The role of leptin in anorexia nervosa: clinical implications

Psychobiology of purging disorder: reduction in circulating leptin levels in purging disorder in comparison with controls

OBJECTIVE

Purging disorder (PD), a recently recognized eating disorder syndrome, is differentiated from bulimia nervosa (BN) based on the absence of objectively large binge episodes. BN has been associated with low serum leptin levels. This study examined whether PD is also characterized by low serum leptin.

METHOD

Participants included women with PD (n = 20) or BN (n = 37), and non-eating disorder controls (n = 33). Blood samples for measurement of leptin and total ghrelin were obtained after overnight fast.

RESULTS

In comparison with control values, leptin levels were significantly decreased in PD (p < .01), as well as in BN (p < .02). Plasma ghrelin levels did not differ significantly across groups.

DISCUSSION

These results provide the first evidence that PD is associated with alteration in a neurobiological pathway influencing eating patterns and body weight. Further research is needed to assess whether low leptin levels in PD and BN are associated with restrained eating and weight suppression.

Leptin-based therapeutics

Leptin, a pluripotent adipokine, has been discovered as a hormone controlling energy balance in hypothalamic neuroendocrine centers. In addition, recent studies provided ample evidence that leptin can be produced by cells other than adipocytes, and that the hormone can regulate many physiological processes other than energy balance and appetite. In this context, it is not surprising that both leptin excess as well as leptin insufficiency have been implicated in various pathologies. Consequently, despite initially disappointing results with recombinant leptin as the drug for obesity management, new leptin receptor modifiers have been developed and emerged as potential treatment modalities for numerous metabolic, immunological and neoplastic diseases. The major focus of this paper is a systematic review of current experimental leptin-based therapies, including pharmacological advantages and limitations of each prodrug category.

Promoter specific DNA methylation and gene expression of POMC in acutely underweight and recovered patients with anorexia nervosa

Proopiomelanocortin (POMC) and its derived peptides, in particular alpha-MSH, have been shown to play a crucial role in the regulation of hunger, satiety and energy homeostasis. Studies in patients with anorexia nervosa (AN) suggest an abnormal expression of appetite-regulating hormones. Hormone expression levels may be modulated by epigenetic mechanisms, which were recently shown to be implicated in the pathophysiology of eating disorders. We hypothesised that POMC promoter specific DNA methylation and gene expression will be affected by malnutrition and therefore differ in AN patients at distinct stages of the disorder. Promoter specific DNA methylation of the POMC gene and expression of POMC mRNA variants were determined in peripheral blood mononuclear cells (PBMC) of 30 healthy control women (HCW), 31 underweight (acAN) and 30 weight-recovered patients with AN (recAN). Malnutrition was characterized by plasma leptin. Expression of the functionally relevant long POMC mRNA transcript was significantly correlated with leptin levels and higher in acAN compared to recAN and HCW. Expression of the truncated form and mean promoter DNA methylation was similar in all three subgroups. Methylation of single CpG residues in the E2F binding site was inversely related to POMC expression. Our preliminary data on pattern of POMC regulation suggests an association with the underweight state rather than with persisting trait markers of AN. In contrast to POMC expression in the central nervous system, peripheral POMC mRNA expression decreased with malnutrition and hypoleptinemia. This may represent a counterregulatory mechanism as part of the crosstalk between the immune and neuroendocrine systems.

The 5-HTTLPR polymorphism, platelet serotonin transporter activity and platelet serotonin content in underweight and weight-recovered females with anorexia nervosa

