| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
INSULIN-GLUCAGON-GI PEPTIDES-DIABETES MELLITUS |
Department of Surgery (H.-M.L., G.W., E.W.E., G.H.G.), University of Texas Medical Branch, Galveston, Texas 77555; and Department of Molecular Genetics (M.K.), Institute of Life Science, Karume-University, Karume, Fukuoka 839-0861, Japan
| Abstract |
|---|
|
|
|---|
| Introduction |
|---|
|
|
|---|
The evidence to date indicates that ghrelin is an important endocrine peptide that links the gastrointestinal system and brain in the regulation of food intake and energy expenditure. Therefore, in the present article, the enteric distribution of ghrelin, ontogeny of stomach ghrelin gene expression, and influence of dietary and endocrine manipulations and vagotomy on stomach ghrelin levels were investigated. In some cases, plasma ghrelin concentrations were measured. We also examined the effects of iv administration of ghrelin on gastrin and insulin secretion in vivo in rats.
| Methods and Materials |
|---|
|
|
|---|
Chemicals and peptides
All chemicals were obtained from Sigma (St. Louis,
MO). Synthetic peptides were purchased from Bachem
(Torrance, CA), with the exception of ghrelin. Synthetic ghrelin was
purchased from Bachem or supplied by M. Kojima.
Animal experiments
Gastrointestinal (GI) expression of ghrelin. Ghrelin
expression (i.e. mRNA levels) and peptide concentrations in
various regions of the GI tract were examined by Northern blotting
analysis and RIA of ghrelin peptide levels using total cellular RNA and
tissue extracts, respectively. Ad libitum (ad lib)-fed adult
male rats were killed and the mucosal epithelial layer of the stomach
fundus, stomach antrum, duodenum, jejunum, and colon scraped and
extracted for either total cellular RNA or ghrelin peptide. Previous
reports indicated by immunohistochemistry that ghrelin is expressed
only in the mucosal epithelium; we have confirmed that the muscle layer
of the GI tract does not produce ghrelin (data not shown). Ghrelin
expression was also analyzed in extracts of the rat pancreas, liver,
and kidney.
Ontogeny of stomach ghrelin gene expression. Findings in Exp 1 show that ghrelin is expressed primarily in the stomach fundus; therefore, the stomach fundus was chosen for the developmental study. Rat fetuses were harvested from timed-pregnant Sprague Dawley rats. Rat fetuses of both sexes were collected at 21 d gestation and the entire stomachs extirpated, taking care not to include pancreas. Litters were born at approximately 22 d gestation and were kept with their mothers until 21 d post partum. After birth, ad libitum-fed (i.e., nursing) male and female Sprague Dawley rat pups were sampled at frequent intervals. At 21 d gestation and at 1, 5, 7, 10, 12, 16, 18, and 22 d old, the entire stomach (full thickness, without the rumen) was extracted for total RNA and ghrelin peptide. For older animals the mucosal layer of only the stomach fundus was harvested. For fetal and some of the early postnatal samples, the stomach fundus specimens from three to four littermates were pooled to constitute one sample. Plasma was collected from nursing pups at 5, 12, 13, 17, and 21 d of age and 30 d of age from weaned pups for measurement of ghrelin levels. With the earlier ages, plasma from littermates was pooled to extract 1.2-ml plasma specimens. All tissue samples were removed quickly after animals were killed and were immediately homogenized in either an RNA or ghrelin peptide extraction solution for measurement of ghrelin expression and peptide levels, respectively. Samples were stored at -80 C until assays or Northern hybridizations were done.
Influence of dietary manipulations and a fasting-refeeding regimen on stomach ghrelin. Adult male Sprague Dawley rats were fed ad lib either a commercial, AIN-76A biscuit diet (Bio-Serve, Frenchtown, NJ) (composition: approximate percent of calories: fat 12%; protein 20%; carbohydrate 65%); a high-fat diet (fat 48%, beef tallow; protein 16%; carbohydrate 34%) or a low-protein diet (fat 12%; protein 5%, casein; carbohydrate 83%) for 30 d. Two percent of the fat calories were derived from safflower oil in the beef tallow diet to supply essential fatty acids. Animals were killed in the ad lib-fed condition. At time of sacrifice, AIN-76A-fed rats, high-fat diet rats, and low-protein diet rats weighed (mean ± SEM) 358 ± 8 g, 367 ± 5 g, and 282 ± 6 g, respectively. For the fasting-refeeding experiment, rats were fasted for 72 h; a portion of the fasted rats was then refed ad lib for 24 h before being killed. All rats had unrestricted access to water. The stomach fundal mucosa was harvested and extracted for total cellular RNA and ghrelin peptide. Plasma was collected for measurement ghrelin levels by RIA.
Influence of endocrine manipulations and vagotomy on stomach ghrelin expression and peptide levels and plasma ghrelin concentrations. Adult male Sprague Dawley rats were given synthetic rat gastrin-17 (150 µg/kg body weight (BW), 3 times a day for 4 d, sc), T4 (50 µg/100 g BW·d for 4 d, ip), GH (400 µg/kg BW, 3 times a day for 3 d, sc), leptin (240 µg/kg BW, 2 times a day for 4 d, sc), or insulin (40 U/kg, 2 times a day for 3 d, sc). The influence of thyroidectomy and truncal vagotomy on stomach ghrelin and plasma ghrelin levels was also examined. Surgeries were done as previously described (8, 9), and rats were killed approximately 14 d after thyroidectomy or vagotomy. Highly purified rat GH and recombinant mouse leptin were used (supplied by A. F. Parlow, National Hormone and Pituitary Program-NIDDK). GH, leptin, insulin, and gastrin were prepared in 0.154 M saline containing 0.1% BSA. T4 was prepared in a mixture of methanol-ammonium hydroxide (2 ml/0.4 ml) and appropriate dilutions made in 0.154 M saline.
