Assessment of serum apelin levels in girls with anorexia nervosa

Apelin-13 and Asprosin in Adolescents with Anorexia Nervosa and Their Association with Psychometric and Metabolic Variables

Anorexia nervosa (AN) is a widespread, metabo-psychiatric disorder with high relapse rates, comorbidity, and mortality. Many regulatory proteins and neurohormones studied to date play essential roles in the etiopathogenesis of eating disorders and the maintenance of psychopathological symptoms. Nevertheless, the regulatory and pathophysiological mechanisms of AN are still poorly understood. In the presented study, the plasma levels of apelin-13 (APE-13) and asprosin (ASP), as well as carbohydrate metabolism parameters and psychometric parameters, were evaluated in low-weight adolescent female patients with AN (AN1), after partial weight normalization (AN2) and in an age-matched healthy control group (CG) were evaluated. APE-13 levels were higher in the AN1 group than in the post-realimentation and the CG group. APE-13 levels were independent of insulin and glucose levels. Plasma ASP levels increased with increasing body weight in patients with AN, correlating with the severity of eating disorder symptoms in emaciation. The presented data suggest that APE-13 and ASP may be AN’s biomarkers-regulation of eating behavior by APE-13 and ASP, the close relationship between them and emotional behavior, and changes in neurohormone levels in patients with eating and affective disorders seem to support these hypotheses. Moreover, their plasma levels seem to be related to the severity of psychopathological symptoms of eating disorders.

Relationships of apelin concentration and APLN T-1860C polymorphism with obesity in Thai children

Background

Childhood obesity represents a serious global health crisis. Apelin and its receptor system are widely distributed throughout the central nervous system and have been demonstrated to serve a role modulating feeding behaviour and energy homeostasis. The purposes of this study were to examine apelin concentrations and anthropometric-cardiometabolic parameters in obese and non-obese children and to identify associations of APLN T-1860C and APLNR G212A polymorphisms with apelin levels and obesity among Thai children.

Methods

This case-control study included an analysis of 325 Thai children: 198 children with obesity and 127 healthy non-obese children. Anthropometric-cardiometabolic variables and apelin concentration were measured. Genotyping of APLN T-1860C and APLNR G212A was performed using the polymerase chain reaction-restriction fragment length polymorphism technique.

Results

The obese group had significantly lower apelin and HDL-C levels but significantly higher triglycerides and glucose (TyG) index values, TG/HDL-C ratio and TC/HDL-C ratio than the non-obese group (p < 0.01). Apelin level was negatively correlated with body size phenotypes and cardiometabolic parameters (p < 0.05). The APLN T-1860C polymorphism (OR = 4.39, 95% CI = 1.25–15.28) and apelin concentration (OR = 0.45, 95% CI = 0.23–0.92) were significantly associated with obesity among female children (p < 0.05) only, after adjusting for potential covariates. However, the APLNR G212A polymorphism showed no significant relationship with apelin concentration or obesity.

Conclusion

These findings in Thai children suggest that apelin concentrations are related to obesity and cardiometabolic parameters. Furthermore, the APLN T-1860C polymorphism may influence susceptibility to obesity among female children.

Function and regulation of apelin/APJ system in digestive physiology and pathology

Apelin is an endogenous ligand of seven-transmembrane G-protein-coupled receptor APJ. Apelin and APJ are distributed in various tissues, including the heart, lung, liver, kidney, and gastrointestinal tract and even in tumor tissues. Studies show that apelin messenger RNA is widely expressed in gastrointestinal (GI) tissues, including stomach and small intestine, which is closely correlated with GI function. Thus, the apelin/APJ system may exert a broad range of activities in the digestive system. In this paper, we review the role of the apelin/APJ system in the digestive system in physiological conditions, such as gastric acid secretion, control of appetite and food intake, cell proliferation, cholecystokinin secretion and histamine release, gut-brain axis, GI motility, and others. In pathological conditions, the apelin/APJ system plays an important role in the healing process of stress gastric injury, the clinical features and prognosis of patients with gastric cancers, the reduction of inflammatory response to enteritis and pancreatitis, the mediation of liver fibrogenesis, the promotion of liver damage, the inhibition of liver regeneration, the contribution of splanchnic neovascularization in portal hypertension, the treatment of colon cancer, and GI oxidative damage. Overall, the apelin/APJ system plays diversified functions and regulatory roles in digestive physiology and pathology. Further exploration of the relationship between the apelin/APJ system and the digestive system will help to find new and effective drugs for treating and alleviating the pain of digestive diseases.

