Increased dopamine D2/D3 receptor binding after recovery from anorexia nervosa measured by positron emission tomography and [11c]raclopride

Aromatic amino acids in weight-recovered females with anorexia nervosa

OBJECTIVE

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

METHOD

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

RESULTS

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

DISCUSSION

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

Dopamine antagonism inhibits anorectic behavior in an animal model for anorexia nervosa

Excessive physical activity is commonly described as symptom of Anorexia Nervosa (AN). Activity-based anorexia (ABA) is considered an animal model for AN. The ABA model mimics severe body weight loss and increased physical activity. Suppression of hyperactivity by olanzapine in anorectic patients as well as in ABA rats suggested a role of dopamine and/or serotonin in this trait. Here, we investigated the effect of a non-selective dopamine antagonist in the ABA model. A dose-response curve of chronic treatment with the non-selective dopaminergic antagonist cis-flupenthixol was determined in the ABA model. Treatment reduced activity levels in both ad libitum fed and food-restricted rats. Treated ABA rats reduced body weight loss and increased food intake. These data support a role for dopamine in anorexia associated hyperactivity. Interestingly, in contrast to leptin treatment, food-anticipatory activity still persists in treated ABA rats.

SLC6A3 and body mass index in the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial

Background

To investigate the contribution of the dopamine transporter to dopaminergic reward-related behaviors and anthropometry, we evaluated associations between polymorphisms at the dopamine transporter gene(SLC6A3) and body mass index (BMI), among participants in the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial.

Methods

Four polymorphisms (rs6350, rs6413429, rs6347 and the 3' variable number of tandem repeat (3' VNTR) polymorphism) at the SLC6A3 gene were genotyped in 2,364 participants selected from the screening arm of PLCO randomly within strata of sex, age and smoking history. Height and weight at ages 20 and 50 years and baseline were assessed by questionnaire. BMI was calculated and categorized as underweight, normal, overweight and obese (<18.5, 18.5–24.9, 25.0–29.9, or ≥ 30 kg/m², respectively). Odds ratios (ORs) and 95% confidence intervals (CIs) of SLC6A3 genotypes and haplotypes were computed using conditional logistic regression.

Results

Compared with individuals having a normal BMI, obese individuals at the time of the baseline study questionnaire were less likely to possess the 3' VNTR variant allele with 9 copies of the repeated sequence in a dose-dependent model (** is referent; OR_*9 = 0.80, OR₉₉ = 0.47, p_trend = 0.005). Compared with individuals having a normal BMI at age 50, overweight individuals (A-C-G-* is referent; OR_A-C-G-9 = 0.80, 95% CI 0.65–0.99, p = 0.04) and obese individuals (A-C-G-* is referent; OR_A-C-G-9 = 0.70, 95% CI 0.49–0.99, p = 0.04) were less likely to possess the haplotype with the 3'variant allele (A-C-G-9).

Conclusion

Our results support a role of genetic variation at the dopamine transporter gene, SLC6A3, as a modifier of BMI.

Perplexities and provocations of eating disorders

BACKGROUND

Etiological hypotheses of eating disorders, anorexia nervosa and bulimia nervosa have not produced informative research for predictably effective treatment.

METHODS

The rationale for applying a model of allostasis, a dysregulation of reward circuits with activation of brain and hormonal stress responses to maintain apparent stability, is developed for eating disorders.

RESULTS

The neurotransmitter systems involved in the allostatic state of a reward system in anorexia nervosa and bulimia nervosa may be similar to those present in drug addiction.

CONCLUSION

The biological vulnerabilities underlying the unique features of eating disorders should be intensively investigated with the advancing techniques in genetics and neuroimaging. Preventing chronicity with early diagnosis and adequate treatment before age 18 is necessary.

