Visceral fat mass is a strong predictor of circulating ghrelin levels in premenopausal women

Time of day differences in appetite and gut hormone responses to meal and stress challenges in adults with normal-weight and obesity

BACKGROUND

. Lifestyle factors like time of eating and stress exposure may impact physiology to promote excess weight gain. To understand behavioral and physiological mechanisms underlying these potential effects, we compared appetite and gut hormone responses to a series of meal and stress challenges beginning in the morning and the afternoon, in adults with normal-weight and obesity.

METHOD

. Thirty-two adults (16 with normal-weight, 16 with obesity) underwent the same test protocol on different days, each following an 8 h fast. On one day the protocol began in the morning (AM condition); on the other day it began in the late afternoon (PM condition). On each day they first received a standardized liquid meal (9:00am/4:00pm), then a stress test (Socially-Evaluated Cold Pressor Test, 11:10am/6:10pm), then an ad libitum buffet meal (11:40am/6:40pm). Appetite and stress ratings were obtained, and blood was drawn for measures of ghrelin, PYY, GLP-1, insulin, glucose, cortisol and leptin. Acetaminophen was administered as a tracer to assess gastric emptying of the liquid meal.

RESULTS

. Across all three challenges, AUC cortisol was lower in the PM vs. AM condition (all p<.001), and AUC insulin and leptin were higher in the obesity vs. normal-weight group (all p<.001). For the standardized liquid meal only, AUC hunger, desire to eat and ghrelin were greater in the PM vs. AM condition (all p<0.05), and AUC ghrelin was lower in the obesity vs. normal-weight group, even when controlling for baseline values (p<0.05). AUC glucose was higher in the evening for the normal-weight group only (condition x group interaction p<0.05). Post-liquid meal gastric emptying as indexed by AUC acetaminophen was slower in the PM vs. AM (p<.01). For the stress test, AUC cortisol was lower in the PM than the AM condition even when controlling for baseline values (p<.05). AUC leptin was lower in the evening in the obesity group only (condition x group interaction p<0.01). PYY showed an acute decrease post-stressor in the normal-weight but not the obesity group (p<.05). Post-stress ad libitum buffet meal intake was similar in the evening and morning conditions, and higher in the obesity group (p<0.05). Only among the obesity group in the evening condition, higher stressor-associated stress ratings were associated with lesser fullness in relation to the buffet meal (p<0.05).

CONCLUSIONS

. Normal-weight individuals and those with obesity may be at risk of evening overeating as a result of differential appetite and gut hormone responses following meal intake and stress exposure.

The effect of acute exercise on pre-prandial ghrelin levels in healthy adults: A systematic review and meta-analysis

BACKGROUND

Ghrelin is a gut hormone with numerous physiological effects, including the regulation of energy balance, insulin sensitivity, vascular health, and body composition. Acylated (AG) and des-acylated (DAG) ghrelin constitute approximately 22 % and 78 % of total plasma ghrelin (TG), respectively. Alterations in the TG concentration and the AG/DAG ratio may be implicated in conditions involving energy imbalances and insulin resistant states (e.g., metabolic syndrome or Type 2 diabetes mellitus). Exercise is a therapeutic option that can potentially optimize ghrelin levels. Understanding the precise intensity and dose of exercise to optimize ghrelin levels may lead to targeted interventions to restore metabolic regulation in obesity and other clinical conditions.

OBJECTIVE

To perform a systematic review and meta-analysis on the effects of acute exercise on pre-prandial levels of TG, AG, and DAG in healthy adults and to determine if sample demographics or exercise doses moderate such effects.

METHODS

Electronic databases (PubMed, Medline, SPORTDiscus, Web of Science, and Google Scholar) were searched with articles published through August 2020. The following criteria was determined a priori for article inclusion: (i) the study was a randomized controlled trial (RCT),(ii) exercise was an acute bout, (iii) the exercise bout for the intervention group(s)/condition was structured, (iv) the control group/condition received no exercise, (v) participants were adults age 18 or older, (vi) ghrelin was sampled through blood, (vii) there was at least one baseline measure and one post-exercise measure of ghrelin, (viii) there were at least 3 timepoints where ghrelin was measured while participants were fasted to allow for pre-prandial total area-under-the-curve (AUC_total) calculation, (ix) participants were healthy with no overt disease, (x) interventions were carried out without any environmental manipulations. Standardized mean difference (SMD) with 95 % confidence intervals were calculated using the restricted maximum likelihood estimation Moderator analyses to determine whether the overall pooled effect was influenced by: sex, ghrelin form, method of ghrelin analysis, age, body mass index, body fat percentage, fitness, intensity of exercise bout, duration of exercise bout, energy expenditure, and length of AUC_total data.

