Anorexia nervosa: towards a neurobiologically based therapy

Expression of guanylate cyclase C in human prefrontal cortex depends on sex and feeding status

Introduction

Guanylate cyclase C (GC-C) has been detected in the rodent brain in neurons of the cerebral cortex, amygdala, midbrain, hypothalamus, and cerebellum.

Methods

In this study we determined GC-C protein expression in Brodmann areas (BA) 9, BA10, BA11, and BA32 of the human prefrontal cortex involved in regulation of feeding behavior, as well as in the cerebellar cortex, arcuate nucleus of hypothalamus and substantia nigra in brain samples of human 21 male and 13 female brains by ELISA with postmortem delay < 24 h.

Results

GC-C was found in all tested brain areas and it was expressed in neurons of the third cortical layer of BA9. The regulation of GC-C expression by feeding was found in male BA11 and BA10-M, where GC-C expression was in negative correlation to the volume of stomach content during autopsy. In female BA11 there was no correlation detected, while in BA10-M there was even positive correlation. This suggests sex differences in GC-C expression regulation in BA11 and BA10-M. The amount of GC-C was higher in female BA9 only when the death occurred shortly after a meal, while expression of GC-C was higher in BA10-O only when the stomach was empty. The expression of GC-C in female hypothalamus was lower when compared to male hypothalamus only when the stomach was full, suggesting possibly lower satiety effects of GC-C agonists in women.

Discussion

These results point toward the possible role of GC-C in regulation of feeding behavior. Since, this is first study of GC-C regulation and its possible function in prefrontal cortex, to determine exact role of GC-C in different region of prefrontal cortex, especially in humans, need further studies.

A Randomized Trial of Deep Brain Stimulation to the Subcallosal Cingulate and Nucleus Accumbens in Patients with Treatment-Refractory, Chronic, and Severe Anorexia Nervosa: Initial Results at 6 Months of Follow Up

Background: The main objective of this study was to assess the safety and efficacy of deep brain stimulation (DBS) in patients with severe anorexia nervosa (AN). Methods: Eight participants received active DBS to the subcallosal cingulate (SCC) or nucleus accumbens (NAcc) depending on comorbidities (affective or anxiety disorders, respectively) and type of AN. The primary outcome measure was body mass index (BMI). Results: Overall, we found no significant difference (p = 0.84) between mean preoperative and postoperative (month 6) BMI. A BMI reference value (BMI-RV) was calculated. In patients that received preoperative inpatient care to raise the BMI, the BMI-RV was defined as the mean BMI value in the 12 months prior to surgery. In patients that did not require inpatient care, the BMI-RV was defined as the mean BMI in the 3-month period before surgery. This value was compared to the postoperative BMI (month 6), revealing a significant increase (p = 0.02). After 6 months of DBS, five participants showed an increase of ≥10% in the BMI-RV. Quality of life was improved (p = 0.03). Three cases presented cutaneous complications. Conclusion: DBS may be effective for some patients with severe AN. Cutaneous complications were observed. Longer term data are needed.

Cyclic estradiol treatment modulates the orexigenic effects of ghrelin in ovariectomized rats

Data from a wide variety of mammalian species indicate that feeding behavior can be influenced by changes in endogenous estrogens and exogenous estrogenic treatments. Ghrelin is an important physiological signal for the regulation of energy balance, and ghrelin treatment increases eating and body weight in male rodents. The following studies evaluated the hypothesis that the inhibitory effects of estradiol on feeding involve interactions with orexigenic peptides by examining the ability of estradiol to modulate the behavioral effects of ghrelin in female rats. In these experiments, adult rats were ovariectomized and assigned to an estradiol benzoate (EB) or an oil (control) group. Three weeks after ovariectomy, animals received two daily subcutaneous injections of EB or the oil vehicle. Animals then received intraperitoneal (ip) injections of ghrelin (6.0 or 12.0 nmol) or saline during the nocturnal and diurnal periods three days after the first injection of estradiol or oil. Food intake, meal size, and meal number were determined during the 2-hour period following ghrelin or saline treatments. Ghrelin significantly increased food intake during nocturnal tests in oil-treated but not estradiol-treated rats. The hyperphagic effects of ghrelin on nocturnal food intake were also accompanied by an increase in meal size, and this effect of ghrelin on meal size was attenuated in estradiol-treated females. These findings support the hypothesis that the effects of estradiol on feeding behavior involve an attenuation of orexigenic signals, possibly by modulating the effects of the peripheral ghrelin signal on hypothalamic neuropeptides involved in the control of food intake.