Effects of ghrelin on insulin and gastrin secretion. Ad
lib-fed male Sprague Dawley rats (
115 g) were given synthetic rat
ghrelin (25 nmol) or saline-containing 0.1%BSA iv into the jugular
vein under ether anesthesia. This experiment was done at 09001130 h.
Serum was then collected at various times after iv ghrelin or vehicle.
Basal serum specimens were also collected from ad lib-fed rats. Serum
gastrin and insulin levels were measured with radioimmunoassays as
described previously (10). The sensitivity and
ID50 (50% inhibition of maximal binding) for the
gastrin and insulin assays are 6 and 20 pg/tube, and 4 and 40 pg/tube,
respectively. The gastrin antiserum does not recognize
cholecystokinin.
RNA purification and Northern blotting analysis. Tissues were homogenized immediately in 4 M guanidinium isothiocyanate containing 25 mM sodium citrate, pH 7.0, 0.5% sodium N-lauroylsarcosine, and 0.1 M ß-mercaptoethanol. Extracts were frozen at -80 C until purification by ultracentrifugation over a cesium chloride cushion (2 ml, 5.7 M) as described previously (11). RNA samples were separated on a 1% agarose gel (30 µg/lane) in a 20 mM 3-[N-morpholino]propanesulfonic acid running buffer system (11, 12) and then transferred to a nylon membrane and subjected to Northern hybridization. 32P-Labeled riboprobes prepared from Strip-EZ RNA kits (catalog no. 1366, Ambion, Inc., Austin, TX) were used for Northern hybridizations. Complementary RNA for rat ghrelin was supplied by M. Kojima (1). The 18S was used to normalize for variations in RNA loading and transfer. Expression levels of ghrelin or the 18S genes were quantitated by phosphoimaging.
Ghrelin RIA; extraction of tissue and plasma ghrelin
A double-antibody RIA procedure was used to measure tissue and
plasma ghrelin levels (1). The ghrelin antiserum was
generated in rabbits against a synthetic C-terminal fragment (residues
1328 with an added N-terminal tyrosine) of rat ghrelin. The ghrelin
antiserum does not recognize other enteric peptides. The sensitivity
and ID50 are 0.01 and 0.2 ng/tube. The intra- and
interassay coefficients of variation are 13% and 20%, respectively.
Ghrelin peptide was extracted from rat tissues by homogenizing tissues
in approximately 10 volumes of 1 M acetic acid containing
20 mM HCl. Homogenates were then boiled for 20 min. The
supernatants were lyophilized and resuspended in assay buffer for the
ghrelin RIA. Extraction efficiency of tissue ghrelin is 7580%. Rat
plasma (1.2 ml/rat) was extracted by use of C18 Sep-Paks
(Waters, Milford, MA). Plasma for ghrelin RIA was
collected into tubes prepared with EDTA (1 mg/ml blood) and a protease
inhibitor (Trasylol, 70 µg/ml blood). For ghrelin
extraction, 1.2 ml plasma is mixed with an equal volume of 0.9% NaCl
and the pH adjusted to 6.86.9 with 12 µl 1 N HCl/1 ml
plasma. Samples were mixed well and added to C18 Sep-Paks prepared with
two 4-ml chloroform washes, followed by two 3-ml methanol washes, two
3-ml washes of acetonitrile (ACN) containing 0.1% trifluoroacetic acid
(TFA) and two 3-ml 0.9% NaCl washes. Disposable glass syringes
are used to add the washes and syringes are changed after the methanol
wash. Plasma specimens are added after the saline wash, followed by two
3-ml saline washes and two 3-ml washes of 5% ACN containing 0.1% TFA.
Ghrelin is eluted off the Sep-Paks with 4 ml 60% ACN containing 0.1%
TFA into tubes containing 10 µl 0.1% Triton. ACN is then evaporated
from the samples and the samples lyophilized. A buffer of 480 µl RIA
is added to lyophilized samples and samples assayed at 100200
µl/sample in duplicate in the ghrelin RIA. Extraction efficiency for
plasma ghrelin is more than 70%.
Statistics
Results are shown as means ± SE. Data were
analyzed by a one-way or two-way ANOVA followed by the Newman-Keuls
test where pertinent. Differences with a value of P <
0.05 were considered significant.
| Results |
|---|
|
|
|---|
|
|
|
|
Intravenous ghrelin stimulates insulin and gastrin secretion
Intravenous administration of ghrelin increased serum gastrin and
insulin levels significantly (Table 3
).
Serum gastrin and insulin levels were increased significantly at 15 and
60 min after iv ghrelin, compared with control-basal levels and to
those levels of rats given iv vehicle. Serum levels of gastrin and
insulin did not change significantly 5 min after iv ghrelin (data not
shown).
|
| Discussion |
|---|
|
|
|---|
In this study, we examined the effects of various endocrine
manipulations on stomach ghrelin expression and peptide levels. Because
ghrelin stimulates GH, insulin, and gastrin secretion, food intake and
body weight gain (1, 5, 6), we expected stomach ghrelin
expression and secretion to be influenced by metabolic factors. Our
results show that stomach ghrelin mRNA and peptide levels are
unaffected by leptin, T4, and insulin treatments.
