Hyperphagia: current concepts and future directions proceedings of the 2nd international conference on hyperphagia

OBJECTIVE

Hyperphagia is a central feature of inherited disorders (e.g., Prader-Willi Syndrome) in which obesity is a primary phenotypic component. Hyperphagia may also contribute to obesity as observed in the general population, thus raising the potential importance of common underlying mechanisms and treatments. Substantial gaps in understanding the molecular basis of inherited hyperphagia syndromes are present as are a lack of mechanistic of mechanistic targets that can serve as a basis for pharmacologic and behavioral treatments.

DESIGN AND METHODS

International conference with 28 experts, including scientists and caregivers, providing presentations, panel discussions, and debates.

RESULTS

The reviewed collective research and clinical experience provides a critical body of new and novel information on hyperphagia at levels ranging from molecular to population. Gaps in understanding and tools needed for additional research were identified.

CONCLUSIONS

This report documents the full scope of important topics reviewed at a comprehensive international meeting devoted to the topic of hyperphagia and identifies key areas for future funding and research.

Association analyses for dopamine receptor gene polymorphisms and weight status in a longitudinal analysis in obese children before and after lifestyle intervention

Background

Dopamine receptors are involved in midbrain reward circuit activation. Polymorphisms in two dopamine receptor genes, DRD2 and DRD4, have been associated with altered perception of food reward and weight gain. The objective of this study was to determine whether the same risk alleles were associated with overweight/obesity and with lower reduction of overweight after a 1-year lifestyle intervention.

Methods

In a longitudinal study the association of polymorphisms in DRD2 (rs18000497, risk allele: T, formerly A1 allele at the TaqI A1 polymorphism) and DRD4 (variable number of tandem repeats (VNTR); 48 bp repeat in exon III; risk alleles: 7 repeats or longer: 7R+) was tested on weight loss success following a 1-year lifestyle childhood obesity intervention (OBELDICKS). An additional exploratory cross-sectional case-control study was performed to compare the same DRD polymorphisms in these overweight/obese children and adolescents versus lean adult controls. Subjects were 423 obese and 28 overweight children participating in lifestyle intervention (203 males), age median 12.0 (interquartile range 10.0–13.7) years, body mass index - standard deviation score (BMI-SDS) 2.4 ± 0.5; 583 lean adults (232 males); age median 25.3 (interquartile range 22.5–26.8) years, BMI 19.1 ± 1.9 kg/m². BMI, BMI-SDS and skinfold thickness measures were assessed at baseline and after 1 year; genotyping was performed for DRD2 risk variant rs1800497 and DRD4 exon III VNTR.

Results

The DRD2 genotype had a nominal effect on success in the weight loss intervention. The weakest BMI-SDS reduction was in children homozygous for two rs1800497 T-alleles (n = 11) compared to the combined group with zero (n = 308) or one (n = 132) rs1800497 T-allele (-0.08 ± 0.36 vs. -0.28 ± 0.34; p < 0.05). There was no association between the DRD4 VNTR alleles and genotypes and success in the weight loss intervention. No associations of the risk alleles of the DRD2 and DRD4 polymorphisms and obesity were observed in the cross-sectional part of the study.

Conclusions

We did not find association between polymorphisms in DRD2 and DRD4 genes and weight status. However, obese carriers of two DRD2 rs1800497 T-alleles may be at risk for weak responses to lifestyle interventions aimed at weight reduction.

Trial registration

Obesity intervention program “Obeldicks” is registered at clinicaltrials.gov (NCT00435734).

Glucocorticoids and insulin resistance in children with acute lymphoblastic leukemia

BACKGROUND

Children treated for acute lymphoblastic leukemia (ALL) are more likely to become overweight. Prolonged exposure to high-dose glucocorticoids may cause insulin resistance and facilitate development of this phenotype.

PROCEDURE

Body mass indices (BMI) and insulin resistance (homeostatic model assessment [HOMA]-IR) were prospectively measured among on- (n = 31) and off-therapy participants (n = 29). On-therapy participants were assessed prior to and while on glucocorticoids (5 days of prednisone 40 mg m(-2) or dexamethasone 6 mg m(-2)) given as part of routine maintenance chemotherapy, with a subset (n = 10) receiving an intravenous glucose tolerance test (IVGTT) while on glucocorticoids.

RESULTS

Baseline HOMA-IR values among on- and off-therapy participants were similar, but among on-therapy participants, HOMA-IR increased significantly with glucocorticoid exposure (median 3.39 vs. 1.26; P < 0.01) with 45.2% of participants having values >4.39 (upper 2.5th percentile among normal weight adolescents). Although baseline HOMA-IR was significantly correlated with current BMI (r = 0.48, P < 0.01), change in HOMA-IR following steroid exposure was not correlated with any demographic or treatment characteristic including current BMI. Among those with IVGTT data, HOMA estimates in general correlated with values derived from a minimal model analysis (r ~ 0.7).

