Fasting and postprandial relationships among plasma leptin, ghrelin, and insulin in prepubertal obese children

Anti-Obesity Effects of Ecklonia cava Extract in High-Fat Diet-Induced Obese Rats

Obesity is becoming a global epidemic as a result of high-calorie food intake and unhealthy lifestyles. Different marine plants, especially brown algae (Ecklonia cava), are traditionally used to treat different health-related issues. The study was carried out to investigate the anti-obesity properties of E. cava 70% ethanol extract. To evaluate the anti-obesity effect of E. cava, both in vitro and in vivo tests were performed. E. cava suppresses pre-adipocyte 3T3-L1 differentiation in a dose-dependent manner. In HFD-induced obese rats’ models, administration of E. cava 125, 250, and 500 mg/kg significantly decreases total body weight and organs, especially liver weight, in all treatment groups. Adipose tissue weight, including subcutaneous, epididymal, peritoneal, and mesenteric adipose tissue, was markedly reduced in E. cava-treated HFD rats in dose-dependent manners. In addition, liver-related biomarkers AST, ALP, ALT, and GGT were evaluated; the lower level of liver-related biomarkers indicates no liver injury or fatty liver issue in E. cava HFD treatment groups. In addition, E. cava treatment has significant effects on the expression of adipogenic and lipogenic (PPAR-γ, FAS, LPL, and SREBP-1c) genes. Altogether, these results show the anti-obesity effect of E. cava. We concluded that E. cava could be a potential candidate for the prevention of obesity-induced by a high-fat diet.

Leptin at birth and at age 7 in relation to appetitive behaviors at age 7 and age 10

Leptin contributes to the control of food intake and energy balance. However, its association with appetitive behaviors during childhood is not well understood. We aimed to investigate the association between leptin, assessed at birth and at 7 years of age (y), and appetitive behaviors assessed at 7 and 10 y. Children from a Portuguese cohort with assessment of leptin levels at birth from umbilical cord blood (n = 645) and at 7 y from venous blood samples (n = 587), were included. The Children's Eating Behavior Questionnaire assessed appetitive behaviors at 7 and 10 y. Weight and height were measured at 7 and 10 y to derive BMI z-scores (BMIz). A series of Generalized Linear Models tested relationships between leptin and appetitive behaviors, adjusting for potential confounders (maternal age, education, pre-pregnancy BMI, smoking during pregnancy, child physical activity and child BMIz), and interaction terms for child sex and child BMIz. At 7 y, 116 boys and 118 girls were classified as having overweight/obesity, and these children had higher leptin levels. Cross-sectional analyses using the 7 y data produced the strongest results. Higher leptin at 7 y was significantly associated with lower scores on Satiety Responsiveness, Food Fussiness and Slowness in Eating, and higher scores on Food Responsiveness, Enjoyment of Food and Emotional Overeating at 7 y. Only the association with Emotional Overeating remained when adjusting for child BMIz. Significant interaction effects between child sex and leptin were found for appetite at 7 y, such that higher leptin was associated with higher Food Responsiveness (p < 0.001) and lower Slowness in Eating (p < 0.001) to a greater extent among boys. Umbilical cord blood leptin was not associated with appetitive behaviors at 7 or 10 y. Our results show that leptin levels are positively associated with food approach and negatively with food avoidant behaviors. Associations were more consistent in cross-sectional analyses (at 7 y), were largely dependent on child weight, and tended to be stronger among boys. Our findings support a role for leptin in affecting appetite, with potential consequences for current weight status and future weight gain.

Obese children aged 4-6 displayed decreased fasting and postprandial ghrelin levels in response to a test meal

AIM

Ghrelin is a hunger hormone that plays a role in glucose homoeostasis and its levels increase before a meal and decrease during and after eating. This study compared the fasting ghrelin and insulin levels of obese children aged 4-6 with those of normal weight children and tested postprandial ghrelin levels in the obese children after a standard breakfast.