Neuroimaging in eating disorders and obesity: implications for research

Medicine and psychiatry have benefited from developments in investigational techniques. Neuroimaging is one such domain that has technically progressed enormously in recent years, resulting in, for example, higher temporal and spatial resolution. Neuroimaging techniques have been widely used in a range of psychiatric disorders, providing new insights into neural brain circuits and neuroreceptor functions in vivo. These imaging techniques allow researchers to study not only the configuration of brain structures but also aspects of normal and anomalous human behavior more accurately.

What potential role is there for medication treatment in anorexia nervosa?

OBJECTIVE

To review selected issues regarding the development of drug treatments for anorexia nervosa (AN).

METHOD

The existing pharmacotherapy literature for AN is reviewed, and the theoretical and practical considerations are discussed.

RESULTS

A very wide variety of drugs have been examined in AN, generally with negative results. There are a number of potential reasons for this finding, including compliance, nutritional deficits, selection of the wrong targets or the wrong outcome measures, use of monotherapy, lack of animal models, or factors intrinsic to AN.

CONCLUSION

Pharmacotherapy provides little benefit in the treatment of AN at present. Several strategies might lead to the identification of more effective agents, including new measurement strategies, identification of novel pharmacologic targets, and consideration of a clinical trials network.

Hypothalamus transcriptome profile suggests an anorexia-cachexia syndrome in the anx/anx mouse model

The anx/anx mouse displays poor appetite and lean appearance and is considered a good model for the study of anorexia nervosa. To identify new genes involved in feeding behavior and body weight regulation we performed an expression profiling in the hypothalamus of the anx/anx mice. Using commercial microarrays we detected 156 differentially expressed genes and validated 92 of those using TaqMan low-density arrays. The expression of a set of 87 candidate genes selected based on literature evidences was also quantified by TaqMan low-density arrays. Our results showed enrichment in deregulated genes involved in cell death, cell morphology, and cancer, as well as an alteration of several signaling circuits involved in energy balance including neuropeptide Y and melanocortin signaling. The expression profile along with the phenotype led us to conclude that anx/anx mice resemble the anorexia-cachexia syndrome typically observed in cancer, infection with human immunodeficiency virus or chronic diseases, rather than starvation, and that anx/anx mice could be considered a good model for the treatment and investigation of this condition.

A high-fat diet prevents and reverses the development of activity-based anorexia in rats

OBJECTIVE

Activity-based anorexia is an animal model of anorexia nervosa in which limited access to standard lab chow combined with voluntary wheel running leads to hypophagia and severe weight loss. This study tested whether activity-based anorexia could be prevented or reversed with palatable foods.

METHOD

Male rats were divided into sedentary or ad libitum-running groups and maintained on 1 h daily access to standard chow plus one of the following: sugar, saccharin, vegetable fat (shortening), or sweet high-fat chow.

RESULTS

Access to the sweet high-fat chow both reversed and prevented the weight loss typical of activity-based anorexia. Vegetable fat attenuated body weight loss, but to a lesser degree than the sweet high-fat diet. The addition of saccharin or sucrose solutions to the standard lab-chow diet had no effect.

CONCLUSION

The results suggest that certain palatable diets may affect the development of, and recovery from, activity-based anorexia.

Brain region binding of the D2/3 agonist [11C]-(+)-PHNO and the D2/3 antagonist [11C]raclopride in healthy humans

