The role of the central nervous system in the psychoneuroendocrine disturbances of anorexia and bulimia nervosa

The tyrosine kinase receptor Tyro3 enhances lifespan and neuropeptide Y (Npy) neuron survival in the mouse anorexia (anx) mutation

Severe appetite and weight loss define the eating disorder anorexia nervosa, and can also accompany the progression of some neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS). Although acute loss of hypothalamic neurons that produce appetite-stimulating neuropeptide Y (Npy) and agouti-related peptide (Agrp) in adult mice or in mice homozygous for the anorexia (anx) mutation causes aphagia, our understanding of the factors that help maintain appetite regulatory circuitry is limited. Here we identify a mutation (C19T) that converts an arginine to a tryptophan (R7W) in the TYRO3 protein tyrosine kinase 3 (Tyro3) gene, which resides within the anx critical interval, as contributing to the severity of anx phenotypes. Our observation that, like Tyro3-/- mice, anx/anx mice exhibit abnormal secondary platelet aggregation suggested that the C19T Tyro3 variant might have functional consequences. Tyro3 is expressed in the hypothalamus and other brain regions affected by the anx mutation, and its mRNA localization appeared abnormal in anx/anx brains by postnatal day 19 (P19). The presence of wild-type Tyro3 transgenes, but not an R7W-Tyro3 transgene, doubled the weight and lifespans of anx/anx mice and near-normal numbers of hypothalamic Npy-expressing neurons were present in Tyro3-transgenic anx/anx mice at P19. Although no differences in R7W-Tyro3 signal sequence function or protein localization were discernible in vitro, distribution of R7W-Tyro3 protein differed from that of Tyro3 protein in the cerebellum of transgenic wild-type mice. Thus, R7W-Tyro3 protein localization deficits are only detectable in vivo Further analyses revealed that the C19T Tyro3 mutation is present in a few other mouse strains, and hence is not the causative anx mutation, but rather an anx modifier. Our work shows that Tyro3 has prosurvival roles in the appetite regulatory circuitry and could also provide useful insights towards the development of interventions targeting detrimental weight loss.

Low serum amylase and obesity, diabetes and metabolic syndrome: A novel interpretation

For the last decade, low serum amylase (hypoamylasemia) has been reported in certain common cardiometabolic conditions such as obesity, diabetes (regardless of type), and metabolic syndrome, all of which appear to have a common etiology of insufficient insulin action due to insulin resistance and/or diminished insulin secretion. Some clinical studies have shown that salivary amylase may be preferentially decreased in obese individuals, whereas others have revealed that pancreatic amylase may be preferentially decreased in diabetic subjects with insulin dependence. Despite this accumulated evidence, the clinical relevance of serum, salivary, and pancreatic amylase and the underlying mechanisms have not been fully elucidated. In recent years, copy number variations (CNVs) in the salivary amylase gene (AMY1), which range more broadly than the pancreatic amylase gene (AMY2A and AMY2B), have been shown to be well correlated with salivary and serum amylase levels. In addition, low CNV of AMY1, indicating low salivary amylase, was associated with insulin resistance, obesity, low taste perception/satiety, and postprandial hyperglycemia through impaired insulin secretion at early cephalic phase. In most populations, insulin-dependent diabetes is less prevalent (minor contribution) compared with insulin-independent diabetes, and obesity is highly prevalent compared with low body weight. Therefore, obesity as a condition that elicits cardiometabolic diseases relating to insulin resistance (major contribution) may be a common determinant for low serum amylase in a general population. In this review, the novel interpretation of low serum, salivary, and pancreas amylase is discussed in terms of major contributions of obesity, diabetes, and metabolic syndrome.

Efficacy of tube feeding in binge-eating/vomiting patients: a 2-month randomized trial with 1-year follow-up

BACKGROUND

In many binge-eating/vomiting patients, abstinence could not be obtained from classical treatments. Since the authors showed that tube feeding (TF) reduced such episodes in anorexia nervosa (AN)-hospitalized patients, they carried out a randomized trial on the efficacy of TF plus cognitive behavioral therapy (CBT) vs CBT alone in AN and bulimia nervosa adult outpatients.

METHODS

The authors randomly assigned 103 ambulatory patients to receive 16 sessions of CBT alone (n = 51) or CBT plus 2 months of TF (n = 52). The main goal was abstinence of binge-eating/vomiting episodes. Other criteria were gains in fat-free mass and muscle mass improvements in nutrition markers, and quality of life (SF-36 Health Survey), depression (Beck Depression Inventory), and anxiety (Hamilton Anxiety Rating Scale) scores. Evaluations were performed at 1, 2 (end of treatment), 5, 8, and 14 months (analysis of variance).