Serotonin (5-HT) pathways play an important role in the pathophysiology of anorexia nervosa (AN). In this study, we investigated functional characteristics of the platelet 5-HT transporter and platelet 5-HT content in AN patients at various stages of their illness in comparison to healthy control woman (HCW) controlling for the 5-HTTLPR deletion/insertion polymorphism and other confounding variables. Fasting blood samples of 58 acutely underweight AN patients (acAN, BMI = 15.2 ± 1.4), 26 AN patients of the initial acAN sample after short-term/partial weight restoration (BMI = 17.3 ± 0.9), 36 weight-recovered AN patients (recAN, BMI = 20.7 ± 2.2) and 58 HCW (BMI = 21.6 ± 2.0) were assessed for kinetic characteristics of platelet 5-HT uptake (V (max), K (m)) and platelet 5-HT content. Plasma leptin served as an indicator of malnutrition. Mean V (max) and K (m) values were significantly higher in recAN subjects in comparison to HCW (2.05 ± 0.62 vs. 1.66 ± 0.40 nmol 5-HT/10(9) platelets min and 432 ± 215 vs. 315 ± 136 nmol, respectively) but there were no differences in platelet 5-HT content (464.8 ± 210.6 vs. 472.0 ± 162.2 ng 5-HT/10(9) platelets). 5-HT parameters in acAN patients and HCW were similar. 5-HTTLPR variants were not related to 5-HT platelet variables. In the longitudinal part of the study we found significantly increased 5-HT content but unchanged 5-HT uptake in AN patients after short-term/partial weight restoration. Our results highlight the importance of malnutrition for the interpretation of abnormalities in neurotransmitter systems in AN. Changes in platelet 5-HT transporter activity were related to the stage of the illness but not to 5-HTTLPR genotype. Increased V (max) and K (m) in recovered AN patients might mirror adaptive modulations of the 5-HT system.

Bone mineral density in partially recovered early onset anorexic patients - a follow-up investigation

BACKGROUND AND AIMS

There still is a lack of prospective studies on bone mineral development in patients with a history of early onset Anorexia nervosa (AN). Therefore we assessed associations between bone mass accrual and clinical outcomes in a former clinical sample. In addition to an expected influence of regular physical activity and hormone replacement therapy, we explored correlations with nutritionally dependent hormones.

METHODS

3-9 years (mean 5.2 +/- 1.7) after hospital discharge, we re-investigated 52 female subjects with a history of early onset AN. By means of a standardized approach, we evaluated the general outcome of AN. Moreover, bone mineral content (BMC) and bone mineral density (BMD) as well as lean and fat mass were measured by dual-energy x-ray absorptiometry (DXA). In a substudy, we measured the serum concentrations of leptin and insulin-like growth factor-I (IGF-I).

RESULTS

The general outcome of anorexia nervosa was good in 50% of the subjects (BMI >/= 17.5 kg/m2, resumption of menses). Clinical improvement was correlated with BMC and BMD accrual (chi2 = 5.62/chi2 = 6.65, p = 0.06 / p = 0.036). The duration of amenorrhea had a negative correlation with BMD (r = -.362; p < 0.01), but not with BMC. Regular physical activity tended to show a positive effect on bone recovery, but the effect of hormone replacement therapy was not significant. Using age-related standards, the post-discharge sample for the substudy presented IGF-I levels below the 5th percentile. IGF-I serum concentrations corresponded to the general outcome of AN. By contrast, leptin serum concentrations showed great variability. They correlated with BMC and current body composition parameters.

CONCLUSIONS

Our results from the main study indicate a certain adaptability of bone mineral accrual which is dependent on a speedy and ongoing recovery. While leptin levels in the substudy tended to respond immediately to current nutritional status, IGF-I serum concentrations corresponded to the individual's age and general outcome of AN.

Eating disorders: the current status of molecular genetic research

Anorexia nervosa (AN) and bulimia nervosa (BN) are complex disorders characterized by disordered eating behavior where the patient's attitude towards weight and shape, as well as their perception of body shape, are disturbed. Formal genetic studies on twins and families suggested a substantial genetic influence for AN and BN. Candidate gene studies have initially focused on the serotonergic and other central neurotransmitter systems and on genes involved in body weight regulation. Hardly any of the positive findings achieved in these studies were unequivocally confirmed or substantiated in meta-analyses. This might be due to too small sample sizes and thus low power and/or the genes underlying eating disorders have not yet been analyzed. However, some studies that also used subphenotypes (e.g., restricting type of AN) led to more specific results; however, confirmation is as yet mostly lacking. Systematic genome-wide linkage scans based on families with at least two individuals with an eating disorder (AN or BN) revealed initial linkage regions on chromosomes 1, 3 and 4 (AN) and 10p (BN). Analyses on candidate genes in the chromosome 1 linkage region led to the (as yet unconfirmed) identification of certain variants associated with AN. Genome-wide association studies are under way and will presumably help to identify genes and pathways involved in these eating disorders. The elucidation of the molecular mechanisms underlying eating disorders might improve therapeutic approaches.

