T-lymphocyte cholecystokinin-8 and beta-endorphin concentrations in eating disorders: I. Anorexia nervosa

Backstage of Eating Disorder-About the Biological Mechanisms behind the Symptoms of Anorexia Nervosa

Anorexia nervosa (AN) represents a disorder with the highest mortality rate among all psychiatric diseases, yet our understanding of its pathophysiological components continues to be fragmentary. This article reviews the current concepts regarding AN pathomechanisms that focus on the main biological aspects involving central and peripheral neurohormonal pathways, endocrine function, as well as the microbiome–gut–brain axis. It emerged from the unique complexity of constantly accumulating new discoveries, which hamper the ability to look at the disease in a more comprehensive way. The emphasis is placed on the mechanisms underlying the main symptoms and potential new directions that require further investigation in clinical settings.

Food choice in disorders of eating behavior: correlations with the psychopathological aspects of the diseases

Eating disorders (ED) are characterized by alterations in food choice and in the quantity and quality of nutrient intake. In a population of 124 female patients with ED (anorexia nervosa restricting subtype [AN-R, n=37]; AN bingeing-purging subtype [AN-BP, n=18]; bulimia nervosa purging subtype [BN-P, n=40]; and binge eating disorder [BED, n=29]) and healthy age-matched controls ([C], n=20) we compared food choice and macronutrient intake with psychopathologic symptoms of the disorders. Data were collected from the probands' 7-day food diaries and the scores from two assessment scales (Eating Disorder Inventory-2 [EDI-2] and Temperament and Character Inventory-revised [TCI-R]) that measure symptom domains, dimensions of personality and character dimensions, respectively. Multiple regression analysis was applied to the nutritional data and scale scores. When compared to the values for the control group, intake of animal proteins (grams) was significantly lower for all patient groups, intake of lactoproteins was lower for the AN-R and AN-BP than BN-P and BED groups, intake of vegetal proteins was higher for the AN-R, AN-BP, BN-P and BED groups, intake of dietary fats was lower for the AN-R and AN-BP subtype groups, and intake of total carbohydrates and oligosaccharides was lower for the AN-R and AN-BP groups, and oligosaccharides also for the BED, when calculated in grams but not when expressed in percent. When studied as percent values animal proteins were lower in patients than in controls, lactoprotein in BN-P and BED, vegetal proteins higher in all the patients, fat lower in AN-R and AN-BP, while carbohydrates did not differ between patients and controls. Significant correlations emerged between food choice and TCI-R and EDI-2 scale scores. Food choice in ED might depend on alterations in neurotransmitter peptides, neuropeptides, and peripheral peptides, which regulate and are regulated by macronutrient intake and underlie psychological and temperamental alterations.

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.

Dysfunctions of leptin, ghrelin, BDNF and endocannabinoids in eating disorders: beyond the homeostatic control of food intake

A large body of literature documents the occurrence of alterations in the physiology of both central and peripheral modulators of appetite in acute patients with anorexia nervosa (AN) and bulimia nervosa (BN). Until more recently the role of most of the appetite modulators in the control of eating behavior was conceptualized solely in terms of their influence on homeostatic control of energy balance. However, it is becoming more and more evident that appetite modulators also affect the non-homeostatic cognitive, emotional and rewarding component of food intake as well as non food-related reward, and, recently, AN and BN have been pathophysiologically linked to dysfunctions of reward mechanisms. Therefore, the possibility exists that observed changes in appetite modulators in acute AN and BN may represent not only homeostatic adaptations to malnutrition, but also contribute to the development and/or the maintenance of aberrant non-homeostatic behaviors, such as self-starvation and binge eating. In the present review, the evidences supporting a role of leptin, ghrelin, brain-derived neurotrophic factor and endocannabinoids in the homeostatic and non-homeostatic dysregulations of patients with AN and BN will be presented. The reviewed literature is highly suggestive that changes in the physiology of these modulators may play a pivotal role in the pathophysiology of eating disorders by providing a possible link between motivated behaviors, reward processes, cognitive functions and energy balance.

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.

Movement correction method for human brain PET images: application to quantitative analysis of dynamic 18F-FDDNP scans

Head movement during a PET scan (especially a dynamic scan) can affect both the qualitative and the quantitative aspects of an image, making it difficult to accurately interpret the results. The primary objective of this study was to develop a retrospective image-based movement correction (MC) method and evaluate its implementation on dynamic 2-(1-{6-[(2-(18)F-fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile ((18)F-FDDNP) PET images of cognitively intact controls and patients with Alzheimer's disease (AD).