An earlier study (5) showed that exogenous leptin
decreases stomach ghrelin expression significantly in mice. The
differences between the two studies might be explained by dosages of
leptin and species differences. The dose of leptin used in the mouse
study (
57 µg/30 g mouse) was approximately 2-fold higher than that
used in our study (
250 µg/225 g rat). We also showed that
thyroidectomy treatment increases stomach ghrelin expression
slightly but significantly, whereas vagotomy lowered stomach ghrelin
expression. Intriguingly, GH treatment lowered stomach ghrelin
expression levels, suggesting that a neuroendocrine feedback loop
exists between stomach ghrelin and pituitary GH. Further studies are
needed to explore whether GH modulates stomach ghrelin peptide stores
and secretion.
Truncal vagotomy increases plasma ghrelin levels indicating that the vagus nerve exerts a tonic inhibitory influence over ghrelin secretion. This finding agrees with the increase in ghrelin secretion observed during a fasted condition, a time when vagal (i.e. parasympathetic) activity is at a nadir. Because one of the documented, biological activities of ghrelin is to stimulate food intake (4, 5, 6, 7), ghrelin secretion is expected to increase during fasting. It can be pointed out that the increased secretion of stomach ghrelin with fasting is unique when contrasted to a majority of gut hormones whose secretion increases with food intake and decreases with fasting. The finding that ghrelin secretion decreases with food intake implies that either a nutrient, a gut or pancreatic hormone released by an ingested nutrient, or both modulate ghrelin secretion. Our present findings indicate that insulin is not involved in the postcibal decline in circulating ghrelin levels because insulin administration increases ghrelin secretion. This finding also bolsters a role for endogenous ghrelin in regulation of food intake. The finding that stomach ghrelin homeostasis (i.e. mRNA, peptide levels) and secretion are responsive to dietary manipulations, caloric restriction, and refeeding is expected because stomach ghrelin cells are exposed to the luminal contents.
Data given in this article show that gastrin clearly stimulates ghrelin secretion. These findings suggest that the reduction in ghrelin secretion in fasted rats with refeeding is not because of food-induced release of gastrin. Another gut peptide may inhibit ghrelin secretion.
The increased secretion of ghrelin with exogenous gastrin and insulin treatments, in view of the increased secretion of ghrelin with fasting, indicates that regulation of ghrelin secretion is complex and that its secretion is stimulated by seemingly contradictory signals. Gastrin and insulin secretion is reduced with fasting (10, 15).
The finding that truncal vagotomy disinhibits ghrelin secretion implies that its secretion is influenced by central neural mechanisms originating in the dorsal vagal complex of the medulla oblongata. The dorsal vagal complex has been shown to modulate gastrointestinal and pancreatic activity (16, 17, 18).
It is difficult to reconcile the elevation in plasma ghrelin levels during acute nutrient restriction (i.e. fasting and protein deprivation) in view of the GH-releasing action of ghrelin. It is conceivable that the GH-releasing action of ghrelin is repressed in the hypothalamus or pituitary, whereas its orexigenic actions are preserved during periods of caloric or nutritional restriction. Multiple ghrelin receptors may exert these various effects in the brain and pituitary. A more plausible explanation is that the protein deprivation causes increased ghrelin secretion to counter protein depletion by stimulating appetite and GH secretion that, in turn, stimulates protein synthesis.
Ghrelin secretion increases with a low-protein diet and decreases with a high-fat diet. Stomach ghrelin expression parallels ghrelin secretion. The decreased ghrelin secretion accompanying increased dietary fat may be owing to an inhibition of its secretion by luminal fat itself or by another enteric hormone or a metabolic signal that is sensitive or dependent on dietary fat. Fat-sensitive signals include PYY, glucagon-like peptide-1, neurotensin, and cholecystokinin from the intestine; leptin and resistin from adipocytes; and FFA from dietary fat (19, 20, 21). The reduction in plasma ghrelin levels with the high-fat diet agrees with a recent article showing decreased circulating ghrelin levels in obese humans (22). The authors of the human study suggest that the reduced plasma ghrelin levels reflect an adaptation to the excessive caloric intake in obese subjects. They also suggest that elevated plasma leptin and insulin levels in obese subjects underline the lower ghrelin secretion. In the present study, we show that exogenous leptin does not affect ghrelin secretion and that exogenous insulin stimulates ghrelin secretion. In the low-protein and high-fat diet rat experiments, the changes in ghrelin secretion may be triggered actually by the altered percentages of dietary carbohydrates. In the low-protein and the high-fat diets, carbohydrate percentages are increased and decreased, respectively. An earlier report indicates that dietary carbohydrates are a primary regulator of GH secretion (23). The hypothesis that dietary carbohydrates modulate ghrelin secretion is under study.
This study shows, for the first time, that ghrelin stimulates gastrin and insulin secretion. Circulating gastrin and insulin levels are increased significantly within 15 min after iv ghrelin administration. Although ghrelin receptors are present in the stomach and pancreas (24, 25, 26), the delayed elevations in serum gastrin and insulin levels at 15 min and again at 60 min suggests that ghrelin may act indirectly to stimulate gastrin and insulin secretion. The ghrelin-induced secretion of gastrin and insulin is not owing to an acute intake of food. Food intake was not stimulated in this experiment. Ghrelin also stimulates gastric acid secretion in rats (27). Therefore, the stimulatory action of ghrelin on acid secretion may be mediated partly by ghrelin-induced release of stomach gastrin.
Together, our findings when considered with the earlier reports from other laboratories, indicate that ghrelin is an important stomach hormone that links enteric nutrition with gastrin and insulin secretion, central neural regulation of GH secretion, growth, and food intake.
| Footnotes |
|---|
This work was supported by grants from the National Institutes of Health (RO1 DK-15241, PO1 DK-35608).