METHODS

We recruited 67 children at Lund University Hospital from 2008 to 2011. They comprised 30 obese children from a weight study and 37 normal weight children receiving minor elective surgery. Their mean ages were 4.7 ± 0.6 and 4.3 ± 0.8 years, respectively. The obese children ate a standard breakfast, and postprandial ghrelin was measured after 60 minutes.

RESULTS

The obese children had lower ghrelin levels than the controls (p < 0.01). A significant inverse relation was found between body mass index and fasting ghrelin levels. Obese children had significantly lower fasting ghrelin levels after a standard breakfast (p < 0.01), but there were no gender-related differences.

CONCLUSION

Obese children aged 4-6 years had reduced ghrelin and increased insulin levels in the fasting state and postprandial ghrelin was suppressed, suggesting that their energy metabolism was already dysregulated at this young age. Early obesity interventions are essential.

Parent reported nutritional risk and laboratory indices of cardiometabolic risk and in preschool-aged children

BACKGROUND

Eating habits formed during childhood may contribute to the increasing prevalence of cardiometabolic disorders. Assessing nutritional risk in young children may help to prevent later cardiometabolic disease. The objective of this study was to determine whether parent-reported nutritional risk in preschool-aged children was associated with laboratory indices of cardiometabolic risk, namely leptin and insulin.

METHODS

In this cross-sectional study, the relationship between nutritional risk as determined by the parent-completed NutriSTEP® questionnaire was assessed and compared to the serum leptin and insulin concentrations, hormones involved in regulation of food intake and biomarkers of adiposity and cardiometabolic risk. The community-based primary care research network for children in Toronto, Canada (TARGet Kids!) was used. The participants were children aged 3-5 years recruited from TARGet Kids! A total of 1856 children were recruited from seven primary care practices. Of these, 1086 children completed laboratory testing. Laboratory data for leptin and insulin were available for 714 and 1054 of those individuals, respectively.

RESULTS

The total NutriSTEP® score was significantly associated with serum leptin concentrations (p=0.003); for each unit increase in the total NutriSTEP® score, there was an increase of 0.01 ng/mL (95% confidence interval [CI] 0.004-0.018) in serum leptin concentrations after adjusting for potential confounders. The total NutriSTEP® score was not significantly associated with serum insulin concentration.

CONCLUSIONS

Parent reported nutritional risk is associated with serum leptin, but not insulin, concentrations in preschool-aged children. The NutriSTEP® questionnaire may be an effective tool for predicting future cardiometabolic risk in preschool-aged children.

Long-term Outcome after Robotic-assisted Gastroplication in Adolescents: Hunger Hormone and Food Preference Changes Two Case Reports

Weight loss surgery (WLS) is efficacious for long-term weight reduction and decreases overall mortality in severely obese patients. The mechanisms implicated in long-term weight loss are not fully understood. Proposed mechanisms include changes in gut hormones and brain regulation of appetite and satiety. We aimed to investigate the long-term ghrelin and leptin profiles and changes in food preference and eating behavior after WLS in adolescent patients. Two obese females aged 15 years and 14 4/12 years, who did not respond to lifestyle changes, including dietary intervention and physical exercise in combination with medical therapy, underwent robotic-assisted gastroplication. Anthropometric measurements, food habits and eating behavior, as well as metabolic and hormonal changes during long-term post-surgical follow-up were monitored. Long-term weight reduction was obtained in both patients, with a significant decrease in waist circumference. Resting energy expenditure showed a decrease over time, with a respiratory quotient that increased showing a shift from oxidation of a high-fat diet before surgery to oxidation of a mixed diet two and three years later. Both subjects improved their eating habits and lifestyle. Co-morbidity resolution was also noted. Increased pre-prandial ghrelin levels as well as higher post-prandial ghrelin and a leptin drop compared with pre-surgery values were observed in both patients. Persistent weight loss after gastroplication is associated with a favorable change in gut hormones and food preferences. The role of hormonal and sensory components in long-term results seems crucial. Particularly in adolescent patients, a multidisciplinary approach and continuous nutritional care is mandatory for weight maintenance and consolidation of changes.