The D(2) receptors exist in either the high- or low-affinity state with respect to agonists, and while agonists bind preferentially to the high-affinity state, antagonists do not distinguish between the two states. [(11)C]-(+)-PHNO is a PET D(2) agonist radioligand and therefore provides a preferential measure of the D(2) (high) receptors. In contrast, [(11)C]raclopride is an antagonist radioligand and thus binds with equal affinity to the D(2) high- and low-affinity states. The aim was to compare the brain uptake, distribution and binding characteristics between [(11)C]-(+)-PHNO and [(11)C]raclopride in volunteers using a within-subject design. Both radioligands accumulated in brain areas rich in D(2)/D(3)-receptors. However, [(11)C]-(+)-PHNO showed preferential uptake in the ventral striatum and globus pallidus, while [(11)C]raclopride showed preferential uptake in the dorsal striatum. Mean binding potentials were higher in the putamen (4.3 vs. 2.8) and caudate (3.4 vs 2.1) for [(11)C]raclopride, equal in the ventral-striatum (3.4 vs. 3.3), and higher in the globus pallidus for [(11)C]-(+)-PHNO (1.8 vs. 3.3). Moreover [(11)C]-(+)-PHNO kinetics in the globus pallidus showed a slower washout than other regions. One explanation for the preferential binding of [(11)C]-(+)-PHNO in the globus pallidus and ventral-striatum could be the presence of a greater proportion of high- vs. low-affinity receptors in these areas. Alternatively, the observed distribution could also be explained by a preferential binding of D(3)-over-D(2) with [(11)C]-(+)-PHNO. This differential binding of agonist vs. antagonist radioligand, especially in the critically important region of the limbic striatum/pallidum, offers new avenues to investigate the role of the dopamine system in health and disease.

Influence of overanxious disorder of childhood on the expression of anorexia nervosa

OBJECTIVE

Childhood anxiety often precedes the onset of anorexia nervosa (AN) and may mark a liability to the emergence of an eating disorder for some women. This study investigates the prevalence of overanxious disorder (OAD) among women with AN and explores how OAD impacts AN symptoms and personality traits.

METHOD

Participants were 637 women with AN who completed an eating disorders history, the Structured Clinical Interview for DSM-IV Axis I Disorders, and assessments for childhood anxiety, eating disorder attitudes, and associated personality traits.

RESULTS

Of 249 women (39.1%) reporting a history of OAD, 235 (94.4%) met criteria for OAD before meeting criteria for AN. In comparison to those without OAD, women with AN and OAD self-reported more extreme personality traits and attitudes and they engaged in more compensatory behaviors.

CONCLUSION

Among individuals with AN, those entering AN on a pathway via OAD present with more severe eating disorder pathology.

Neurobiology of anorexia and bulimia nervosa

Anorexia nervosa (AN) and bulimia nervosa (BN) are related disorders of unknown etiology that most commonly begin during adolescence in women. AN and BN have unique and puzzling symptoms, such as restricted eating or binge-purge behaviors, body image distortions, denial of emaciation, and resistance to treatment. These are often chronic and relapsing disorders, and AN has the highest death rate of any psychiatric disorder. The lack of understanding of the pathogenesis of this illness has hindered the development of effective interventions, particularly for AN. Individuals with AN and BN are consistently characterized by perfectionism, obsessive-compulsiveness, and dysphoric mood. Individuals with AN tend to have high constraint, constriction of affect and emotional expressiveness, ahendonia and asceticism, whereas individuals with BN tend to be more impulsive and sensation seeking. Such symptoms often begin in childhood, before the onset of an eating disorder, and persist after recovery, suggesting they are traits that create a vulnerability for developing an ED. There is growing acknowledgement that neurobiological vulnerabilities make a substantial contribution to the pathogenesis of AN and BN. Considerable evidence suggests that altered brain serotonin (5-HT) function contributes to dysregulation of appetite, mood, and impulse control in AN and BN. Brain imaging studies, using 5-HT specific ligands, show that disturbances of 5-HT function occur when people are ill, and persist after recovery from AN and BN. It is possible that a trait-related disturbance of 5-HT neuronal modulation predates the onset of AN and contributes to premorbid symptoms of anxiety, obsessionality, and inhibition. This dysphoric temperament may involve an inherent dysregulation of emotional and reward pathways which also mediate the hedonic aspects of feeding, thus making these individuals vulnerable to disturbed appetitive behaviors. Restricting food intake may become powerfully reinforcing because it provides a temporary respite from dysphoric mood. Several factors may act on these vulnerabilities to cause AN to start in adolescence. First, puberty-related female gonadal steroids or age-related changes may exacerbate 5-HT dysregulation. Second, stress and/or cultural and societal pressures may contribute by increasing anxious and obsessional temperament. Individuals with AN may discover that reduced dietary intake, by reducing plasma tryptophan availability, is a means by which they can modulate brain 5-HT functional activity and anxious mood. People with AN enter a vicious cycle which accounts for the chronicity of this disorder because caloric restriction results in a brief respite from dysphoric mood. However, malnutrition and weight loss, in turn, produce alterations in many neuropeptides and monoamine function, perhaps in the service of conserving energy, but which also exaggerates dysphoric mood. In summary, this article reviews findings in brain chemistry and neuroimaging that shed new light on understanding the psychopathology of these difficult and frustrating disorders.