Abbreviations: ACN, Acetonitrile; ad lib, ad libitum; BW, body weight; GHS-R, GH secretagogue receptor; GI, gastrointestinal; PYY, peptide YY; TFA, trifluoroacetic acid.
Received June 7, 2001.
Accepted for publication September 27, 2001.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
S. Sangiao-Alvarellos, M. J. Vazquez, L. Varela, R. Nogueiras, A. K. Saha, F. Cordido, M. Lopez, and C. Dieguez Central Ghrelin Regulates Peripheral Lipid Metabolism in a Growth Hormone-Independent Fashion Endocrinology, October 1, 2009; 150(10): 4562 - 4574. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Patterson, K. G. Murphy, S. R. Patel, N. A. Patel, H. C. Greenwood, J. H. Cooke, D. Campbell, G. A. Bewick, M. A. Ghatei, and S. R. Bloom Hypothalamic Injection of Oxyntomodulin Suppresses Circulating Ghrelin-Like Immunoreactivity Endocrinology, August 1, 2009; 150(8): 3513 - 3520. [Abstract] [Full Text] [PDF] |
||||
![]() |
B Beck and S Richy Dietary modulation of ghrelin and leptin and gorging behavior after weight loss in the obese Zucker rat J. Endocrinol., July 1, 2009; 202(1): 29 - 34. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Mano-Otagiri, H. Ohata, A. Iwasaki-Sekino, T. Nemoto, and T. Shibasaki Ghrelin suppresses noradrenaline release in the brown adipose tissue of rats J. Endocrinol., June 1, 2009; 201(3): 341 - 349. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. BERTACCINI, R. PERNETTI, D. MARCHIORI, U. PAGOTTO, F. PALLADORO, F. PALMIERI, G. VITULLO, M. GUIDI, and G. MARTORANA Variations in Blood Ghrelin Levels in Prostate Cancer Patients Submitted to Hormone Suppressive Treatment Anticancer Res, April 1, 2009; 29(4): 1345 - 1348. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Edfalk, P. Steneberg, and H. Edlund Gpr40 Is Expressed in Enteroendocrine Cells and Mediates Free Fatty Acid Stimulation of Incretin Secretion Diabetes, September 1, 2008; 57(9): 2280 - 2287. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Morgado, M. K. Gordon, M. del Carmen Minana-Solis, E. Meza, S. Levine, C. Escobar, and M. Caba Hormonal and metabolic rhythms associated with the daily scheduled nursing in rabbit pups Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2008; 295(2): R690 - R695. [Abstract] [Full Text] [PDF] |
||||
![]() |
X. Qi, J. T. Reed, G. Wang, S. Han, E. W. Englander, and G. H. Greeley Jr. Ghrelin secretion is not reduced by increased fat mass during diet-induced obesity Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2008; 295(2): R429 - R435. [Abstract] [Full Text] [PDF] |
||||
![]() |
K Scrimgeour, M J Gresham, L R Giles, P C Thomson, P C Wynn, and R E Newman Ghrelin secretion is more closely aligned to energy balance than with feeding behaviour in the grower pig J. Endocrinol., July 1, 2008; 198(1): 135 - 145. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. E. Wertz-Lutz, J. A. Daniel, J. A. Clapper, A. Trenkle, and D. C. Beitz Prolonged, moderate nutrient restriction in beef cattle results in persistently elevated circulating ghrelin concentrations J Anim Sci, March 1, 2008; 86(3): 564 - 575. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. P. Esler, J. Rudolph, T. H. Claus, W. Tang, N. Barucci, S.-E. Brown, W. Bullock, M. Daly, L. DeCarr, Y. Li, et al. Small-Molecule Ghrelin Receptor Antagonists Improve Glucose Tolerance, Suppress Appetite, and Promote Weight Loss Endocrinology, November 1, 2007; 148(11): 5175 - 5185. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. J Little, M. Horowitz, and C. Feinle-Bisset Modulation by high-fat diets of gastrointestinal function and hormones associated with the regulation of energy intake: implications for the pathophysiology of obesity Am. J. Clinical Nutrition, September 1, 2007; 86(3): 531 - 541. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Takahashi, Y. Kurose, M. Sakaida, Y. Suzuki, S. Kobayashi, T. Sugino, M. Kojima, K. Kangawa, Y. Hasegawa, and Y. Terashima Ghrelin differentially modulates glucose-induced insulin secretion according to feeding status in sheep J. Endocrinol., September 1, 2007; 194(3): 621 - 625. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. J. Page, J. A. Slattery, C. Milte, R. Laker, T. O'Donnell, C. Dorian, S. M. Brierley, and L. A. Blackshaw Ghrelin selectively reduces mechanosensitivity of upper gastrointestinal vagal afferents Am J Physiol Gastrointest Liver Physiol, May 1, 2007; 292(5): G1376 - G1384. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Gromada, I. Franklin, and C. B. Wollheim {alpha}-Cells of the Endocrine Pancreas: 35 Years of Research but the Enigma Remains Endocr. Rev., February 1, 2007; 28(1): 84 - 116. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Granata, F. Settanni, L. Biancone, L. Trovato, R. Nano, F. Bertuzzi, S. Destefanis, M. Annunziata, M. Martinetti, F. Catapano, et al. Acylated and Unacylated Ghrelin Promote Proliferation and Inhibit Apoptosis of Pancreatic {beta}-Cells and Human Islets: Involvement of 3',5'-Cyclic Adenosine Monophosphate/Protein Kinase A, Extracellular Signal-Regulated Kinase 1/2, and Phosphatidyl Inositol 3-Kinase/Akt Signaling Endocrinology, February 1, 2007; 148(2): 512 - 529. [Abstract] [Full Text] [PDF] |
