Impaired cholecystokinin secretion in bulimia nervosa

Gut hormones, adipokines, and pro- and anti-inflammatory cytokines/markers in loss of control eating: A scoping review

Loss of control (LOC) eating is the defining feature of binge-eating disorder, and it has particular relevance for bariatric patients. The biomarkers of LOC eating are unclear; however, gut hormones (i.e., ghrelin, cholecystokinin [CCK], peptide YY [PYY], glucagon-like peptide 1 [GLP-1], and pancreatic polypeptide [PP]), adipokines (i.e., leptin, adiponectin), and pro- and anti-inflammatory cytokines/markers (e.g., high-sensitivity C-reactive protein [hsCRP]) are candidates due to their involvement in the psychophysiological mechanisms of LOC eating. This review aimed to synthesize research that has investigated these biomarkers with LOC eating. Because LOC eating is commonly examined within the context of binge-eating disorder, is sometimes used interchangeably with subclinical binge-eating, and is the latent construct underlying disinhibition, uncontrolled eating, and food addiction, these eating behaviors were included in the search. Only studies among individuals with overweight or obesity were included. Among the identified 31 studies, 2 studies directly examined LOC eating and 4 studies were conducted among bariatric patients. Most studies were case-control in design (n = 16) and comprised female-dominant (n = 13) or female-only (n = 13) samples. Studies generally excluded fasting total ghrelin, fasting CCK, fasting PYY, and fasting PP as correlates of the examined eating behaviors. However, there was evidence that the examined eating behaviors were associated with lower levels of fasting acyl ghrelin (the active form of ghrelin) and adiponectin, higher levels of leptin and hsCRP, and altered responses of postprandial ghrelin, CCK, and PYY. The use of GLP-1 analog was able to decrease binge-eating. In conclusion, this review identified potential biomarkers of LOC eating. Future studies would benefit from a direct focus on LOC eating (especially in the bariatric population), using longitudinal designs, exploring potential mediators and moderators, and increased inclusion of the male population.

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.

Gastric interoception and gastric myoelectrical activity in bulimia nervosa and binge-eating disorder

OBJECTIVE

Identifying factors that control food intake is crucial to the understanding and treatment of eating disorders characterized by binge eating. In healthy individuals, stomach distension plays an important role in the development of satiation, but gastric sensations might be overridden in binge eating. The present study investigated the perception of gastric signals (i.e., gastric interoception) and gastric motility in patients experiencing binge-eating episodes, that is, bulimia nervosa (BN) and binge-eating disorder (BED).

METHOD

Twenty-nine patients with BN or BED (ED group) and 32 age-, sex-, and BMI-matched healthy controls (HC group) participated in the study. The onset of satiation and stomach fullness were assessed using a novel 2-step water load test (WLT-II). Gastric myoelectrical activity (GMA) was measured by electrogastrography (EGG) before and after ingestion of noncaloric water.

RESULTS

Individuals in the ED group drank significantly more water until reporting satiation during the WLT-II. The percentage of normal gastric myoelectrical power was significantly smaller in the ED group compared to HC, and negatively related to the number of objective binge-eating episodes per week in patients with BN or BED. Power in the bradygastria range was greater in ED than in HC participants.

DISCUSSION

Patients with EDs have a delayed response to satiation compared to HC participants, together with abnormal GMA. Repeated binge-eating episodes may induce disturbances to gastric motor function.

Pressure overload changes mesenteric afferent nerve responses in a stress-dependent way in a fasting rat model

It is well known that overload changes the mechanical properties of biological tissues and fasting changes the responsiveness of intestinal afferents. This study aimed to characterize the effect of overload on mechanosensitivity in mesenteric afferent nerves in normal and fasted Sprague-Dawley rats. Food was restricted for 7 days in the Fasting group. Jejunal whole afferent nerve firing was recorded during three distensions, i.e., ramp distension to 80 cmH₂O luminal pressure (D1), sustained distension to 120 cmH₂O for 2 min (D2), and again to 80 cmH₂O (D3). Multiunit afferent recordings were separated into low-threshold (LT) and wide-dynamic-range (WDR) single-unit activity for D1 and D3. Intestinal deformation (strain), distension load (stress), and firing frequency of mesenteric afferent nerve bundles [spike rate increase ratio (SRIR)] were compared at 20 cmH₂O and 40 cmH₂O and maximum pressure levels among distensions and groups. SRIR and stress changes showed the same pattern in all distensions. The SRIR and stress were larger in the Fasting group compared to the Control group (P < 0.01). SRIR was lower in D3 compared to D1 in controls (P < 0.05) and fasting rats (P < 0.01). Total single units and LT were significantly lower in Fasting group than in Controls at D3. LT was significantly higher in D3 than in D1 in Controls. Furthermore, correlation was found between SRIR with stress (R = 0.653, P < 0.001). In conclusion, overload decreased afferent mechanosensitivity in a stress-dependent way and was most pronounced in fasting rats. Fasting shifts LT to WDR and high pressure shifts WDR to LT in response to mechanical stimulation.

Eating Disorders and Gastrointestinal Diseases

Eating disorders (ED) are frequently associated with a wide range of psychiatric or somatic comorbidities. The most relevant ED are anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorders (BED). Patients with ED exhibit both upper and lower gastrointestinal (GI) symptoms. Evidence of alterations throughout the GI tract in ED will be analyzed given the role of the GI tract in food intake and its regulation. It remains a matter of debate whether GI disorders are inherent manifestations of ED or the results of malnutrition occurring from ED. Moreover, recent clinical studies have highlighted the growing role of intestinal microbiota in the pathogenesis of ED, making it possible to hypothesize a modulation of intestinal microbiota as a co-adjuvant to standard therapy. The aim of this review is to analyze the link between ED and GI diseases and to present, where known, the potential key factors underlying these conditions. Conclusions: The presence of GI disorders should be investigated in patients with ED. Screening for ED should also be encouraged in individuals seeking treatment for unexplained GI complaints to better address therapeutic issues that surround these difficult medical conditions.