RESULTS

The analysis included 24 studies that consisted of 52 trials, n = 504 (age 27.0 (8.8) years, BMI 24.7 (2.7) kg/m²) and measured AG (n = 38 trials), DAG (n = 7), and TG (n = 7). The overall model indicated that exercise lowered ghrelin levels compared to control (no exercise); (SMD=-0.44, p < 0.001), and exercise intensity exhibited an inverse relationship with ghrelin levels (regression coefficient (ß)=-0.016, p = 0.04). There was no significant difference by ghrelin form (p = 0.18).

DISCUSSION

Acute exercise significantly lowers plasma ghrelin levels, with higher intensity exercise associated with greater ghrelin suppression. The majority of studies applied a moderate intensity exercise bout and measured AG, with limited data on DAG. This exercise dose may be clinically significant in individuals with metabolic dysregulation and energy imbalance as a therapy to optimize AG levels. More work is needed to compare moderate and high intensity exercise and the ghrelin response in clinical populations.

Post-weight loss changes in fasting appetite- and energy balance-related hormone concentrations and the effect of the macronutrient content of a weight maintenance diet: a randomised controlled trial

PURPOSE

We investigated the effects of the macronutrient composition of diets with differing satiety values on fasting appetite-related hormone concentrations after weight loss and examined whether the hormone secretion adapted to changes in body fat mass (FM) and fat-free mass (FFM) during the weight maintenance period (WM).

METHODS

Eighty-two men and women with obesity underwent a 7-week very-low-energy diet (VLED) and were then randomised to a higher-satiety food (HSF) group or a lower-satiety food (LSF) group during 24-weeks of the WM. The groups consumed isoenergetic foods with different satiety ratings and macronutrient compositions.

RESULTS

During the WM, the HSF group consumed more protein and dietary fibre and less fat than the LSF group, but the groups showed similar changes in body weight and fasting appetite-related hormones. In the whole study sample, VLED induced 12 kg (p < 0.001) weight loss. At the end of the WM, weight regain was 1.3 kg (p = 0.004), ghrelin concentration increased, whereas leptin, insulin, and glucose concentrations decreased compared to pre-VLED levels (p < 0.001 for all). Peptide YY did not differ from pre-VLED levels. Changes in ghrelin levels were inversely associated with changes in FFM during weeks 0-12 of the WM (p = 0.002), while changes in leptin and insulin levels were positively associated with changes in FM during weeks 0-12 (p = 0.015 and p = 0.038, respectively) and weeks 12-24 (p < 0.001 and p = 0.022) of the WM.

CONCLUSIONS

The macronutrient composition of an isoenergetic WM diet did not affect fasting appetite-related hormone concentrations. Leptin and insulin adjusted to the reduced FM, whereas ghrelin reflected FFM during the first months of the WM.

TRIAL REGISTRATION

isrctn.com, ID 67529475.

Effects of 7-day intake of hydrogen-rich water on physical performance of trained and untrained subjects

Hydrogen-rich water (HRW) is used as a supplement to improve performance and reduce fatigue in athletes. However, the potentially beneficial effects of HRW intake could be mediated by the training status of athletes. The purpose of the study was to analyse the ergogenic effect of intake of HRW for one week on aerobic and anaerobic performance, both in trained and untrained individuals. Thirty-seven volunteers participated in the study and were divided into two experimental groups: trained cyclists and untrained subjects. A double-blind crossover design was performed in which all subjects took a placebo (PW) and nano-bubble HRW (pH: 7.5; hydrogen concentration: 1.9 ppm; oxidation-reduction potential (ORP): -600 mV). At the end of 7-day intake, performance was assessed by an incremental VO₂max test and by a maximum anaerobic test. After HRW intake, only trained cyclists improved their performance in the anaerobic test with an increase in peak power (from 766.2 ± 125.6 to 826.5 ± 143.4 W; d = .51) and mean power (from 350.0 ± 53.5 to 380.2 ± 71.3 W; d = .51), and a decrease in the fatigue index (from 77.6 ± 5.8 to 75.1 ± 5.9%; d = .45). The findings demonstrate that the ergogenic effect of HRW is mediated by the training status, and that 7-day intake of HRW would be an effective strategy for improving anaerobic performance in trained cyclists.

