Letter to the Editor: Similar fasting ghrelin levels in binge eating/purging anorexia nervosa and restrictive anorexia nervosa

Gastrointestinal peptides in eating-related disorders

Food intake is tightly controlled by homeostatic signals sensitive to metabolic need for the regulation of body weight. This review focuses on the peripherally-secreted gastrointestinal peptides (i.e., ghrelin, cholecystokinin, glucagon-like peptide 1, and peptide tyrosine tyrosine) that contribute to the control of appetite and discusses how these peptides or the signals arising from their release are disrupted in eating-related disorders across the weight spectrum, namely anorexia nervosa, bulimia nervosa, and obesity, and whether they are normalized following weight restoration or weight loss treatment. Further, the role of gut peptides in the pathogenesis and treatment response in human weight conditions as identified by rodent models are discussed. Lastly, we review the incretin- and hormone-based pharmacotherapies available for the treatment of obesity and eating-related disorders.

Ghrelin as a possible biomarker and maintaining factor in patients with eating disorders reporting childhood traumatic experiences

OBJECTIVE

The recent conceptualization of ghrelin as a stress hormone suggested that its chronic alterations may have a role in maintaining overeating behaviors in subjects with eating disorders (EDs) reporting childhood traumatic experiences. The aim of this study was to investigate the alterations of ghrelin levels in patients with EDs, their associations with early trauma, binge and emotional eating, and possible moderation/mediation models.

METHOD

Sixty-four patients with EDs and 42 healthy controls (HCs) had their plasma ghrelin levels measured and completed questionnaires evaluating general and ED-specific psychopathology, emotional eating, and childhood traumatic experiences.

RESULTS

Participants with anorexia nervosa had higher ghrelin levels than HCs in body mass index (BMI)-adjusted comparisons. Moreover, patients reporting a history of childhood trauma had higher ghrelin levels. Childhood sexual abuse (CSA), BMI, and self-induced vomiting were independent predictors of ghrelin levels. Moderation analyses showed that ghrelin levels were associated with binge and emotional eating only for higher levels of childhood trauma. Elevated ghrelin was a significant mediator for the association of CSA with binge eating.

CONCLUSIONS

These results support the hypothesis that chronic alterations in ghrelin levels following childhood traumatic experiences could represent a neurobiological maintaining factor of pathological overeating behaviors in EDs.

Ghrelin concentration as an indicator of eating-disorder risk in obese women

AIM

Eating disorders (EDs), disordered eating (DE) and obesity are thought to have overlapping aetiological processes. DE in obesity can jeopardize weight-loss results, and acyl ghrelin (AG) is a hormone that stimulates food intake and reward processes. The main study objective was to determine whether higher-than-expected concentrations of AG in common obesity are associated with DE symptoms.

METHODS

The study population included 84 women, aged 20-55 years, free of established EDs: 55 were severely obese (OB) and 29 were of normal weight (NW). OB participants were stratified into two groups according to their median concentration of fasting AG distribution. The OB women with a high fasting plasma ghrelin concentration (HGC) were compared with both OB women with a low fasting plasma ghrelin concentration (LGC) and NW women. Participants were assessed by the Eating Disorder Inventory (EDI-2), Three-Factor Eating Questionnaire (TFEQ) and Hospital Anxiety and Depression Scale (HADS). Fasting glucose, insulin, leptin and ghrelin plasma concentrations were also quantified.

RESULTS

Between the two AG groups of OB women, there was no statistical difference in either anthropometric or metabolic parameters, HADS, TFEQ or fasting hunger scores. However, the HGC group scored significantly higher than the LGC group on the drive-for-thinness subscale of EDI-2 (9.30±0.99 vs. 6.46±0.83, respectively; P=0.033).

CONCLUSION

Results support the hypothesis of a potential relationship between fasting plasma AG concentrations and ED risk, regardless of mood and anxiety. AG may be considered a potential biomarker of vulnerability for developing EDs.