Eating Disorders and Gastrointestinal Diseases

Eating disorders (ED) are frequently associated with a wide range of psychiatric or somatic comorbidities. The most relevant ED are anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorders (BED). Patients with ED exhibit both upper and lower gastrointestinal (GI) symptoms. Evidence of alterations throughout the GI tract in ED will be analyzed given the role of the GI tract in food intake and its regulation. It remains a matter of debate whether GI disorders are inherent manifestations of ED or the results of malnutrition occurring from ED. Moreover, recent clinical studies have highlighted the growing role of intestinal microbiota in the pathogenesis of ED, making it possible to hypothesize a modulation of intestinal microbiota as a co-adjuvant to standard therapy. The aim of this review is to analyze the link between ED and GI diseases and to present, where known, the potential key factors underlying these conditions. Conclusions: The presence of GI disorders should be investigated in patients with ED. Screening for ED should also be encouraged in individuals seeking treatment for unexplained GI complaints to better address therapeutic issues that surround these difficult medical conditions.

Abnormalities in Glucose Metabolism, Appetite-Related Peptide Release, and Pro-nflammatory Cytokines Play a Central Role in Appetite Disorders in Peritoneal Dialysis

Background: Appetite disorders are frequent and scantly studied in peritoneal dialysis (PD) patients and are associated with malnutrition and cardiovascular complications. Objective: We investigated the relationship between uremic insulin resistance, pro-inflammatory cytokines, and appetite-related peptides release (ARPr) with eating-behavior disorders in PD patients. Methods: We included 42 PD patients (12 suffering anorexia, 12 obese with high food-intake, and 18 asymptomatic) and 10 controls. We measured blood levels of ARPr including orexigens [neuropeptide-Y (NPY), ghrelin, and nitric-oxide], anorexigens [cholecystokinin, insulin, corticotropin-releasing factor, leptin, and adiponectin (Ad)], and cytokines (TNF-α, sTNFα-R2, and IL-6) both at baseline and after administering a standard-food stimulus (SFS). We also measured the expression of TNF-α, leptin and Ad-encoding mRNAs in abdominal adipose tissue. We compared these markers with eating motivation measured by a Visual Analog Scale (VAS). Results: Anorexics showed both little appetite, measured by a VAS, and low levels of orexigens that remained constant after SFS, coupled with high levels of anorexigens at baseline and after SFS. Obeses showed higher appetite, increased baseline levels of orexigens, lower baseline levels of anorexigens and cytokines and two peaks of NPY after SFS. The different patterns of ARPr and cytokines pointed to a close relationship with uremic insulin resistance. In fact, the euglycemic-hyperglycemic clamp reproduced these disorders. In anorexics, TNF-α fat expression was increased. In obese patients, leptin expression in fat tissue was down-regulated and showed correlation with the appetite. Conclusion: In PD, appetite is governed by substances that are altered at baseline and abnormally released. Such modulators are controlled by insulin metabolism and cytokines and, while anorexics display inflammatory predominance, obese patients predominantly display insulin resistance.

Meal-Related Acyl and Des-Acyl Ghrelin and Other Appetite-Related Hormones in People with Obesity and Binge Eating

OBJECTIVE

Potential mechanisms of abnormal food intake, such as dysregulation of meal-related appetite hormones, including acyl ghrelin (AG) and des-acyl ghrelin (DAG), were investigated among men and women with obesity, with and without binge eating (BE).

METHODS

Participants (n = 42: 19 female, 23 male) were assigned to a liquid meal and water condition in counterbalanced order, and blood samples for measuring hormones were obtained before and after these conditions.

RESULTS

Participants with BE had significantly lower fasting and postingestive AG concentrations than participants without BE in both conditions. During the meal condition, postprandial decreases in AG concentrations were significantly smaller for the BE group than for the non-BE group. There were no significant differences in DAG by BE group. Leptin increased significantly less after meals for those with BE compared with those without BE. There were no differences in other hormones by BE group. Fasting and postmeal hunger ratings were significantly higher for those with BE than for those without BE.

CONCLUSIONS

In individuals with BE, lower fasting AG may be due to downregulation by habitual overeating, and a smaller postmeal decline in AG may contribute to overeating. Lower postmeal leptin concentrations may also contribute to overeating.

Satiation deficits and binge eating: Probing differences between bulimia nervosa and purging disorder using an ad lib test meal

Purging disorder (PD) has been included as a named condition within the DSM-5 category of Other Specified Feeding or Eating Disorder and differs from bulimia nervosa (BN) in the absence of binge-eating episodes. The current study evaluated satiation through behavioral and self-report measures to understand how this construct may explain distinct symptom presentations for bulimia nervosa (BN) and purging disorder (PD). Women (N = 119) were recruited from the community if they met DSM-5 criteria for BN (n = 57), PD (n = 31), or were free of eating pathology (n = 31 controls). Participants completed structured clinical interviews and questionnaires and an ad lib test meal during which they provided reports of subjective states. Significant group differences were found on self-reported symptoms, ad lib test meal intake, and subjective responses to food intake between individuals with eating disorders and controls and between BN and PD. Further, ad lib intake was associated with self-reported frequency and size of binge episodes. In a multivariable model, the amount of food consumed during binges as reported during clinical interviews predicted amount of food consumed during the ad lib test meal, controlling for other binge-related variables. Satiation deficits distinguish BN from PD and appear to be specifically linked to the size of binge episodes. Future work should expand exploration of physiological bases of these differences to contribute to novel interventions.

Rigor and reproducibility via laboratory studies of eating behavior: A focused update and conceptual review

OBJECTIVE

The eating behavior of individuals with eating disorders has been examined in laboratory settings over the last 30 years. In this focused review, we build on prior research and highlight several feeding laboratory paradigms that have successfully demonstrated quantifiable and observable behavioral disturbances, and thereby add rigor and reproducibility to the examination of disturbances of eating behavior. This review describes the measures commonly obtained via these laboratory techniques. Supporting Information Appendices with detailed information about implementation are provided to allow for the reproducible execution of these techniques across labs.