Leptin Regulation of Immune Responses

Leptin is a regulatory hormone with multiple roles in the immune system. We favor the concept that leptin signaling 'licenses' various immune cells to engage in immune responses and/or to differentiate. Leptin is an inflammatory molecule that is capable of activating both adaptive and innate immunity. It can also 'enhance' immune functions, including inflammatory cytokine production in macrophages, granulocyte chemotaxis, and increased Th17 proliferation. Leptin can also 'inhibit' cells; CD4(+) T cells are inhibited from differentiating into regulatory T cells in the presence of elevated leptin, while NK cells can exhibit impaired cytotoxicity under the same circumstances. Consequently, understanding the effect of leptin signaling is important to appreciate various aspects of immune dysregulation observed in malnutrition, obesity, and autoimmunity.

Appetite-related peptides in childhood and adolescence: role of ghrelin, PYY, and GLP-1

During childhood and adolescence, a number of factors, including age, puberty, sex, race, and body composition, may contribute to differences in satiety, food intake, and appetite-related peptides. These peptides include the orexigenic peptide ghrelin and anorexigenic gut peptides peptide YY (PYY) and glucagon-like peptide-1 (GLP-1). For example, lower fasting ghrelin levels, lower postprandial ghrelin suppression, and blunted PYY and GLP-1 responses to food intake could contribute to a dysregulation of appetite in already obese children and adolescents. Whereas, changes in these peptides observed during puberty could facilitate growth. A greater understanding of the major moderating factors of appetite-related peptides in the pediatric population is essential to improve interpretation of study findings and for effective tailoring of strategies targeting appetite control to individuals. While more studies are needed, there is some evidence to suggest that exercise-based lifestyle interventions could be a potential therapeutic strategy to improve appetite-peptide profiles in overweight and obese children and adolescents. The aim of this review is (i) to discuss the potential moderating factors of ghrelin, PYY, and GLP-1, including age and puberty, sex, race and body composition; and (ii) to examine the effects of exercise interventions on these appetite-related gut peptides in children and adolescents.

Blunted suppression of acyl-ghrelin in response to fructose ingestion in obese adolescents: the role of insulin resistance

OBJECTIVE

Fructose consumption has risen alongside obesity and diabetes. Gut hormones involved in hunger and satiety (ghrelin and PYY) may respond differently to fructose compared with glucose ingestion. This study evaluated the effects of glucose and fructose ingestion on ghrelin and PYY in lean and obese adolescents with differing insulin sensitivity.

METHODS

Adolescents were divided into lean (n = 14), obese insulin sensitive (n = 12) (OIS), and obese insulin resistant (n = 15) (OIR). In a double-blind, cross-over design, subjects drank 75 g of glucose or fructose in random order, serum was obtained every 10 minutes for 60 minutes.

RESULTS

Baseline acyl-ghrelin was highest in lean and lowest in OIR (P = 0.02). After glucose ingestion, acyl-ghrelin decreased similarly in lean and OIS but was lower in OIR (vs. lean, P = 0.03). Suppression differences were more pronounced after fructose (lean vs. OIS, P = 0.008, lean vs. OIR, P < 0.001). OIS became significantly hungrier after fructose (P = 0.015). PYY was not significantly different at baseline, varied minimally after glucose, and rose after fructose.

CONCLUSIONS

Compared with lean, OIS adolescents have impaired acyl-ghrelin responses to fructose but not glucose, whereas OIR adolescents have blunted responses to both. Diminished suppression of acyl-ghrelin in childhood obesity, particularly if accompanied by insulin resistance, may promote hunger and overeating.