METHODS

Dynamic (18)F-FDDNP PET images, used for in vivo imaging of beta-amyloid plaques and neurofibrillary tangles, were obtained from 12 AD patients and 9 age-matched controls. For each study, a transmission scan was first acquired for attenuation correction. An accurate retrospective MC method that corrected for transmission-emission and emission-emission misalignments was applied to all studies. No restriction was assumed for zero movement between the transmission scan and the first emission scan. Logan analysis, with the cerebellum as the reference region, was used to estimate various regional distribution volume ratio (DVR) values in the brain before and after MC. Discriminant analysis was used to build a predictive model for group membership, using data with and without MC.

RESULTS

MC improved the image quality and quantitative values in (18)F-FDDNP PET images. In this subject population, no significant difference in DVR value was observed in the medial temporal (MTL) region of controls and patients with AD before MC. However, after MC, significant differences in DVR values in the frontal, parietal, posterior cingulate, MTL, lateral temporal (LTL), and global regions were seen between the 2 groups (P < 0.05). In controls and patients with AD, the variability of regional DVR values (as measured by the coefficient of variation) decreased on average by more than 18% after MC. Mean DVR separation between controls and patients with AD was higher in frontal, MTL, LTL, and global regions after MC. Group classification by discriminant analysis based on (18)F-FDDNP DVR values was markedly improved after MC.

CONCLUSION

The streamlined and easy-to-use MC method presented in this work significantly improves the image quality and the measured tracer kinetics of (18)F-FDDNP PET images. The proposed MC method has the potential to be applied to PET studies on patients having other disorders (e.g., Down syndrome and Parkinson's disease) and to brain PET scans with other molecular imaging probes.

New targets in the treatment of anorexia nervosa

The pathophysiology of anorexia nervosa (AN) is complex and involves alterations of serotonin, dopamine and histamine neurotransmitters. In addition, receptor activity is disturbed, presumably in response to the neurotransmitter changes. These alterations are reviewed in relation to symptomatology and outcome of AN. Neuropeptide and peripheral orexigenic and satiety peptide research is in its infancy but holds much promise to shed light on the pathophysiological mechanisms involved in this illness. Current drug therapies have not demonstrated the efficacy desired in the treatment of AN. Current therapies are reviewed and new drug targets are explored. Compounds that interact with serotonin, histamine and dopamine receptors may offer unique treatment opportunities. In the future, the manipulation of peptides may add to the therapeutic potential of pharmacotherapy.

[The auto-addictive hypothesis of pathological eating disorders]

The pathogenic role of self-addiction. Addiction to an endogenous chemical is a new paradigm termed 'self-addiction'. It may contribute to the development of certain habits, the pathological nature of which may set-in on the basis of this "self-addictive"dimension. Pathological eating habits could be inscribed in this perspective. Two extreme situations. In well-fed populations, the ingestion of food does not represent a limiting phase in the global feeding process. Its pathological management may, however, lead to two extreme situations: the absence of ingestion (anorexia) and excessive ingestion (bulimia). In favour of the self-addictive hypothesis. Eating disorders are associated with abnormal levels of endorphins and share clinical similarities with psychoactive drug abuse. The key role of endorphins has recently been demonstrated in animals with regard to certain aspects of normal, pathological and experimental eating habits (food restriction combined with stress, locomotor hyperactivity). The factors leading to pathological eating habits. Neurobiological bases for eating disorders and their durability have recently come to light in the recent implication of abnormalities in the recompense system in the onset of addiction. The endorphin self-addictive model in fact appears the most pertinent with regard to the clinical profile of eating habits and integrates the role of stress.

Neuropeptides in eating disorders

The past decade has witnessed a dramatic acceleration in research on the role of the neuropeptides in the regulation of eating behavior and body weight homeostasis. This expanding research focus has been driven in part by increasing public health concerns related to obesity and the eating disorders anorexia nervosa (AN) and bulimia nervosa (BN). Preclinical advances have been facilitated by the development of new molecular and behavioral research methodologies. With a focus on clinical investigations in AN and BN, this article reviews research on selected hypothalamic and gut-related peptide systems with prominent effects on eating behavior. Studies of the orexigenic peptides neuropeptide Y and the opioid peptides have shown state-related abnormalities in patients with eating disorders. With respect to gut-related peptides, there appears to be substantial evidence for blunting in the meal-related release of the satiety promoting peptide cholecystokinin in BN. Fasting plasma levels of the orexigenic peptide ghrelin have been found to be elevated in patients with AN. As discussed in this review, additional studies will be needed to assess the role of nutritional and body weight changes in neuropeptide alterations observed in symptomatic eating disorder patients, and to identify stable trait-related abnormalities in neuropeptide regulation that persist in individuals who have recovered from an eating disorder.