METHODS/RESULTS

Literature documenting the existence of objective abnormalities in eating behavior among individuals with eating disorders or in comparison to healthy controls (n > 40) is briefly summarized. These protocols, conducted across at least 17 independent labs, are sensitive and reproducible, can be used to assess subjective and physiological parameters associated with eating, and elucidate the impact of treatment. Laboratory studies from patients with eating disorders compared with healthy controls reproducibly demonstrate both that patients with Anorexia Nervosa ingest fewer calories and that individuals with Bulimia Nervosa and Binge-Eating Disorder ingest more calories when asked to binge-eat.

DISCUSSION

Feeding laboratory studies have the potential for quantifying the characteristic behavioral psychopathology of patients with eating disorders, and may provide a useful tool to explore the potential utility of new treatments for individuals with Anorexia Nervosa, Bulimia Nervosa, and Binge-Eating Disorder.

Gastrointestinal Manifestations of Eating Disorders

Individuals with eating disorders, including anorexia nervosa and bulimia nervosa, may present with a range of gastrointestinal (GI) manifestations. The oral cavity, salivary glands, GI tract, pancreas, and liver can be impacted by nutritional restrictive and binge/purging behaviors. Complications are often reversible with appropriate nutritional therapy. At times, however, the complications in these disorders may be severe, irreversible and even life threatening. Given the often covert nature of eating disorders, the practitioner must be attentive to subtle clues that may indicate their presence. Extensive diagnostic evaluations of the GI manifestations of eating disorders should be used only when nutritional rehabilitation does not remedy the problems.

Postprandial Cholecystokinin Secretion in Elderly with Protein-Energy Undernutrition

OBJECTIVE

Malnutrition is currently observed in aged people, and cholecystokinin is an important peripheral satiety signal. The aim of this study was to examine the effect of aging and protein-energy malnutrition on postprandial cholecystokinin (CCK) release.

DESIGN

Non-randomized, cross-sectional comparison by age group.

SETTING

Gastroenterology section of a teaching hospital.

PARTICIPANTS

Twenty-one human volunteers divided into three groups: young healthy subjects (Group 1: mean 29 years, n = 7), aged healthy subjects (Group 2, mean 80 years, n = 7), and aged subjects with an important degree of malnutrition (Group 3, mean 84.6 years, n = 7).

INTERVENTION

Each subject ingested a standardized liquid meal after an overnight fast.

MAIN OUTCOME MEASURES

Plasma cholecystokinin was measured using a sensitive bioassay before and after the ingestion of the liquid meal.

RESULTS

Basal cholecystokinin levels were similar (0.9 to 1 pM equivalent CCK-8) in the three groups. Postprandial levels were significantly increased over basal (P less than 0.05). The maximal cholecystokinin value was lower in Group 1 (3.5 +/- 0.8 pM equivalent CCK-8) and Group 2 (3.3 +/- 0.77 pM equivalent CCK-8) than in Group 3 (8.3 +/- 2 pM equivalent CCK-8) (P less than 0.05). Integrated plasma cholecystokinin was also similar in Group 1 (171 +/- 38 pM.60 min), (P less than 0.05).

CONCLUSION

The increase of postprandial maximal levels of cholecystokinin is more related to malnutrition than to aging.

Preliminary examination of glucagon-like peptide-1 levels in women with purging disorder and bulimia nervosa

OBJECTIVE

This study examined pre- and postprandial glucagon-like peptide 1 (GLP-1) levels in women with bulimia nervosa (BN), purging disorder (PD), and non-eating disorder control women to better understand whether alterations in satiation-related hormones in BN may be linked to binge-eating episodes or other altered ingestive behaviors.

METHOD

Participants included women with BN (n = 19), PD (n = 14), or controls (n = 14). Participants provided subjective ratings for hunger and fullness and plasma samples before and after consumption of a standardized test meal.

RESULTS

As expected, GLP-1 levels increased significantly following test meal consumption; however, participants with BN displayed significantly lower GLP-1 levels compared to PD and control participants both before and after consumption of the test meal. There were no significant differences between PD and control participants in GLP-1 levels, but individuals with PD displayed significantly higher levels of fullness throughout the test meal as compared to both control and BN participants.

DISCUSSION

Our findings provide preliminary evidence that reduced GLP-1 levels in individuals with BN may be associated with binge-eating episodes. Additionally, increased fullness in individuals with PD does not appear to be accounted for by exaggerated postprandial GLP-1 release.

Different effects of cholestyramine on postprandial secretions of cholecystokinin and peptide YY in women with bulimia nervosa

OBJECTIVE

Patients with bulimia nervosa (BN) are reported to have decreased postprandial levels of cholecystokinin (CCK) and peptide YY (PYY). Fatty nutrients are the most powerful stimulus for releasing these peptides. Cholestyramine is an anion exchanger which adsorbs bile salts and reduces the digestion of lipids, affecting the secretion of both CCK and PYY. To further characterise the physiology of these peptides in BN, we aimed to investigate the effects of cholestyramine (12 g, per os) or placebo administered with a high-fat meal on CCK and PYY secretions in bulimic versus healthy women.

RESULTS

Postprandial CCK levels significantly increased in both healthy and bulimic women after placebo + the high-fat meal, without any significant difference between the two groups. Cholestyramine administration significantly increased postprandial CCK responses in both healthy and bulimic women; however, significantly lower CCK levels were observed in BN. Postprandial PYY levels significantly increased after placebo administration in healthy women after the high-fat meal, whereas no significant changes were found in bulimic women. Cholestyramine, administered with the high-fat meal, significantly reduced postprandial PYY response in healthy women, but not in bulimic women. Finally, there was a negative correlation of the area under the curve with respect to the increase of PYY (after placebo administration) with binge frequency in the bulimic women.

CONCLUSION

In BN an altered postprandial secretion of CCK may be evidenced when cholestyramine is combined with a high-fat meal. Instead, the postprandial secretion of PYY is significantly blunted and not affected by cholestyramine administration.