A Continuous Metabolic Syndrome Score Is Associated with Specific Biomarkers of Inflammation and CVD Risk in Prepubertal Children

BACKGROUND/AIMS

We aimed to evaluate the use of a continuous metabolic syndrome (MetS) score and to assess the associations of this score with risk biomarkers of inflammation, endothelial damage and cardiovascular disease (CVD) in prepubertal children.

METHODS

A total of 677 prepubertal children (295 obese, 146 overweight, and 236 normal-weight) were recruited. MetS traits, markers of inflammation, endothelial damage and CVD risk were measured, and a continuous MetS score was calculated, consisting of the sum/5 of the standardised scores of the MetS components.

RESULTS

The continuous MetS score was significantly associated with active plasminogen activator inhibitor-1 (r = 0.406, p < 0.001), adiponectin (r = -0.212, p < 0.001), resistin (r = 0.263, p < 0.001), C-reactive protein (r = 0.254, p < 0.001), tumour necrosis factor alpha (r = 0.120, p = 0.003), myeloperoxidase (r = 0.188, p < 0.001) and sE-selectin (r = 0.278, p < 0.001). Children in the normal-weight, overweight and obese groups with MetS totalled 0 (0%), 1 (0.7%) and 24 (8.7%), respectively, whereas the at-risk children identified using the continuous MetS score in each group totalled 2 (0.85%), 17 (11.6%) and 167 (56.6%), respectively.

CONCLUSIONS

The association of the continuous MetS score with specific risk biomarkers of inflammation, endothelial damage and CVD supports its use in the early identification of children at increased risk of metabolic dysfunction.

Obesity, sex and pubertal status affect appetite hormone responses to a mixed glucose and whey protein drink in adolescents

BACKGROUND AND OBJECTIVES

Little information is available on how food intake regulatory hormones may be altered during pubertal development and across the weight spectrum in adolescents. Therefore, the effect of obesity, sex and pubertal status on subjective appetite and appetite hormones in response to a mixed glucose and whey protein drink was determined in 8-18 year old adolescents.

PATIENTS AND METHODS

A cross-sectional cohort study was conducted at the Hospital for Sick Children, Toronto. After a 12 h fast, normal weight (n = 5 female, 4 male) and obese (n = 5 female, 4 male) adolescents (Experiment 1), and pre-early pubertal (n = 10) and mid-late pubertal (n = 10) obese male adolescents (Experiment 2) consumed a 250 ml glucose (30 g) and whey protein (30 g) beverage. Insulin, PYY, ghrelin and subjective appetite were measured over 120 min.

RESULTS

Obese adolescents (Experiment 1) have higher insulin, PYY and lower ghrelin (P < 0·006) than normal weight controls, with a more pronounced effect in males (P < 0·037). Puberty (Experiment 2) did not affect insulin (P = 0·305), but the change in PYY in response to the drink was greater (P = 0·032) and ghrelin was lower (P = 0·026) in mid-late pubertal than pre-early pubertal obese males. Average appetite 60 min post-drink was higher in obese and mid-late pubertal adolescents, but not related to hormone changes.

CONCLUSIONS

Obesity, sex and pubertal status affect macronutrient-stimulated appetite hormone secretion and these factors may alter food intake in obese children during pubertal development.

Systematic review of ghrelin response to food intake in pediatric age, from neonates to adolescents

OBJECTIVE

Food intake and energy balance are regulated during the lifespan with critical changes in each specific period (infancy, adulthood, aging). Some of ghrelin's changes may contribute to the regulation of food intake and weight in children. We aimed to analyze the ghrelin response to feeding in lean or obese subjects from birth to adolescence.

METHODS

We searched PubMed, Scopus, Google Scholar, Cochrane, and EMBASE (December 1999 to February 2013) and identified 62 relevant articles, of which 29 were suitable to be included.