The Association Between Salivary Ghrelin Levels with Anthropometric Measures in Underweight, Normal, Overweight and Obese Healthy Adult Males

OBJECTIVES

The study aimed to measure salivary ghrelin levels in healthy adult males and investigate their association with age, weight, height, total as well as regional body fat and muscle mass. The study also aimed to investigate the relative contribution of body mass index (BMI), waist circumference (WC), hip circumference (HC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) in predicting salivary ghrelin levels in the studied groups.

METHODS

A sample of young adult males was divided into underweight, normal weight, overweight, and obese groups, according to their BMI. Standardised methods were used to measure height, WC and HC. Total body fat, visceral fat, subcutaneous fat, total and regional muscle mass were assessed by bioelectrical impedance technique utilising Karada scan. Salivary ghrelin concentrations were assessed using enzyme-linked immunosorbent assay.

RESULTS

A total of 90 adult males were included in the analysis (underweight n=9, normal weight n=41, overweight n=22, and obese n=18). One-way ANOVA test revealed significant differences among the groups in all of the variables except height and salivary ghrelin levels. Multiple linear regression revealed a significant association between salivary ghrelin levels with total fat, subcutaneous fat, visceral fat and muscle mass in the obese group. The analysis also revealed that BMI, WC, HC, WHR and WHtR were reliable predictors for salivary ghrelin levels in the obese group but not in other groups.

CONCLUSIONS

Anthropometric measures can be used as predictors for salivary ghrelin levels in healthy obese adults. However, they are poor predictors for salivary ghrelin levels in healthy lean, normal and overweight adults.

Exploration of associations between the FTO rs9939609 genotype, fasting and postprandial appetite-related hormones and perceived appetite in healthy men and women

BACKGROUND

The fat mass and obesity-associated gene (FTO) rs9939609 A-allele has been associated with obesity risk. Although the exact mechanisms involved remain unknown, the FTO rs9939609 A-allele has been associated with an impaired postprandial suppression of appetite.

OBJECTIVES

To explore the influence of FTO rs9939609 genotype on fasting and postprandial appetite-related hormones and perceived appetite in a heterogeneous sample of men and women.

DESIGN

112 healthy men and women aged 18-50-years-old completed three laboratory visits for the assessment of FTO rs9939609 genotype, body composition, aerobic fitness, resting metabolic rate, visceral adipose tissue, liver fat, fasting leptin, and fasting and postprandial acylated ghrelin, total PYY, insulin, glucose and perceived appetite. Participants wore accelerometers for seven consecutive days for the assessment of physical activity and sedentary behaviour. Multivariable general linear models quantified differences between FTO rs9939609 groups for fasting and postprandial appetite outcomes, with and without the addition of a priori selected physiological and behavioural covariates. Sex-specific univariable Pearson's correlation coefficients were quantified between the appetite-related outcomes and individual characteristics.

RESULTS

95% confidence intervals for mean differences between FTO rs9939609 groups overlapped zero in unadjusted and adjusted general linear models for all fasting (P ≥ 0.28) and postprandial (P ≥ 0.19) appetite-related outcomes. Eta² values for explained variance attributable to FTO rs9939609 were <5% for all outcomes. An exploratory correlation matrix indicated that associations between fasting and postprandial acylated ghrelin, total PYY and general or abdominal adiposity were also small (r = -0.23 to 0.15, P ≥ 0.09). Fasting leptin, glucose and insulin and postprandial insulin concentrations were associated with adiposity outcomes (r = 0.29 to 0.81, P ≤ 0.033).