CONCLUSIONS

High-dose glucocorticoids given as part of routine chemotherapy were associated with a significantly increased insulin resistant state. Given the amount and duration of glucocorticoids children with ALL experience, these physiologic changes could be an important contributor to the development of therapy-related obesity.

Brain-derived neurotrophic factor and its relation to leptin in obese children before and after weight loss

OBJECTIVE

Brain-derived neurotrophic factor (BDNF) is a regulator of energy homeostasis and food intake through hypothalamic signaling. Currently, data regarding BDNF in children with obesity are lacking. We evaluated serum BDNF concentrations in obese children, both before and after lifestyle intervention, in reference to those of lean children.

METHODS

A total of 90 (24 normal weight; 66 obese) children were studied utilizing a cross-sectional clinical outpatient study design. In addition, longitudinal data analysis was performed in 30 obese children participating in a lifestyle intervention for one year.

RESULTS

Fasting serum BDNF concentrations were higher in obese vs. normal weight children (BDNF 20.3±1.0 vs. 12.5±1.7 ng/mL, respectively, mean±SEM, p<0.001) and correlated significantly to BMI standard deviation score (r=0.426, p<0.001), and leptin (r=0.414, p<0.01). BDNF concentrations were not regulated in response to food, 60 min after ingestion of a liquid test meal. After one year lifestyle intervention, delta BDNF correlated significantly to delta leptin (r=0.475, p<0.01), but not to changes of insulin resistance index HOMA-IR, systolic and diastolic blood pressure, HDL, LDL, and triglycerides. In a multiple stepwise linear regression adjusted for pubertal stage, age, sex, and BMI, delta BDNF correlated significantly (p<0.05) to delta leptin and delta triceps skinfold and in tendency to delta subscapularis skinfold thickness (p=0.050).

CONCLUSIONS

Our results in children do not indicate a significant relationship between BDNF and insulin resistance or cardiovascular risk factors. However, the correlation between changes of BDNF and changes of leptin suggests a relationship between BDNF and fat mass.

Treatment with glucagon-like Peptide-1 agonist exendin-4 in a patient with hypothalamic obesity secondary to intracranial tumor

BACKGROUND/AIMS

Patients with hypothalamic tumors frequently experience severe obesity, and its treatment with diet, exercise, and/or pharmacologic treatment has had limited effect. Glucagon-like peptide-1 agonist exenatide (exendin-4), used for treatment of type 2 diabetes, causes persistent weight loss via signaling in the brainstem.

METHODS

We report the case of a 17-year-old patient with obesity resulting from a hypothalamic germ cell tumor. He was treated by chemoradiotherapy and exenatide at a dose of 5 µg subcutaneously twice daily.

RESULTS

Exenatide resulted in a 29-kg weight loss (BMI reduction from 37.1 to 29.1) after 2.5 years of treatment; significant weight gain occurred shortly after exenatide was discontinued.

CONCLUSION

Exenatide resulted in considerable reduction of body weight in a patient with severe hypothalamic obesity. This novel observation requires follow-up clinical studies for establishing the effects of exenatide in patients with disrupted hypothalamic energy regulatory pathways.

Glucagon-like peptide-1 agonist exendin-4 leads to reduction of weight and caloric intake in a rat model of hypothalamic obesity

BACKGROUND

Hypothalamic obesity caused by damage of medial hypothalamic nuclei presents a therapeutic challenge. Glucagon-like peptide-1 agonist exenatide (synthetic version of exendin-4 (Ex4)), used for treatment of diabetes, causes weight loss via hindbrain signaling.

METHODS

We tested Ex4 in an established rat model of medial hypothalamic lesions. Lesion and control animals were administered either daily intraperitoneal injections of 1 µg·kg(-1) Ex4 or saline for 9 days.

RESULTS

In our rat model, a significant difference in percent baseline food intake (lesion -20.8%, control -13.6%; p < 0.001) and percent change in body weight (lesion -4.9%/9 days, control -3.2%/9 days; p < 0.05) was observed during Ex4 treatment compared with saline.

CONCLUSION

Ex4 resulted in reduction of food intake and body weight. Follow-up studies are required to further elucidate its effects on energy homeostasis and to establish Ex4 as a potential drug for treatment of hypothalamic obesity.

Fibroblast growth factor 21 (FGF-21) and its relation to obesity, metabolic syndrome, and nonalcoholic fatty liver in children: a longitudinal analysis

CONTEXT

Fibroblast growth factor 21 (FGF-21), a potent activator of glucose uptake, has been proposed to be related to insulin resistance, metabolic syndrome (MetS), nonalcoholic fatty liver disease (NAFLD), and weight status.

OBJECTIVE

Our objective was to study the relationships between FGF-21, parameters of MetS, and NAFLD before and after weight loss in obese children.

DESIGN AND SETTING

This was a cross-sectional comparison between obese and normal-weight children and longitudinal 1-yr follow-up study in obese children participating in a lifestyle intervention in a primary care setting.