Assessment of Serum Concentrations of Ghrelin, Obestatin, Omentin-1, and Apelin in Children with Type 1 Diabetes

The increasing knowledge on the functions of gastric peptides and adipokines in the body allows the assumption of their major role linking the process of food intake, nutritional status, and body growth, largely through the regulation of glucose metabolism and insulin resistance. The aim of the study was the assessment of serum levels of selected gastric peptides and adipocytokines in children with type 1 diabetes, with respect to the disease duration. The study involved 80 children aged 4-18 years (M/F -37/43). Children with type 1 diabetes (n = 46) were compared to the control group (n = 34). The study group was divided into 4 subgroups: (I) patients with newly diagnosed type 1 diabetes, after an episode of ketoacidosis (n = 10), (II) patients with type 1 diabetes of duration no longer than 5 years (n = 9), (III) patients with 5 to 10 years of DT1 (n = 20), and (IV) patients with type 1 diabetes of duration longer than 10 years (n = 7). The concentrations of gastric peptide and adipocytokines across all subgroups were lower than in the control group. The differences were statistically significant (p < 0.0001), which may be of importance in the development of the disease complications.

Serum Omentin Levels in Adolescent Girls With Anorexia Nervosa and Obesity

It is believed that omentin is secreted by stromal cells of adipose tissue and modulates insulin sensitivity. Data from a few studies have shown lower serum omentin in obese children and higher in anorexia nervosa. However, to date, there is lack of research on serum omentin concentrations in adolescent patients in a wide range of body mass index (BMI) and insulin resistance. In this cross-sectional study omentin-1 serum concentrations were evaluated using commercially available ELISA kit in 47 Polish girls with restrictive anorexia nervosa (AN), 50 with simple obesity (OB) and 39 healthy controls (C). The mean serum omentin-1 concentration in girls with AN was statistically significantly higher than that of C and OB girls. Statistically significant (P<0.0001) negative correlations between the serum concentrations of omentin-1 and body weight (r=−0.73), BMI (r=−0.75), standard deviation score for body mass index (BMI-SDS) (r=−0.75), insulin (r=−0.81) and HOMA-IR index (r=−0.82) were seen in the entire examined population. We conclude, that omentin-1 is the nutritional marker reflecting body weight and insulin resistance. Our findings support the hypothesized role of omentin in maintenance of body weight and regulation of appetite and suggest the adaptation of its secretion to body weight and glucose metabolism.

Apelin and G212A apelin receptor gene polymorphism in obese and diabese youth

OBJECTIVE

The apelinergic system has been previously described to participate in fluid homeostasis, cardiac contractility, blood pressure and neo-vascularization. The role of apelin in obesity and glucose metabolism has also lately gained interest; however, it still remains obscure. This study aimed to assess serum apelin levels in obese youngsters and to investigate any possible association with the G212A polymorphism of the apelin receptor (APLNR) gene.

METHODS

Ninety obese individuals and 90 matched for age and gender lean controls were included. Anthropometric measurements, data of glucose metabolism, including an oral glucose tolerance test, and serum apelin levels were obtained. The presence of the G212A polymorphism of the APLNR gene was also analyzed in the obese group.

RESULTS

Obese participants had significantly lower serum apelin levels as compared with controls (P = 0.011). After being grouped according to their status of glucose metabolism, only obese subjects with impaired glucose metabolism (diabese) exhibited lower apelin levels as compared with controls. The presence of the G212A polymorphism did not differ from the HapMap-reported frequencies in Caucasians (GG = 53.3%/GA = 38.9%/ΑΑ = 7.8% vs. GG = 46.9%/GA = 39.8%/ΑΑ = 13.3%, P = 0.232). The GG and GA obese subgroups had significantly lower apelin levels as compared with the AA group (P = 0.013 and P = 0.016, respectively).