CONCLUSIONS

Associations between the FTO rs9939609 genotype and fasting or postprandial appetite-related outcomes were weak in healthy men and women.

IgG Anti-ghrelin Immune Complexes Are Increased in Rheumatoid Arthritis Patients Under Biologic Therapy and Are Related to Clinical and Metabolic Markers

Rheumatoid arthritis (RA) is a systemic autoimmune disease associated with increased risk of cardiovascular disease and metabolic alterations. The mechanisms underlying these alterations remain unclear. Ghrelin is a gastrointestinal hormone with potent effects on food intake, body weight, metabolism, and immune response. Recent studies reported the presence of anti-ghrelin autoantibodies in healthy subjects and the levels and affinity of these autoantibodies were altered in anorectic and obese individuals. In this cross-sectional study we analyzed anti-ghrelin autoantibodies in RA patients and evaluated its relationship with clinical, body-composition and metabolic parameters. Clinical measurements of RA patients included the disease activity score-28 (DAS-28), inflammatory biomarkers, autoantibodies (RF and anti-CCP), body composition, glucose and lipid profile. Serum ghrelin levels were measured by enzyme-linked immunosorbent assay (ELISA). Free and total anti-ghrelin autoantibodies quantification (IgG and IgA isotypes) was performed by in-house ELISA. RA patients had lower IgG anti-ghrelin autoantibodies levels and higher immune complexes percentage (IgG+ghrelin) compared to the control group, while the IgA anti-ghrelin autoantibodies showed no significant differences. In the bivariate analysis, the percentage of IgG anti-ghrelin immune complexes positively correlated with BMI and ghrelin whereas in the multivariate regression model, the variables associated were DAS-28, body weight, visceral fat, LDL-C and TG (R ² = 0.72). The percentage of IgA anti-ghrelin immune complexes positively correlated with RF and anti-CCP and the multivariate regression model showed an association with RF and body fat percentage (R ² = 0.22). Our study shows an increased percentage of IgG anti-ghrelin immune complexes in RA patients despite ghrelin levels were similar in both groups, suggesting an increase in the affinity of these autoantibodies toward ghrelin. The associations found in the multiple regression analysis for anti-ghrelin immune complexes support the previously reported functions of these natural autoantibodies as carriers and modulators of the stability and physiological effect of the hormone. However, in RA both the disease activity and the RF appear to influence the formation of these anti-ghrelin immune complexes.

Acute and Chronic Effects of Exercise on Appetite, Energy Intake, and Appetite-Related Hormones: The Modulating Effect of Adiposity, Sex, and Habitual Physical Activity

Exercise facilitates weight control, partly through effects on appetite regulation. Single bouts of exercise induce a short-term energy deficit without stimulating compensatory effects on appetite, whilst limited evidence suggests that exercise training may modify subjective and homeostatic mediators of appetite in directions associated with enhanced meal-induced satiety. However, a large variability in responses exists between individuals. This article reviews the evidence relating to how adiposity, sex, and habitual physical activity modulate exercise-induced appetite, energy intake, and appetite-related hormone responses. The balance of evidence suggests that adiposity and sex do not modify appetite or energy intake responses to acute or chronic exercise interventions, but individuals with higher habitual physical activity levels may better adjust energy intake in response to energy balance perturbations. The effect of these individual characteristics and behaviours on appetite-related hormone responses to exercise remains equivocal. These findings support the continued promotion of exercise as a strategy for inducing short-term energy deficits irrespective of adiposity and sex, as well as the ability of exercise to positively influence energy balance over the longer term. Future well-controlled studies are required to further ascertain the potential mediators of appetite responses to exercise.

Association of ghrelin with cardiometabolic risk factors in Iranian adolescents: the CASPIAN-III study

Introduction: Current evidence suggests that ghrelin could contribute to the development of metabolic syndrome (MetS) in adults, but limited experience exists in adolescents. This study aims to explore the association of ghrelin levels with the MetS components among Iranian adolescents.