PATIENTS

Patients included 60 obese and 40 lean children of same age, gender, and pubertal stage.

INTERVENTION

The outpatient 1-yr intervention program was based on exercise, behavior, and nutrition therapy.

MAIN OUTCOMES MEASURES

We evaluated fasting serum FGF-21, weight status [body mass index (BMI) expressed as sd score (SDS)], body fat, insulin resistance index (homeostasis model assessment), leptin, transaminases, free fatty acids (FFA), waist circumference, blood pressure, and lipids.

RESULTS

Compared with the normal-weight children, obese children demonstrated significantly (P < 0.001) increased FGF-21, leptin, and homeostasis model assessment levels. FGF-21 was significantly (P < 0.05) correlated to BMI, SDS-BMI, FFA, and leptin both in cross-sectional and longitudinal analyses but not to any additional analyzed parameter. Children with and without MetS or NAFLD did not differ significantly with respect to their FGF-21 concentrations. A decrease of SDS-BMI was associated with a significant (P = 0.038) decrease of FGF-21 levels (mean -34%).

CONCLUSIONS

FGF-21 concentrations are reversibly increased in obese children and are related to leptin and FFA. However, our data do not support a significant relationship between FGF-21, insulin resistance, and features of MetS or NAFLD in children.

Mechanisms affecting neuroendocrine and epigenetic regulation of body weight and onset of puberty: potential implications in the child born small for gestational age (SGA)

Signaling peptides produced in peripheral tissues such as gut, adipose tissue, and pancreas communicate with brain centers, such as hypothalamus and hindbrain to manage energy homeostasis. These regulatory mechanisms of energy intake and storage have evolved during long periods of hunger in the evolution of man to protect the species from extinction. It is now clear that these circuitries are influenced by prenatal and postnatal environmental factors including endocrine disruptive chemicals. Hypothalamic appetite regulatory systems develop and mature in utero and early infancy, and involve signaling pathways that are important also for the regulation of puberty onset. Recent studies in humans and animals have shown that metabolic pathways involved in regulation of growth, body weight gain and sexual maturation are largely affected by epigenetic programming that can impact both current and future generations. In particular, intrauterine and early infantile developmental phases of high plasticity are susceptible to factors that affect metabolic programming that therefore, affect metabolic function throughout life. In children born small for gestational age, poor nutritional conditions during gestation can modify metabolic systems to adapt to expectations of chronic undernutrition. These children are potentially poorly equipped to cope with energy-dense diets and are possibly programmed to store as much energy as possible, leading to later obesity, metabolic syndrome, disturbed regulation of normal puberty and early onset of cardiovascular disease. Most cases of disturbed energy balance are likely a result of a combination of genetics, epigenetics and environment. This review will discuss potential mechanisms linking intrauterine growth retardation with changes in growth, energy homeostasis and sexual maturation.

Vitamin D deficiency in obese rats exacerbates nonalcoholic fatty liver disease and increases hepatic resistin and Toll-like receptor activation

Childhood obesity is associated with type 2 diabetes mellitus and nonalcoholic fatty liver disease (NAFLD). Recent studies have found associations between vitamin D deficiency (VDD), insulin resistance (IR), and NAFLD among overweight children. To further explore mechanisms mediating these effects, we fed young (age 25 days) Sprague-Dawley rats with a low-fat diet (LFD) alone or with vitamin D depletion (LFD+VDD). A second group of rats was exposed to a Westernized diet (WD: high-fat/high-fructose corn syrup) that is more typically consumed by overweight children, and was either replete (WD) or deficient in vitamin D (WD+VDD). Liver histology was assessed using the nonalcoholic steatohepatitis (NASH) Clinical Research Network (CRN) scoring system and expression of genes involved in inflammatory pathways were measured in liver and visceral adipose tissue after 10 weeks. In VDD groups, 25-OH-vitamin D levels were reduced to 29% (95% confidence interval [CI]: 23%-36%) compared to controls. WD+VDD animals exhibited significantly greater hepatic steatosis compared to LFD groups. Lobular inflammation as well as NAFLD Activity Score (NAS) were higher in WD+VDD versus the WD group (NAS: WD+VDD 3.2 ± 0.47 versus WD 1.50 ± 0.48, P < 0.05). Hepatic messenger RNA (mRNA) levels of Toll-like receptors (TLR)2, TLR4, and TLR9, as well as resistin, interleukins (IL)-1β, IL-4, and IL-6 and oxidative stress marker heme oxygenase (HO)-1, were higher in WD+VDD versus WD animals (P < 0.05). Logistic regression analyses showed significant associations between NAS score and liver mRNA levels of TLRs 2, 4, and 9, endotoxin receptor CD14, as well as peroxisome proliferator activated receptor (PPAR)γ, and HO-1.

CONCLUSION

VDD exacerbates NAFLD through TLR-activation, possibly by way of endotoxin exposure in a WD rat model. In addition it causes IR, higher hepatic resistin gene expression, and up-regulation of hepatic inflammatory and oxidative stress genes.