RESULTS AND CONCLUSIONS

Total ghrelin response to meals is particular, with refractoriness in neonates and lean children and an inhibition that starts from puberty. Total ghrelin levels are decreased after meals, irrespective of pubertal stages in obese children and adolescents. Conversely, total ghrelin is decreased after an oral glucose tolerance test in all ages, with the exception of neonates. Data on unacylated ghrelin response are scant but resemble those of total ghrelin. The acylated ghrelin response to meals or oral glucose tolerance test is discordant, although a precocious inhibition followed by a rise back is present in both lean and obese children. The post-feeding profile in children with Prader-Willi syndrome is also peculiar, with a conserved and deeper inhibition of all ghrelin forms.

Fat mass, and not diet, has a large effect on postprandial leptin but not on adiponectin concentrations in cats

Leptin and adiponectin play important roles in carbohydrate and lipid metabolism in different species. Information is limited on the effects of diet, weight gain, and fat mass on their concentrations in cats. This study compared fasting and postprandial blood leptin and total adiponectin concentrations before and after 8 wk of ad libitum feeding to promote weight gain in adult cats (n = 32) fed either a low-carbohydrate, high-protein (23% and 47% ME) or a high-carbohydrate, low-protein (51% and 21% ME) diet. There were significant effects of total, abdominal, and nonabdominal fat mass, but not diet or body weight, on mean 24-h and peak leptin (P < 0.01); observed increases in mean and peak leptin were greatest for abdominal fat mass (50% and 56% increase for every extra 100 g, respectively). After weight gain, postprandial leptin concentration increased markedly relative to when cats were lean, and the duration of the increase was longer after a mean weight gain of 37% with the low-carbohydrate, high-protein diet group compared with 17% with the high-carbohydrate, low-protein group (P ≤ 0.01). Adiponectin was lower than fasting at some time points during the postprandial period in both groups (P ≤ 0.05). For both fasting and mean 24-h adiponectin, there was no significant diet effect (P ≥ 0.19) or changes in weight gain relative to when cats were lean (P ≥ 0.29). In conclusion, fat mass, and not diet, has a large effect on postprandial leptin but not adiponectin concentrations in cats.

Insulin resistance and inflammation markers: correlations in obese adolescents

AIMS AND OBJECTIVES

To ascertain whether inflammation markers also correlate with parameters related to insulin resistance and the metabolic syndrome in a group of adolescents.

BACKGROUND

Obesity is now considered a chronic low-grade inflammatory process, characterised by alterations in the systemic concentrations of some inflammation markers. Adiponectin, leptin and other inflammatory proteins have been shown to correlate with insulin resistance and the metabolic syndrome in adults.

DESIGN

Cross-sectional study in two groups of obese and normal weight adolescents.

METHODS

Serum levels of adiponectin, leptin, ceruloplasmin and insulin levels were determined and correlated among them and with anthropometric parameters, blood pressure body mass index and body mass index z-score.

RESULTS

Waist circumference, body mass index and blood pressure values correlated significantly with both homoeostasis model assessment for insulin resistance and insulin levels. Ceruloplasmin also correlated with both parameters with a high level of significance. However, leptin levels did not correlate with either homoeostasis model assessment for insulin resistance or insulin, and adiponectin correlated with homoeostasis model assessment for insulin resistance but not insulin. All inflammation markers studied correlated with the body mass index z-score. These correlations were stronger in the group of obese individuals compared to lean ones.

CONCLUSIONS

We found a relationship between insulin resistance and some inflammation in adolescents, which was particularly strong in obese individuals and was associated with the development of metabolic syndrome. Among the inflammation markers studied, ceruloplasmin revealed as a potential string marker of insulin resistance in obese adolescents.

RELEVANCE TO CLINICAL PRACTICE

The results obtained in this study imply a significant advance in the field of clinical practice of nursing. The adequate understanding by nursing personnel of the inflammatory processes inherent to obesity constitutes a key factor for the prevention of the disease and its complications in adolescents.