Changes in perceptions and emotions before and after refeeding in anorexia nervosa: a pilot study

Objective: Physiological and psychological distortions associated with eating are recognised within the syndrome of anorexia nervosa. The purpose of this study was to compare subgroups of restricting and bulimic anorexic patients (AN-R and AN-B) with control subjects, and with themselves after six weeks of refeeding and weight gain, on a series of indices before and after a standard meal. Method: Nineteen consecutively admitted female AN patients completed visual analogue ratings of hunger, satiety, depression, urge to binge, urge to vomit and food craving during the first week and sixth week of hospitalisation. A female control group of seven subjects completed similar ratings for one week. The patient ratings were compared to those of the control subjects at baseline before and after a meal. Further comparisons between the two patient groups were also carried out six weeks after treatment. Results: As expected, AN patients reported significantly higher ratings of depression, urges to vomit, urges to binge and higher satiety levels when compared to controls. Comparisons between the patient subgroups revealed that at baseline AN-B patients had significantly higher urges to vomit that AN-R patients after meals, and reported significantly less satiety both before and after eating. Also, an increase in depression after the meal, at baseline, was reported by both groups although after six weeks higher levels of depression were recorded before rather than after the meal. There was also a significant decrease in food cravings after six weeks compared to baseline for both patient groups.

Conclusions: The findings in this study provide further evidence that clinically significant differences exist between subtypes of patients suffering from anorexia nervosa, and highlight the differential, change in various symptoms during intense hospital treatment.

CCK response in bulimia nervosa and following remission

The core defining features of bulimia nervosa (BN) are repeated binge eating episodes and inappropriate compensatory (e.g., purging) behavior. Previous studies suggest an abnormal post-prandial response in the satiety-signaling peptide cholecystokinin (CCK) in persons with BN. It is unknown whether this altered response persists following remission or if it may be a potential target for the development of clinical treatment strategies. To examine the nature of this altered response, this study assessed whether CCK normalizes following remission from BN (RBN). This study prospectively evaluated the plasma CCK response and corresponding eating behavior-related ratings (e.g., satiety, fullness, hunger, urge to binge and vomit) in individuals with BN-purging subtype (n=10), RBN-purging subtype (n=14), and healthy controls (CON, n=13) at baseline, +15, +30, and +60 min following the ingestion of a standardized liquid test meal. Subject groups did not significantly differ in CCK response to the test meal. A significant relationship between CCK response and satiety ratings was observed in the RBN group (r=.59, p<.05 two-tailed). A new and unanticipated finding in the BN group was a significant relationship between CCK response and ratings of "urge to vomit" (r=.86, p<.01, two-tailed). Unlike previous investigations, CCK response did not differ in BN and CON groups. Thus the role of symptom severity remains an area of further investigation. Additionally, findings suggest that in this sample, CCK functioning following remission from BN-purging subtype is not different from controls. It remains unknown whether or not CCK functioning may be a protective or liability factor in the stabilization and recovery process. Replication studies utilizing a larger sample size are needed to further elucidate the role of CCK in recovery from BN and its potential target of related novel treatment strategies.

Sex differences in the physiology of eating

Hypothalamic-pituitary-gonadal (HPG) axis function fundamentally affects the physiology of eating. We review sex differences in the physiological and pathophysiological controls of amounts eaten in rats, mice, monkeys, and humans. These controls result from interactions among genetic effects, organizational effects of reproductive hormones (i.e., permanent early developmental effects), and activational effects of these hormones (i.e., effects dependent on hormone levels). Male-female sex differences in the physiology of eating involve both organizational and activational effects of androgens and estrogens. An activational effect of estrogens decreases eating 1) during the periovulatory period of the ovarian cycle in rats, mice, monkeys, and women and 2) tonically between puberty and reproductive senescence or ovariectomy in rats and monkeys, sometimes in mice, and possibly in women. Estrogens acting on estrogen receptor-α (ERα) in the caudal medial nucleus of the solitary tract appear to mediate these effects in rats. Androgens, prolactin, and other reproductive hormones also affect eating in rats. Sex differences in eating are mediated by alterations in orosensory capacity and hedonics, gastric mechanoreception, ghrelin, CCK, glucagon-like peptide-1 (GLP-1), glucagon, insulin, amylin, apolipoprotein A-IV, fatty-acid oxidation, and leptin. The control of eating by central neurochemical signaling via serotonin, MSH, neuropeptide Y, Agouti-related peptide (AgRP), melanin-concentrating hormone, and dopamine is modulated by HPG function. Finally, sex differences in the physiology of eating may contribute to human obesity, anorexia nervosa, and binge eating. The variety and physiological importance of what has been learned so far warrant intensifying basic, translational, and clinical research on sex differences in eating.

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.

Gastric emptying and symptoms of bulimia nervosa: effect of a prokinetic agent

OBJECTIVE

Previous studies have suggested that delayed gastric emptying and abnormal postprandial release of hormones that influence satiation, particularly cholecystokinin (CCK), may play an important role in the pathophysiology of bulimia nervosa (BN). This study was designed to test these hypotheses as well as the efficacy of the prokinetic agent erythromycin in patients with BN.

METHOD

Thirty-two normal-weight women with BN and 24 control participants consumed a large liquid test meal. Gastric emptying and pre- and postprandial release of CCK, peptide YY (PYY), and ghrelin were determined. Participants with BN were then recruited for double-blind treatment with erythromycin up to 500 mg three times daily vs. placebo for 6 weeks, following which they consumed a repeat test meal with gastric emptying and appetitive hormone measurements.

RESULTS

CCK release at 15 min following the meal was marginally lower (p=0.1) in BN than in control participants. Rate of gastric emptying and postprandial hormone release were similar in BN and controls. BN patients assigned to erythromycin compared to those assigned to placebo had more rapid gastric emptying following treatment, but there were no differences in release of CCK, PYY, or ghrelin following the post-treatment test meal. Moreover, treatment with erythromycin was not associated with clinical response.

DISCUSSION

The current study does not support the clinical utility of moderate dose erythromycin in treating BN. Furthermore, the findings suggest that a modest increase in gastric emptying rate is associated neither with altered postprandial hormonal release nor with clinical benefit in these patients. While providing no evidence for the effectiveness of prokinetic agents in this setting, our findings do not preclude the possibility that a greater increase in gastric emptying rate might prove beneficial.