Seasonal BMI differences between restrictive and purging anorexia nervosa subtypes

OBJECTIVE

Seasonal differences in anorexia nervosa is an area of research which has received scarce attention in the literature. The aim of this study was to explore patterns of seasonal variation in body weight in anorexia nervosa patients admitted to an eating disorders unit from January 2007 to December 2011.

METHOD

Anorexia nervosa restrictive (ANR) and binge eating/purging (ANBP) subtypes were compared with respect to BMI on admission during the Warm and Cold Semester, and in terms of lenght of hospital stay.

RESULTS

The main result was that BMI differences between ANBP and ANR patients were due to bodyweight differences during the colder months of the year (p < 0.01) whereas no difference in bodyweight on admission was observed between both subtypes during the Warm Semester months. Furthermore, ANR patients' bodyweight was lower when admitted during the Cold compared to the Warm Semester (p < 0.05). Length of stay was significantly associated with reduced BMI in ANR patients (p < 0.01), but not so for ANBP patients.

DISCUSSION

To our knowledge, this is the first study in the literature providing data on seasonal variations in the BMI on admission of anorexia nervosa patients, and in the length of hospitalization.

The role of "mixed" orexigenic and anorexigenic signals and autoantibodies reacting with appetite-regulating neuropeptides and peptides of the adipose tissue-gut-brain axis: relevance to food intake and nutritional status in patients with anorexia nervosa and bulimia nervosa

Eating disorders such as anorexia (AN) and bulimia nervosa (BN) are characterized by abnormal eating behavior. The essential aspect of AN is that the individual refuses to maintain a minimal normal body weight. The main features of BN are binge eating and inappropriate compensatory methods to prevent weight gain. The gut-brain-adipose tissue (AT) peptides and neutralizing autoantibodies play an important role in the regulation of eating behavior and growth hormone release. The mechanisms for controlling food intake involve an interplay between gut, brain, and AT. Parasympathetic, sympathetic, and serotoninergic systems are required for communication between brain satiety centre, gut, and AT. These neuronal circuits include neuropeptides ghrelin, neuropeptide Y (NPY), peptide YY (PYY), cholecystokinin (CCK), leptin, putative anorexigen obestatin, monoamines dopamine, norepinephrine (NE), serotonin, and neutralizing autoantibodies. This extensive and detailed report reviews data that demonstrate that hunger-satiety signals play an important role in the pathogenesis of eating disorders. Neuroendocrine dysregulations of the AT-gut-brain axis peptides and neutralizing autoantibodies may result in AN and BN. The circulating autoantibodies can be purified and used as pharmacological tools in AN and BN. Further research is required to investigate the orexigenic/anorexigenic synthetic analogs and monoclonal antibodies for potential treatment of eating disorders in clinical practice.

Role of ghrelin in the pathophysiology of eating disorders: implications for pharmacotherapy

Ghrelin is the only known circulating orexigenic hormone. It increases food intake by interacting with hypothalamic and brainstem circuits involved in energy balance, as well as reward-related brain areas. A heightened gut-brain ghrelin axis is an emerging feature of certain eating disorders such as anorexia nervosa and Prader-Willi syndrome. In common obesity, ghrelin levels are lowered, whereas post-meal ghrelin levels remain higher than in lean individuals. Agents that interfere with ghrelin signalling have therapeutic potential for eating disorders, including obesity. However, most of these drugs are only in the preclinical phase of development. Data obtained so far suggest that ghrelin agonists may have potential in the treatment of anorexia nervosa, while ghrelin antagonists seem promising for other eating disorders such as obesity and Prader-Willi syndrome. However, large clinical trials are needed to evaluate the efficacy and safety of these drugs.

Ghrelin in eating disorders

Ghrelin is the only known circulating hormone that acts on peripheral and central targets to increase food intake and promote adiposity. The present review focuses on the possible clinical relevance of ghrelin in the regulation of human feeding behavior in individuals with obesity and other eating disorders such as Prader-Willi syndrome, anorexia nervosa, bulimia nervosa and binge-eating.