Genetic findings in anorexia and bulimia nervosa

Anorexia nervosa (AN) and bulimia nervosa (BN) are complex disorders associated with disordered eating behavior. Heritability estimates derived from twin and family studies are high, so that substantial genetic influences on the etiology can be assumed for both. As the monoaminergic neurotransmitter systems are involved in eating disorders (EDs), candidate gene studies have centered on related genes; additionally, genes relevant for body weight regulation have been considered as candidates. Unfortunately, this approach has yielded very few positive results; confirmed associations or findings substantiated in meta-analyses are scant. None of these associations can be considered unequivocally validated. Systematic genome-wide approaches have been performed to identify genes with no a priori evidence for their relevance in EDs. Family-based scans revealed linkage peaks in single chromosomal regions for AN and BN. Analyses of candidate genes in one of these regions led to the identification of genetic variants associated with AN. Currently, an international consortium is conducting a genome-wide association study for AN, which will hopefully lead to the identification of the first genome-wide significant markers.

Psychopathology in underweight and weight-recovered females with anorexia nervosa

OBJECTIVE

To compare general and eating disorder-specific psychopathology in patients with acute anorexia nervosa (acAN), weight-recovered patients (recAN) and healthy control women (HCW).

METHODS

One hundred anorexia nervosa patients (66 acAN and 34 recAN) and 88 HCW were included in our study. Psychopathology was assessed by self-report questionnaires [Symptom Check List 90 Revised (SCL-90-R), Eating Disorder Inventory-2 (EDI- 2)] as well as by interview [Structured Interview of Anorexia Nervosa and Bulimic Syndromes (SIAB-EX)] and compared using multivariate analysis of variance. Plasma leptin levels were determined using enzyme linked immunosorbent assay.

RESULTS

Mean comparisons indicated highly significant differences between acAN and recAN subjects on all psychopatholgy variables, except for perfectionism. RecAN subjects did not differ from HCW. Partial weight recovery was associated with decreasing levels of psychopathology. Correlational analyses suggested strong negative associations between leptin levels and psychopathology.

CONCLUSION

Prolonged malnutrition, as indicated by suppressed plasma leptin levels, is strongly related to eating disorder-specific as well as general psychopathological symptoms. Weight recovery is associated with the absence of psychopathology. These data emphasize the interaction between somatic and psychological variables.

Aspectos da leptina na anorexia nervosa: possíveis efeitos benéficos no tratamento da hiperatividade

Pesquisas recentes demonstram a relação direta da leptina na regulação do balanço energético e como um dos fatores envolvidos em transtornos alimentares. Com ação no sistema nervoso central, a leptina interfere na ingestão alimentar, no metabolismo da glicose, no peso corporal, na produção de hormônios sexuais e na atividade física. As pesquisas realizadas tanto em seres humanos como em animais demonstram que a queda nos níveis de leptina está relacionada aos sintomas apresentados na anorexia nervosa: a baixa ingestão alimentar, a perda excessiva de peso corporal, a amenorréia e a hiperatividade. Assim, o grau de hipoleptinemia não é apenas uma forte indicação de baixa reserva de tecido adiposo, mas também de severa desordem, sendo que os níveis de leptina podem ser utilizados para avaliar melhor a gravidade da doença. Pesquisas estão sendo realizadas com o objetivo de discutir a possibilidade de utilização da leptina como coadjuvante no tratamento de pacientes com anorexia nervosa para a diminuição da hiperatividade. Acredita-se que o tratamento com leptina associado à medicação e à psicoterapia, poderia ser benéfico em pacientes anoréxicas extremamente ativas, deixando-as mais suscetíveis ao tratamento adicional. Uma realimentação suficiente, a medicação, a psicoterapia e um ambiente acolhedor durante o tratamento com leptina devem ser assegurados. Assim, este artigo tem como objetivo discorrer sobre a leptina e aspectos relacionados à anorexia, e discutir como esta informação pode ser importante na avaliação clínica de pacientes com este transtorno alimentar.