Aetiopathogenesis and pathophysiology of bulimia nervosa: biological bases and implications for treatment

Bulimia nervosa is an eating disorder characterised by recurrent episodes of binge eating and associated efforts to purge the ingested calories through self-induced vomiting, laxative or diuretic abuse, fasting or intensive exercise. The aetiopathogenesis and pathophysiology of the disorder are currently unclear. Biological bases have been proposed repeatedly, based on several lines of evidence: hunger, satiety and food choice are regulated by neurotransmitters and neuropeptides, and impairment of eating habits may be related to alterations in the secretion of these chemicals; genetic studies suggest that these neurotransmitter systems are dysfunctional in individuals with bulimia nervosa; and the frequent comorbidity of bulimia nervosa with major depressive and obsessive-compulsive disorders, conditions in which multiple alterations of brain biochemical functions have been demonstrated. Data in the literature suggest that levels of noradrenaline (norepinephrine) and serotonin (5-hydroxytryptamine; 5-HT) are lower in individuals with bulimia nervosa than in healthy controls. Levels of dopamine are similar to, or lower than, those in controls. After remission of the disorder, noradrenergic function returns to that seen in controls, whereas dopaminergic and serotonergic function rebound to levels higher than in controls. Among the neuropeptides, alterations in the levels of neuropeptide Y, peptide YY, beta-endorphin, corticotrophin-releasing hormone, somatostatin, cholecystokinin and vasopressin have been found in the symptomatic phase of bulimia nervosa, with a return to levels seen in controls after remission. Pharmacological treatment of bulimia nervosa that is directed at correction of the neurochemical alterations observed is difficult because of the complexity of the impairments. However, such treatment is necessary and should be continued long after symptomatic remission to ensure reinstitution of cerebral biochemical homeostasis.

The effects of cholecystokinin on stimulation-induced feeding and self-stimulation

Cholecystokinin (CCK) is a peptide hormone which controls a number of important functions during the process of digestion. It is present in the gut and the central nervous system, although its exact role in the latter is not yet clear. Our interest was in the effects of intraperitoneal and intracerebral injections of CCK on brain stimulation reward and stimulation-induced feeding. Period thresholds for rewarding stimulation were unaffected by either route of peptide administration, whereas stimulation-induced feeding thresholds were weakly increased by centrally injected CCK. In addition, we evaluated stimulation-induced feeding using a more resolved measure and found it to provide clearer results. By actually measuring the amount of food eaten during a stimulation-induced feeding session, and not only the occurrence of feeding, CCK was shown to systematically decrease the total intake as a function of dose in an inverse manner. The efficiency of food utilization was calculated for each animal during the different phases of the experiment in order to monitor the effects of CCK on the animals' overall health. Centrally administered CCK appeared to increase the animals' efficiency and, furthermore, this level was sustained for the entire post-injection phase, about 2 weeks, suggesting a relatively enduring increase in metabolic rate. While the functional role of central CCK and other gastric peptides requires clarification, analyses which exploit the stimulation-induced feeding paradigm need to make use of more clearly defined microstructural variables.

Endogenous opiates: 1995

This article is the eighteenth installment of our annual review of research concerning the opiate system. It includes articles published during 1995 reporting the behavioral effects of the opiate peptides and antagonists, excluding the purely analgesic effects. The specific topics covered this year include stress: tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic function; mental illness and mood; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; electrical-related activity; general activity and locomotion; sex, pregnancy, and development; immunological responses; and other behaviors.

T-lymphocyte concentrations of cholecystokinin-8 and beta-endorphin in eating disorders: II. Bulimia nervosa

Concentrations of cholecystokinin-8 (CCK-8) and beta-endorphin (beta-EP) in T-lymphocytes of 26 women with bulimia nervosa (BN) and in 26 age- and sex-matched healthy comparison subjects were measured. Ten patients were then treated with 300 mg/day of fluvoxamine, p.o., and five patients were treated with 300 mg/day of amineptine, p.o., for 4 months. Concentrations of the two peptides were measured again after 1, 2, and 4 months of therapy. Basal CCK-8 values were significantly lower in patients than in healthy subjects. During fluvoxamine therapy, CCK-8 values increased, reaching normal levels by month 4 of treatment. No such increase occurred during amineptine therapy. Baseline beta-EP values were normal in the bulimic patients but had declined by month 4 of fluvoxamine therapy.