Adipocytokines, gut hormones and growth factors in anorexia nervosa

Anorexia nervosa is a complex eating disorder of unknown etiology which affects adolescent girls and young women and leads to chronic malnutrition. Clinical manifestations of prolonged semistarvation include a variety of physical features and psychiatric disorders. The study of different biological factors involved in the pathophysiology of anorexia nervosa is an area of active interest. In this review we have described the role of adipocytokines, neurotrophins, peptides of the gastrointestinal system and growth factors in appetite regulation, energy balance and insulin sensitivity in anorexia nervosa patients.

Ghrelin and obestatin circadian levels differentiate bingeing-purging from restrictive anorexia nervosa

CONTEXT

Anorexia nervosa (AN) patients present with restrictive food behavior (AN-R). Some of them develop episodes of bulimia (AN-BP) without any clear pathophysiological explanation to date. Their clinical differentiation is important but not easily performed. Orexigenic/anorexigenic peptides measurements could provide some clues for that matter.

OBJECTIVE

The objective of the study was to determine whether the circadian profile of total and acylated ghrelin, obestatin, and peptide YY (PYY) levels is different in AN-R subjects when compared with AN-BP patients.

DESIGN AND SETTINGS

This was a cross-sectional study in an endocrinological unit.

PATIENTS AND CONTROL SUBJECTS

Four groups of age-matched young women: 22 AN-R, 10 AN-BP, 16 normal-weight bulimia nervosa (BN), and nine controls.

MAIN OUTCOME MEASURES

Twelve-point circadian profiles of plasma total and acylated ghrelin, obestatin, and PYY were measured.

RESULTS

Total and acylated ghrelin and obestatin circadian levels were increased in AN-R when compared with controls but decreased in both AN-BP and BN groups (P < 0.001). PYY was decreased in all groups with eating disorders. Acylated to total ghrelin ratio was decreased in AN-BP and BN (P < 0.001), whereas obestatin to acylated ghrelin and PYY to acylated ghrelin ratios were increased in both groups with bingeing-purging behavior (P < 0.0001).

CONCLUSIONS

Patients with AN-associated bingeing-purging behavior present a very different profile of appetite regulatory peptides when compared with the pure restrictive type. The assessment of ghrelin (and eventually obestatin) could be of particular interest for differential diagnosis. Very low ghrelin levels and increased anorexigenic to orexigenic peptide ratios suggest either a lack of adaptation to a starvation state or a higher facility to cope with undernutrition.

New frontiers in endocrinology of eating disorders

Alterations of both central and peripheral feeding regulatory substances occur in the acute phases of anorexia nervosa (AN) and bulimia nervosa (BN) and, generally, reverse after recovery. Some of these alterations are believed not only to sustain the altered eating behavior but also to contribute to certain psychopathological aspects and/or etiopathogenetic processes of eating disorders (EDs). It has been suggested that EDs are clinical conditions linked to reward-related mechanisms leading to a kind of addiction to self-starvation and/or overeating. Most of the feeding regulatory substances, which are dysregulated in EDs, are also implicated in the modulation of reward, emotional, and cognitive functions, thus representing possible links between altered nutritional regulation, motivated behaviors and reward processes. In this chapter, the ED literature dealing with ghrelin, brain-derived neurotrophic factor, opioid peptides, and endocannabinoids, which have prominent effects on eating behavior, body weight, reward, emotional, and cognitive functions, is reviewed in view of the above suggested links. Moreover, the potential therapeutics of new medications developed on the basis of neuroendocrine aberrations found in EDs is also presented.

Plasma obestatin, ghrelin, and ghrelin/obestatin ratio are increased in underweight patients with anorexia nervosa but not in symptomatic patients with bulimia nervosa

INTRODUCTION

Peptides of the gut-brain axis have a pivotal role in the regulation of energy homeostasis. Obestatin, a sibling of ghrelin derived from preproghrelin, is thought to oppose ghrelin effects on food intake. Because changes in ghrelin levels have been associated with anorexia nervosa (AN) and bulimia nervosa (BN), the investigation of obestatin production may further contribute to understanding the role of peripheral peptides in patients with eating disorders.

METHODS

In the present study, we measured circulating blood levels of obestatin and ghrelin and assessed their relationships with anthropometric and clinical measures in 20 AN patients, 21 BN patients, and 20 appropriate healthy controls.