Ghrelin and PYY levels in adolescents with severe obesity: effects of weight loss induced by long-term exercise training and modified food habits

This study investigated (a) changes in ghrelin and peptide YY (PYY) concentrations during a weight reduction programme and (b) baseline ghrelin and PYY levels as predictors of weight loss in 32 severely obese adolescents (BMI z score = 4.1). Subjects spent an academic year in an institution for childhood obesity. Fasting ghrelin and PYY, leptin, insulin levels and insulin resistance were measured at baseline (month 0) and during the programme (months 3, 6, 9). In addition, 15 normal-weight teenagers served as reference for the baseline assessments. At baseline, obese teenagers had lower ghrelin and PYY concentrations than normal-weight adolescents (P < 0.05). Moreover, they showed significantly higher leptin, insulin levels and homeostasis model assessment (HOMA) (P < 0.0001). During the lifestyle modification, there was a significant decrease in body weight among obese teenagers, associated with an increase in ghrelin (apparent from month 6; P < 0.05), a decrease in leptin (from month 3; P < 0.05) and a decrease in insulin and HOMA (from month 3; P < 0.0001), without any significant change in PYY. Anthropometrical changes were correlated neither with baseline ghrelin levels nor with changes in ghrelin and PYY after the lifestyle modification. However, higher baseline PYY tended to correlate with greater anthropometrical changes (P < 0.1). In adolescents with severe obesity, a long-term combination of supervised aerobic exercises and a balanced diet led to weight reduction and increased ghrelin concentrations, without any change in PYY concentrations. Moreover, baseline PYY concentrations might be considered as predictors of weight loss.

Growth hormone treatment, final height, insulin-like growth factors, ghrelin, and adiponectin in four siblings with Seckel syndrome

OBJECTIVE

To report on the effect of growth hormone (GH) treatment on final height (FH) and to describe the insulin-like growth factor (IGF) system, ghrelin, and adiponectin (ADPN) in children with Seckel syndrome.

SUBJECTS AND RESULTS

Four severely growth-retarded Iraqi siblings (two girls and two boys) with Seckel syndrome were referred at ages 16.5, 14.4, 12.4, and 10.4 years. They were born at term, but their growth was retarded and birth weight ranged between 1 and 1.5 kg. The children were healthy and had a normal response to GH provocative test. Long-term GH treatment of the youngest brother and sister increased the FH by 7.2 and 3.4 cm, respectively, compared with their older brother and sister. At FH, body mass index standard deviation scores (BMISDS) ranged from -3.0 to -3.9. Serum levels of immunoreactive IGF-1, bioactive IGF-1, and IGF-binding protein 3 were all within normal to high range before GH treatment and increased after GH treatment. Fasting plasma ghrelin remained severely reduced. Despite low BMISDS, plasma ADPN was moderately reduced and showed an almost complete absence of the low-molecular-weight subform.

CONCLUSION

This is the first report on the effect of GH treatment on FH in children with Seckel syndrome. GH may have increased FH. In addition to growth defects and reduced BMISDS, patients with Seckel syndrome are characterized by low fasting ghrelin levels, low total ADPN, and near deficiency of the low-molecular-weight ADPN subform. The possible significance of the hormonal changes requires further investigations.

Neuroimaging, gut peptides and obesity: novel studies of the neurobiology of appetite

Two major biological players in the regulation of body weight are the gut and the brain. Peptides released from the gut convey information about energy needs to areas of the brain involved in homeostatic control of food intake. There is emerging evidence that human food intake is also under the control of cortical and subcortical areas related to reward and cognition. The extent to which gut hormones influence these brain areas is not fully understood. Novel methods combining the study of neural activity and hormonal signalling promise to advance our understanding of gut-brain interactions. Here, we review a growing number of animal and human studies using neuroimaging methods (functional magnetic resonance imaging, positron emission tomography) to measure brain activation in relation to nutrient loads and infusion of gut peptides. Implications for current and future pharmacological treatments for obesity are discussed.