||||
![]() |
X. Zhu, Y. Cao, K. Voodg, and D. F. Steiner On the Processing of Proghrelin to Ghrelin J. Biol. Chem., December 15, 2006; 281(50): 38867 - 38870. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. E. Wertz-Lutz, T. J. Knight, R. H. Pritchard, J. A. Daniel, J. A. Clapper, A. J. Smart, A. Trenkle, and D. C. Beitz Circulating ghrelin concentrations fluctuate relative to nutritional status and influence feeding behavior in cattle J Anim Sci, December 1, 2006; 84(12): 3285 - 3300. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. E Mitchell, R. Nogueiras, K. Rance, D V. Rayner, S. Wood, C. Dieguez, and L. M Williams Circulating hormones and hypothalamic energy balance: regulatory gene expression in the Lou/C and Wistar rats. J. Endocrinol., September 1, 2006; 190(3): 571 - 579. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Komatsu, T. Chiba, H. Yamaza, K. To, H. Toyama, Y. Higami, and I. Shimokawa Effect of leptin on hypothalamic gene expression in calorie-restricted rats. J. Gerontol. A Biol. Sci. Med. Sci., September 1, 2006; 61(9): 890 - 898. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Nogueiras, S. Tovar, S. E Mitchell, P. Barrett, D V. Rayner, C. Dieguez, and L. M Williams Negative energy balance and leptin regulate neuromedin-U expression in the rat pars tuberalis. J. Endocrinol., August 1, 2006; 190(2): 545 - 553. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. ThidarMyint, H. Yoshida, T. Ito, and H. Kuwayama Dose-dependent response of plasma ghrelin and growth hormone concentrations to bovine ghrelin in Holstein heifers. J. Endocrinol., June 1, 2006; 189(3): 655 - 664. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Li, X. Wu, Y. Zhao, S. Chen, and C. Owyang Ghrelin acts on the dorsal vagal complex to stimulate pancreatic protein secretion Am J Physiol Gastrointest Liver Physiol, June 1, 2006; 290(6): G1350 - G1358. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Mingrone, L. Granato, E. Valera-Mora, A. Iaconelli, M. F Calvani, R. Bracaglia, M. Manco, G. Nanni, and M. Castagneto Ultradian ghrelin pulsatility is disrupted in morbidly obese subjects after weight loss induced by malabsorptive bariatric surgery Am. J. Clinical Nutrition, May 1, 2006; 83(5): 1017 - 1024. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Bellone, R. Baldelli, G. Radetti, A. Rapa, D. Vivenza, A. Petri, S. Savastio, M. Zaffaroni, F. Broglio, E. Ghigo, et al. Ghrelin Secretion in Preterm Neonates Progressively Increases and Is Refractory to the Inhibitory Effect of Food Intake J. Clin. Endocrinol. Metab., May 1, 2006; 91(5): 1929 - 1933. [Abstract] [Full Text] [PDF] |
||||
![]() |
H Takahashi, Y Kurose, S Kobayashi, T Sugino, M Kojima, K Kangawa, Y Hasegawa, and Y Terashima Ghrelin enhances glucose-induced insulin secretion in scheduled meal-fed sheep. J. Endocrinol., April 1, 2006; 189(1): 67 - 75. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. R Christ, M. Zehnder, C. Boesch, R. Trepp, P. E Mullis, P. Diem, and J. Decombaz The effect of increased lipid intake on hormonal responses during aerobic exercise in endurance-trained men. Eur. J. Endocrinol., March 1, 2006; 154(3): 397 - 403. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Nakahara, M. Nakagawa, Y. Baba, M. Sato, K. Toshinai, Y. Date, M. Nakazato, M. Kojima, M. Miyazato, H. Kaiya, et al. Maternal Ghrelin Plays an Important Role in Rat Fetal Development during Pregnancy Endocrinology, March 1, 2006; 147(3): 1333 - 1342. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. Wei, X. Qi, J. Reed, J. Ceci, H.-Q. Wang, G. Wang, E. W. Englander, and G. H. Greeley Jr. Effect of chronic hyperghrelinemia on ingestive action of ghrelin Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2006; 290(3): R803 - R808. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Doi, T. Shono, M. Nishi, H. Furuta, H. Sasaki, and K. Nanjo IA-2beta, but not IA-2, is induced by ghrelin and inhibits glucose-stimulated insulin secretion PNAS, January 24, 2006; 103(4): 885 - 890. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. L. Drazen, T. P. Vahl, D. A. D'Alessio, R. J. Seeley, and S. C. Woods Effects of a Fixed Meal Pattern on Ghrelin Secretion: Evidence for a Learned Response Independent of Nutrient Status Endocrinology, January 1, 2006; 147(1): 23 - 30. [Abstract] [Full Text] [PDF] |
||||
![]() |
T L Peeters Ghrelin: a new player in the control of gastrointestinal functions Gut, November 1, 2005; 54(11): 1638 - 1649. [Full Text] [PDF] |
||||
![]() |