Regulating satiety in bulimia nervosa: the role of cholecystokinin

PURPOSE

Individuals with bulimia nervosa (BN) report altered perceptions in hunger, fullness, and satiety. This article reviews the role of cholecystokinin (CCK), a satiety-producing hormone, in the regulation of binge eating in those who suffer from BN.

CONCLUSION

Studies have shown that CCK is decreased in individuals with BN when compared with healthy controls. Decreased CCK functioning may contribute to impaired satiety and thus binge eating in this patient population. Depending on the macronutrient composition of food choices, CCK release can be differentially influenced. For instance, protein is a potent stimulator of a CCK response. Eating more protein-rich meals increases the release of CCK, increasing satiety and ending a meal.

PRACTICE IMPLICATIONS

Knowledge of CCK functioning and the utility of manipulating the macronutrient composition of meals may inform standard behavioral treatment strategies for those who suffer from BN.

Empirical classification of eating disorders

Current diagnostic criteria for anorexia nervosa (AN) and bulimia nervosa (BN) account for a minority of individuals with clinically significant disorders of eating, raising concerns about the clinical utility of current definitions. This review examines evidence for the validity of current and alternative approaches to defining eating disorders and implications for draft criteria for the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Although this review largely supports the predictive validity of distinctions among AN, BN, and the newly proposed binge eating disorder (BED), it also highlights that our tendency to "study what we define" has created a gap between the problems that people have and what we know about those problems. Future research on the causes and consequences of eating disorders should include more heterogeneous groups to enable identification of meaningful boundaries that distinguish between disorders based on etiological and predictive validity.

Women with bulimia nervosa exhibit attenuated secretion of glucagon-like peptide 1, pancreatic polypeptide, and insulin in response to a meal

BACKGROUND

The eating disorder bulimia nervosa (BN) is characterized by frequent episodes of binge eating, followed regularly by inappropriate compensatory behavior, such as self-induced vomiting.

OBJECTIVE

The current investigation was designed to examine possible alterations in the secretion of the gastrointestinal satiety peptides glucagon-like peptide 1 (GLP-1) and pancreatic polypeptide (PP) in women with BN.

DESIGN

Twenty-one women with BN and 17 healthy control subjects of comparable age and BMI were recruited. After fasting overnight, the subjects provided blood samples during ingestion of a standardized meal and self-rated their appetite on a visual analog scale. Fasting and meal-related secretion of the incretin GLP-1 and the meal-related feedback signal PP and insulin and glucose as indicators of the metabolic homeostasis were analyzed.

RESULTS

Women with BN had significantly lower fasting and postprandial serum concentrations of GLP-1 (P < 0.01) and PP (P < 0.05) than did the control subjects. Furthermore, both the basal (P < 0.001) and peak (P < 0.05) concentrations of insulin were significantly attenuated in the bulimic subjects, whereas glucose concentrations were normal. As a consequence, the bulimic homeostasis model assessment of insulin index values were also lower (P < 0.001).

CONCLUSIONS

Women with BN secrete abnormally low amounts of GLP-1 and PP, possibly because of the adaption to large meals in the form of enlarged gastric capacity and reduced muscle tone in the gastric wall. Attenuated secretion of these gastrointestinal satiety peptides may play a role in the maintenance of bulimic behavior.

The importance of eating behavior in eating disorders

A disturbance in eating behavior is the defining characteristic of the clinical eating disorders, Anorexia Nervosa, Bulimia Nervosa, and Binge Eating Disorder. Surprisingly little research has been devoted to assessing objectively the nature of the eating disturbances in these disorders, to elucidating what factors contribute to the development and persistence of these disturbances, or to describing how they change with treatment. This review, which is based on a Mars lecture delivered at the 2010 meeting of the Society for the Study of Ingestive Behavior, reviews objective information about the nature of the disturbances of eating behavior in eating disorders. These data suggest that more detailed knowledge of eating behavior is an essential component of a full understanding of eating disorders and may provide a foundation for studies of pathophysiology and for the development of new treatment methods.

The development of satiation in bulimia nervosa

Bulimia nervosa (BN) is characterized by the recurrent consumption of excessive amounts of food (binge eating) followed by inappropriate compensatory behaviors. A leading hypothesis is that the persistence of BN may be due, in part, to a disturbance in the development of satiation. Because patients with BN consume larger meals than controls, previous studies have not been able to directly compare the development of satiation. In order to address this problem, subjects consumed large meals of predetermined size without knowing when they would be stopped. Twenty-one women with BN and 13 control women participated in a study in which they rated hunger and fullness during the course of a 975 g liquid meal eaten from an opaque reservoir. Subjects' ratings were obtained after each 75 g increment of consumption. There were no statistically significant differences between the two groups in the mean ratings of hunger or of fullness before, after, or during the meal. Individuals with BN consumed the meal more rapidly than control participants. These results suggest that, when individuals with BN are not instructed to binge eat and do not control meal size, they do not manifest a disturbance in reported satiation over the course of a large liquid meal.

Systematic review and meta-analysis of the baseline concentrations and physiologic responses of gut hormones to food in eating disorders

BACKGROUND

Disturbances in gastrointestinal hormones have been widely identified in persons with eating disorders (EDs) and have been implicated in their clinical pathologies.

OBJECTIVE

The objective was to identify, critically examine, and summarize studies investigating the short-term response of gastrointestinal hormones to food in persons with an ED, including the subtypes anorexia nervosa and bulimia nervosa.

DESIGN

A priori inclusion and exclusion criteria were set and included a procedure in which a test meal or glucose load was given and blood hormone concentrations measured. All studies included a healthy control group for comparison. The outcome variable was defined as the mean difference between fasting plasma hormone concentrations and the maximum postprandial peak or nadir. The difference in baseline values between groups was also examined. Pooled standardized mean differences were calculated and analyzed where possible.

RESULTS

A total of 28 studies were identified, including sufficient studies to perform a meta-analysis for ghrelin, peptide YY, cholecystokinin, insulin, and pancreatic polypeptide. Persons with an ED had higher baseline concentrations of ghrelin (large effect), peptide YY (medium effect), and cholecystokinin (medium effect for ED, large effect for anorexia nervosa). The response of insulin to food was decreased in persons with an ED (medium effect). No further differences were found in the release of gut peptides to a standardized test meal.

CONCLUSIONS

All of the studies had low power for the different subtypes of EDs. High heterogeneity among the studies was observed, and limitations are discussed. The findings suggest that the physiologic changes observed in patients with EDs are highly variable and subject to multiple confounding factors.

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.

Knowledge Development: The Roy Adaptation Model and Bulimia Nervosa

The utility of nursing theory as a framework to understand, explain, and propose nursing research is essential to knowledge development. The purpose of this column is to provide an examination of the Roy adaptation model as a basis for knowledge development in bulimia nervosa. This chronic and debilitating disorder is complex, poorly understood, and characterized by repeated binge eating and purging episodes. A careful examination of the major concepts and theoretical linkages of the Roy adaptation model in relationship to bulimia nervosa is necessary to determine the value of this framework to generate future knowledge and research for practice.

The diagnostic validity of the criteria for binge eating disorder

OBJECTIVE

This paper considers whether the criteria currently used to classify the diagnosis of binge eating disorder (BED) are valid and appropriate.

METHOD

We review evidence that reflects on the validity of the current criteria for binge eating episodes and BED, using literature retrieved through major psychology and psychiatry search engines (e.g., PsycInfo, PubMed).

RESULTS

Evidence from experimental research points to the relative importance of episode frequency, the amount of food consumed at episodes, the subjective sense of loss of control over eating, and several additional criteria associated with binge episodes in BED. Evidence on the differences in psychopathology between BED and bulimia nervosa and between BED and obesity without binge eating, as related to diagnostic criteria, is reviewed.

CONCLUSION

Although evidence concerning the diagnostic criteria of BED is mixed, broadening certain diagnostic criteria for binge eating episodes and BED might more accurately reflect the research literature and increase the number of individuals eligible for inclusion in treatment programs.

De-stabilization of the positive vago-vagal reflex in bulimia nervosa

Bulimia nervosa is characterized by consuming large amounts of food over a defined period with a loss of control over the eating. This is followed by a compensatory behavior directed at eliminating the consumed calories, usually vomiting. Current treatments include antidepressants and/or behavioral therapies. Consensus exists that these treatments are not very effective and are associated with high relapse rates. We review evidence from literature and present original data to evaluate the hypothesis that bulimia involves alterations in vago-vagal function. Evidence in support of this include (1) laboratory studies consistently illustrate deficits in meal size, meal termination, and satiety in bulimia; (2) basic science studies indicate that meal size and satiation are under vagal influences; (3) anatomical, behavioral and physiological data suggest that achieving satiety and the initiation of emesis involve common neural substrates; (4) abnormal vagal and vago-vagal reflexive functions extend to non-eating activational stimuli; and (5) studies from our laboratory modulating vagal activation have shown significant effects on binge/vomit frequencies and suggest a return of normal satiation. We propose a model for the pathophysiology of bulimia based upon de-stabilization of a bi-stable positive vago-vagal feedback loop. This model is not meant to be complete, but rather to stimulate anatomical, psychobiological, and translational neuroscience experiments aimed at elucidating the pathophysiology of bulimia and developing novel treatment strategies.

Progress in developing cholecystokinin (CCK)/gastrin receptor ligands that have therapeutic potential

Gastrin and cholecystokinin (CCK) are two of the oldest hormones and within the past 15 years there has been an exponential increase in knowledge of their pharmacology, cell biology, receptors (CCK1R and CCK2R), and roles in physiology and pathological conditions. Despite these advances there is no approved disease indication for CCK receptor antagonists and only a minor use of agonists. In this review, the important factors determining this slow therapeutic development are reviewed. To assess this it is necessary to briefly review what is known about the roles of CCK receptors (CCK1R and CCK2R) in normal human physiology, their role in pathologic conditions, the selectivity of available potent CCKR agonists/antagonists as well as to review their use in human conditions to date and the results. Despite extensive studies in animals and in humans, recent studies suggest that monotherapy with CCK1R agonists will not be effective in obesity, nor CCK2R antagonists in panic disorders or CCK2R antagonists to inhibit growth of pancreatic cancer. Areas that require more study include the use of CCK2R agonists for imaging tumors and radiotherapy, CCK2R antagonists in hypergastrinemic states especially with long-term PPI use and for potentiation of analgesia as well as use of CCK1R antagonists for a number of gastrointestinal disorders [motility disorders (irritable bowel syndrome, dyspepsia, and constipation) and pancreatitis (acute and chronic)].

Effect of eating rate on binge size in Bulimia Nervosa

Bulimia Nervosa (BN) is an eating disorder characterized by recurrent episodes of binge eating. During binge eating episodes, patients often describe the rapid consumption of food, and laboratory studies have shown that during binges patients with BN eat faster than normal controls (NC), but the hypothesis that a rapid rate of eating contributes to the excessive intake of binge meals has not yet been experimentally tested. The aim of this study was to assess the effect of eating rate on binge size in BN, in order to determine whether binge size is mediated, in part, by rate of eating. Thirteen BN and 14 NC subjects were asked to binge eat a yogurt shake that was served at a fast rate (140 g/min) on one occasion and at a slow rate (70 g/min) on another. NC subjects consumed 169 g more when eating at the fast rate than when eating at the slow rate. In contrast, consumption rates failed to influence binge size in patients with BN (fast: 1205 g; slow: 1195 g). Consequently, there was a significant group by rate interaction. As expected, patients with BN consumed more overall than NC subjects (1200 g vs. 740 g). When instructed to binge in the eating laboratory, patients with BN ate equally large amounts of food at a slow rate as at a fast rate. NC subjects ate less at a slow rate. These findings indicate that in a structured laboratory meal paradigm binge size is not affected by rate of eating.

Satiety and test meal intake among women with binge eating disorder

OBJECTIVE

The purpose of the study was to measure test meal consumption and the changes in hunger and fullness during a test meal in obese individuals with and without binge eating disorder (BED) and normal-weight controls.

METHOD

Twelve women with BED, 12 obese control participants, and 12 normal-weight control participants participated in two single-item test meal sessions. In one session participants were instructed to "binge," and the other eat a normal meal. Participants made ratings of hunger and fullness on visual analog scales after every 75-g increment of food.

RESULTS

In comparison to obese or normal-weight controls, patients with BED consumed significantly more food to reach a similar level of fullness or hunger.

CONCLUSION

Individuals with BED consumed significantly more food and showed blunted changes in hunger and fullness during both the binge and nonbinge meals. These findings suggest that individuals with BED may have disturbances in satiety that in some ways resemble those described among individuals with bulimia nervosa.

Appetite signaling: from gut peptides and enteric nerves to brain

The signaling systems underlying eating behavior control are complex. The current review focuses on gastrointestinal (GI) signaling systems as physiological key functions for metabolic control. Many of the peptides that are involved in the regulation of food intake in the brain are also found in the enteric nervous system and enteroendocrine cells of the mucosa of the GI tract. The only identified hunger-driving signal from the GI tract is ghrelin, which is mainly found in the mucosa of the stomach. Neuropeptides in the brain that influence food intake, of which neuropeptide Y, agouti gene-related peptide and orexins are stimulatory, while melanocortins and alpha-melanocortin stimulating hormone are inhibitory, are influenced by peptide signaling from the gut. These effects may take place directly through action of gut peptide in the brain or through nervous signaling from the periphery to the brain. The criteria for considering a gut hormone or neurotransmitter in a satiety signal seem to be fulfilled for cholecystokinin, glucagon-like peptide-1 and peptide YY(3-36). Other endogenous gut signals do not fulfill these criteria as they do not increase food intake in knock-out animals or in response to receptor antagonism, or display an inconsistent temporal profile with satiety and termination of the meal. Satiety signals from the GI tract act through the arcuate nucleus of the hypothalamus and the solitary tract nucleus of the brain stem, where neuronal networks directly linked to hypothalamic centers for food intake and eating behavior are activated. We have primarily focused on GI effects of various gut peptides involved in the regulation of food intake, using motor activity as a biomarker for the understanding of gut peptide effects promoting satiety.

Modulation of appetite by gonadal steroid hormones

Several sex differences in eating, their control by gonadal steroid hormones and their peripheral and central mediating mechanisms are reviewed. Adult female rats and mice as well as women eat less during the peri-ovulatory phase of the ovarian cycle (estrus in rats and mice) than other phases, an effect under the control of cyclic changes in estradiol secretion. Women also appear to eat more sweets during the luteal phase of the cycle than other phases, possibly due to simultaneous increases in estradiol and progesterone. In rats and mice, gonadectomy reveals further sex differences: orchiectomy decreases food intake by decreasing meal frequency and ovariectomy increases food intake by increasing meal size. These changes are reversed by testosterone and estradiol treatment, respectively. A variety of peripheral feedback controls of eating, including ghrelin, cholecystokinin (CCK), glucagon, hepatic fatty acid oxidation, insulin and leptin, has been shown to be estradiol-sensitive under at least some conditions and may mediate the estrogenic inhibition of eating. Of these, most progress has been made in the case of CCK. Neurons expressing estrogen receptor-alpha in the nucleus tractus solitarius of the brainstem appear to increase their sensitivity to CCK-induced vagal afferent input so as to lead to an increase in the satiating potency of CCK, and consequently decreased food intake, during the peri-ovulatory period in rats. Central serotonergic mechanisms also appear to be part of the effect of estradiol on eating. The physiological roles of other peripheral feedback controls of eating and their central mediators remain to be established.

Gastrointestinal disturbances in eating disorders: clinical and neurobiological aspects

Symptoms of the upper and lower gastrointestinal (gastrointestinal) tract have been described in anorexia nervosa and bulimia nervosa. Studies focusing on general outcome and medical comorbidity describe a worse outcome in the binge eating/purging subtype of anorexia nervosa compared to the restricting subtype. Both anorexia nervosa subtypes experience substantial delays in gastric emptying as well as constipation. These gastrointestinal disturbances may play a role in anorexia nervosa patients' difficulties with refeeding and weight restoration. Bulimia nervosa patients showed increased gastric emptying capacity, with delayed gastric emptying and diminished gastric relaxation. In addition, diminished release of cholecystokinin and abnormalities in enteric autonomic function were found in bulimia nervosa patients. These factors may play a role in the perpetuation of the disease. Gastrointestinal disturbances develop secondary to the disordered eating behaviour and the concomitant malnutrition and subside mostly with the resumption of normal food intake and body weight. Knowledge of these changes may be of critical importance in avoiding misdiagnosis and successful therapy.

Evidence for a vagal pathophysiology for bulimia nervosa and the accompanying depressive symptoms

BACKGROUND

The bilateral vagus nerves (Cranial X) provide both afferent and efferent connections between the viscera and the caudal medulla. The afferent branches increasingly are being recognized as providing significant input to the central nervous system for modulation of complex behaviors. In this paper, we review evidence from our laboratory that increases in vagal afferent activity are involved in perpetuating binge-eating and vomiting in bulimia nervosa. Preliminary findings are also presented which suggest that a subgroup of depressions may have a similar pathophysiology.

METHODS

Two main approaches were used to study the role of vagal afferents. Ondansetron (ONDAN), a 5-HT3 antagonist, was used as a pharmacological tool for inhibiting or reducing vagal afferent neurotransmission. Second, somatic pain detection thresholds were assessed for monitoring a physiological process known to be modulated by vagal afferents, including the gastric branches involved in meal termination and satiety. High levels of vagal activity result in an increase in pain detection thresholds. Depressive symptoms were assessed using the Beck Depression Inventory (BDI). Positron Emission Tomography (PET) was used to identify higher cortical brain areas activated by vagal stimulation produced by proximal gastric distention in normal eating subjects.

