderwald
Plasma obestatin is lower at fasting and not suppressed by insulin in insulin-resistant humans
Am J Physiol Endocrinol Metab, November 1, 2007; 293(5): E1393 - E1398.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
E. T. Vestergaard, T. K. Hansen, L. C. Gormsen, P. Jakobsen, N. Moller, J. S. Christiansen, and J. O. L. Jorgensen
Constant intravenous ghrelin infusion in healthy young men: clinical pharmacokinetics and metabolic effects
Am J Physiol Endocrinol Metab, June 1, 2007; 292(6): E1829 - E1836.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Damjanovic, S. S.
Right arrow Articles by Djukic, V. B.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Damjanovic, S. S.
Right arrow Articles by Djukic, V. B.
Related Collections
Right arrow Metabolism

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals