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Wellman M, Budin R, Woodside B, Abizaid A. Energetic demands of lactation produce an increase in the expression of growth hormone secretagogue receptor in the hypothalamus and ventral tegmental area of the rat despite a reduction in circulating ghrelin. J Neuroendocrinol 2022; 34:e13126. [PMID: 35365872 DOI: 10.1111/jne.13126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/07/2022] [Accepted: 02/08/2022] [Indexed: 12/26/2022]
Abstract
Lactating rats show changes in the secretion of hormones and brain signals that promote hyperphagia and facilitate the production of milk. Little is known, however, about the role of ghrelin in the mechanisms sustaining lactational hyperphagia. Here, we used Wistar female rats that underwent surgery to sever the galactophores to prevent milk delivery (GC rats) and decrease the energetic drain of milk delivery. We compared plasma acyl-ghrelin concentrations and growth hormone secretagogue receptor (GHSR) mRNA expression in different brain regions of GC rats with those of sham operated lactating and nonlactating rats. Additional lactating and nonlactating rats were implanted with cannulae aimed at the lateral ventricles and were used to compare feeding responses to central ghrelin or GHSR antagonist infusions to those of nonlactating rats receiving similar infusions on day 14-16 postpartum (pp). Results show lower plasma acyl-ghrelin concentrations on day 15 pp sham operated lactating rats compared to GC or nonlactating rats. These changes occur in association with increased GHSR mRNA expression in the hypothalamic arcuate nucleus (ARC) and ventral tegmental area (VTA) of sham operated lactating rats. Despite lactational hyperphagia, infusions of ghrelin (0.25 or 1 μg) resulted in similar increases in food intake in lactating and nonlactating rats. In addition, infusions of the GHSR antagonist JMV3002 (4 μg in 1 μl of vehicle) produced greater suppression of food intake in lactating rats than in nonlactating rats. These data suggest that, despite lower plasma ghrelin, the energetic drain of lactation increases sensitivity to the orexigenic effects of ghrelin in brain regions important for food intake and energy balance, and these events are associated with lactational hyperphagia.
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Affiliation(s)
- Martin Wellman
- Neuroscience Department, Carleton University, Ottawa, Ontario, Canada
| | - Radek Budin
- Centre for Studies in Behavioural Neurobiology, Psychology Department, Concordia University, Montreal, Quebec, Canada
| | - Barbara Woodside
- Centre for Studies in Behavioural Neurobiology, Psychology Department, Concordia University, Montreal, Quebec, Canada
| | - Alfonso Abizaid
- Neuroscience Department, Carleton University, Ottawa, Ontario, Canada
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Karakulak M, Saygili U, Temur M, Yilmaz Ö, Özün Özbay P, Calan M, Coşar H. Comparison of umbilical cord ghrelin concentrations in full-term pregnant women with or without gestational diabetes. Endocr Res 2017; 42:79-85. [PMID: 27352223 DOI: 10.1080/07435800.2016.1194855] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
PURPOSE Ghrelin is a potent orexigenic peptide hormone secreted from the gastrointestinal tract that plays a crucial role in the regulation of lipids and glucose metabolism. Ghrelin also has links with fetal development and growth. Gestational diabetes mellitus (GDM) causes fetal macrosomia, but there is no available evidence of a relationship between ghrelin levels and birth weight in women with GDM. The purpose of this study is to investigate whether umbilical cord ghrelin concentrations are altered in full-term pregnant women with GDM compared to women without GDM and whether birth weight is correlated with ghrelin levels. MATERIALS AND METHODS Sixty pregnant women with GDM and 64 healthy pregnant women without GDM were included in this cross-sectional study. Blood samples were drawn from the umbilical vein following birth. Ghrelin concentrations were measured using enzyme-linked immunosorbent assay (ELISA). RESULTS Umbilical vein ghrelin levels were decreased in women with GDM (879.6 ± 256.1 vs. 972.2 ± 233.6 pg/ml in women without GDM, p=0.033), whereas birth weights were higher for babies in the GDM than in the non-GDM group (3448 ± 410 vs. 3308 ± 365 gr, respectively, p=0.046). Umbilical ghrelin levels were inversely correlated with birth weight (r=-0.765, p<0.001). Multiple regression analysis revealed that birth weight was independently and negatively associated with umbilical ghrelin levels (β= -2.077, 95% CI=-2.652 to -1.492, p=0.002). CONCLUSIONS Umbilical ghrelin levels were lower in GDM women. Birth weight was inversely associated with umbilical ghrelin levels. This association may be explained by a negative feedback mechanism between ghrelin and birth weight.
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Affiliation(s)
- Murat Karakulak
- a Silivri State Hospital , Department of Obstetrics and Gynecology , Istanbul , Turkey
| | - Uğur Saygili
- b Dokuzeylul University Medical School , Department of Obstetrics and Gynecology , Izmir , Turkey
| | - Muzaffer Temur
- c Manisa Merkezefendi Hospital , Department of Obstetrics and Gynecology , Manisa , Turkey
| | - Özgür Yilmaz
- c Manisa Merkezefendi Hospital , Department of Obstetrics and Gynecology , Manisa , Turkey
| | - Pelin Özün Özbay
- d Aydin Obstetrics and Pediatrics Hospital Department of Obstetrics and Gynecology , Aydin , Turkey
| | - Mehmet Calan
- e Izmir Bozyaka Research Hospital , Department of Endocrinology Izmir , Turkey
| | - Hese Coşar
- f M.D. Manisa Merkezefendi Hospital , Department of Pediatrics Division of Neonatology , Manisa , Turkey
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Nuttall FQ, Almokayyad RM, Gannon MC. The ghrelin and leptin responses to short-term starvation vs a carbohydrate-free diet in men with type 2 diabetes; a controlled, cross-over design study. Nutr Metab (Lond) 2016; 13:47. [PMID: 27453716 PMCID: PMC4957917 DOI: 10.1186/s12986-016-0106-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 07/13/2016] [Indexed: 02/05/2023] Open
Abstract
Background We recently have reported the 24-hour glucose, insulin and glucagon responses to a 72-hour fast compared to a 72-hour macronutrient-sufficient, carbohydrate-free diet in men with type 2 diabetes. The 72-hour time period was used because it is the time required for the major metabolic adjustments to a lack of food to be instituted. As part of that study, ghrelin and leptin responses were monitored. Methods Twenty-four-hour total ghrelin and overnight fasting leptin concentrations were determined in males with type 2 diabetes when ingesting a standard, mixed meal diet (control), followed by a carbohydrate-free diet for 72 h or were starved for 72 h, using a crossover design. Results A rise in ghrelin concentration before and a decrease after meals was present when the standard diet was ingested. However, in contrast to literature reports in normal subjects, a circadian variation was not apparent. Meal related changes were absent with starvation. A carbohydrate-free diet resulted in a daylong decrease in ghrelin. It also resulted in a 19 % decrease in the overnight fasting leptin concentration. Leptin was decreased 54 % with total starvation. Conclusion Ingestion of a typical mixed-meal diet results in meal-related changes in ghrelin similar to those reported in normal subjects, although the circadian rhythm was not apparent. Except for the lack of meal-related changes, starvation did not change the concentration. A carbohydrate-free, high fat diet resulted in a daylong suppression of ghrelin. The leptin concentration was decreased by both the carbohydrate-free diet and starvation. Trial registration ClinicalTrials.gov Identifier: NCT01469104.
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Affiliation(s)
- Frank Quentin Nuttall
- Section of Endocrinology, Metabolism & Nutrition, and the Metabolic Research Laboratory (111G), Minneapolis VA Health Care System, 1 Veterans Drive, Minneapolis, MN 55417 USA ; Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, 516 Delaware Street, SE, MMC 101, Minneapolis, MN 55455 USA
| | - Rami Mahmoud Almokayyad
- Section of Endocrinology, Metabolism & Nutrition, and the Metabolic Research Laboratory (111G), Minneapolis VA Health Care System, 1 Veterans Drive, Minneapolis, MN 55417 USA ; Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, 516 Delaware Street, SE, MMC 101, Minneapolis, MN 55455 USA ; Present address: Park Nicollet Health Care System, Minneapolis, MN USA
| | - Mary Carol Gannon
- Section of Endocrinology, Metabolism & Nutrition, and the Metabolic Research Laboratory (111G), Minneapolis VA Health Care System, 1 Veterans Drive, Minneapolis, MN 55417 USA ; Department of Medicine, Division of Diabetes, Endocrinology and Metabolism, University of Minnesota, 516 Delaware Street, SE, MMC 101, Minneapolis, MN 55455 USA ; Department of Food Science & Nutrition, University of Minnesota, 1334 Eckles Avenue, St Paul, MN 55108 USA
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Khodyrev DS, Nikitin AG, Brovkin AN, Lavrikova EY, Lebedeva NO, Vikulova OK, Shamkhalova MS, Shestakova MV, Nosikov VV, Averyanov AV. Association of polymorphisms of the ADIPOQ, ADIPOR1 and ADIPOR2 genes with type 2 diabetes mellitus. DIABETES MELLITUS 2015. [DOI: 10.14341/dm201525-11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The study of hereditary predisposition to multifactorial diseases is essential for diagnosis and selection of the optimal treatment. The study of polymorphisms of candidate genes whose products are involved in the pathogenesis of multifactorial diseases is of great clinical importance. Aim. The aim of this study was to investigate the association of rs2241766 and rs1501299 polymorphisms in the ADIPOQ gene, rs2275737 and rs2275738 polymorphisms in the ADIPOR1 gene and rs11061971 and rs16928751 polymorphisms in the ADIPOR2 gene with the development of type 2 diabetes mellitus (T2DM) in the Russian population. Materials and methods. The study included a group of 500 patients with T2DM diagnosed based on standard diagnostic criteria (T2DM+). The control group (T2DM-) was a random sample of 500 patients with no evidence of the disease and was matched to the T2DM+ group for gender, age and body mass index. The determination of alleles and genotypes was performed using real-time polymerase chain reaction with TaqMan probes. The X2 test and contingency tables were used to compare the distribution of allele and genotype frequencies. A p-value of
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Japur CC, Diez-Garcia RW, de Oliveira Penaforte FR, de Sá MFS. Imbalance Between Postprandial Ghrelin and Insulin Responses to an Ad Libitum Meal in Obese Women With Polycystic Ovary Syndrome. Reprod Sci 2014; 21:1020-1026. [PMID: 24520086 DOI: 10.1177/1933719114522521] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Obese women with polycystic ovary syndrome (PCOS) may have impairment in the regulation of food intake associated with ghrelin and insulin. In order to compare postprandial ghrelin and insulin responses to an ad libitum meal, we assessed 30 obese women with PCOS and 23 obese women without PCOS (control group). Blood samples were taken under fasting conditions, preprandially, and 15, 45, 75, and 135 minutes after the beginning of an ad libitum meal and ghrelin and insulin concentrations were analyzed. Insulin resistance (IR) was classified using basal insulin, quantitative insulin sensitivity check index, and homeostasis model assessment index. Mean ad libitum food intake was similar between the groups (468 ± 150 vs 444 ± 165 g, P = .60). The IR was found in 56.6% in PCOS group compared with 30.4% in the control group (P < .01). The postprandial ghrelin response was similar in both the groups but the insulin area under the curve (AUC) tend to be greater in the PCOS group (12807 ± 8149.4 vs 8654.4 ± 7232.3 μIU/mL/min; P = .057). The ghrelin AUC was negatively correlated with the insulin AUC (r = -.5138; P = .01) only in the control group. The imbalance in the feedback mechanisms between insulin and ghrelin, present in obese women, especially those with IR, may affect food intake throughout the day and that could be a mechanism for the development of obesity in PCOS.
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Affiliation(s)
- Camila Cremonezi Japur
- Department of Gynecology and Obstetrics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil Laboratory of Eating Practices and Behavior (PratiCA), Course of Nutrition and Metabolism, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Rosa Wanda Diez-Garcia
- Laboratory of Eating Practices and Behavior (PratiCA), Course of Nutrition and Metabolism, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
| | - Fernanda Rodrigues de Oliveira Penaforte
- Laboratory of Eating Practices and Behavior (PratiCA), Course of Nutrition and Metabolism, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil Department of Nutrition, Institute of Health Sciences, Federal University of Triângulo Mineiro, Uberaba, Brazil
| | - Marcos Felipe Silva de Sá
- Department of Gynecology and Obstetrics, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, Brazil
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The effect of the intracerebroventricular injection of Ghrelin agonist on diabetes type 2 disease in male wistar rats. Int J Diabetes Dev Ctries 2013. [DOI: 10.1007/s13410-013-0165-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Brownley KA, Heymen S, Hinderliter AL, Galanko J, Macintosh B. Low-glycemic load decreases postprandial insulin and glucose and increases postprandial ghrelin in white but not black women. J Nutr 2012; 142:1240-5. [PMID: 22649264 DOI: 10.3945/jn.111.146365] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Alterations in appetite hormones favoring increased postprandial satiety have been implicated in both the glycemic control and potential weight-loss benefits of a low-glycemic diet. Racial differences exist in dietary glycemic load and appetite hormone concentrations. This study examined the impact of glycemic load on appetite hormones in 20 black women [10 normal weight, BMI = 22.8 ± 1.42 (mean ± SD); 10 obese, BMI = 35.1 ± 2.77] and 20 white women (10 normal weight, BMI = 22.9 ± 1.45; 10 obese, BMI = 34.3 ± 2.77). Each woman completed two 4.5-d weight-maintenance, mixed-macronutrient, high-glycemic vs. low-glycemic load diets that concluded with a test meal of identical composition. Blood samples collected before and serially for 3 h after each test meal were assayed for plasma ghrelin and serum insulin and glucose concentrations. Compared with the high-glycemic load meal, the low-glycemic load meal was associated with lower insulin(AUC) (P = 0.02), glucose(AUC) (P = 0.01), and urge to eat ratings (P = 0.05) but with higher ghrelin(AUC) (P = 0.008). These results suggest the satiating effect of a low-glycemic load meal is not directly linked to enhanced postprandial suppression of ghrelin. Notably, these effects were significant among white but not black women, suggesting that black women may be less sensitive than white women to the glucoregulatory effects of a low-glycemic load. These findings add to a growing literature demonstrating racial differences in postprandial appetite hormone responses. If reproducible, these findings have implications for individualized diet prescription for the purposes of glucose or weight control in women.
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Affiliation(s)
- Kimberly A Brownley
- Department of Psychiatry, University of North Carolina, Chapel Hill, NC, USA.
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8
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Moran TH, Dailey MJ. Intestinal feedback signaling and satiety. Physiol Behav 2011; 105:77-81. [PMID: 21315751 DOI: 10.1016/j.physbeh.2011.02.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 01/28/2011] [Accepted: 02/01/2011] [Indexed: 01/18/2023]
Abstract
Peptidergic and neural signals arising from the presence of food in the gastrointestinal track provide feedback signals to the brain about the nature and quantity of consumed nutrients. Peptide secreting cells are differentially distributed along the gastrointestinal tract. How ingested nutrients activate or inhibit peptide secretion is complex and depends upon local, hormonal and neural mechanisms. The mode of action of the various peptides is equally complex involving endocrine, paracrine and neurocrine signaling. The success of bariatric surgical approaches to obesity treatment is secondary to alterations in gastrointestinal feedback signaling and roles of increased secretion of lower gut peptides such as peptide YY (PYY) and glucagon like peptide 1 (GLP-1) in mediating the superior effects of Roux-en-Y gastric bypass (RYGB) surgery are becoming evident. Direct nutrient delivery to jejunal sites that models the site of gastric-jejunal anastamosis in RYGB is especially effective at inhibiting food intake. Such infusions also stimulate the release of lower gut peptides suggesting a role for increased gut peptide signaling in sustaining such feeding inhibitions. Thus, gut peptides are clear targets for future obesity therapeutic developments.
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Affiliation(s)
- Timothy H Moran
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Ross 618, 720 Rutland Ave., Baltimore, MD 21205, United States.
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Brownley KA, Heymen S, Hinderliter AL, MacIntosh B. Effect of glycemic load on peptide-YY levels in a biracial sample of obese and normal weight women. Obesity (Silver Spring) 2010; 18:1297-303. [PMID: 19875990 PMCID: PMC5776013 DOI: 10.1038/oby.2009.368] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Black women suffer a disproportionately higher rate of obesity than their white counterparts. Reasons for this racial disparity may reflect underlying differences in the appetite suppressing peptide-YY (PYY). The PYY response to food is differentially influenced by macronutrient content but the effect of glycemic load on PYY response is unknown. This study examined whether glycemic load influences fasting and postprandial PYY levels and whether fasting and postprandial PYY levels are lower in obese black women compared to normal weight black women and to white women. Data were collected from 40 women (20 black, 20 white; 10 each normal weight vs. obese) at the University of North Carolina Clinical and Translational Research Center (CTRC). Participants completed in counterbalanced order two 4(1/2)-day weight-maintenance, mixed macronutrient high vs. low glycemic load diets followed by a test meal of identical composition. Total PYY levels were assessed before and after each test meal. Results show no differences in fasting PYY levels but significantly less postprandial PYY area under the curve (PYY(AUC)) in the group of obese black women compared to each other group (race x obesity interaction, P < 0.04). PYY(AUC) was positively related to insulin sensitivity (P < 0.004) but was not affected by glycemic load (main and interactive effects, P > 0.27). These findings indicate that postprandial PYY secretion is not affected by glycemic load but is blunted in obese black women compared with normal weight black women and with white women; additionally, they begin to address whether blunted PYY secretion contributes uniquely to the pathogenesis of obesity in black women.