The role of leptin and cortisol in hyperactivity in patients with acute and weight-recovered anorexia nervosa

INTRODUCTION

In food-restricted rats, leptin as well as corticotropin releasing factor attenuate semistarvation-induced hyperactivity (SIH). Results from studies in patients with anorexia nervosa (AN) showed an association between excessive physical activity (PA) and leptin. One recent report suggests a role for cortisol in PA. In this study, we assessed the relationships between PA and both, cortisol and leptin levels at the same time in patients with acute anorexia nervosa (acAN) in comparison to recovered patients (recAN).

METHODS

Plasma leptin, plasma cortisol, body mass index (BMI), and expert-ratings of qualities of PA were assessed in 36 acAN patients, 27 recAN patients and 44 healthy control woman (HCW). Regression analyses were used to predict PA using BMI, leptin and cortisol levels as predictor variables.

RESULTS

Leptin levels but not cortisol significantly contributed to the prediction of PA in acAN. In recAN PA was not elevated and not related to endocrine parameters but correlated positively with core eating disorder symptoms.

CONCLUSIONS

Our work lends support to the proposed inverse association between peripheral leptin levels and excessive physical activity in AN. This relationship is specific to the state of semistarvation. The role of additional mediators remains to be clarified.

High ambient temperature reverses hypothalamic MC4 receptor overexpression in an animal model of anorexia nervosa

The potential involvement of the melanocortin system in the beneficial effects of heat application in rats submitted to activity-based anorexia (ABA), an analogous model of anorexia nervosa (AN), was studied. Once ABA rats had lost 20% of body weight, half of the animals were exposed to a high ambient temperature (HAT) of 32 degrees C, whereas the rest were maintained at 21 degrees C. Control sedentary rats yoked to ABA animals received the same treatment. ABA rats (21 degrees C) showed increased Melanocortin 4 (MC4) receptor and Agouti gene Related Peptide (AgRP) expression, and decreased pro-opiomelanocortin (POMC) mRNA levels (Real Time PCR), with respect to controls. Heat application increased weight gain and food intake, and reduced running rate in ABA rats, when compared with ABA rats at 21 degrees C. However, no changes in body weight and food intake were observed in sedentary rats exposed to heat. Moreover, heat application reduced MC4 receptor, AgRP and POMC expression in ABA rats, but no changes were observed in control rats. These results indicate that hypothalamic MC4 receptor overexpression could occur on the basis of the characteristic hyperactivity, weight loss, and self-starvation of ABA rats, and suggest the involvement of hypothalamic melanocortin neural circuits in behavioural changes shown by AN patients. Changes in AgRP and POMC expression could represent an adaptative response to equilibrate energy balance. Moreover, the fact that HAT reversed hypothalamic MC4 receptor overexpression in ABA rats indicates the involvement of brain melanocortin system in the reported beneficial effects of heat application in AN. A combination of MC4 receptor antagonists and heat application could improve the clinical management of AN.

Aromatic amino acids in weight-recovered females with anorexia nervosa

OBJECTIVE

Most previous studies investigating amino acid levels in anorexia nervosa (AN) have focused on acutely underweight patients. The present study assessed the availability of aromatic amino acids in the plasma of weight-recovered outpatients with AN (recAN) in comparison to acutely underweight AN patients (acAN) and healthy control woman (HCW).

METHOD

Plasma tryptophan (TRP), tyrosine (TYR), and phenylalanine (PHEN) as well as leptin concentration were determined in 32 recAN, 32 acAN, and 32 HCW.

RESULTS

Both recAN and acAN patients showed significantly lower levels of TRP and PHEN when compared to HCW. TYR was reduced in acAN patients only.

DISCUSSION

Normal weight and normal leptin levels but lower availability of TRP and PHEN in recAN patients might indicate that outside a tightly controlled setting these patients still engage in abnormal eating patterns. Reduced peripheral availability of these precursor amino acids could impact on 5-HT and catecholamine functioning in the brain.

Leptin-mediated neuroendocrine alterations in anorexia nervosa: somatic and behavioral implications

Hypoleptinemia is a key endocrinological feature of anorexia nervosa (AN). Several symptoms in acute AN are related to the low circulating leptin levels including amenorrhea and semi-starvation-induced hyperactivity. The drop in leptin levels results from the loss of fat mass; once leptin levels fall below specific thresholds the hypothalamic-pituitary-gonadal and -thyroid axes are down-regulated; in contrast, the hypothalamic-pituitary-adrenal axis is up-regulated. Hypoleptinemia is the major signal underlying both somatic and behavioral adaptations to starvation. Because the mechanisms involved in this adaptation are similar in rodents and humans, rodent models can be used to investigate the relevant central pathways which underly the respective starvation-induced symptoms. During therapeutically induced weight gain, leptin levels can intermittently increase above normal concentrations. This hyperleptinemia could predispose to renewed weight loss.