Leptin's effect on hyperactivity: potential downstream effector mechanisms

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

Psychopathological and nutritional correlates of plasma homovanillic acid in adolescents with anorexia nervosa

Dopaminergic abnormalities have been described in anorexia nervosa but studies about plasma level of homovanillic acid (pHVA) have yielded conflicting results probably due to the small number and the heterogeneity of patients. Plasma HVA, nutritional and hormonal parameters and several scales - the Eating Attitudes Test (EAT), the Beck Depression Inventory (BDI), the Leyton Obsessional Inventory-child version (LOI-C) and the State and Trait Anxiety Inventory (STAI) - were assessed in 44 adolescent anorexia nervosa patients (mean age 14.7 years, SD 1.7) consecutively admitted to an Eating Disorder Unit. They were evaluated at admission, at discharge and, in 34 cases, after 9 months of follow-up. pHVA was also assessed in 16 control adolescents. Patients had significantly higher pHVA than controls (p = .002). About 31% of patients had a very high level of pHVA, a significantly higher (p = .006) mean score in the BDI and a non significantly higher mean score in the EAT. After weight recovery some laboratory parameters improved as well as the EAT (p = .019), the BDI (p = 001) and the Interference score of the LOI-C (p = .004). Moreover, pHVA decreased significantly (p=.036). At follow-up, patients with normal weight had lower (p = .037) pHVA than patients with low weight. The conclusion would be that there is a dopaminergic dysfunction in anorexic patients, specially in a subgroup with high depressive and anorexic symptomatology. With weight recovery and psychopathological improvement, pHVA tends to normalization.

Altered insula response to taste stimuli in individuals recovered from restricting-type anorexia nervosa

Anorexia nervosa (AN) is an illness characterized by aversion to ingestion of normally palatable foods. We examined whether there is a primary disturbance of taste processing and experience of pleasure using a sucrose/water task in conjunction with functional magnetic resonance imaging (fMRI). To avoid confounding effects of illness, 16 women recovered from restricting-type AN were compared to 16 control women (CW). We used a region of interest-based fMRI approach to test the idea that individuals with AN have differential neural activation in primary and secondary taste cortical regions after sucrose and water administration. Compared to CW, individuals recovered from AN showed a significantly lower neural activation of the insula, including the primary cortical taste region, and ventral and dorsal striatum to both sucrose and water. In addition, insular neural activity correlated with pleasantness ratings for sucrose in CW, but not in AN subjects. Altered taste processing may occur in AN, based on differences in activity in insular-striatal circuits. These data provide the first evidence that individuals with AN process taste stimuli differently than controls, based on differences in neural activation patterns.

Food restriction markedly increases dopamine D2 receptor (D2R) in a rat model of obesity as assessed with in-vivo muPET imaging ([11C] raclopride) and in-vitro ([3H] spiperone) autoradiography

INTRODUCTION

Dopamine (DA) regulates food intake by modulating food reward and motivation but its involvement in obesity is much less understood. Recent evidence points to the involvement of leptin in the DA-related modulation of food intake. Here we assess DA D2 receptors (D2R) in a genetic rodent obesity model characterized by leptin-receptor deficiency and assess the influence of food restriction on these receptors.

METHODS

We compared D2R levels between Zucker Obese (fa/fa) and Lean (Fa/Fa) rats at 1 and 4 months of age and in two different feeding conditions (restricted and unrestricted food access) using in-vivo muPET imaging ([11C] raclopride, which is a method sensitive to competition with endogenous DA) and in-vitro ([3H] spiperone washed to ensure no competition with endogenous DA) autoradiography (ARG).