Deep-brain stimulation for anorexia nervosa

OBJECTIVE

Anorexia nervosa (AN) is a complex and severe, sometimes life-threatening, psychiatric disorder with high relapse rates under standard treatment. After decades of brain-lesioning procedures offered as a last resort, deep-brain stimulation (DBS) has come under investigation in the last few years as a treatment option for severe and refractory AN.

METHODS AND RESULTS

In this jointly written article, Sun et al. (the Shanghai group) report an average of 65% increase in body weight in four severe and refractory patients with AN after they underwent the DBS procedure (average follow-up: 38 months). All patients weighed greater than 85% of expected body weight and thus no longer met the diagnostic criteria of AN at last follow-up. Nuttin et al. (the Leuven group) describe other clinical studies that provide evidence for the use of DBS for AN and further discuss patient selection criteria, target selection, and adverse event of this evolving therapy.

CONCLUSION

Preliminary results from the Shanghai group and other clinical centers showed that the use of DBS to treat AN may be a valuable option for weight restoration in otherwise-refractory and life-threatening cases. The nature of this procedure, however, remains investigational and should not be viewed as a standard clinical treatment option. Further scientific investigation is essential to warrant the long-term efficacy and safety of DBS for AN.

Low-dose olanzapine monotherapy in girls with anorexia nervosa, restricting subtype: focus on hyperactivity

OBJECTIVE

The aim of this study was to evaluate the efficacy of olanzapine in girls with anorexia nervosa, restricting subtype (ANr).

METHODS

Thirteen patients (mean age 13.7 +/- 2.3 years, age range 9.6-16.3 years) enrolled in a multimodal treatment for ANr were evaluated with standardized measures at baseline and after 1 and 6 months after starting low-dose olanzapine monotherapy (mean dose 4.13 mg/day).

RESULTS

A significant improvement was evident on weight (body mass index, BMI), global functioning (Children's Global Assessment Scale, CGAS), eating attitudes (Eating Attitudes Test-26, EAT-26), anxious-depressive symptoms (Child Behavior Checklist, CBCL) and hyperactivity (Structured Inventory for Anorexic and Bulimic Syndromes, SIAB). At the end of the 6-month follow up, 7 patients were responders according to an improvement of at least 50% in the EAT-26 results. The only measure that improved significantly in responders, but not in nonresponders, was hyperactivity (SIAB). Clinical improvement, in terms of both body mass index (BMI) recovery and global functioning, paralleled the improvement of hyperactivity, was evident at the end of the first month of treatment, and further increased in the following 5 months, with minimal side effects.

CONCLUSIONS

Low-dose olanzapine monotherapy may be useful as adjunctive treatment of youths with ANr. It is suggested that efficacy may be mediated by a decrease of hyperactivity.

Estradiol and the control of food intake

Gonadal steroids are among the many factors that influence food intake and body weight in mammals. Hormonal effects on these processes are particularly striking in female rats, which show large increases in food intake and body weight after ovariectomy. A key role of estradiol in the control of food intake and energy balance in humans is evidenced by the fact that the incidence of obesity increases greatly after menopause [American College of Obstetricians and Gynecologists. Body mass index and insulin resistance. Obstet Gynecol 2004;104:5s-10]. The actions of estradiol on neural systems that regulate eating may also account in part for sex differences in food intake and eating disorders, which occur much more frequently in young women [Sodersten P, Bergh C. Anorexia nervosa: towards a neurobiologically based therapy. Eur J Pharmacol 2003;480:67-74]. This paper presents a minireview of research examining the changes in feeding that occur during the ovarian cycle, the effects of estradiol withdrawal and replacement on food intake and body weight, and the neurobiological mechanisms by which estradiol influences feeding behavior. A model of hormone action on food intake that emerges from this research views estradiol as an indirect control of eating and meal size, producing changes in feeding behavior by modulating the central processing of both satiating and orexigenic peptides that represent direct controls of eating. Some of the shortcomings of the model and directions for future research are discussed.