Adolescent eating disorders: definitions, symptomatology, epidemiology and comorbidity

Eating disorders have morbidity and mortality rates that are among the highest of any mental disorders and are associated with significant functional impairment. This article provides an up-to-date review on recent developments and expanding knowledge in adolescent anorexia nervosa, bulimia nervosa, and related disorders. It covers diagnoses and assessment, recognition of typical symptoms, medical and psychiatric comorbidities, and current trends in epidemiology.

Leptin and its associations with measures of psychopathology in patients with anorexia nervosa

Apart from energy homeostasis leptin has been shown to be involved in a number of neuronal networks. The aim of this study was to investigate how the residual variance of leptin levels, after controlling for BMI, is linked to eating-disorder-specific psychopathology and sexual desire in patients with anorexia nervosa (AN) compared to healthy controls. The sample included 57 subjects with acute AN and 77 healthy controls. Psychopathology was determined by EDI-2 and SCL-90-R and sexual problems were rated according to the Structured Interview of Anorexia Nervosa and Bulimic Syndromes (SIAB-EX). Plasma leptin was assessed by ELISA. Patients with a high drive for thinness had lower leptin levels at a given BMI and low leptin levels were associated with sexual problems, i.e. the absence of sexual desire and intimate relationships. Our results are in accordance with recent animal experiments linking low leptin levels with decreased sexual interest irrespective of body weight.

Lack of association of genetic variants in genes of the endocannabinoid system with anorexia nervosa

BACKGROUND

Several lines of evidence indicate that the central cannabinoid receptor 1 (CNR1) as well as the major endocannabinoid degrading enzymes fatty acid amide hydrolase (FAAH), N-acylethanolamine-hydrolyzing acid amidase (NAAA) and monoglyceride lipase (MGLL) are implicated in mediating the orexigenic effects of cannabinoids. The aim of this study was to analyse whether nucleotide sequence variations in the CNR1, FAAH, NAAA and MGLL genes are associated with anorexia nervosa (AN).

METHODS

We analysed the association of a previously described (AAT)n repeat in the 3' flanking region of CNR1 as well as a total of 15 single nucleotide polymorphisms (SNPs) representative of regions with restricted haplotype diversity in CNR1, FAAH, NAAA or MGLL in up to 91 German AN trios (patient with AN and both biological parents) using the transmission-disequilibrium-test (TDT). One SNP was additionally analysed in an independent case-control study comprising 113 patients with AN and 178 normal weight controls. Genotyping was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, ARMS-PCR or using 3730xl capillary sequencers.

RESULTS

The TDT revealed no evidence for association for any of the SNPs or the (AAT)n repeat with AN (all two-sided uncorrected p-values > 0.05). The lowest p-value of 0.11 was detected for the A-allele of the CNR1 SNP rs1049353 for which the transmission rate was 59% (95% confidence interval 47%...70%). Further genotyping of rs1049353 in 113 additional independent patients with AN and 178 normal weight controls could not substantiate the initial trend for association (p = 1.00).

CONCLUSION

As we found no evidence for an association of genetic variation in CNR1, FAAH, NAAA and MGLL with AN, we conclude that genetic variations in these genes do not play a major role in the etiology of AN in our study groups.

Neuropsychologische Befunde bei Anorexia und Bulimia nervosa im Kindes- und Jugendalter

Zusammenfassung: Anorexia und Bulimia nervosa sind häufige psychiatrische Erkrankungen des Kindes- und Jugendalters, die insbesondere Mädchen betreffen. Im Akutzustand der Starvation treten bei Essstörungen eine Vielzahl von hormonellen, neuropsychologischen und hirnmorphologischen Veränderungen auf, von denen einige nur teilweise reversibel sind. Komorbide psychiatrische Erkrankungen verkomplizieren das Krankheitsbild und erschweren adäquate therapeutische Interventionen. Der folgende Artikel setzt sich ausführlich mit den neuropsychologischen Defiziten bei Essstörungen, möglichen Einflussfaktoren auf die kognitive Leistungsfähigkeit und daraus resultierenden Implikationen für den klinischen Alltag auseinander.