Genotype-phenotype analysis in congenital adrenal hyperplasia due to P450 oxidoreductase deficiency

CONTEXT

P450 oxidoreductase deficiency (PORD) is a unique congenital adrenal hyperplasia variant that manifests with glucocorticoid deficiency, disordered sex development (DSD), and skeletal malformations. No comprehensive data on genotype-phenotype correlations in Caucasian patients are available.

OBJECTIVE

The objective of the study was to establish genotype-phenotype correlations in a large PORD cohort.

DESIGN

The design of the study was the clinical, biochemical, and genetic assessment including multiplex ligation-dependent probe amplification (MLPA) in 30 PORD patients from 11 countries.

RESULTS

We identified 23 P450 oxidoreductase (POR) mutations (14 novel) including an exonic deletion and a partial duplication detected by MLPA. Only 22% of unrelated patients carried homozygous POR mutations. p.A287P was the most common mutation (43% of unrelated alleles); no other hot spot was identified. Urinary steroid profiling showed characteristic PORD metabolomes with variable impairment of 17α-hydroxylase and 21-hydroxylase. Short cosyntropin testing revealed adrenal insufficiency in 89%. DSD was present in 15 of 18 46,XX and seven of 12 46,XY individuals. Homozygosity for p.A287P was invariably associated with 46,XX DSD but normal genitalia in 46,XY individuals. The majority of patients with mild to moderate skeletal malformations, assessed by a novel scoring system, were compound heterozygous for missense mutations, whereas nearly all patients with severe malformations carried a major loss-of-function defect on one of the affected alleles.

CONCLUSIONS

We report clinical, biochemical, and genetic findings in a large PORD cohort and show that MLPA is a useful addition to POR mutation analysis. Homozygosity for the most frequent mutation in Caucasians, p.A287P, allows for prediction of genital phenotype and moderate malformations. Adrenal insufficiency is frequent, easily overlooked, but readily detected by cosyntropin testing.

Functional neuroimaging in craniopharyngioma: a useful tool to better understand hypothalamic obesity?

OBJECTIVE

To use functional magnetic resonance imaging (fMRI) in craniopharyngioma (CP) patients to examine the hypothesis that hypothalamic damage due to CP and its treatment results in enhanced perception of food reward and/or impaired central satiety processing.

METHODS

Pre- and post-meal responses to visual food cues in brain regions of interest (ROI; bilateral nucleus accumbens, bilateral insula, and medial orbitofrontal cortex) were assessed in 4 CP patients versus 4 age- and weight-matched controls. Stimuli consisted of images of high- ('fattening') and low-calorie ('non-fattening') foods in blocks, alternating with non-food object blocks. After the first fMRI scan, subjects drank a high-calorie test meal to suppress appetite, then completed a second fMRI scan. Within each ROI, we calculated mean z-scores for activation by fattening as compared to non-fattening food images.

RESULTS

Following the test meal, controls showed suppression of activation by food cues while CP patients showed trends towards higher activation.

CONCLUSION

These data, albeit in a small group of patients, support our hypothesis that perception of food cues may be altered in hypothalamic obesity (HO), especially after eating, i.e. in the satiated state. The fMRI approach is encouraging for performing future mechanistic studies of the brain response to food cues and satiety in patients with hypothalamic or other forms of childhood obesity.

Pregnancy-associated plasma protein A in obese children: relationship to markers and risk factors of atherosclerosis and members of the IGF system

BACKGROUND

Pregnancy-associated plasma protein A (PAPPA) is a large placenta-derived glycoprotein, which serves as a protease of several IGF-binding proteins (IGFBPs). In non-pregnant adults, measurable PAPPA levels were detected and have been implicated in the pathophysiology of atherosclerotic plaques. However, data in children is lacking.

OBJECTIVE

To study the relationship between PAPPA, markers of atherosclerosis, and members of the IGF system in pediatric obesity.

PATIENTS AND DESIGN

Eighty-two obese and 52 nonobese children and 1-year longitudinal follow-up study for obese cohort.

INTERVENTION

Outpatient 1-year intervention program based on exercise, behavior, and nutrition therapy.

MAIN OUTCOME MEASURES

Changes in PAPPA levels, carotid intima media thickness (IMT), weight, blood pressure, lipids, metabolic markers, and members of IGF system.

RESULTS

Baseline PAPPA (PAPPA(BL)) serum levels did not differ between obese and lean subjects. PAPPA(BL) correlated significantly with IGF1, IGFBP1, and serum cholesterol. During the 1-year-program mean IMT decreased from 0.66 ± 0.01 to 0.63 ± 0.01 mm (P<0.05) and PAPPA from 1.83 ± 0.12 to 1.58 ± 0.11 μU/l (P<0.00). In linear regression analysis with IMT after intervention as dependent variable, PAPPA contributed significantly to the observed variance. The longitudinal change of PAPPA correlated significantly with the change of serum triglycerides.