Electrical stimulation in the lateral hypothalamus in rats in the activity-based anorexia model

Object

One quarter of patients with anorexia nervosa have a poor outcome and continue to suffer chronically or die. Electrical brain stimulation may be of therapeutic benefit in some of these patients; however, the brain target for inducing symptom relief is unknown. In this study, the authors evaluated the effects of acute and chronic electrical stimulation in the lateral hypothalamus on food intake, locomotor activity, and survival time in rats in an activity-based anorexia model.

Methods

In an acute experiment, the authors electrically stimulated at 100 Hz and 0, 25, 50 and 75% of the maximal stimulation amplitude (that is, the amplitude leading to severe side effects) in the lateral hypothalamus on consecutive days during 4 test sessions in 10 rats and evaluated food intake and locomotor activity. In a chronic experiment, they compared food intake, wheel revolutions, and survival time between 6 rats that underwent electrical stimulation in the lateral hypothalamus (50% of maximal stimulation amplitude) and 8 rats that did not undergo stimulation.

Results

In the acute experiment, overall electrical stimulation (25, 50, and 75% combined) and stimulation at 75% of the maximal stimulation amplitude significantly decreased the locomotor activity. However, if the authors omitted results of 1 rat, in which the electrode tip was not located in the lateral hypothalamus on one side but rather in the supraoptic chiasm, the remaining results did not yield significance. No other differences were observed.

Conclusions

When the findings of the current study are extrapolated to patients with anorexia nervosa, the authors do not expect major effects on symptoms with electrical stimulation at high frequency in the lateral hypothalamus.

Pharmacological treatment of anorexia nervosa: a retrospective study in preadolescents and adolescents

To date, studies addressing the role of pharmacotherapy in the treatment of anorexia nervosa are limited, especially in childhood and adolescence. The aim of this retrospective naturalistic study was to evaluate the efficacy and safety of pharmacotherapy in 19 anorexic preadolescents and adolescents referred, for the first time, to a specialist psychiatry unit. Almost all the patients showed an improvement both in their eating behaviors, and in their mood and obsessive symptoms. No evidence was found of dangerous adverse events. Combined with a multidisciplinary approach that includes nutritional rehabilitation and psychotherapy, adjunctive pharmacotherapy may be useful in addressing both eating disorder psychopathology and comorbid psychiatric disorders.

Understanding eating disorders

The outcome in eating disorders remains poor and commonly used methods of treatment have little, if any effect. It is suggested that this situation has emerged because of the failure to realize that the symptoms of eating disorder patients are epiphenomena to starvation and the associated disordered eating. Humans have evolved to cope with the challenge of starvation and the neuroendocrine mechanisms that have been under this evolutionary pressure are anatomically versatile and show synaptic plasticity to allow for flexibility. Many of the neuroendocrine changes in starvation are responses to the externally imposed shortage of food and the associated neuroendocrine secretions facilitate behavioral adaptation as needed rather than make an individual merely eat more or less food. A parsimonious, neurobiologically realistic explanation why eating disorders develop and why they are maintained is offered. It is suggested that the brain mechanisms of reward are activated when food intake is reduced and that disordered eating behavior is subsequently maintained by conditioning to the situations in which the disordered eating behavior developed via the neural system for attention. In a method based on this framework, patients are taught how to eat normally, their physical activity is controlled and they are provided with external heat. The method has been proven effective in a randomized controlled trial.

A G-protein-coupled estrogen receptor is involved in hypothalamic control of energy homeostasis