RESULTS

Double-blind treatment of severe bulimia nervosa subjects with ONDAN resulted in a rapid and significant decrease in binge-eating and vomiting compared to placebo controls. The decrease in abnormal eating episodes was accompanied by a return of normal satiety. Pain detection thresholds measured weekly over the course of the treatment protocol were found to dynamically fluctuate in association with bulimic episodes. Thresholds were the most elevated during periods of short-term abstinence from the behaviors, suggesting that not engaging in a binge/vomit episode is accompanied by an increase in vagal activity. ONDAN also resulted in abolition of the fluctuations in pain thresholds. Depressive symptoms in these subjects also were reduced by ONDAN. Like pain thresholds, depressive symptoms varied dynamically with the bulimic behaviors, with BDI scores increasing (more depressed) as more time elapsed since the last bulimic episode. PET studies indicated that mechanical distention of the stomach with a balloon (a non-nutritive stimulus) was associated with the activation of several brain loci, including those associated with vagal activation (parabrachial nucleus), emotive aspects of eating (lateral inferior frontal and orbitofrontal), and depressive symptoms (anterior cingulate).

CONCLUSIONS

The results of the ONDAN study in bulimia nervosa subjects suggest that cyclic increases in vagal activity drive the urge to binge-eat and vomit. The alterations in vagal firing patterns are possibly a physiological adaptation to the high levels of vagal stimulation initially provided by voluntarily binge-eating and vomiting for weight control. The depressive symptoms that occur in association with the urge to binge-eat are also likely due to the cyclic increase in vagal activity. This suggestion is supported by the reduction of depressive symptoms during ONDAN treatment in bulimia subjects and PET imaging studies in normal eating subjects showing that brain loci classically involved in depression are activated by vagal stimulation administered by mechanical gastric distention. In normal eating individuals, depressions accompanying visceral diseases may also be vagally mediated. Ondansetron and other drugs known to modulate vagal activity may be helpful in treating depressions of this origin.

Gastric compliance in bulimia nervosa

Bulimia nervosa (BN) is a psychiatric illness characterized by eating binges followed by inappropriate behavioral attempts to compensate for the binges, usually vomiting or laxative abuse. Patients with BN have disturbances in the development of satiety during a meal as well as disturbances in functions of the upper gastrointestinal tract such as slowed gastric emptying, impaired gastric accommodation reflex and blunted cholecystokinin release. The present study examined gastric compliance and sensory responses to gastric distention in women with BN and controls. Sixteen women with BN and 13 healthy control subjects swallowed an inflatable bag that was placed in the proximal stomach. The bag was inflated to produce increasing steps of pressure against the stomach wall, before and after consumption of a 200 ml (200 Kcal) liquid meal. Pressure and volume were recorded for 2-min periods, beginning at 0 mm Hg pressure and increasing in steps of 2 mm Hg until subjects reported discomfort, gastric volume reached 600 ml, or pressure reached 20 mm Hg. At each pressure step subjects made sensory ratings. Gastric compliance was calculated as the slope of the best-fit straight line of each subject's gastric volume vs. gastric pressure. There was a significant postmeal increase in gastric compliance in both groups of subjects but there was no difference in compliance between patients with BN and controls. Patients with BN appeared to have diminished sensitivity to gastric distention. In conclusion, although other studies have described gastrointestinal abnormalities associated with BN, the current study found gastric compliance of patients with BN to be normal.

Eating behavior among women with anorexia nervosa

BACKGROUND

Disturbed eating and severe caloric restriction are characteristic features of patients with anorexia nervosa (AN). Despite the importance of eating behavior in the presentation of AN, there have been relatively few objective laboratory studies of eating behavior among persons with eating disorders.

OBJECTIVE

The purpose of the study was to obtain objective measures of eating behavior among patients with AN before and immediately after weight restoration and to compare those measures with measures among control subjects.

DESIGN

Twelve patients hospitalized for AN and 12 control subjects participated in the study. Eleven of the 12 patients were retested at 90% of ideal body weight.

RESULTS

The average meal consumption was 103.97 +/- 102.08 g for patients at low weight and 178.03 +/- 202.97 g after weight restoration (NS). Control subjects consumed significantly more than did AN patients at both time points, and the average meal size was 489.58 +/- 187.64 g. Patients showed significant decreases in psychological and eating-disordered symptoms after weight restoration.

CONCLUSION

These data suggest that patients with AN show a persistent disturbance in eating behavior, despite the restoration of body weight and significant improvements in eating-disordered and psychological symptoms.

Peripheral interaction of ghrelin with cholecystokinin on feeding regulation

Ghrelin and cholecystokinin (CCK) are gastrointestinal hormones regulating feeding. Both transmitted via the vagal afferent, ghrelin elicits starvation signals, whereas CCK induces satiety signals. We investigated the interaction between ghrelin and CCK functioning in short-term regulation of feeding in Otsuka Long-Evans Tokushima fatty (OLETF) rats, which have a disrupted CCK type A receptor (CCK-AR), and their lean littermates, Long-Evans Tokushima Otsuka (LETO) rats. Intravenous administration of ghrelin increased 2-h food intake in both OLETF and LETO rats. Because OLETF rats are CCK insensitive, iv-administered CCK decreased 2-h food intake in LETO, but not in OLETF, rats. Although preadministration of CCK to LETO rats blocked food intake induced by ghrelin, CCK preadministration to OLETF rats did not affect ghrelin-induced food intake. Conversely, preadministration of ghrelin to LETO rats blocked feeding reductions induced by CCK. In electrophysiological studies, once gastric vagal afferent discharges were altered by ghrelin or CCK administration, they could not be additionally affected by serial administrations of either CCK or ghrelin, respectively. The induction of Fos expression in the hypothalamic arcuate nucleus by ghrelin was also attenuated by CCK preadministration. Using immunohistochemistry, we also demonstrated the colocalization of GH secretagogue receptor (GHS-R), the cellular receptor for ghrelin, with CCK-AR in vagal afferent neurons. These results indicate that the vagus nerve plays a crucial role in determining peripheral energy balance. The efficiency of ghrelin and CCK signal transduction may depend on the balance of their respective plasma concentration and/or on interactions between GHS-R and CCK-AR.