CONCLUSION

In this cohort of obese children, PAPPA serum levels correlated significantly with other cardiovascular risk factors. The lack of a direct correlation between PAPPA and IMT suggests that the described association of atherosclerotic plaques and increased PAPPA levels might reflect an indirect mechanism of PAPPA with cardiovascular risk factors such as serum lipids rather than a direct effect on the vasculature.

Lack of association between apelin, insulin resistance, cardiovascular risk factors, and obesity in children: a longitudinal analysis

Apelin has been proposed as a novel beneficial adipokine that is related to insulin resistance, cardiovascular risk factors, and obesity. However, findings in humans are controversial; and longitudinal analyses in childhood are still missing. We compared apelin levels between 80 obese and 40 lean children of the same age, sex, and pubertal stage. In addition, we analyzed the relationships between apelin levels and weight status (as standard deviation of body mass index [SDS-BMI]), body fat, insulin resistance (homeostasis model assessment [HOMA]), leptin, and cardiovascular risk factors associated with obesity (waist circumference, blood pressure, lipids, and adiponectin) in 80 obese children before and after participating in a 1-year lifestyle intervention. Apelin levels did not differ significantly (P = .061) between obese (1.50 ± 0.47 ng/mL, mean ± SD) and lean children (1.67 ± 0.49 ng/mL). Apelin concentrations were not significantly related to age, pubertal stage, SDS-BMI, body fat, leptin, or any cardiovascular risk factor. In longitudinal analyses, no significant correlations were found between changes of apelin and changes of SDS-BMI, body fat, leptin, HOMA, or any cardiovascular risk factor. Adiponectin, HOMA, blood pressure, waist circumference, and triglycerides improved significantly in 39 obese children with SDS-BMI reduction, whereas leptin decreased significantly and apelin did not change significantly in these children. In 41 children with increase of SDS-BMI, no significant changes were observed in 1-year follow-up period. This is the first study demonstrating that weight loss in obese children was not associated with a change of apelin concentrations. Our data do not support a significant relationship in childhood between apelin on one hand and leptin, HOMA, cardiovascular risk factors, or weight status on the other.

Relationship between MTNR1B (melatonin receptor 1B gene) polymorphism rs10830963 and glucose levels in overweight children and adolescents

AIMS

The G-allele of the single nucleotide polymorphism (SNP) rs10830963 in MTNR1B (melatonin receptor 1B gene) is associated with type 2 diabetes mellitus and glucose levels in adults. The aim of this study was to analyze whether there is an allele-dosage effect on glucose metabolism in overweight children and to explore if changes in glucose metabolism in a lifestyle intervention do also depend on genotype.

METHODS

We genotyped rs10830963 in 1118 overweight children and adolescents [mean age 10.7 yr, mean body mass index (BMI) 27.8 kg/m2]; 340 of these individuals completed a 1-yr lifestyle intervention (mean age 10.7 yr, mean BMI 27.9 kg/m2). The degree of overweight [BMI-SDS (standard deviation score)], fasting insulin, glucose, homeostasis model assessment for insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI) were measured before and after intervention.

RESULTS

We showed a significant relationship between rs10830963 and basal glucose levels [β:1.101, 95% confidence interval (CI) 0.316-1.886 mg/dL per risk allele; p = 0.006] by linear regression adjusted for age, age(2), and sex. There was no effect of the allele on insulin or indices of insulin resistance or sensitivity. After the 1-yr lifestyle intervention, we observed a significant reduction of BMI-SDS as well as an improvement of HOMA-IR and QUICKI, but no evidence for an association between rs10830963 genotype and changes of glucose levels.

CONCLUSIONS

The G-allele of rs10830693 in the MTNR1B gene was significantly related to glucose levels, while an impact of this genetic variant on the changes in glucose metabolism in children participating in a lifestyle intervention was not observable.

Changes in adipose-derived inflammatory cytokines and chemokines after successful lifestyle intervention in obese children

Obesity has been associated with low-grade chronic systemic inflammation, potentially leading to insulin resistance. This study was designed to examine relationships between cardiovascular risk factors, insulin resistance, and simultaneously measured inflammatory parameters in obese children. We examined serum inflammatory parameters in 115 obese children and 30 normal-weight controls; 62 obese children were followed longitudinally in a 1-year obesity intervention study. Serum concentrations of adipose tissue hormones adiponectin and resistin as well as adipocytokines were assessed. Cross-sectional analysis showed significant correlations between standard deviation score body mass index and resistin (P = .0004) as well as monocyte chemoattractant protein-1 (MCP-1, P = .04). Increased homeostasis model assessment of insulin resistance index greater than 95th percentile was present in 32% of obese patients, correlating with adiponectin (r = -0.40, P = .0007). Significant correlations were found between adiponectin and several mediators of inflammation (interleukins [ILs] IL-1β, IL-6, and IL-8 and tumor necrosis factor-α). In longitudinal analysis, substantial weight loss (change standard deviation score body mass index >0.5) observed after intervention in 29 children was associated with a significant decrease in blood pressure, homeostasis model assessment of insulin resistance index, and serum concentrations of insulin and IL-1β, IL-8, and MCP-1, but increase of adiponectin (all Ps < .05). In 33 children without substantial weight loss, resistin and MCP-1 levels increased after 1 year. Changes in IL-1β correlated positively with changes of weight status, interferon-γ, IL-6, IL-8, and tumor necrosis factor-α (all Ps < .01). Our study demonstrates significant correlations between different metabolic risk factors at baseline and after changes of weight status and that weight loss in obese children reduces low-grade inflammation, insulin resistance, and blood pressure.