L. Friis-Hansen, N. Wierup, J. F. Rehfeld, and F. Sundler Reduced Ghrelin, Islet Amyloid Polypeptide, and Peptide YY Expression in the Stomach of Gastrin-Cholecystokinin Knockout Mice Endocrinology, October 1, 2005; 146(10): 4464 - 4471. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. Janssen, N. H. Prins, B. Moreaux, A. L. Meulemans, and R. A. Lefebvre Characterization of 5-HT7-receptor-mediated gastric relaxation in conscious dogs Am J Physiol Gastrointest Liver Physiol, July 1, 2005; 289(1): G108 - G115. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Nishi, H. Hiejima, H. Mifune, T. Sato, K. Kangawa, and M. Kojima Developmental Changes in the Pattern of Ghrelin's Acyl Modification and the Levels of Acyl-Modified Ghrelins in Murine Stomach Endocrinology, June 1, 2005; 146(6): 2709 - 2715. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Sato, Y. Fukue, H. Teranishi, Y. Yoshida, and M. Kojima Molecular Forms of Hypothalamic Ghrelin and Its Regulation by Fasting and 2-Deoxy-D-Glucose Administration Endocrinology, June 1, 2005; 146(6): 2510 - 2516. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. P. Goldstone, M. Patterson, N. Kalingag, M. A. Ghatei, A. E. Brynes, S. R. Bloom, A. B. Grossman, and M. Korbonits Fasting and Postprandial Hyperghrelinemia in Prader-Willi Syndrome Is Partially Explained by Hypoinsulinemia, and Is Not Due to Peptide YY3-36 Deficiency or Seen in Hypothalamic Obesity Due to Craniopharyngioma J. Clin. Endocrinol. Metab., May 1, 2005; 90(5): 2681 - 2690. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Nishi, H. Hiejima, H. Hosoda, H. Kaiya, K. Mori, Y. Fukue, T. Yanase, H. Nawata, K. Kangawa, and M. Kojima Ingested Medium-Chain Fatty Acids Are Directly Utilized for the Acyl Modification of Ghrelin Endocrinology, May 1, 2005; 146(5): 2255 - 2264. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Iwakura, K. Hosoda, C. Son, J. Fujikura, T. Tomita, M. Noguchi, H. Ariyasu, K. Takaya, H. Masuzaki, Y. Ogawa, et al. Analysis of Rat Insulin II Promoter-Ghrelin Transgenic Mice and Rat Glucagon Promoter-Ghrelin Transgenic Mice J. Biol. Chem., April 15, 2005; 280(15): 15247 - 15256. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Kojima and K. Kangawa Ghrelin: Structure and Function Physiol Rev, April 1, 2005; 85(2): 495 - 522. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. Wei, G. Wang, X. Qi, E. W. Englander, and G. H. Greeley Jr. Characterization and Regulation of the Rat and Human Ghrelin Promoters Endocrinology, March 1, 2005; 146(3): 1611 - 1625. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Lee, M. Hadi, G. Hallden, and G. W. Aponte Peptide YY and Neuropeptide Y Induce Villin Expression, Reduce Adhesion, and Enhance Migration in Small Intestinal Cells through the Regulation of CD63, Matrix Metalloproteinase-3, and Cdc42 Activity J. Biol. Chem., January 7, 2005; 280(1): 125 - 136. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Dezaki, H. Hosoda, M. Kakei, S. Hashiguchi, M. Watanabe, K. Kangawa, and T. Yada Endogenous Ghrelin in Pancreatic Islets Restricts Insulin Release by Attenuating Ca2+ Signaling in {beta}-Cells: Implication in the Glycemic Control in Rodents Diabetes, December 1, 2004; 53(12): 3142 - 3151. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Rindi, A. Torsello, V. Locatelli, and E. Solcia Ghrelin Expression and Actions: A Novel Peptide for an Old Cell Type of the Diffuse Endocrine System Experimental Biology and Medicine, November 1, 2004; 229(10): 1007 - 1016. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Sanchez, P. Oliver, A. Palou, and C. Pico The Inhibition of Gastric Ghrelin Production by Food Intake in Rats Is Dependent on the Type of Macronutrient Endocrinology, November 1, 2004; 145(11): 5049 - 5055. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Arosio, C. L. Ronchi, P. Beck-Peccoz, C. Gebbia, C. Giavoli, V. Cappiello, D. Conte, and M. Peracchi Effects of Modified Sham Feeding on Ghrelin Levels in Healthy Human Subjects J. Clin. Endocrinol. Metab., October 1, 2004; 89(10): 5101 - 5104. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Nogueiras, S. Tovar, S. E. Mitchell, D. V. Rayner, Z. A. Archer, C. Dieguez, and L. M. Williams Regulation of Growth Hormone Secretagogue Receptor Gene Expression in the Arcuate Nuclei of the Rat by Leptin and Ghrelin Diabetes, October 1, 2004; 53(10): 2552 - 2558. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Ueno, M. G. Dube, A. Inui, P. S. Kalra, and S. P. Kalra Leptin Modulates Orexigenic Effects of Ghrelin and Attenuates Adiponectin and Insulin Levels and Selectively the Dark-Phase Feeding as Revealed by Central Leptin Gene Therapy Endocrinology, September 1, 2004; 145(9): 4176 - 4184. [Abstract] [Full Text] [PDF] |
||||
![]() |