Methods: In this case-control study, 32 adolescents with MetS and 148 healthy controls were selected randomly from the childhood and Adolescence Surveillance and Prevention of Adult Non communicable disease (CASPIAN-III) study. MetS was defined according to the Adult Treatment Panel III (ATP III) criteria modified for children and adolescents. Anthropometric measures (including body mass index [BMI], waist circumference [WC] and waist to height ratio [WHtR]), blood pressure (BP) and biochemical data (including fasting blood sugar [FBS], triglyceride [TG], high-density lipoprotein cholesterol [HDL-C], low-density lipoprotein cholesterol [LDL-C], total cholesterol [TC] and gerlin) were measured.

Results: Total ghrelin level was significantly higher in students without MetS compared to those with MetS (748.89 ± 85.04 vs. 728.72 ± 90.36 [pg/mL]; P < 0.001). Significant negative correlations were seen between ghrelin levels and BMI, WC, WHtR, TG, and TC. Ghrelin had also relatively strong inverse correlations with FBS (r = −0.59, P< 0.001), LDL-C (r = −0.56, P < 0.001), and positive correlation with HDL-C (r = 0.60, P < 0.001). Compared with the children with MetS, in those without MetS, ghrelin was significantly associated with HDL-C and LDL-C. A decreasing trend was observed in the mean ghrelin level across increasing number of MetS components (P for trend <0.001).

Conclusion: We observed a relationship between ghrelin concentration and MetS components in adolescents.

Ghrelin and Blood Pressure Regulation

Ghrelin is a growth hormone-releasing polypeptide that was first isolated from the rat stomach in 1999. High expression of growth hormone secretagogue receptor, the ghrelin receptor, in the heart, kidney, and blood vessels provides evidence of ghrelin activity in blood pressure regulation. Circulating ghrelin concentrations are reported to be inversely correlated with blood pressure, and the acute and chronic effects of ghrelin in decreasing blood pressure have been reported in animals with normal blood pressure, healthy individuals, animals and patients with heart failure, and animals with hypertension. The mechanism by which ghrelin regulates blood pressure appears to be related to modulation of the autonomic nervous system, direct vasodilatory activities, and kidney diuresis. Thus, modulation of the signaling pathway through ghrelin may provide a novel concept for treating hypertension. In this review, we discuss the current evidence and potential mechanisms of ghrelin activity in blood pressure regulation.

Fasting gut hormone levels change with modest weight loss in obese adolescents

BACKGROUND

Gut hormones change with weight loss in adults but are not well studied in obese youth.

OBJECTIVE

The primary aim was to evaluate how gut hormones and subjective appetite measure change with dietary weight loss in obese adolescents.

METHODS

Participants were a subset of those taking part in the 'Eat Smart Study'. They were aged 10-17 years with body mass index (BMI) > 90th centile and were randomized to one of three groups: wait-listed control, structured reduced carbohydrate or structured low-fat dietary intervention for 12 weeks. Outcomes were fasting glucose, insulin, leptin, adiponectin, total amylin, acylated ghrelin, active glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide (GIP), pancreatic polypeptide (PP) and total peptide tyrosine-tyrosine. Pre- and postprandial subjective sensations of appetite were assessed using visual analogue scales.

RESULTS

Of 87 'Eat Smart' participants, 74 participated in this sub-study. The mean (standard deviation) BMI z-score was 2.1 (0.4) in the intervention groups at week 12 compared with 2.2 (0.4) in the control group. Fasting insulin (P = 0.05) and leptin (P = 0.03) levels decreased, while adiponectin levels increased (P = 0.05) in the intervention groups compared with control. The intervention groups were not significantly different from each other. A decrease in BMI z-score at week 12 was associated with decreased fasting insulin (P < 0.001), homeostatic model of assessment-insulin resistance (P < 0.001), leptin (P < 0.001), total amylin (P = 0.03), GIP (P = 0.01), PP (P = 0.02) and increased adiponectin (P < 0.001). There was no significant difference in appetite sensations.

CONCLUSIONS

Modest weight loss in obese adolescents leads to changes in some adipokines and gut hormones that may favour weight regain.