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Affiliation(s)
- Kimberly A Brownley
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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Plasma ghrelin levels and polymorphisms of ghrelin gene in Chinese obese children and adolescents. Ir J Med Sci 2010; 179:345-9. [PMID: 20517652 DOI: 10.1007/s11845-010-0494-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 05/03/2010] [Indexed: 10/19/2022]
Abstract
AIM To evaluate the role of fasting plasma ghrelin levels [ln(ghrelin)] and polymorphisms of ghrelin gene in Chinese obese children. METHODS Genotyping for ghrelin polymorphism was performed in 230 obese and 100 normal weight children. Among them, plasma ghrelin levels were measured in 91 obese and 23 health subjects. RESULTS (1) Bivariate correlation analysis showed the ln(ghrelin) was inversely correlated with abnormality of glucose metabolism (r = -0.240, P = 0.023). Stepwise multiple regression analysis showed that abnormality of glucose metabolism was an independent determinant of plasma ghrelin levels (P = 0.023). (2) There was no difference in frequency of Leu72Met polymorphisms between obese and control groups (36.09 vs. 41.00%). CONCLUSION Ghrelin is associated with obesity in childhood, especially associated with the glucose homeostasis. Lower ghrelin levels might be a result of obesity, but not a cause of obesity. The Leu72Met polymorphism of ghrelin gene is not associated with obesity and metabolic syndrome in Chinese children.
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The effect of ingested macronutrients on postprandial ghrelin response: a critical review of existing literature data. INTERNATIONAL JOURNAL OF PEPTIDES 2010; 2010. [PMID: 20798765 PMCID: PMC2925100 DOI: 10.1155/2010/710852] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 10/10/2009] [Accepted: 12/14/2009] [Indexed: 01/12/2023]
Abstract
Ghrelin is a powerful orexigenic gut hormone with growth hormone releasing activity. It plays a pivotal role for long-term energy balance and short-term food intake. It is also recognized as a potent signal for meal initiation. Ghrelin levels rise sharply before feeding onset, and are strongly suppressed by food ingestion. Postprandial ghrelin response is totally macronutrient specific in normal weight subjects, but is rather independent of macronutrient composition in obese. In rodents and lean individuals, isoenergetic meals of different macronutrient content suppress ghrelin to a variable extent. Carbohydrate appears to be the most effective macronutrient for ghrelin suppression, because of its rapid absorption and insulin-secreting effect. Protein induces prolonged ghrelin suppression and is considered to be the most satiating macronutrient. Fat, on the other hand, exhibits rather weak and insufficient ghrelin-suppressing capacity. The principal mediators involved in meal-induced ghrelin regulation are glucose, insulin, gastrointestinal hormones released in the postabsorptive phase, vagal activity, gastric emptying rate, and postprandial alterations in intestinal osmolarity.
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Rudovich N, Möhlig M, Otto B, Pivovarova O, Spranger J, Weickert MO, Pfeiffer AFH. Effect of meglitinides on postprandial ghrelin secretion pattern in type 2 diabetes mellitus. Diabetes Technol Ther 2010; 12:57-64. [PMID: 20082586 DOI: 10.1089/dia.2009.0129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
BACKGROUND A progressive weight gain is associated with various pharmacological options improving glycemic control in type 2 diabetes mellitus (T2DM). Ghrelin has been implicated in the regulation of feeding behavior and energy balance in humans. Based on evidence that functional ATP-sensitive channels are present in ghrelin-producing cells, we hypothesized that meglitinides may affect circulating ghrelin levels in subjects with type 2 diabetes. METHODS In a single-blinded randomized three-period crossover study (n = 20), repaglinide or nateglinide was given in combination with metformin for two treatment periods over a 1-week period, respectively, separated by a 1-week treatment with placebo. Liquid meal challenge tests (LMCTs) with single preprandial doses of repaglinide (2 mg), nateglinide (120 mg), or placebo were performed at the end of each treatment period. Ten control subjects without diabetes underwent a single LMCT without any medication. RESULTS Fasting ghrelin concentrations were not different between all treatments and between patients with diabetes and control subjects. Subjects with T2DM treated with placebo showed no suppression of ghrelin in the LMCT. After administration of meglitinides a nadir of serum ghrelin was observed at 60 min (8.6% of baseline [P = 0.038] for repaglinide and 7.5% of baseline [P = 0.081] for nateglinide), which was similar to the secretion pattern seen in control subjects. No correlations between postprandial insulin or glucose levels and circulating ghrelin concentrations were observed. CONCLUSIONS Treatment with meglitinides reconstructed postprandial ghrelin secretion patterns to those of controls without diabetes. This observation may help to improve the control of feeding behavior in patients with T2DM.
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Affiliation(s)
- Natalia Rudovich
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, 14558 Nuthetal, Germany.