RESULTS

Compared with healthy women, patients with BN showed no significant differences in plasma obestatin and ghrelin concentrations and in the ghrelin/obestatin ratio, whereas underweight AN patients displayed significantly increased circulating levels of both obestatin (P<0.009) and ghrelin (P<0.002) and an increased ghrelin/obestatin ratio (P<0.04). Moreover, in AN women, positive correlations emerged between the ghrelin/obestatin ratio and current body weight and body mass index.

CONCLUSIONS

Underweight AN patients are characterized by increased concentrations of ghrelin and obestatin and a higher ghrelin to obestatin ratio. No changes in circulating ghrelin or obestatin as well as in ghrelin to obestatin ratio seem to occur in acutely ill patients with BN. Although those changes likely reflect the physiological state of symptomatic AN individuals, they may also contribute to the pathophysiology of the disorder.

Appetite-Related Gut Peptides in Obesity and Binge Eating Disorder

The worldwide increase in obesity prevalence is a result of positive energy balance, with energy intake exceeding expenditure. The eating behavior in obesity ranges from mild passive overconsumption to excessive overeating with loss of control observed in binge eating disorder (BED). The signaling systems that underlie appetite control in BED are complex and, at this point, not well understood. The present review highlights the current knowledge of key components of the gut peptide system and examines evidence of defects in signaling that differentiate obese binge eaters from obese non-binge eaters. The signaling network underlying hunger, satiety, and metabolic status includes leptin and insulin from energy stores and cholecystokinin, glucagon-like peptide-1, peptide YY(3-36), and ghrelin from the gastrointestinal tract. Of the many gastrointestinal peptides, ghrelin is the only established appetite-stimulating one, whereas cholecystokinin, glucagon-like peptide-1, and peptide YY(3-36) promote satiety. Adipose tissue provides hormonal signals via leptin and insulin to the brain about energy stores and likely from adiponectin and resistin. Binge eating has been related to a dysfunction in the ghrelin signaling system. Moreover, the larger gastric capacity observed in BED may further reduce satiety signals and contribute to overeating.

Neuroendocrine dysregulation of food intake in eating disorders

Anorexia nervosa (AN) and bulimia nervosa (BN) are psychiatric disorders characterized by abnormal eating behaviors and imbalance of energy homeostasis. Changes of both central and peripheral neuroendocrine substances involved in the modulation of food intake and energy expenditure have been described in acutely ill patients with eating disorders. This review selectively focuses on the most recent findings supporting abnormal changes in the physiology of some peripheral adipokines and gut-secreted peptides, brain-derived neurotrophic factor and endocannabinoids in patients with AN or BN. Literature data do suggest a dysregulation of these neuroendocrine feeding regulators but, at the moment, they do not allow to establish the state or trait-dependent nature of those aberrations. It has been proposed, although not definitively proved, that neuroendocrine alterations, even when secondary to malnutrition and/or to aberrant eating behaviors, 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. Future studies should clarify whether neuroendocrine alterations are part of the genetically transmitted biological vulnerability to eating disorders.

No differences are seen in the regional cerebral blood flow in the restricting type of anorexia nervosa compared with the binge eating/purging type

AIMS

Anorexia nervosa (AN) is subdivided into the restricting type (AN-R) and the binge-eating/purging type (AN-BP), but differences in cerebral blood flow between patients with these types of AN and healthy controls have not been investigated.

METHODS

The present study was designed to elucidate any such differences using resting single photon emission computed tomography (SPECT) studies to compare the differences in cerebral perfusion among both types of AN and a healthy control group. Resting regional cerebral blood flow was assessed using SPECT with technetium-99m hexamethylpropyleneamine oxime in 13 female AN-R patients, 13 female AN-BP patients, and 10 healthy women as controls with 3-D stereotactic surface projections.

RESULTS

The analytic program of the SPECT images showed bilateral decreased perfusion of the subcallosal gyrus (SCG), midbrain and posterior cingulate gyrus (PCG) in both AN-R and AN-BP patients, as compared with the controls. There were no clear differences between the AN-R and AN-BP groups. There were no significant differences in cerebral blood flow between patients with AN-R and AN-BP.