Improved acylated ghrelin suppression at 2 years in obese patients with type 2 diabetes: effects of bariatric surgery vs standard medical therapy

OBJECTIVE

Roux-en-Y gastric bypass (RYGB) produces more durable glycemic control than sleeve gastrectomy (SG) or intensive medical therapy (IMT). However, the contribution of acylated ghrelin (AG), a gluco-regulatory/appetite hormone, to improve glucose metabolism and body composition in patients with type 2 diabetes (T2D) following RYGB is unknown.

DESIGN

STAMPEDE (Surgical Treatment and Medication Potentially Eradicate Diabetes Efficiently) was a prospective, randomized controlled trial.

SUBJECTS

Fifty-three (body mass index: 36±3 kg m(-2), age: 49±9 years) poorly controlled patients with T2D (HbA1c (glycated hemoglobin): 9.7±2%) were randomized to IMT, IMT+RYGB or IMT+SG and underwent a mixed-meal tolerance test at baseline, 12, and 24 months for evaluation of AG suppression (postprandial minus fasting) and beta-cell function (oral disposition index; glucose-stimulated insulin secretion × Matsuda index). Total/android body fat (dual-energy X-ray absorptiometry) was also assessed.

RESULTS

RYGB and SG reduced body fat comparably (15-23 kg) at 12 and 24 months, whereas IMT had no effect. Beta-cell function increased 5.8-fold in RYGB and was greater than IMT at 24 months (P<0.001). However, there was no difference in insulin secretion between SG vs IMT at 24 months (P=0.32). Fasting AG was reduced fourfold following SG (P<0.01) and did not change with RYGB or IMT at 24 months. AG suppression improved more following RYGB than SG or IMT at 24 months (P=0.01 vs SG, P=0.07 vs IMT). At 24 months, AG suppression was associated with increased postprandial glucagon-like peptide-1 (r=-0.32, P<0.02) and decreased android fat (r=0.38; P<0.006).

CONCLUSIONS

Enhanced AG suppression persists for up to 2 years after RYGB, and this effect is associated with decreased android obesity and improved insulin secretion. Together, these findings suggest that AG suppression is partly responsible for the improved glucose control after RYGB surgery.

A link between FTO, ghrelin, and impaired brain food-cue responsivity

Polymorphisms in the fat mass and obesity-associated gene (FTO) are associated with human obesity and obesity-prone behaviors, including increased food intake and a preference for energy-dense foods. FTO demethylates N6-methyladenosine, a potential regulatory RNA modification, but the mechanisms by which FTO predisposes humans to obesity remain unclear. In adiposity-matched, normal-weight humans, we showed that subjects homozygous for the FTO "obesity-risk" rs9939609 A allele have dysregulated circulating levels of the orexigenic hormone acyl-ghrelin and attenuated postprandial appetite reduction. Using functional MRI (fMRI) in normal-weight AA and TT humans, we found that the FTO genotype modulates the neural responses to food images in homeostatic and brain reward regions. Furthermore, AA and TT subjects exhibited divergent neural responsiveness to circulating acyl-ghrelin within brain regions that regulate appetite, reward processing, and incentive motivation. In cell models, FTO overexpression reduced ghrelin mRNA N6-methyladenosine methylation, concomitantly increasing ghrelin mRNA and peptide levels. Furthermore, peripheral blood cells from AA human subjects exhibited increased FTO mRNA, reduced ghrelin mRNA N6-methyladenosine methylation, and increased ghrelin mRNA abundance compared with TT subjects. Our findings show that FTO regulates ghrelin, a key mediator of ingestive behavior, and offer insight into how FTO obesity-risk alleles predispose to increased energy intake and obesity in humans.

Serum ghrelin level and TNF-α/ghrelin ratio in patients with previous myocardial infarction

BACKGROUND AND AIMS

Studies investigating serum ghrelin level in atherosclerosis yielded contradictory results. Interaction of ghrelin with adipocytokines is obscure in cardiovascular diseases. We undertook this study to determine which molecules influence ghrelin level and to see whether post-myocardial infarction (MI) patients have decreased ghrelin levels.

METHODS

In this cross-sectional study, acyl-ghrelin concentration was determined by radioimmunoassay in sera of 171 patients (ages 62 ± 6 years, mean ± SD) with previous MI and 81 age-matched referent subjects. We evaluated the associations of ghrelin with insulin, adiponectin, leptin, resistin, fetuin-A and tumor necrosis factor-alpha (TNF-α).