RESULTS

Both ARG and muPET showed that D2R were higher at 1 month than at 4 months of age and that food restricted animals had higher D2R than unrestricted animals. However there were significant differences in the results obtained at 4 months between ARG and muPET. ARG showed that at 1 month and at 4 months unrestricted lean rats (Le U) had significantly higher D2R binding than obese unrestricted rats (Ob U) but showed no differences between restricted obese (Ob R) and restricted lean rats (Le R). It also showed that D2R decline between 1 and 4 months of age was significantly attenuated in food restricted rats [both obese and lean]. In contrast, muPET showed that at 4 months of age, Ob U showed greater D2R availability than Le U rats but like ARG showed no differences between Ob R and Le R rats.

CONCLUSION

The lower D2R binding in Ob U than Le U rats observed with ARG most likely reflects decreases in striatal D2 receptors levels whereas the increased availability observed with muPET is likely to reflect reduced DA release (resulting in decreased competition with endogenous DA). Lack of a significant difference between Ob R and Le R suggests that the differences in dopamine activity and D2R levels between Ob and Le Zucker rats are modulated by access to food. The ARG finding of an attenuation of the age-related loss of D2R binding corroborates previous studies of the salutary effects of food restriction in the aging process. Because [11C] raclopride is sensitive to competition with endogenous DA, the higher D2R binding in obese rats with raclopride despite the lower D2R levels shown with spiperone could reflect lower extracellular DA in the Ob rats and merits further investigation.

Serotonin transporter binding after recovery from eating disorders

RATIONALE

Several lines of evidence suggest that altered serotonin (5-HT) function persists after recovery from anorexia nervosa (AN) and bulimia nervosa (BN).

OBJECTIVES

We compared 11 subjects who recovered (>1 year normal weight, regular menstrual cycles, no binging or purging) from restricting-type AN (REC RAN), 7 who recovered from bulimia-type AN (REC BAN), 9 who recovered from BN (REC BN), and 10 healthy control women (CW).

MATERIALS AND METHODS

Positron emission tomography (PET) imaging with [11C]McN5652 was used to assess the 5-HT transporter (5-HTT). For [11C]McN5652, distribution volume (DV) values were determined using a two-compartment, three-parameter tracer kinetic model, and specific binding was assessed using the binding potential (BP, BP=DVregion of interest/DVcerebellum-1).

RESULTS

After correction for multiple comparisons, the four groups showed significant (p<0.05) differences for [11C]McN5652 BP values for the dorsal raphe and antero-ventral striatum (AVS). Post-hoc analysis revealed that REC RAN had significantly increased [11C]McN5652 BP compared to REC BAN in these regions.

CONCLUSIONS

Divergent 5-HTT activity in subtypes of eating disorder subjects may provide important insights as to why these groups have differences in affective regulation and impulse control.

Central dysregulations in the control of energy homeostasis and endocrine alterations in anorexia and bulimia nervosa

In the last decades we have come to understand that the hypothalamus is a key region in controlling energy homeostasis. A number of control models have been proposed to explain the regulation of feeding behavior in physiological and pathological conditions, but all those based on imbalances of single factors fail to explain the disrupted regulation of energy supply in eating disorders such as anorexia nervosa and bulimia nervosa, as well as other psychiatric disorders. A growing amount of evidence demonstrates that many signaling molecules originated within the brain or coming from the adipose tissue or the gastro-enteric tract are involved in the highly complex process controlling food intake and energy expenditure. The recent discovery of leptin, ghrelin, and other factors have made it possible to penetrate in the still undefined pathophysiology of eating disorders with the hope of finding effective treatments for such diseases.

Neuropsychological study of underweight and "weight-recovered" anorexia nervosa compared with bulimia nervosa and normal controls

OBJECTIVE

To compare executive, memory and visuospatial functioning of DSM-IV anorexia nervosa (AN), bulimia nervosa (BN), and normal controls (NC).