CONCLUSIONS

Abnormalities of the neuronal circuits containing the SCG, midbrain and PCG are possibly relevant to trait-related AN.

The physiology and potential clinical applications of ghrelin, a novel peptide hormone

Ghrelin, a peptide hormone originally identified as the endogenous ligand of the growth hormone secretagogue receptor, is secreted primarily from the stomach and secondarily from the small intestine and colon. Ghrelin may also be expressed in the pancreatic islets, hypothalamus, pituitary, and several tissues in the periphery. The growth hormone secretagogue receptor is widely expressed, suggesting diverse physiologic roles for ghrelin. A growing body of evidence suggests that, in addition to its predictable effect on growth hormone secretion, ghrelin has an important role in the short-term regulation of appetite and the long-term regulation of energy balance and glucose homeostasis. Recent studies have implicated ghrelin in the regulation of gastrointestinal, cardiovascular, and immune function and have suggested a role for ghrelin in bone physiology. The identification of obestatin, a novel peptide hormone derived from the same gene as ghrelin, has recently added further complexity to ghrelin physiology. Obestatin appears to have actions opposite of ghrelin on energy homeostasis and gastrointestinal function. Despite the rapid progress, many questions remain unanswered, including the regulation of ghrelin and obestatin secretion, the downstream pathways that mediate their effects, and their precise physiologic endocrine and paracrine roles. This review presents data on ghrelin structure, expression, and function, with emphasis placed on human studies, highlighting areas that require future investigation and providing speculation about potential clinical applications of ghrelin agonists or antagonists.

No association of the Arg51Gln and Leu72Met polymorphisms of the ghrelin gene with anorexia nervosa or bulimia nervosa

Genetic factors likely contribute to the biological vulnerability to anorexia nervosa (AN) and bulimia nervosa (BN). We investigated whether the Arg51Gln and/or the Leu72Met gene polymorphisms of the human ghrelin, a peptide involved in the regulation of eating behavior, were associated to AN and/or BN. Two-hundred-ninety-two Caucasian women (114 with BN, 59 with AN and 119 healthy controls) participated into the study. No significant differences were found in the frequencies of the Arg51Gln and the Leu72Met ghrelin gene variants among patients with AN or BN and healthy controls. Moreover, no significant differences emerged in eating-related phenotypic variables between patients carrying the Leu72Met genotype as compared to those with the Leu72Leu genotype. These results suggest that the Arg51Gln and the Leu72Met polymorphisms of the human ghrelin gene do not contribute to the genetic susceptibility to AN and BN.

Plasma ghrelin in anorexia, bulimia, and binge-eating disorder: relations with eating patterns and circulating concentrations of cortisol and thyroid hormones

The present study was designed to investigate the relations between plasma ghrelin concentrations, eating patterns, and circulating concentrations of cortisol and thyroid hormones in women with anorexia nervosa, bulimia nervosa, and binge-eating disorder. The patterns of disordered eating behavior were assessed using the Eating Attitudes Test (EAT-26) and the Bulimia Test-Revised (BULIT-R). In women with eating disorders, but not in healthy control women, plasma ghrelin concentrations were negatively correlated with body mass index (BMI) and plasma concentrations of thyreotropin (TSH), free T3 and free T4, and positively correlated with plasma concentrations of cortisol. The ghrelin concentrations of women with binge-eating and purging behavior were significantly lower than those of women with anorexia nervosa, restricting type, and there was a negative relation between the frequency and severity of binge-eating and purging behavior, as measured by the BULIT-R total score, and ghrelin concentrations. In a multivariate regression model controlling for the confounding effects of body mass index (BMI) and age, higher ghrelin concentrations were correlated with lower BULIT-R total scores. The results of this study did not confirm the hypothesis advanced in previous studies that ghrelin concentrations are higher in patients with binge-eating/purging forms of eating disorders. Based on these data, we suggest that, in women with eating disorders, ghrelin concentrations best reflect nutritional status rather than specific patterns of disordered eating behavior.