RESULTS

Patients had lower ghrelin levels compared to referent subjects (240.55 ± 59.33 vs. 337.96 ± 30.75 pg/mL, p <0.001) even after excluding diabetic and obese patients (240.63 ± 54.08 vs. 337.96 ± 30.75, p <0.001). In multivariate analysis, insulin (β = -0.327, p <0.001) and adiponectin (β = 0.301, p <0.001) determined ghrelin level (R(2) = 0.199, p <0.001). There was no association between ghrelin and TNF-α levels. In discriminant analysis using ghrelin, adiponectin, leptin, fetuin-A, resistin and TNF-α, the structure matrix revealed ghrelin and TNF-α as strongest predictors for belonging to the patient group (0.760 and -0.569, respectively). Using these two parameters, 89.7% of cases were correctly classified. Subjects with high TNF-α/ghrelin ratio had 11.25 times higher chance for belonging to the patient group (95% CI 5.80-21.80; χ(2) (1) = 215.6, p <0.001)

CONCLUSIONS

Acylated ghrelin levels are decreased in patients with coronary atherosclerosis, independently of body weight and the presence of type 2 diabetes mellitus. Ghrelin level is determined by elevated insulin and decreased adiponectin levels. Ghrelin alone or in combination with TNF-α may prove to be a novel indicator of coronary atherosclerosis.

Serum concentrations of adiponectin, leptin, resistin, ghrelin and insulin and their association with obesity indices in obese normo- and hypertensive patients - pilot study

INTRODUCTION

Hypertension often coexists with obesity. Adipokines, ghrelin and insulin play important roles in the pathogenesis of both diseases. The aim of this study was to compare adiponectin, leptin, resistin, insulin and ghrelin mean serum concentrations and insulin resistance (HOMA-IR) in normo- and hypertensive patients with obesity.

MATERIAL AND METHODS

ALL INCLUDED PATIENTS WERE DIVIDED ON THE FOLLOWING GROUPS: non-diabetic hypertensive patients with class I obesity (group A, n = 21) and class II/III obesity (group B, n = 10), and normotensive obese (class I)patients (group C, n = 7). Correlations between obesity indices (body mass index [BMI], waist-to-hip ratio [WHR], waist circumference [WC]), HOMA-IR, and hormone and adipokine serum levels were also analyzed.

RESULTS

Leptin level and HOMA-IR were significantly higher in group B compared to group C (9.74 ±3.88 ng/ml vs. 4.53 ±3.00 ng/ml; p < 0.02 and 3.30 ±1.59 vs. 1.65 ±0.41; p < 0.02, respectively). A negative correlation between WC and adiponectin level (R = -0.6275; p < 0.01) and a positive correlation between WC and insulin concentration (R = 0.5122; p< 0.05) as well as with HOMA-IR (R = 0.5228; p < 0.02) were found in group A. Negative correlations between BMI and ghrelin level (R = -0.7052; p < 0.05), WHR and adiponectin level (R = -0.6912; p < 0.05) and WHR and leptin level (R = -0.6728; p < 0.05) were observed in group B.

CONCLUSIONS

Insulin resistance and leptin may be important pathogenic factors in hypertensive patients with severe obesity. Indices of abdominal obesity (WC, WHR) correlate better than BMI with HOMA-IR, insulin, adiponectin and leptin serum levels in hypertensive obese patients.

Neuroendocrine and metabolic activities of ghrelin gene products

Acylated ghrelin (AG) is a 28 amino acid gastric peptide a natural ligand for the growth hormone secretagogue (GHS) receptor type 1a (GHS-R1a), endowed with GH-secreting and orexigenic properties. Besides, ghrelin exerts several peripheral metabolic actions, including modulation of glucose homeostasis and stimulation of adipogenesis. Notably, AG administration causes hyperglycemia in rodents as in humans. Ghrelin pleiotropy is supported by a widespread expression of the ghrelin gene, of GHS-R1a and other unknown ghrelin binding sites. The existence of alternative receptors for AG, of several natural ligands for GHS-R1a and of acylation-independent ghrelin non-neuroendocrine activities, suggests that there might be a complex 'ghrelin system' not yet completely explored. Moreover, the patho-physiological implications of unacylated ghrelin (UAG), and obestatin (Ob), the other two ghrelin gene-derived peptides, need to be clarified. Within the next few years, we may better understand the 'ghrelin system', where we might envisage clinical applications.