METHOD

A comparison of women involving: (i) 16 AN with body mass indices (BMI) < or = 17.5 kg/m(2); (ii) 12 AN with BMI > 18.5 kg/m(2) for at least 3 months; (iii) 13 BN; and (iv) 16 NC participants was performed with groups of similar age and intelligence. Groups were assessed with EDE-12, MADRS, HAMA, Cognitive Drug Research (CDR) battery, and Bechara tasks.

RESULTS

Significant impairments in CDR Power of Attention were present in underweight AN and BN participants. CDR Morse Tapping was significantly impaired in all clinical groups. The BN and weight-recovered AN groups were significantly impaired on CDR immediate word recall. The BN group alone was significantly impaired on CDR delayed word recall.

CONCLUSION

Attentional impairment is similar in AN and BN. Impaired motor tasks in AN persist after "weight-recovery" and are similar to impairments in BN. BN may be discriminated from AN on word recall.

Regional cerebral blood flow after recovery from anorexia or bulimia nervosa

OBJECTIVE

Abnormalities of regional cerebral blood flow (rCBF) have been found in individuals who are ill with anorexia (AN) or bulimia nervosa (BN). Little is known about whether rCBF normalizes after recovery from AN and BN.

METHOD

Eighteen control women (CW), 10 recovered restricting type AN, 8 recovered AN with a binging history, and 9 recovered BN participants without a history of AN were studied using positron emission tomography and [(15)O]water in order to assess rCBF.

RESULTS

Partial volume corrected rCBF values in cortical and subcortical brain regions were similar between groups. Neither current body mass index nor age correlated with rCBF values.

CONCLUSION

The results from this study indicate that rCBF normalizes with long-term recovery. Thus, altered rCBF is unlikely to confound functional imaging studies in AN or BN after recovery.

Altered dopamine D2 receptor function and binding in obese OLETF rat

A decrease in D2-like receptor (D2R) binding in the striatum has been reported in obese individuals and drug addicts. Although natural and drug rewards share neural substrates, it is not clear whether such effects also contribute to overeating on palatable meals as an antecedent of dietary obesity. Therefore, we investigated receptor density and the effect of the D2R agonist quinpirole (0.05, 0.5 mg/kg, S.C.) on locomotor activity and sucrose intake in a rat model of diet-induced obesity, the CCK-1 receptor-deficient Otsuka Long Evans Tokushima Fatty (OLETF) rat. Compared to age-matched lean controls (LETO), OLETF rats expressed significantly lower [125I]-iodosulpride binding in the accumbens shell (-16%, p<0.02). Whereas the high dose of quinpirole increased motor activity in both strains equally, the low dose reduced activity more in OLETF. Both doses significantly reduced sucrose intake in OLETF but not LETO rats. These findings demonstrate an altered D2R signaling in obese OLETF rats similar to drug-induced sensitization and suggest a link between this effect and avidity for sucrose in this model.

Dopamine D2 receptors contribute to increased avidity for sucrose in obese rats lacking CCK-1 receptors

Accumulating evidence has indicated a link between dopamine signaling and obesity in both animals and humans. We have recently demonstrated heightened avidity to sapid sweet solutions in the obese cholecystokinin (CCK)-1 receptor deficient Otsuka Long Evans Tokushima fatty (OLETF) rat. To investigate the dopamine dependence and the respective contribution of D1 and D2 receptor subtypes in this phenomenon, real and sham intake of 0.3 M sucrose solution was compared between prediabetic, obese OLETF and age-matched lean Long-Evans Tokushima Otsuka (LETO) cohorts following peripheral (i.p.) administration of equimolar doses (50-800 nmol/kg) of the D1 (R-(+) 7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine, SCH23390) and D2 (raclopride) selective receptor antagonists. Both antagonists were potent in reducing sucrose intake in both strains with both drugs suppressing sham intake starting at lower doses than real intake (200 nmol/kg vs. 400 nmol/kg for SCH23390, and 400 nmol/kg vs. 600 nmol/kg for raclopride, respectively). Furthermore, when percent suppression of intake, a measure that controlled for the higher baseline sucrose intake by obese rats was analyzed, OLETF rats expressed an increased sensitivity to raclopride in reducing ingestion of sucrose with a 1.7- and 2.9-fold lower inhibitory dose threshold (ID50) for real and sham intake conditions, respectively, compared with LETO controls. In contrast, SCH23390 caused no differential strain effect with respect to dosage whether sucrose was real or sham fed. These findings demonstrate that D2 receptors are involved in heightened increased consumption of sucrose observed in the OLETF obese rat.