RESULTS

TF patients were rapidly and more frequently abstinent at the end of treatment (2 months) than the CBT patients: 81% vs 29% (P < .001). Fat-free mass, biological markers, depressive state (-58% vs -26%), anxiety (-48% vs -15%), and quality of life (+42% vs +13%) were more improved in the TF group than in the CBT group (P < .05). One year later, more TF patients remained abstinent (68% vs 27%, P = .02); they were less anxious, were less depressed, and had better quality of life than the CBT patients (P < .05).

CONCLUSION

TF combined with CBT offered better results than CBT alone.

Recovery and chronicity in anorexia nervosa: brain activity associated with differential outcomes

BACKGROUND

The course of anorexia nervosa varies from rapid recovery to a chronic debilitating illness. This study aimed to identify functional neural correlates associated with differential outcomes.

METHODS

Brain reactions to food and emotional visual stimuli were measured with functional magnetic resonance imaging in nine women who had long-term recovery from restricting anorexia nervosa. These were compared with age- and education-matched groups of eight women chronically ill with restricting anorexia nervosa and nine healthy control women.

RESULTS

In response to food stimuli, increased medial prefrontal and anterior cingulate activation, as well as a lack of activity in the inferior parietal lobule, differentiated the recovered group from the healthy control subjects. Increased activation of the right lateral prefrontal, apical prefrontal, and dorsal anterior cingulate cortices differentiated these recovered subjects from chronically ill patients. Group differences were specific to food stimuli, whereas processing of emotional stimuli did not differ between groups.

CONCLUSIONS

Separate neural correlates underlie trait and state characteristics of anorexia nervosa. The medial prefrontal response to disease-specific stimuli may be related to trait vulnerability. Lateral and apical prefrontal involvement is associated with a good outcome.

Urinary peptide levels in women with eating disorders. A pilot study

The aim of this study was to evaluate whether the urinary excretion of low molecular weight peptides is increased in women with a history of anorexia nervosa/self starvation. The study group consisted of 12 women aged 20-38 years who were treated in a specialised day care unit for eating disorders in Stockholm between January and December 1998; the controls were eight women with primary bulimia treated in the same unit (A) and ten healthy women without any eating disorder (B). The chromatographically measured urinary peptide levels in the study group were significantly higher than those in control group A (and B when one highly influential individual with very low peptide excretion in the study group was excluded from the analyses). These findings offer some support to the speculative hypothesis that eating disorder symptoms may be linked to increased levels of neuroactive peptides, although it is necessary to define the peptides further before any definite conclusion can be drawn. Furthermore, the study group was characterised by many interpersonal differences in eating behaviour that could explain the increased urinary peptide levels.

Comorbidity of obsessive-compulsive disorders and duration of eating disorders

OBJECTIVE

This study explored the comorbidity of obsessive-compulsive disorder (OCD) and eating disorders (ED) and examined the relationship between OCD comorbidity and the duration of ED. Subjects with OCD were expected to show a longer history of ED.

METHOD

ED females (N = 237; 84 with anorexia nervosa and 153 with bulimia nervosa) were assessed using the Structured Clinical Interview for DSM-IV Axis I disorders (SCID-1). Data were analyzed by logistic regression to determine whether OCD comorbidity is associated with duration of ED.

RESULTS

The total sample showed a prevalence rate for OCD of 29.5%. OCD prevalence did not differ between anorexic and bulimic subjects. OCD comorbidity was significantly associated with a longer history of ED.

CONCLUSION

The findings of the study support previous research indicating a high comorbidity of ED with OCD. The results also suggest that OCD may play a role in the course of ED. Prospective studies are necessary to examine this hypothesis further.

Anorexia nervosa: manifestations and management for the gastroenterologist

Anorexia nervosa is a complex psychiatric disorder with significant morbidity and mortality. It is important for gastroenterologists to be aware of the physiological effects and potential complications of anorexia nervosa, as they are frequently involved in treating patients with this disorder. We review the classic, GI, and neuroendocrinological features of anorexia nervosa. We also discuss gender differences and treatment options in anorexia nervosa. Further studies of GI physiology and pharmacology are needed to determine whether any disturbances may be amenable to therapeutic intervention. Future treatments directed at improving GI sensorimotor function and neurohormonal abnormalities in patients with anorexia nervosa may impact their nutritional rehabilitation and may have important health economic implications as patients avoid hospitalization and are restored to full activities in society. The current team approach, which incorporates psychiatrists, psychologists, nutritionists, pediatricians, internists, and gastroenterologists in the treatment of patients with anorexia nervosa, will continue to be essential.