Estrogens are involved in the hypothalamic control of multiple homeostatic functions including reproduction, stress responses, energy metabolism, sleep cycles, temperature regulation, and motivated behaviors. The critical role of 17beta-estradiol (E2) is evident in hypoestrogenic states (e.g., postmenopause) in which many of these functions go awry. The actions of E2 in the brain have been attributed to the activation of estrogen receptors alpha and beta through nuclear, cytoplasmic, or membrane actions. However, we have identified a putative membrane-associated estrogen receptor that is coupled to desensitization of GABAB and mu-opioid receptors in guinea pig and mouse hypothalamic proopiomelanocortin neurons. We have synthesized a new nonsteroidal compound, STX, which selectively targets the Galphaq-coupled phospholipase C-protein kinase C-protein kinase A pathway, and have established that STX is more potent than E2 in mediating this desensitization in an ICI 182, 780-sensitive manner in both guinea pig and mouse neurons. Both E2 and STX were fully efficacious in estrogen receptor alpha,beta knock-out mice. Moreover, in vivo treatment with STX, similar to E2, attenuated the weight gain in hypoestrogenic female guinea pigs. Therefore, this membrane-delimited signaling pathway plays a critical role in the control of energy homeostasis and may provide a novel therapeutic target for treatment of postmenopausal symptoms and eating disorders in females.

Autoantibodies against neuropeptides are associated with psychological traits in eating disorders

Previously, we identified that a majority of patients with anorexia nervosa (AN) and bulimia nervosa (BN) as well as some control subjects display autoantibodies (autoAbs) reacting with alpha-melanocyte-stimulating hormone (alpha-MSH) or adrenocorticotropic hormone, melanocortin peptides involved in appetite control and the stress response. In this work, we studied the relevance of such autoAbs to AN and BN. In addition to previously identified neuropeptide autoAbs, the current study revealed the presence of autoAbs reacting with oxytocin (OT) or vasopressin (VP) in both patients and controls. Analysis of serum levels of identified autoAbs showed an increase of IgM autoAbs against alpha-MSH, OT, and VP as well as of IgG autoAbs against VP in AN patients when compared with BN patients and controls. Further, we investigated whether levels of these autoAbs correlated with psychological traits characteristic for eating disorders. We found significantly altered correlations between alpha-MSH autoAb levels and the total Eating Disorder Inventory-2 score, as well as most of its subscale dimensions in AN and BN patients vs. controls. Remarkably, these correlations were opposite in AN vs. BN patients. In contrast, levels of autoAbs reacting with adrenocorticotropic hormone, OT, or VP had only few altered correlations with the Eating Disorder Inventory-2 subscale dimensions in AN and BN patients. Thus, our data reveal that core psychobehavioral abnormalities characteristic for eating disorders correlate with the levels of autoAbs against alpha-MSH, suggesting that AN and BN may be associated with autoAb-mediated dysfunctions of primarily the melanocortin system.

Phobic memory and somatic vulnerabilities in anorexia nervosa: a necessary unity?

Anorexia nervosa is a clinically significant illness that may be associated with permanent medical complications involving almost every organ system. The paper raises a question whether some of them are associated with premorbid vulnerability such as subcellular ion channel abnormalities ('channelopathy') that determines the clinical expression of the bodily response to self-imposed malnutrition. Aberrant channels emerge as a tempting, if rather speculative alternative to the notion of cognitively-driven neurotransmitter modulation deficit in anorexia nervosa. The concept of channelopathies is in keeping with some characteristics of anorexia nervosa, such as a genetically-based predisposition to hypophagia, early onset, cardiac abnormalities, an appetite-enhancing efficacy of some antiepileptic drugs, and others. The purpose of this article is to stimulate further basic research of ion channel biophysics in relation to restrictive anorexia.

Laparophobia: a cognitive perspective on appetite control in anorexia nervosa

Decades of research have demonstrated that anorexia nervosa (AN) may be associated with aberrant cognition, yet, its role in maintaining stringent dieting has received relatively little attention from mainstream researchers of eating disorders. The purpose of the present article is to highlight cognitive ('top-down') factors that are considered responsible for anticipatory anxiety of stoutness and frank fat-phobia (laparophobia). A cognitive model proposed departs from the formulation suggesting that phobia of over-eating is superimposed on avoidant tendencies ('environmental autonomy syndrome'), whereas excessive exercising becomes a natural coping strategy with laparophobia, an instrument of reward. AN ideation involves complex neuronal circuitries and multiple neurochemical components that may conceivably represent a mirror image of those underlying obesity. The emphasis on phobia and aberrant membrane excitability akin to channelopathies behoves the clinicians to be aware of potential uses of drugs acting at the gamma-aminobutyric acid and the N-methyl-D-aspartate/AMPA [2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl) propionic acid] receptors sites as the adjuncts to conventional agents in managing AN.