The role of ghrelin in GH secretion and GH disorders

In humans, growth hormone (GH) is secreted from the anterior pituitary in a pulsatile pattern. The traditional view is that this secretory pattern is driven by two counter regulatory neurohormones, GHRH and somatostatin. Ghrelin, the natural ligand for the growth hormone (GH)-secretagogue receptor (GHS-R), is produced in the stomach. Ghrelin is the strongest GH secretagogue known to date, but the role of endogenous ghrelin in the regulation of circulating GH levels remains controversial. The following review examines the evidence suggesting that endogenous ghrelin may be a key regulator of GH peak amplitude and discusses studies of diseases with altered GH levels, where it is found that in these states GH and ghrelin levels change in a similar way.

Meta-analysis of the relationship between obestatin and ghrelin levels and the ghrelin/obestatin ratio with respect to obesity

INTRODUCTION

The association between gastrointestinal hormones, obestatin and ghrelin, and obesity are controversial. Here, the authors summarize results of published works in this field by using meta-analysis.

METHODS

Studies that evaluated these hormones and were published before December 2009 were collected from PubMed, HighWire Press and ProQuest Health and Medical Complete. Software Review Manager 4.2 was used (Cochrane Collaboration, Oxford, England). Differences between obese and normal weight (NW) groups were compared using fixed or random effects models based on heterogeneity.

RESULTS

In obestatin group, 9 studies with 566 participants were included and had significant heterogeneity (I² = 98.6%, P < 0.01). Obestatin of NW groups was 64.19 pg/mL [95% confidence interval (CI) = 36.11-92.26, P < 0.01] higher than those of obese groups. In total ghrelin group, 21 studies with 1187 participants were included and had significant heterogeneity (I² = 97.9%, P < 0.01). Total ghrelin of NW groups was 145.53 pg/mL (95%CI = 109.59-181.47, P < 0.01) higher than those of obese groups. In active ghrelin group, 6 studies with 265 participants were included and had significant heterogeneity (I² = 98.10%, P < 0.01). Active ghrelin in NW groups was 53.22 pg/mL (95%CI = 25.92-80.53, P < 0.01) higher than those of obese groups. In ghrelin/obestatin group, 5 studies with 259 participants were included and had significant heterogeneity (I² = 94.2, P < 0.01). The ratios in NW groups were 2.49 pg/mL (95%CI = 0.03-4.9, P = 0.05) higher than those of obese groups but without significance.

CONCLUSIONS

Obestatin, total and active ghrelin in NW groups were significantly higher than those of obese groups. Ghrelin/obestatin ratios in NW groups were also higher but without significance.

Integrating GHS into the Ghrelin System

Oligopeptide derivatives of metenkephalin were found to stimulate growth-hormone (GH) release directly by pituitary somatotrope cells in vitro in 1977. Members of this class of peptides and nonpeptidyl mimetics are referred to as GH secretagogues (GHSs). A specific guanosine triphosphatate-binding protein-associated heptahelical transmembrane receptor for GHS was cloned in 1996. An endogenous ligand for the GHS receptor, acylghrelin, was identified in 1999. Expression of ghrelin and homonymous receptor occurs in the brain, pituitary gland, stomach, endothelium/vascular smooth muscle, pancreas, placenta, intestine, heart, bone, and other tissues. Principal actions of this peptidergic system include stimulation of GH release via combined hypothalamopituitary mechanisms, orexigenesis (appetitive enhancement), insulinostasis (inhibition of insulin secretion), cardiovascular effects (decreased mean arterial pressure and vasodilation), stimulation of gastric motility and acid secretion, adipogenesis with repression of fat oxidation, and antiapoptosis (antagonism of endothelial, neuronal, and cardiomyocyte death). The array of known and proposed interactions of ghrelin with key metabolic signals makes ghrelin and its receptor prime targets for drug development.