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Guo ZF, Ren AJ, Zheng X, Qin YW, Cheng F, Zhang J, Wu H, Yuan WJ, Zou L. Different responses of circulating ghrelin, obestatin levels to fasting, re-feeding and different food compositions, and their local expressions in rats. Peptides 2008; 29:1247-54. [PMID: 18400333 DOI: 10.1016/j.peptides.2008.02.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 02/24/2008] [Accepted: 02/26/2008] [Indexed: 02/06/2023]
Abstract
Obestatin, a sibling of ghrelin derived from preproghrelin, opposes several physiological actions of ghrelin. Our previous study has demonstrated that both plasma ghrelin and obestatin levels were decreased significantly 2h after food intake in human. To further expand current knowledge, we investigated the temporal profiles of their levels in ad libitum fed rats, 48h fasted rats and 48h fasted rats refed 2h with a standard chow, crude fiber, 50% glucose or water, and their expressions in stomach, liver and pancreatic islets immunohistochemically. Plasma ghrelin and obestatin levels were measured by EIA. Plasma leptin, insulin and glucose levels were also evaluated. Both plasma ghrelin and obestatin levels increased significantly in fasted rats compared with ad libitum fed rats. The ingestion of standard chow produced a profound and sustained suppression of ghrelin levels, whereas plasma obestatin levels decreased significantly but recovered quickly. Intake of crude fiber or 50% glucose, however, produced a more profound and sustained suppression of obestatin levels, though they had relatively less impact on ghrelin levels. Plasma glucose was the only independent predictor of ghrelin levels, obestatin levels, and ghrelin to obestatin ratios. Obestatin immunoreactivity was detected in the fundus of stomach, liver and pancreatic islets, with roughly similar patterns of distribution to ghrelin. These data show quantitative and qualitative differences in circulating ghrelin and obestatin responses to the short-term feeding status and nutrient composition, and may support a role for obestatin in regulating metabolism and energy homeostasis.
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Affiliation(s)
- Zhi-Fu Guo
- Department of Cardiovascular Diseases, Changhai Hospital, Second Military Medical University, Shanghai 200433, China.
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Weickert MO, Loeffelholz CV, Arafat AM, Schöfl C, Otto B, Spranger J, Möhlig M, Pfeiffer AF. Euglycemic hyperinsulinemia differentially modulates circulating total and acylated-ghrelin in humans. J Endocrinol Invest 2008; 31:119-24. [PMID: 18362502 DOI: 10.1007/bf03345577] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ghrelin is a powerful orexigenic gut hormone. Circulating concentrations of total ghrelin are downregulated by food intake in both acute and chronic hyperinsulinemic states. However, in blood des-acylated (des-acyl) ghrelin is the predominant form that has no orexigenic effects in humans. Circulating acyl-ghrelin has been shown to be suppressed post-prandially and by pharmacological hyperinsulinemia. However, up to now responses of circulating acyl-ghrelin to moderate hyperinsulinemic and hyperinsulinemic-hyperlipidemic clamp conditions have not been reported. Fourteen healthy subjects were investigated using two-stepped euglycemic-hyperinsulinemic clamps (40 mU insulin/ m2/min; mean 148+/-7 min till steady state, followed by 300 min lipid/heparin infusion). Responses of total ghrelin and acyl-ghrelin were measured at timed intervals throughout the clamps. Des-acyl-ghrelin concentrations were calculated by subtraction. Total ghrelin significantly decreased vs baseline concentrations (819+/-92 vs 564+/-58 pg/ml, p<0.001), thereby confirming previous observations. Des-acyl ghrelin closely followed total ghrelin concentrations and significantly decreased vs baseline (772+/-92 vs 517+/-56 pg/ml, p<0.001). In contrast, neither euglycemichyperinsulinemia nor euglycemic-hyperinsulinemic- hyperlipidemia suppressed acyl-ghrelin below baseline concentrations throughout the clamps (46+/-3 vs 47+/-8 pg/ml, p=0.90). In conclusion, moderate hyperinsulinemic and hyperinsulinemic- hyperlipidemic clamp conditions differentially modulated circulating total ghrelin and acylghrelin in humans. Factors other than changes in insulin and lipid concentrations are likely to contribute to the previously reported post-prandial reduction of circulating acyl-ghrelin.
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Affiliation(s)
- M O Weickert
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany.
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Abstract
The appetite-modulating peptide ghrelin is predominantly produced and secreted by the stomach and shows a strong growth hormone-releasing activity, which is mediated by the activation of the so-called growth hormone secretagogue type 1a receptor. Ghrelin is involved in the regulation of energy balance by increasing food intake and reducing fat utilization. Additionally, it stimulates lactotroph and corticotroph function, influences the pituitary gonadal axis, inhibits pro-inflammatory cytokine expression, controls gastric motility and acid secretion and influences pancreatic exocrine and endocrine function, as well as impacting on glucose metabolism. This review summarizes the known functions of ghrelin and its role in the regulation of the gut–brain axis.
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Affiliation(s)
- Bärbel Otto
- Medical Department--Innenstadt, University Hospital Munich, Germany.