Heat reversal of activity-based anorexia: implications for the treatment of anorexia nervosa

OBJECTIVE

Activity-based anorexia (ABA) provides an animal model of anorexia nervosa (AN). In this model, rats given restricted access to food but unrestricted access to activity wheels, run excessively while reducing food intake, lose a sizeable percentage of body weight, become hypothermic, and can fail to recover unless removed from these conditions.

METHOD

Once rats had lost 20% of body weight under standard ABA conditions, they were assigned to one of two ambient temperature (AT) conditions.

RESULTS

Increased AT reduced running rates and led to weight gain in active rats. The effect of increasing AT on food intake was dependent on whether the rats were sedentary or active. Although warming reduced food intake in the sedentary rats their body weight remained stable, whereas in active rats increased AT did not reduce food intake and weight gain gradually rose.

CONCLUSION

From a translational perspective, these findings offer a fresh perspective to the disorder, and underscore the need for further studies to assess the effects of heat treatment in patients as an innovative adjunctive treatment for anorexia nervosa.

Behavioral neuroendocrinology and treatment of anorexia nervosa

Outcome in anorexia nervosa remains poor and a new way of looking at this condition is therefore needed. To this aim, we review the effects of food restriction and starvation in humans. It is suggested that body weight remains stable and relatively low when the access to food requires a considerable amount of physical activity. In this condition, the human homeostatic phenotype, body fat content is also low and as a consequence, the synthesis and release of brain neurotransmitters are modified. As an example, the role of neuropeptide Y is analyzed in rat models of this state. It is suggested that the normal behavioral role of neuropeptide Y is to facilitate the search for food and switch attention from sexual stimuli to food. Descriptive neuroendocrine studies on patients with anorexia nervosa have not contributed to the management of the patients and the few studies in which hormones have been administered have, at best, reversed an endocrine consequence secondary to starvation. In a modified framework for understanding the etiology and treatment of anorexia nervosa it is suggested that the condition emerges because neural mechanisms of reward and attention are engaged. The neural neuropeptide Y receptor system may be involved in the maintenance of the behavior of eating disorder patients because the localization of these receptors overlaps with the neural systems engaged in cue-conditioned eating in limbic and cortical areas. The eating behavior of patients with anorexia nervosa, and other eating disorders as well, is viewed as a cause of the psychological changes of the patients. Patients are trained to re-learn normal eating habits using external support and as they do, their symptoms, including the psychological symptoms, dissolve.

Nature against nurture: calcification in the right thalamus in a young man with anorexia nervosa and obsessive-compulsive personality disorder

This report describes the case of a young man with a large calcification in the right thalamus that was first diagnosed at 9 years of age. Case history reveals specific eating rituals and other obsessive-compulsive personality traits during the patient's childhood and adolescence, fulfilling diagnostic criteria of obsessive-compulsive personality disorder. After a critical life event the patient develops anorexia nervosa. We suggest that our case and further literature provide evidence for an involvement of specific thalamic structures, such as the dorsomedial nucleus, in the development of anorexia nervosa. Furthermore, the treatment of the patient by a combined psychotherapeutic and pharmacotherapeutic approach is described. We focus on the beneficial effect of the atypical antipsychotic olanzapine, which can induce weight gain by an increase of leptin levels.

S100B in underweight and weight-recovered patients with anorexia nervosa

Anorexia nervosa (AN) commonly arises during adolescence, leading to interruptions of somatic and psychological development as well as to cortical atrophy and reductions of brain volume. While most brain changes shift towards normal with weight restoration, it is not certain whether they are related to the loss of brain cells, neuropil or merely due to fluid shifts. We measured S100B serum concentrations and psychometric characteristics in 34 patients with acute AN, 19 weight-recovered patients and 35 healthy control women (HCW). Plasma tryptophan and leptin levels were determined as markers for malnutrition and neuroendocrine adaptation to semi-starvation. Peripheral S100B concentrations of acute and former AN patients were not elevated and not statistically different from HCW. BMI, peripheral leptin levels and measures of psychopathology as well as executive cognitive functioning did not correlate with S100B. Plasma tryptophan was positively related to S100B. Our results are in line with our previous findings showing unaltered GFAP and NSE plasma levels in patients with acute AN. Together they do not support hypotheses comprising the degeneration of glial or neuronal cells to explain common signs of brain atrophy in patients with acute AN.