A novel rodent model that mimics the metabolic sequelae of obese craniopharyngioma patients

Patients with craniopharyngioma (CP), a tumor located in the pituitary and/or hypothalamus, are susceptible to developing obesity and many metabolic complications. The study aim was to create a rodent model that mimics the complex neuroanatomical and metabolic disturbances commonly seen in obese CP patients. We compared the metabolic phenotype of animals with three distinct types of hypothalamic lesions: 1) destruction of the arcuate nucleus (ARC) induced by monosodium glutamate (MSG), 2) electrolytic lesion of the adjacent ventromedial nucleus (VMN) alone, 3) both the VMN and dorsomedial nucleus (DMN), or a 4) combined medial hypothalamic lesion (CMHL) affecting the VMN, DMN, and the ARC. Only the CMHL model exhibited all key features observed in patients with hypothalamic obesity induced by CP. These features included excessive weight gain due to increased adiposity, increased food intake, and pronounced hyperinsulinemia and hyperleptinemia. Similar to characteristics of patients with CP, CMHL animals exhibited reduced plasma levels of alpha-melanocyte stimulating hormone and reduced ambulatory activity compared with weight-matched controls. Therefore, the CMHL model best mimics the complex metabolic abnormalities observed in obese CP patients compared with lesions to other hypothalamic areas and provides a foundation for future pharmacological approaches to treat obesity in children with hypothalamic damage.

Longitudinal association between IGFBP-1 levels and parameters of the metabolic syndrome in obese children before and after weight loss

BACKGROUND

Insulin-like growth factor binding protein 1 (IGFBP-1) is a marker of insulin resistance. We hypothesized that IGFBP-1 is associated with the metabolic syndrome (MetS), which is related to insulin resistance.

METHODS

We examined 51 obese Caucasian children (mean age 12.1 ? 2.3, 55% male, mean body mass index [BMI] 31.8 ? 4.8 kg/m(2)). Anthropometrical markers, pubertal stage, hepatic ultrasound, waist circumference, blood pressure, fasting serum IGFBP-1, IGFBP-3, IGF-I, adiponectin, leptin, transaminases, glucose, insulin, triglycerides, and HDL-cholesterol concentrations were determined at onset and the end of the one-year lifestyle intervention.

RESULTS

In contrast to IGF-I and IGFBP-3, IGFBP-1 correlated significantly to most parameters of the MetS in cross-sectional (waist circumference: r = -0.45, triglycerides: r = -0.29; insulin: r = -0.31; HOMA: r = -0.30) and longitudinal analyses (? triglycerides: r = ?0.22; ? Insulin: r = ?0.25; ? HOMA: r = ?0.62). The association between changes of HOMA and changes of IGFBP-1 was stronger than the associations between changes of leptin or adiponectin, and changes of HOMA. The risk for the MetS was inversely related to IGFBP-1 levels (odds ratio:-0.05 per additional IGFBP-1 unit; 95% confidence interval: -0.08 up to -0.02; p = 0.019) in a multiple logistic regression analyses adjusted to BMI, pubertal stage, age, and gender. The nine obese children with the MetS had significantly lower IGFBP-1 levels (1.6 ? 1.3 ngm/l) than the 42 obese children without the MetS (4.0 ? 3.8 ng/ml). The eleven obese children with fatty liver assessed by ultrasound had significantly lower IGFBP-1 levels (1.5 ? 1.3 ngm/l) than the 40 obese children without fatty liver (4.2 ? 4.1 ng/ml).

CONCLUSION

The strong relationships between IGFBP-1, insulin resistance, and the MetS suggest that IGFBP-1 might be a promising marker for these entities in obesity. This study is registered at clinicaltrials.gov (NCT00435734).

Common variants near MC4R: exploring gender effects in overweight and obese children and adolescents participating in a lifestyle intervention

OBJECTIVE

Association with obesity and increased insulin levels have been reported for two variants (rs17782313 and rs12970134) located downstream of the melanocortin-4 receptor gene (MC4R).

METHODS

We investigated whether these variants have sex-specific effects on overweight, obesity and 14 related phenotypes in 889 overweight and obese children and adolescents. We also explored the impact of the variants on weight change in 367 of the 889 cases who participated in an intervention program. Prior to these analyses we showed that both variants were associated with overweight/obesity in the analyzed 889 cases versus 442 normal-weight and lean controls (case-control study).