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16
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Heinonen MV, Karhunen LJ, Chabot ED, Toppinen LK, Juntunen KS, Laaksonen DE, Siloaho M, Liukkonen KH, Herzig KH, Niskanen LK, Mykkänen HM. Plasma ghrelin levels after two high-carbohydrate meals producing different insulin responses in patients with metabolic syndrome. ACTA ACUST UNITED AC 2007; 138:118-25. [PMID: 17030069 DOI: 10.1016/j.regpep.2006.08.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2006] [Revised: 08/31/2006] [Accepted: 08/31/2006] [Indexed: 11/23/2022]
Abstract
Ghrelin is an orexigenic peptide produced in the stomach and its plasma levels are decreased acutely in response to ingested nutrients. To further clarify the role of insulin on ghrelin secretion, the present study was designed to investigate whether circulating ghrelin is affected differently by two mixtures of whole-grain breads known to produce low or high insulin responses in obese non-diabetic subjects with metabolic syndrome. After an overnight fast eight obese subjects with the metabolic syndrome (3 men and 5 women; BMI 33.7+/-0.7 kg/m(2); age 55.6+/-1.8 y) received two different meals consisting of whole-grain rye or wheat breads. The comparison group (3 men and 5 women; BMI 22.5+/-0.5 kg/m(2); age 26.0+/-0.9 y) received a wheat bread meal. Blood samples were collected postprandially at time intervals for 2 h. Feelings of hunger and satiety were analyzed using the visual analogue scales. Ghrelin concentrations decreased after bread meals in lean individuals, but not in obese individuals with the metabolic syndrome. Despite the difference in plasma insulin response, there was no difference in plasma ghrelin or feelings of hunger and satiety in patients with metabolic syndrome. After both rye and wheat bread meals, the decrease in ghrelin concentrations seen in normal-weight individuals after wheat bread meal was absent in subjects with metabolic syndrome. Despite the different plasma insulin response in obese patients, ghrelin levels did not change in response to either type of bread meals. In addition, ghrelin levels did not correlate with insulin, glucose, HOMA1-IR and satiety and hunger ratings in either study groups. This indicates that regulation of ghrelin might be altered in obese patients with metabolic syndrome independently of insulin.
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Affiliation(s)
- Miika V Heinonen
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, Finland
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17
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Prodam F, Me E, Riganti F, Gramaglia E, Bellone S, Baldelli R, Rapa A, van der Lely AJ, Bona G, Ghigo E, Broglio F. The nutritional control of ghrelin secretion in humans: the effects of enteral vs. parenteral nutrition. Eur J Nutr 2006; 45:399-405. [PMID: 17061019 DOI: 10.1007/s00394-006-0613-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Accepted: 08/02/2006] [Indexed: 11/27/2022]
Abstract
BACKGROUND The nutritional control of ghrelin has not been fully clarified yet. Particularly, the influence of aminoacids and lipids is controversial and, moreover, whether the intraluminal gastric contact with nutrients is required or if the modulatory action of nutrients on ghrelin secretion is mediated by insulin is still matter of debate. AIM OF THE STUDY To clarify the role of nutrients in the control of ghrelin secretion evaluating the effects of intravenous and oral lipids and aminoacids compared with glucose and fructose load in healthy subjects. METHODS A total of 6 healthy overnight-fasted volunteers underwent the following testing sessions: (a) iv arginine (ARG, 0.5 g/kg); (b) oral protein load (PRO, 50 g); (c) iv lipid-heparin infusion (Li He, Intralipid 10% 250 ml); (d) oral fat load (OIL, soy oil 40 g); (e) oral glucose load (OGL, 100 g); (f) oral fructose load (OFL, 100 g); (g) iv saline (SAL, 3 ml); (h) oral water load (WL, 200 ml). Total ghrelin, insulin, and glucose were assayed every 15 min from 0 up to +180 min. RESULTS WL and SAL did not modify insulin, glucose and ghrelin. ARG induced a prompt but transient increase (P < 0.05) of insulin and glucose (P < 0.01), without modifying ghrelin secretion. PRO induced a mild but sustained increase of insulin secretion (P < 0.05) without affecting glucose and ghrelin. Li-He progressively increased circulating glucose (P < 0.01) without modifying insulin and ghrelin secretion. No significant variations in circulating glucose, insulin, and ghrelin occurred after OIL. OGL significantly (P < 0.01) increased insulin and glucose levels and progressively decreased (P < 0.05) ghrelin levels. OFL induced a mild (P < 0.05) increase of insulin without modifying glucose levels. Similarly, OFL was followed by a milder decrease (P < 0.05) of ghrelin levels. CONCLUSIONS Differently from carbohydrates and independently from their modulatory effect on insulin secretion and glucose levels, both lipids and aminoacids play a negligible role in the acute control of ghrelin secretion either after acute enteral and parenteral administration.
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Affiliation(s)
- Flavia Prodam
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Turin, c.so Dogliotti, 14 Turin, Italy
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18
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Laferrère B, Hart AB, Bowers CY. Obese subjects respond to the stimulatory effect of the ghrelin agonist growth hormone-releasing peptide-2 on food intake. Obesity (Silver Spring) 2006; 14:1056-63. [PMID: 16861611 PMCID: PMC2824649 DOI: 10.1038/oby.2006.121] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE The administration of the growth hormone (GH) secretagogue GH-releasing peptide (GHRP)-2, like ghrelin, increases food intake (FI) in lean healthy men. The aim of this study was to investigate whether this effect occurs in obese subjects and whether it is dose-dependent. RESEARCH METHODS AND PROCEDURES Nineteen subjects (10 lean and nine obese), all healthy and weight stable, received a double-blind randomized subcutaneous infusion of GHRP-2 at high dose (HD; 1 mug/kg per hour), low dose (0.1 microg/kg per hour), or placebo for 270 minutes over three study visits. Blood for hormone assays was collected through an intravenous forearm catheter. Hunger and fullness were rated on visual analog scales before and after a fixed breakfast (320 kcal at 120 minutes) and a buffet lunch at 240 minutes. Before lunch, subjects received taped instructions to eat as much as they wanted. RESULTS GHRP-2 infusion significantly increased ad libitum FI in a dose-dependent manner by 10.2 +/- 3.9% at low dose (p = 0.011) and by 33.5 +/- 5.8% at HD (p = 0.000) compared with placebo. Obesity status did not influence the effect of GHRP-2 on FI. All subjects had greater ratings of appetite before but similar levels of fullness after the meal with the HD GHRP-2. Serum GH levels increased dose dependently in all subjects. DISCUSSION The dual stimulatory effect of GHRP-2 on FI and human GH is dose dependent. Obese individuals retain their ability to respond to GHRP-2 both in terms of FI and human GH.