Olanzapine therapy in anorexia nervosa: psychobiological effects

Dopamine impairments occur in anorexia nervosa. The aim of this study was to see whether treatment with the atypical dopamine antagonist antipsychotic olanzapine improves the disorder. Thirty anorexics, 18 restricted and 12 bingeing-purging, underwent a 3-month course of cognitive behavioral therapy, plus at random and double-blinded oral olanzapine (2.5 mg for 1 month, 5 mg for 2 months) in half and oral placebo in the other half of them. BMI, psychopathological aspects (eating disorder inventory, Hamilton Rating Scale, Buss-Durkee Rating Scale, Yale Brown Cornell for Eating Disorders Rating Scale, temperament-character inventory), and homovanillic acid blood concentrations for dopamine secretion, were monitored at baseline and then monthly during the trial. At the end of the trial BMI, total eating disorder inventory, total Yale Brown Cornell for Eating Disorders Rating Scale, Buss-Durkee Rating Scale, Hamilton Rating Scale scores and in olanzapine-treated patients the subitems of eating disorder inventory ineffectiveness and maturity fear, of Buss-Durkee Rating Scale direct aggressiveness, of temperament-characteristic inventory persistence had improved significantly. When stratified for anorexia nervosa subtype, BMI changes were significant among anorexia nervosa bingeing-purging patient, 'depression' (Hamilton Rating Scale) and 'direct aggressiveness' (Buss-Durkee Rating Scale) among anorexia nervosa bingeing-purging patients, 'persistence' (temprerament-characteristic inventory), among anorexics restricted patients, with a trend toward significance for obsessivity-compulsivity (Yale Brown Cornell for Eating Disorders Rating Scale). homovanilic acid blood levels increased significantly in the cognitive behavioral therapy+olanzapine group. No correlations were observed between homovanilic acid concentrations and psychopathological parameters. The pharmacological treatment can significantly improve specific aspects of anorexia nervosa.

Getting beneath the phenotype of anorexia nervosa: the search for viable endophenotypes and genotypes

Treatment for anorexia nervosa has changed little from that described by Gull over a century ago. To focus merely on symptomatic relief from "not eating," as occurs with some forms of hospital care, is primitive. The evidence base to guide treatment is thin. Nevertheless, there is hope that better understanding of the causes and maintaining factors may translate into more sophisticated treatments. This review aims to look beyond the overt and startling "not eating" phenotype of anorexia nervosa and consider eating disorder endophenotypes. The first part of the review sets the eating behaviour, clinical, and psychopathological features into the context of what is now understood about the central control of appetite. The evidence base for a framework of potential eating disorder endophenotypes follows. Finally, ideas about how to translate endophenotypes into treatment are introduced.

Effects of intravenous glucose on dopaminergic function in the human brain in vivo