RESULTS

In explorative analyses we observed higher diastolic blood pressure levels in males (rs17782313: β = 2.52 mm Hg per risk allele; p = 0.003) but reduced blood pressure level in females for the same risk allele (β = -1.72 mm Hg; p = 0.039). We also detected a greater BMI standard deviation score (BMI-SDS) reduction in females with the risk allele at rs17782313 (β = 0.086 per risk allele; p = 0.021). Additionally, we observed evidence for an association of the same risk allele with insulin levels (β = 0.029 log (μU/ml); p = 0.044) with no sex-specific effect. For the remaining 11 phenotypes, we observed no evidence for a (sex-specific) association.

CONCLUSIONS

In sum, our data support the associations of variants rs17782313 and rs12970134 near MC4R with early onset obesity and increased insulin levels. Exploratory evidence for sex-specific effects of the risk alleles were observed for diastolic blood pressure and BMI-SDS reduction.

Studies of different female rat models of hypothalamic obesity

Hypothalamic obesity (HO) is a major and unsolved problem in patients with medial hypothalamic lesions and is associated with hyperinsulinemia and hyperleptinemia. The purpose of this study was to create a rodent model that mimics metabolic changes in HO for use in therapeutic testing. Female Sprague-Dawley rats were used to test the individual and combined effects of two types of medial hypothalamic lesions: arcuate nucleus (ARC) lesions by injection of monosodium glutamate at neonatal age, and ventromedial nucleus (VMN) lesions by passing an anodal current through an electrode placed in the VMN at age 80 days. Adiposity in ARC-lesioned animals was associated with decreased food intake and stunted growth, while VMN lesions were associated with hyperphagia but not reduced growth. The greatest weight gain (weight at age 200 days 712 +/- 65 vs. 451 +/- 19 g in controls), hyperphagia (food intake 10 days following surgery 33 +/- 0.8 vs. 18.5 +/- 0.7 g/day in sham-treated rats), hyperinsulinemia and hyperleptinemia occurred in rats that received both ARC and VMN lesions. Thus, the combined medial hypothalamic lesions result in an obesity phenotype similar to that of patients that suffer from HO and are consequently more suitable for testing potential therapeutics for this disorder than lesions of single hypothalamic nuclei.

Appetite-regulating hormone changes in patients with craniopharyngioma

Patients with craniopharyngioma (CP), an embryological tumor located in the hypothalamic and/or pituitary region, often suffer from uncontrolled eating and severe obesity. We aimed to compare peripherally secreted hormones involved in controlling food intake in normal weight and obese children and adolescents with CP vs. controls. Plasma insulin, glucose, total ghrelin, and peptide-YY (PYY) levels were assessed under fasting conditions as well as 60 min after liquid mixed meal in four groups: Normal weight (n = 12) and obese (n = 15) CP patients, and 12 normal weight and 15 obese otherwise healthy BMI-, gender- and age-matched controls. Homeostasis model assessment of insulin resistance (HOMA(IR)), as well as quantitative insulin sensitivity check index (QUICKI) were calculated. Obese CP subjects had significantly higher HOMA(IR), higher baseline and postmeal insulin but lower ghrelin levels, weaker postmeal changes for PYY, and lower QUICKI compared to obese controls. QUICKI data from all CP patients correlated positively with ghrelin and PYY % postmeal changes (ghrelin: r = 0.38, P = 0.023; PYY r = 0.40, P = 0.017) and negatively with standard deviation score-BMI (SDS-BMI: r = -0.49, P = 0.002). Tumor growth of 87% obese and 58% of normal weight CP patients affected the hypothalamic area which was associated with higher SDS-BMI and weaker % postmeal ghrelin changes (P = 0.014) compared to CP patients without hypothalamic tumor involvement. Blunted postmeal ghrelin and PYY responses in obese CP subjects are likely due to their higher degree of insulin resistance and lower insulin sensitivity compared to matched obese controls. Thus, insulin resistance in CP patients seems to affect eating behavior by affecting meal responses of gut peptides.

Vitamin d deficiency in obese children and its relationship to insulin resistance and adipokines

Low-serum concentrations of 25-hydroxyvitamin D [25(OH)D] are associated with insulin resistance in adults. Less data are available in pediatric populations. Serum 25(OH)D serum concentrations were assessed in 125 obese and 31 nonobese children (age 11.9 ± 2.7 y, range 6-16 y, 49% male) living in Bonn, Germany. The relationship between 25(OH)D, measured by liquid chromatography-tandem mass spectrometry, and measures of insulin sensitivity and adipokines adiponectin and resistin were analyzed. Seventy-six % of subjects were 25(OH)D deficient (<20 ng/mL). Higher insulin, homeostasis model assessment-insulin resistance (HOMA-IR r = -0.269, P = 0.023), and hemoglobin A1c (HbA(1c)) as well as lower quantitative insulin-sensitivity check index (QUICKI r = 0.264, P = 0.030) values were found in obese children with lower 25(OH)D concentrations even after adjustment for gender, age, and body mass index. Furthermore, 25(OH)D correlated significantly with adiponectin, but not with resistin. Our results suggest that hypovitaminosis D is a risk factor for developing insulin resistance independent of adiposity.