J.-P. Chanoine and A. C. K. Wong Ghrelin Gene Expression Is Markedly Higher in Fetal Pancreas Compared with Fetal Stomach: Effect of Maternal Fasting Endocrinology, August 1, 2004; 145(8): 3813 - 3820. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Lin, N. Gletsu, K. Fugate, D. McClusky, L. H. Gu, J.-L. Zhu, B. J. Ramshaw, D. A. Papanicolaou, T. R. Ziegler, and C. D. Smith The Effects of Gastric Surgery on Systemic Ghrelin Levels in the Morbidly Obese Arch Surg, July 1, 2004; 139(7): 780 - 784. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. E. Salfen, J. A. Carroll, D. H. Keisler, and T. A. Strauch Effects of exogenous ghrelin on feed intake, weight gain, behavior, and endocrine responses in weanling pigs J Anim Sci, July 1, 2004; 82(7): 1957 - 1966. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. J. van der Lely, M. Tschop, M. L. Heiman, and E. Ghigo Biological, Physiological, Pathophysiological, and Pharmacological Aspects of Ghrelin Endocr. Rev., June 1, 2004; 25(3): 426 - 457. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. D. Salbe, M. H. Tschop, A. DelParigi, C. A. Venti, and P. A. Tataranni Negative Relationship between Fasting Plasma Ghrelin Concentrations and ad Libitum Food Intake J. Clin. Endocrinol. Metab., June 1, 2004; 89(6): 2951 - 2956. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. L. Teff, S. S. Elliott, M. Tschop, T. J. Kieffer, D. Rader, M. Heiman, R. R. Townsend, N. L. Keim, D. D'Alessio, and P. J. Havel Dietary Fructose Reduces Circulating Insulin and Leptin, Attenuates Postprandial Suppression of Ghrelin, and Increases Triglycerides in Women J. Clin. Endocrinol. Metab., June 1, 2004; 89(6): 2963 - 2972. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Broglio, C. Gottero, P. Van Koetsveld, F. Prodam, S. Destefanis, A. Benso, C. Gauna, L. Hofland, E. Arvat, A. J. van der Lely, et al. Acetylcholine Regulates Ghrelin Secretion in Humans J. Clin. Endocrinol. Metab., May 1, 2004; 89(5): 2429 - 2433. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. Zhang, L. Zhao, T. R. Lin, B. Chai, Y. Fan, I. Gantz, and M. W. Mulholland Inhibition of Adipogenesis by Ghrelin Mol. Biol. Cell, May 1, 2004; 15(5): 2484 - 2491. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Bellone, N. Castellino, F. Broglio, A. Rapa, D. Vivenza, G. Radetti, J. Bellone, C. Gottero, E. Ghigo, and G. Bona Ghrelin Secretion in Childhood Is Refractory to the Inhibitory Effect of Feeding J. Clin. Endocrinol. Metab., April 1, 2004; 89(4): 1662 - 1665. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. P. Goldstone, E. L. Thomas, A. E. Brynes, G. Castroman, R. Edwards, M. A. Ghatei, G. Frost, A. J. Holland, A. B. Grossman, M. Korbonits, et al. Elevated Fasting Plasma Ghrelin in Prader-Willi Syndrome Adults Is Not Solely Explained by Their Reduced Visceral Adiposity and Insulin Resistance J. Clin. Endocrinol. Metab., April 1, 2004; 89(4): 1718 - 1726. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. L. Anderson, S. Jeftinija, and C. G. Scanes Growth Hormone Secretion: Molecular and Cellular Mechanisms and In Vivo Approaches Experimental Biology and Medicine, April 1, 2004; 229(4): 291 - 302. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Wierup, S. Yang, R. J. McEvilly, H. Mulder, and F. Sundler Ghrelin Is Expressed in a Novel Endocrine Cell Type in Developing Rat Islets and Inhibits Insulin Secretion from INS-1 (832/13) Cells J. Histochem. Cytochem., March 1, 2004; 52(3): 301 - 310. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Lanfranco, R. Giordano, M. Pellegrino, L. Gianotti, J. Ramunni, A. Picu, M. Baldi, E. Ghigo, and E. Arvat Free Fatty Acids Exert an Inhibitory Effect on Adrenocorticotropin and Cortisol Secretion in Humans J. Clin. Endocrinol. Metab., March 1, 2004; 89(3): 1385 - 1390. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. INUI, A. ASAKAWA, C. Y. BOWERS, G. MANTOVANI, A. LAVIANO, M. M. MEGUID, and M. FUJIMIYA Ghrelin, appetite, and gastric motility: the emerging role of the stomach as an endocrine organ FASEB J, March 1, 2004; 18(3): 439 - 456. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Wang, Y. Anini, W. Wei, X. Qi, A.-M. O'Carroll, T. Mochizuki, H.-Q. Wang, M. R. Hellmich, E. W. Englander, and G. H. Greeley Jr. Apelin, a New Enteric Peptide: Localization in the Gastrointestinal Tract, Ontogeny, and Stimulation of Gastric Cell Proliferation and of Cholecystokinin Secretion Endocrinology, March 1, 2004; 145(3): 1342 - 1348. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. L. Williams, H. J. Grill, D. E. Cummings, and J. M. Kaplan Vagotomy Dissociates Short- and Long-Term Controls of Circulating Ghrelin Endocrinology, December 1, 2003; 144(12): 5184 - 5187. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. E. Caminos, R. Nogueiras, M. Blanco, L. M. Seoane, S. Bravo, C. V. Alvarez, T. Garcia-Caballero, F. F. Casanueva, and C. Dieguez Cellular Distribution and Regulation of Ghrelin Messenger Ribonucleic Acid in the Rat Pituitary Gland Endocrinology, November 1, 2003; 144(11): 5089 - 5097. [Abstract] [Full Text] [PDF] |
||||
![]() |