Immunological disturbance and infectious disease in anorexia nervosa: a review

OBJECTIVE

Severely malnourished patients with anorexia nervosa (AN) are reported to show fewer symptomatic viral infections and a poorer response to bacterial infection than controls. They are also reported to show mild immune system changes, although the relevance of these to altered infection disease presentation in AN and AN pathophysiology is unknown. Thus, in this paper, we suggest a range of immune system changes that might underpin these altered responses to common pathogens, and review a number of recent infectious disease findings for their utility in explaining the pathophysiology of AN.

METHODS

A systematic review of the literature pertaining to immunity and infectious disease in AN was performed.

RESULTS

AN is associated with leucopenia, and the increased spontaneous and stimulated levels of proinflammatory cytokines [i.e. interleukin (IL)-1β, IL-6 and tumour necrosis factor α). A range of less consistent findings are also reviewed. Most of these data were not controlled for length of illness, degree of malnutrition, micronutrient or vitamin deficiencies or recent refeeding and starvation.

CONCLUSION

Cytokine disturbances have been suggested to be causally related to AN symptomatology and pathophysiology of AN, although the evidence supporting this assertion is lacking. Immune and cytokine changes in AN do, however, occur in association with a decreased incidence of symptomatic viral infection, decreased clinical response to bacterial infection leading to delayed diagnosis and increased morbidity and mortality associated with the infections.

Leptin's effect on hyperactivity: potential downstream effector mechanisms

Up to 80% of patients with Anorexia Nervosa (AN) demonstrate hyperactivity. Hyperactivity counteracts weight gain during treatment and is associated with poor outcome of the disease. We hypothesized that hyperactivity in AN patients has a neurobiological basis and used an animal model-based translational approach to gain insight in mechanisms underlying this hyperactivity. Previously we and others showed that leptin treatment attenuates hyperactivity in the rat activity-based anorexia (ABA) model. The mechanisms involved in this process are, however, unknown. Here we describe potential downstream effector mechanisms involved in the attenuation of hyperactivity by leptin treatment in ABA rats.

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.

Genetic epidemiology, endophenotypes, and eating disorder classification

OBJECTIVE

To explore how genetic epidemiology has informed the identification of endophenotypes and how endophenotypes may inform future classification of eating disorders.

METHOD

Literature review and synthesis.

RESULTS

Although a number of endo- and subphenotypes have been suggested for eating disorders, few reach the rigorous definitions developed for candidate endophenotypes.

CONCLUSION

Further study of endophenotypes and subphenotypes for eating disorders may assist with developing a more homogenous classification system that more closely reflects underlying biological mechanisms, and provides a clearer focus for the development of coherent models and treatments.

Differing effects of acute and chronic stressors on plasma osteocalcin and leptin in rats

Stressor activation of the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis can have profound effects on bone and also appetite and metabolism. We tested in rats the response of plasma osteocalcin (pOC, a bone biomarker that is acutely stress responsive), corticosterone, and leptin to (1) ethanol consumption (5% w/v) in a liquid diet (compared with ad libitum and pair-fed rats), (2) acute restraint, and (3) acute (once, 1 h) and (4) chronic (1 h/day for 7 weeks) social aggression. Basal pOC concentration did not differ with ethanol diet or social interaction, but was elevated by both foot restraint immobilization (Imo) and restraint in wire mesh cylinders (WMR). As previously reported for chronic Imo, ingestion of ethanol blunted the pOC response to Imo. Plasma corticosterone concentration was increased by acute WMR and acute social interaction but was unaltered by chronic social interaction. Plasma leptin concentration was markedly increased by Imo in ad libitum fed, but only slightly in ethanol or pair-fed rats. In contrast, the data reflect significant differences between acute and chronic stressor effects since chronic social stress had little effect on pOC or plasma corticosterone, but tended to decrease leptin level in relation to dominance. Lack of significant impact of prolonged ethanol intake or social aggression suggests physiological adaptation.