Hypothalamic obesity in patients with craniopharyngioma: profound changes of several weight regulatory circuits

One of the most striking examples of dysfunctional hypothalamic signaling of energy homeostasis is observed in patients with hypothalamic lesions leading to hypothalamic obesity (HO). This drastic condition is frequently seen in patients with craniopharyngioma (CP), an embryological tumor located in the hypothalamic and/or pituitary region, frequently causing not only hypopituitarism, but also leading to damage of medial hypothalamic nuclei due to the tumor and its treatment. HO syndrome in CP patients is characterized by fatigue, decreased physical activity, uncontrolled appetite, and morbid obesity, and is associated with insulin and leptin resistance. Mechanisms leading to the profoundly disturbed energy homeostasis are complex. This review summarizes different aspects of important clinical studies as well as data obtained in rodent studies. In addition a model is provided describing how medial hypothalamic lesion can interact simultaneously with several weight-regulating circuitries.

Changes in dynamic insulin and gastrointestinal hormone secretion in obese children

BACKGROUND

Disturbed satiety and hunger perception in obese individuals has been reported, however data on the dynamic changes of hormonal mediators are sparse.

OBJECTIVE

To evaluate the secretion pattern of insulin, ghrelin, peptide-YY (PYY), and amylin via 0 to 180 min oral glucose tolerance testing in obese and lean children.

SUBJECTS AND METHODS

A prospective clinical study was conducted on lean (n=9) and obese (n=20) Caucasian children of comparable age, gender, and pubertal stage. Serial blood samples were collected.

RESULTS

Compared to baseline, levels of acylated ghrelin showed a significant decrease in lean (p<0.05) but not in obese children. PYY increase was blunted and of shorter duration (60 min) in obese children. Amylin levels increased in both groups, and attained significantly higher levels in obese children (p<0.05).

CONCLUSION

Glucose stimulated gut hormone secretion differed between obese and lean children, and may explain the disturbed satiety observed in obese children.

Roles of gastrointestinal and adipose tissue peptides in childhood obesity and changes after weight loss due to lifestyle intervention

Childhood obesity is a global epidemic and associated with an increased risk of hypertension, diabetes mellitus, and coronary heart disease, in addition to psychological disorders. Interventions such as bariatric surgery are highly invasive and lifestyle modifications are often unsuccessful because of disturbed perceptions of satiety. New signaling peptides discovered in recent years that are produced in peripheral tissues such as the gut, adipose tissue, and pancreas communicate with brain centers of energy homeostasis, such as the hypothalamus and hindbrain. This review discusses the major known gut- and adipose tissue-derived hormones involved in the regulation of food intake and energy homeostasis and their serum levels in childhood obesity before and after weight loss as well as their relationship to consequences of obesity. Since most of the changes of gastrointestinal hormones and adipokines normalize in weight loss, pharmacological interventions based on these hormones will likely not solve the obesity epidemic in childhood. However, a better understanding of the pathways of body weight- and food intake-regulating gut- and adipose tissue-derived hormones will help to find new strategies to treat obesity and its consequences.

Changes of peripheral alpha-melanocyte-stimulating hormone in childhood obesity

Relationships of blood circulating melanocortins to childhood obesity are not well established. We evaluated serum alpha-melanocyte-stimulating hormone (alpha-MSH) in lean children and different study groups of childhood obesity. We examined serum alpha-MSH in 52 otherwise healthy children with childhood obesity (Ob; mean age, 11 years; 32 girls/20 boys), 27 normal-weight children of same age, 7 additional obese patients with reduced melanocortin-4 receptor function (MC4Rmut), and 22 patients with craniopharyngioma (CP). Fasting serum alpha-MSH and leptin were measured by radioimmunoassay. Serum alpha-MSH was also evaluated 1 hour after 500-kcal liquid meal (CP and Ob) and at the end of 1-year lifestyle intervention in 24 Ob patients. The alpha-MSH levels were similar in obese vs lean children but significantly lower in CP (P < .001) and significantly higher (P < .05) in MC4Rmut patients compared with Ob. One hour after liquid meal, alpha-MSH increased in patients with Ob but not with CP. After 1 year, alpha-MSH levels increased significantly in the successful weight reduction Ob subgroup despite unchanged cortisol levels. The alpha-MSH changes correlated to weight status changes (r = 0.67, P = .0003) but not to changes of cortisol, insulin, or homeostasis model assessment of insulin resistance index. Persistently low alpha-MSH levels in CP patients are suspected to be due to pituitary or hypothalamic damage. High peripheral levels in MC4Rmut carriers indicate up-regulation of alpha-MSH. Changes of weight status are associated with changes of peripheral alpha-MSH.