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Affiliation(s)
- Blandine Laferrère
- Obesity Research Center, St. Luke's Roosevelt Hospital Center, New York, NY 10025, USA.
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19
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Tritos NA, Kokkotou EG. The physiology and potential clinical applications of ghrelin, a novel peptide hormone. Mayo Clin Proc 2006; 81:653-60. [PMID: 16706263 DOI: 10.4065/81.5.653] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Ghrelin, a peptide hormone originally identified as the endogenous ligand of the growth hormone secretagogue receptor, is secreted primarily from the stomach and secondarily from the small intestine and colon. Ghrelin may also be expressed in the pancreatic islets, hypothalamus, pituitary, and several tissues in the periphery. The growth hormone secretagogue receptor is widely expressed, suggesting diverse physiologic roles for ghrelin. A growing body of evidence suggests that, in addition to its predictable effect on growth hormone secretion, ghrelin has an important role in the short-term regulation of appetite and the long-term regulation of energy balance and glucose homeostasis. Recent studies have implicated ghrelin in the regulation of gastrointestinal, cardiovascular, and immune function and have suggested a role for ghrelin in bone physiology. The identification of obestatin, a novel peptide hormone derived from the same gene as ghrelin, has recently added further complexity to ghrelin physiology. Obestatin appears to have actions opposite of ghrelin on energy homeostasis and gastrointestinal function. Despite the rapid progress, many questions remain unanswered, including the regulation of ghrelin and obestatin secretion, the downstream pathways that mediate their effects, and their precise physiologic endocrine and paracrine roles. This review presents data on ghrelin structure, expression, and function, with emphasis placed on human studies, highlighting areas that require future investigation and providing speculation about potential clinical applications of ghrelin agonists or antagonists.
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Affiliation(s)
- Nicholas A Tritos
- Department of Endocrinology, Lahey Clinic Medical Center, Burlington, MA 01805, USA.
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Perez-Tilve D, Nogueiras R, Mallo F, Benoit SC, Tschoep M. Gut hormones ghrelin, PYY, and GLP-1 in the regulation of energy balance [corrected] and metabolism. Endocrine 2006; 29:61-71. [PMID: 16622293 DOI: 10.1385/endo:29:1:61] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2005] [Revised: 11/30/1999] [Accepted: 11/15/2005] [Indexed: 02/07/2023]
Abstract
The first hormone discovered in the gastrointestinal tract was secretin, isolated from duodenal mucosa. Some years later, two additional gastrointestinal hormones, gastrin and cholecystokinin (CCK), were discovered, but it was not until the 1970s that gastrointestinal endocrinology studies became more prevalent, resulting in the discovery of many more hormones. Here, we examine the role of gut hormones in energy balance regulation and their possible use as pharmaceutical targets for obesity.
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Affiliation(s)
- Diego Perez-Tilve
- Department of Psychiatry, University of Cincinnati Genome Research Institute, Cincinnati, OH 45237, USA
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21
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Maffeis C, Bonadonna RC, Consolaro A, Vettor R, Banzato C, Silvagni D, Bogoni G, Pellegrino M, Tatò L. Ghrelin, insulin sensitivity and postprandial glucose disposal in overweight and obese children. Eur J Endocrinol 2006; 154:61-8. [PMID: 16381992 DOI: 10.1530/eje.1.02055] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
OBJECTIVE To explore the changes of ghrelin circulating levels induced by a mixed meal and their relationship with postprandial substrate oxidation rates in overweight and obese children with different levels of insulin sensitivity. METHODS A group of ten boys (age 9-12 years) with different levels of overweight (standard deviation score of body mass index: 1.6-3.2) was recruited. Body composition was measured by dual-energy X-ray absorptiometry. Insulin sensitivity was assessed by a frequently sampled i.v. glucose tolerance test. Pre-prandial and postprandial (3 h) substrate oxidation was measured by indirect calorimetry. The energy content of the test meal (16% protein, 36% carbohydrate and 48% fat) was 40% of pre-prandial energy expenditure (kJ/day). RESULTS Pre-prandial serum concentration of total ghrelin was 701.4+/-66.9 pg/ml (S.E.M.). The test meal induced a rapid decrease in ghrelin levels and maximal decrease was 27.3+/-2.7% below baseline. Meal intake induced a progressive increase of the carbohydrate oxidation rate for 45 min after food ingestion, followed by a slow decrease without returning to pre-prandial values. Postprandial cumulative carbohydrate oxidation was 16.9+/-0.8 g/3 h. Insulin sensitivity and postprandial maximal decrease of ghrelin concentration showed a significant correlation (r = 0.803, P < 0.01). Moreover, the postprandial carbohydrate oxidation rate correlated with the area under the curve for both insulin (r = 0.673, P < 0.03) and ghrelin (r = -0.661, P < 0.04). CONCLUSIONS A relevant association between postprandial insulin-mediated glucose metabolism and ghrelin secretion in children with different levels of overweight was found. It is possible that the maintenance of an adequate level of insulin sensitivity and glucose oxidation may affect appetite regulation by favoring a more efficient postprandial ghrelin reduction.
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Affiliation(s)
- Claudio Maffeis
- Department of Mother and Child, Biology-Genetics, Unit of Pediatrics, University of Verona, P. le L.A. Scuro 10, 37 134 Verona, Italy.