X. Qi, J. Reed, E. W. Englander, V. Chandrashekar, A. Bartke, and G. H. Greeley Jr. Evidence That Growth Hormone Exerts a Feedback Effect on Stomach Ghrelin Production and Secretion Experimental Biology and Medicine, October 1, 2003; 228(9): 1028 - 1032. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. M. Poykko, E. Kellokoski, S. Horkko, H. Kauma, Y. A. Kesaniemi, and O. Ukkola Low Plasma Ghrelin Is Associated With Insulin Resistance, Hypertension, and the Prevalence of Type 2 Diabetes Diabetes, October 1, 2003; 52(10): 2546 - 2553. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Broglio, C. Gottero, A. Benso, F. Prodam, S. Destefanis, C. Gauna, M. Maccario, R. Deghenghi, A. J. van der Lely, and E. Ghigo Effects of Ghrelin on the Insulin and Glycemic Responses to Glucose, Arginine, or Free Fatty Acids Load in Humans J. Clin. Endocrinol. Metab., September 1, 2003; 88(9): 4268 - 4272. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. M. Zigman and J. K. Elmquist Minireview: From Anorexia to Obesity--The Yin and Yang of Body Weight Control Endocrinology, September 1, 2003; 144(9): 3749 - 3756. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. E. Cummings and M. H. Shannon Ghrelin and Gastric Bypass: Is There a Hormonal Contribution to Surgical Weight Loss? J. Clin. Endocrinol. Metab., July 1, 2003; 88(7): 2999 - 3002. [Full Text] [PDF] |
||||
![]() |
A Asakawa, A Inui, T Kaga, G Katsuura, M Fujimiya, M A Fujino, and M Kasuga Antagonism of ghrelin receptor reduces food intake and body weight gain in mice Gut, July 1, 2003; 52(7): 947 - 952. [Abstract] [Full Text] |
||||
![]() |
C. Anderwald, G. Brabant, E. Bernroider, R. Horn, A. Brehm, W. Waldhausl, and M. Roden Insulin-Dependent Modulation of Plasma Ghrelin and Leptin Concentrations Is Less Pronounced in Type 2 Diabetic Patients Diabetes, July 1, 2003; 52(7): 1792 - 1798. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. U. Freda, C. M. Reyes, I. M. Conwell, R. E. Sundeen, and S. L. Wardlaw Serum Ghrelin Levels in Acromegaly: Effects of Surgical and Long-Acting Octreotide Therapy J. Clin. Endocrinol. Metab., May 1, 2003; 88(5): 2037 - 2044. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Broglio, A. Benso, C. Castiglioni, C. Gottero, F. Prodam, S. Destefanis, C. Gauna, A. J. van der Lely, R. Deghenghi, M. Bo, et al. The Endocrine Response to Ghrelin as a Function of Gender in Humans in Young and Elderly Subjects J. Clin. Endocrinol. Metab., April 1, 2003; 88(4): 1537 - 1542. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. K. Reimer, G. Pacini, and B. Ahren Dose-Dependent Inhibition by Ghrelin of Insulin Secretion in the Mouse Endocrinology, March 1, 2003; 144(3): 916 - 921. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Arosio, C. L. Ronchi, C. Gebbia, V. Cappiello, P. Beck-Peccoz, and M. Peracchi Stimulatory Effects of Ghrelin on Circulating Somatostatin and Pancreatic Polypeptide Levels J. Clin. Endocrinol. Metab., February 1, 2003; 88(2): 701 - 704. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Moller, J. Nygren, T. K. Hansen, H. Orskov, J. Frystyk, and K. S. Nair Splanchnic Release of Ghrelin in Humans J. Clin. Endocrinol. Metab., February 1, 2003; 88(2): 850 - 852. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Volante, E. Allia, E. Fulcheri, P. Cassoni, E. Ghigo, G. Muccioli, and M. Papotti Ghrelin in Fetal Thyroid and Follicular Tumors and Cell Lines: Expression and Effects on Tumor Growth Am. J. Pathol., February 1, 2003; 162(2): 645 - 654. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. Sibilia, G. Rindi, F. Pagani, D. Rapetti, V. Locatelli, A. Torsello, N. Campanini, R. Deghenghi, and C. Netti Ghrelin Protects Against Ethanol-Induced Gastric Ulcers in Rats: Studies on the Mechanisms of Action Endocrinology, January 1, 2003; 144(1): 353 - 359. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Schaller, A. Schmidt, J. Pleiner, W. Woloszczuk, M. Wolzt, and A. Luger Plasma Ghrelin Concentrations Are Not Regulated by Glucose or Insulin: A Double-Blind, Placebo-Controlled Crossover Clamp Study Diabetes, January 1, 2003; 52(1): 16 - 20. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Hosoda, M. Kojima, and K. Kangawa Ghrelin and the Regulation of Food Intake and Energy Balance Mol. Interv., December 1, 2002; 2(8): 494 - 503. [Abstract] [Full Text] |
||||
![]() |
A. DelParigi, M. Tschop, M. L. Heiman, A. D. Salbe, B. Vozarova, S. M. Sell, J. C. Bunt, and P. A. Tataranni High Circulating Ghrelin: A Potential Cause for Hyperphagia and Obesity in Prader-Willi Syndrome J. Clin. Endocrinol. Metab., December 1, 2002; 87(12): 5461 - 5464. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. R. Cunha and K. E. Mayo Ghrelin and Growth Hormone (GH) Secretagogues Potentiate GH-Releasing Hormone (GHRH)-Induced Cyclic Adenosine 3',5'-Monophosphate Production in Cells Expressing Transfected GHRH and GH Secretagogue Receptors Endocrinology, December 1, 2002; 143(12): 4570 - 4582. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. Schofl, R. Horn, T. Schill, H. W. Schlosser, M. J. Muller, and G. Brabant Circulating Ghrelin Levels in Patients with Polycystic Ovary Syndrome J. Clin. Endocrinol. Metab., October 1, 2002; 87(10): 4607 - 4610. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Ariyasu, K. Takaya, H. Hosoda, H. Iwakura, K. Ebihara, K. Mori, Y. Ogawa, K. Hosoda, T. Akamizu, M. Kojima, et al. Delayed Short-Term Secretory Regulation of Ghrelin in Obese Animals: Evidenced by a Specific RIA for the Active Form of Ghrelin Endocrinology, September 1, 2002; 143(9): 3341 - 3350. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 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 |