CONCLUSION

Obese (especially diabese) youngsters demonstrated lower serum apelin levels; the G212A polymorphism of the APLNR gene was found to exert a favourable effect on circulating apelin levels in childhood obesity.

Central and peripheral peptides regulating eating behaviour and energy homeostasis in anorexia nervosa and bulimia nervosa: a literature review

A large body of literature suggests the occurrence of a dysregulation in both central and peripheral modulators of appetite in patients with anorexia nervosa (AN) and bulimia nervosa (BN), but at the moment, the state or trait-dependent nature of those changes is far from being clear. It has been proposed, although not definitively proved, that peptide alterations, even when secondary to malnutrition and/or to aberrant eating behaviours, might contribute to the genesis and the maintenance of some symptomatic aspects of AN and BN, thus affecting the course and the prognosis of these disorders. This review focuses on the most significant literature studies that explored the physiology of those central and peripheral peptides, which have prominent effects on eating behaviour, body weight and energy homeostasis in patients with AN and BN. The relevance of peptide dysfunctions for the pathophysiology of eating disorders is critically discussed.

Regulation of feeding behavior, gastrointestinal function and fluid homeostasis by apelin

Apelin was first identified and characterized from bovine stomach extracts as an endogenous ligand for the APJ receptor. Apelin/APJ system is abundantly present in peripheral tissues and central nervous system. Apelin plays a broad role in regulating physiological and pathological functions. Recently, many reports have showed the effects of apelin on feeding behavior, however the results are inconsistent, due to different administration routes, animal species, forms of apelin, etc. Apelin has been involved in stimulating gastric cell proliferation, cholecystokinin (CCK) secretion, histamine release, gastric acid and bicarbonate secretion, and regulation of gastrointestinal motility. In addition, apelin produced regulatory effects on drinking behavior, diuresis, arginine vasopressin (AVP) release and glucocorticoids secretion. This article reviews the role of apelin on feeding behavior, gastrointestinal function and fluid homeostasis.

Serum apelin-12 level is elevated in schoolchildren with atopic asthma

BACKGROUND

There are limited data on the role of adipokines in atopic asthma.

AIM

To determine serum level of apelin-12 (APE-12) in asthmatic children in relation to BMI and gender.

METHODS

Serum APE-12 levels were measured using ELISA in 89 asthmatic children (61 boys and 28 girls, aged 7.0-17.0 years) and in 33 healthy children. Among examined asthmatics 59 (19 girls and 40 boys) had normal weight and 30 (9 girls and 21 boys) were obese.

RESULTS

The mean serum levels of APE-12 were significantly (p < 0.001) higher both in obese (174.1 ± 5.9 pg/mL) and non-obese asthmatic children (171.0 ± 4.0 pg/mL) than in healthy children (130.6 ± 2.1 pg/mL), regardless of gender. No relationships between examined the adipokine level and asthma severity, spirometric parameters, degree of allergic sensitization, BMI, BMI-SDS were observed.

CONCLUSION

Increased serum level of APE-12 suggests that this adipokine may be implicated in the pathogenesis of childhood atopic asthma.

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.

Apelin, diabetes, and obesity

Apelin is a peptide known as the ligand of the G-protein-coupled receptor APJ. Several active apelin forms exist such as apelin-36, apelin-17, apelin-13, and the pyroglutamated form of apelin-13. Apelin and APJ are expressed in the central nervous system, particularly in the hypothalamus and in many peripheral tissues. Apelin has been shown to be involved in the regulation of cardiovascular and fluid homeostasis, food intake, cell proliferation, and angiogenesis. In addition to be an ubiquitous peptide, apelin is also produced and secreted by adipocytes and thus considered as an adipokine. This has opened a new field of investigation establishing a link between apelin and metabolic disorders (obesity, type 2 diabetes, etc.) which is the focus of the present review. Several studies, but not all, have reported an increase of plasma apelin concentrations in humans and in animal models with different metabolic pathologies. Moreover, important roles for apelin both in glucose and lipid metabolism have been highlighted as well as the associated signaling pathways. Apelin appears as a beneficial adipokine with anti-obesity and anti-diabetic properties and thus as a promising therapeutic target in metabolic disorders.