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Rudovich NN, Dick D, Moehlig M, Otto B, Spranger J, Rochlitz HJ, Ristow M, Tschoep M, Pfeiffer AFH. Ghrelin is not suppressed in hyperglycemic clamps by gastric inhibitory polypeptide and arginine. ACTA ACUST UNITED AC 2005; 127:95-9. [PMID: 15680475 DOI: 10.1016/j.regpep.2004.10.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2004] [Revised: 10/19/2004] [Accepted: 10/27/2004] [Indexed: 02/07/2023]
Abstract
UNLABELLED Systemic ghrelin concentration falls rapidly after nutrient ingestion in vivo. The effect incretins on ghrelin secretion in humans remains unclear. We quantified circulating ghrelin concentrations under hyperglycemic conditions combined with infusion of gastric inhibitory polypeptide (GIP) and arginine. METHODS Eight healthy volunteers were studied with a hyperglycemic clamp followed by addition of GIP (2 pmol.kg(-1).min(-1), 60-115 min) and an arginine-bolus and -infusion (10 mg.kg(-1).min(-1), 90-115 min). RESULTS Hyperglycemia alone increased circulating insulin concentrations (p<0.01), and decreased ghrelin concentrations to 89.8% of basal (p=0.208). GIP-infusion resulted in circulating insulin concentration of 1109+/-942 pmol/l (p<0.02) and no further decrease of ghrelin (86.2% of baseline, p=0.050). Under arginine- and GIP-infusion together, insulin concentrations increased progressively to 3005+/-1604 pmol/l (p<0.01) without further decreasing in ghrelin concentrations (98.9% of baseline, p=0.575). CONCLUSIONS Hyperglycemic hyperinsulinemia and further increases of hyperinsulinemia to supraphysiological and high supraphysiological concentrations under GIP- and arginine-infusion do not significantly decrease ghrelin concentrations in healthy subjects. Moreover, there is no dose-dependent suppression of ghrelin by insulin in the hyperglycemic condition. Neither GIP nor arginine affected ghrelin release.
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Affiliation(s)
- Natalia N Rudovich
- Department of Clinical Nutrition, German Institute of Human Nutrition Potsdam-Rehbrücke, Arthur-Scheunert-Street 114-116, 14558 Nuthetal, Germany
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23
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Poppitt SD, Leahy FE, Keogh GF, Wang Y, Mulvey TB, Stojkovic M, Chan YK, Choong YS, McArdle BH, Cooper GJS. Effect of high-fat meals and fatty acid saturation on postprandial levels of the hormones ghrelin and leptin in healthy men. Eur J Clin Nutr 2005; 60:77-84. [PMID: 16118648 DOI: 10.1038/sj.ejcn.1602270] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE Ghrelin and leptin play a role in control of food intake and adiposity but mechanisms regulating these hormones in man are poorly defined and evidence that dietary fats may have adverse effects is inconclusive. We investigated whether high-fat meals, which differed in saturated fatty acid (SFA) content acutely modified these hormones. DESIGN Randomised, double-blind, crossover trial. A high-fat (HF) test meal (59 +/- 4 g fat; 71% of energy as fat) was given for breakfast on two occasions. Meals comprised either high (approximately 70:30) or low (approximately 55:45) saturated:unsaturated fatty acid (SFA:USFA) ratio. Fasting and postprandial measurements of serum total ghrelin (RIA), leptin (enzyme-linked immunosorbent assay (ELISA)) and insulin (RIA) were made over 6 h. Postprandial measurements were also made at 10 and 24 h following a fat-exclusion lunch, snack and dinner. SUBJECTS A total of 18 lean, healthy men. RESULTS There was no significant effect of the fatty meal (time, P > 0.05), nor a differential effect of SFA:USFA ratio (treatment*time, P > 0.05) on ghrelin over 6h. Leptin decreased in response to both HF treatments (time, P < 0.001) but increased SFA content did not further inhibit hormone secretion (treatment*time, P > 0.05). There was no significant correlation between ghrelin or leptin and circulating insulin (P>0.05). CONCLUSION We conclude that HF diets may adversely effect serum leptin, although the circadian decrease may account in part for this response. Increasing dietary SFAs had no deleterious effects on leptin or total ghrelin.
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Affiliation(s)
- S D Poppitt
- Human Nutrition & Metabolic Unit, University of Auckland, Auckland, New Zealand.
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Beck B, Max JP, Fernette B, Richy S. Adaptation of ghrelin levels to limit body weight gain in the obese Zucker rat. Biochem Biophys Res Commun 2004; 318:846-51. [PMID: 15147948 DOI: 10.1016/j.bbrc.2004.04.106] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2004] [Indexed: 11/25/2022]
Abstract
In this study, we measured the ghrelin, leptin, and insulin variations in lean and obese Zucker fa/fa rats during the acute phase of body weight gain. At 2 months of age, plasma insulin and leptin concentrations in fa/fa rats were, respectively, 470% and 3700% higher than in lean rats (p <0.0001). Plasma ghrelin was significantly lower (-24.6%; p <0.02) than in lean rats. At 6 months of age, ghrelin increased in both genotypes but the difference was no more significant. The inverse correlations existing between ghrelin and either body weight (BW), insulin or leptin at 2 months of age were no more observable in 6-month-old rats. At 6 months of age, the lean rats had the same body weight as the 2-month-old obese rats. In these body weight-matched rats, ghrelin was not correlated with BW but it remained negatively correlated with insulin and leptin. At the same body weight, obese rats had a much lower plasma ghrelin than lean rats (717+/-42 vs. 1754+/-83 pg/ml; p <0.0001). These data indicate that body composition rather than body weight is the primary factor for the down-regulation of the ghrelin system. This down-regulation constitutes a mechanism of defense of the organism against the development of obesity at least during the first part of life.
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Affiliation(s)
- Bernard Beck
- UHP/EA 3453-IFR 111-Systèmes Neuromodulateurs des Comportements Ingestifs-38, rue Lionnois, 54000 Nancy, France.
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