Plasma concentrations of tumor necrosis factor-alpha (TNF-alpha) and soluble TNF receptors in patients with bulimia nervosa

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is a cytokine with numerous immunological and metabolic activities. In addition, TNF-alpha can stimulate a variety of physiological, neuroendocrine and behavioural responses of the central nervous system. In experimental animals, TNF-alpha induces changes in physiological and behavioural parameters which have also been observed in eating disorders. The biological activities of TNF-alpha are mediated by two structurally related, but functionally distinct receptors, TNF-RI and TNF-RII. Since injection of TNF-alpha results in increased shedding of TNF-alpha receptors, it is likely that TNF-alpha release is reflected by soluble TNF-receptors (sTNF-Rs) levels.

AIMS

We studied plasma concentrations of TNF-alpha and two sTNF-Rs (sTNF-RI and sTNF-RII) in female patients with bulimia nervosa.

DESIGN AND PATIENTS

Twenty female patients with bulimia nervosa (BN) and 20 age-matched normal women (N) were studied.

MEASUREMENTS

Plasma TNF-alpha concentrations were measured by enzyme immunoassay kit and plasma concentrations of sTNF-RI and sTNF-RII were measured by enzyme-linked immunosorbent assay.

RESULTS

Plasma TNF-alpha concentrations in BN were significantly higher than those in N (4.7+/- 0.5 ng/l vs. 1.6+/-0.1 ng/l; P<0.01). Although no significant difference was observed in plasma sTNF-RI concentrations between the two groups, plasma sTNF-RII concentrations in BN were significantly higher than those in N (2080.0+/-107.5 ng/l vs. 1569.5 +/-84.0 ng/l; P<0.01). Plasma TNF-alpha concentrations were significantly related to plasma sTNF-RI concentrations (r = 0.511, P<0.05) and to plasma sTNF-RII concentrations (r = 0.532, P<0.05) in bulimic patients. However, plasma TNF-alpha concentrations were not related to body fat mass or to bulimic behaviours in these patients.

CONCLUSIONS

Our present findings suggest that the adipose tissue may not be the immediate source of TNF-alpha in bulimic patients but the increase in plasma TNF-alpha in these patients may be derived from the central nervous system sources. The elevated sTNF-RII may reflect different shedding kinetics compared with sTNF-RI in bulimic patients.

CSF oxytocin and vasopressin levels after recovery from bulimia nervosa and anorexia nervosa, bulimic subtype

BACKGROUND

When ill, people with eating disorders have disturbances of the neuropeptides vasopressin and oxytocin.

METHODS

To avoid the confounding effects of the ill state, we studied women who were recovered (more than 1 year, normal weight, and regular menstrual cycles, no bingeing or purging) from bulimia nervosa (rBN) or binge eating/purging-type anorexia nervosa (rAN-BN), and matched healthy control women.

RESULTS

Vasopressin was elevated in rAN-BN and showed a trend towards elevation in rBN. In rBN, elevated cerebrospinal fluid vasopressin may be related to having a lifetime history of major depression. In comparison, cerebrospinal fluid oxytocin was normal in recovered subjects, but elevated levels in some rBN might be related to birth control pill use.

CONCLUSIONS

These data confirm and extend the possibility that elevated cerebrospinal fluid vasopressin may be related to the pathophysiology of eating disorders, and/or a lifetime history of major depression.

Diet Restriction Increases Enkephalin- and Dynorphin-like Immunoreactivity in Rat Brain and Attenuates Long-term Retention of Passive Avoidance

The present study examines effects of diet restriction (DR) on behavior and on the opioid peptides enkephalin (Enk) and dynorphin (Dyn). Female rats were assigned to ad libitum food intake (AL), DR 60% (DR60) or 40% (DR40) of AL. After 4 weeks, DR reduced fearful behavior in the elevated plus maze. DR rats displayed good retention of passive avoidance at 24 h, but DR40 rats had reduced retention, at 5 and 11 days post training. Changes in Enk- and Dyn-like immunoreactivity (LI) in the hippocampal mossy fibers (MF), hypothalamus, septum, central nucleus of amygdala (CeAm) and thalamus depended on the severity of DR. In DR60, Enk-LI and Dyn-LI were not changed except for reduction in CeAm. In DR40, Dyn-LI increased significantly above AL levels in MF, CeAm and hypothalamus, whereas Enk-LI increased significantly above AL levels in the CA3 subregion of the MF system and in thalamus. Serum glucose was tightly correlated with Enk-LI reaching highest values in the MF (r= -0.82). Increased opioid-LI in CeAm and MF was associated with reduced fearfulness in the elevated plus maze. Thus, hippocampal and amygdala opioid subsystems are uniquely sensitive to DR and may be relevant to psychophysiological problems in human starvation including anorexia.