Dopamine is known to regulate food intake by modulating food reward via the mesolimbic circuitry of the brain. The objective of this study was to compare the effects of high energy input (i.v. glucose) on striatal and thalamic dopamine release in overweight and lean individuals. We hypothesized that glucose would induce dopamine release and positive ratings (e.g., satiety) in Behavioral Analog Scales, particularly in food-deprived lean subjects. [(11)C]raclopride PET was performed for 12 lean (mean BMI = 22 kg/m(2)) and 12 overweight (mean BMI = 33 kg/m(2)) healthy subjects. Each subject was imaged twice in a blinded counter-balanced setting, after 300 mg/kg i.v. glucose and after i.v. placebo. Dopamine D2 receptor binding potentials (BPs) were estimated. The voxel-based analysis of the baseline scans indicated lower striatal BPs in the overweight group and a negative correlation between BMIs and BPs. Intravenous glucose did not have a significant effect on BPs in overweight or lean subjects (male and female groups combined). However, BP changes were opposite in the two gender groups. In male subjects, significant BP reductions after glucose were seen in the right and left caudate nucleus, left putamen, and right thalamus. In female subjects, increases in BP secondary to glucose were seen in the right caudate nucleus and right and left putamen. The sexually dimorphic effect of glucose was seen in both overweight and lean subjects. Although gender differences were not among the a priori hypotheses of the present study and, therefore, they must be considered to be preliminary findings, we postulate that this observation is a reflection of an interaction between glucose, sex steroids (estrogen), leptin, and dopamine.

Motor- and food-related metabolic cerebral changes in the activity-based rat model for anorexia nervosa: a voxel-based microPET study

Anorexia nervosa (AN) is a disorder that is difficult to treat with psycho- or pharmacotherapy. In order to identify involved neurocircuitry, we investigated the cerebral metabolic alterations in the activity-based anorexia (ABA) rat model, where restriction of the food intake period induces hyperactivity and decreased body weight. Cerebral (18)F-fluorodeoxyglucose uptake was investigated in rats in the activity-based anorexia model (n=9) and compared to controls (n=10), using a CTI Focus microPET 220. Regional metabolic changes were investigated using statistical parametric mapping (SPM2) and correlated to weight and hyperactivity measures on a voxel-by-voxel basis. Higher regional metabolism was found in ABA rats in the mediodorsal thalamus, ventral pontine nuclei and cerebellum, while hypometabolism was seen in the left rhinal and bilateral insular cortex, and bilateral ventral striatum (p<0.001). A positive correlation was observed between body weight loss and brain metabolism in the cingulate cortex and surrounding motor and somatosensory cortex (p<0.001). Thus, in the ABA model metabolic changes are present in brain areas related to disease status and weight loss, which share several characteristics with the human disease.

Set shifting deficit in anorexia nervosa

Anorexia nervosa (AN) is a severe mental illness characterized in part by rigid thinking and ritualized behaviors involving eating and weight. Cognitive rigidity may play a role in the perpetuation of symptoms, and may provide information as to important brain-based abnormalities. Neuropsychological studies of patients with AN have shown cognitive dysfunction, but few have focused on cognitive flexibility. This study assessed set shifting in patients with AN, as a measure of cognitive flexibility. In this study, 15 patients with AN were compared with 11 healthy controls using a neuropsychological battery including the Wisconsin Card Sort Test (WCST). While patients with AN did not differ from controls on 5 measures of neuropsychological function, they made significantly more perseverative errors on the WCST, indicating a problem in set shifting. This finding suggests that patients with AN have a specific neurocognitive abnormality that may play a role in the development and persistence of this disorder.

Positron emission tomography studies in eating disorders: multireceptor brain imaging, correlates with behavior and implications for pharmacotherapy

Modern imaging techniques that visualize disease-specific organ neurotransmitter or protein receptor sites are increasingly able to define pathological processes on a molecular level. One of those imaging modalities, positron emission tomography (PET), for the assessment of brain neuroreceptor binding has revolutionized the in vivo assessment of biologic markers that may be related to human behavior. Such studies may help identify chemical targets that may be directly related to psychiatric pathology and, thus, opportunities for pharmacological intervention. In this review, we describe results from PET studies in eating disorders (EDs). Eating disorders are frequently debilitating illnesses that are quite homogeneous in their presentation. Those studies that identified particular serotonin and dopamine receptor alterations can distinguish recovered ED subjects from controls as well as ED subgroups. Furthermore, correlations of receptor binding with behavioral constructs, such as harm avoidance or novelty seeking, could be found. These recognized receptors may now help us to move away from rather nonspecific treatment approaches in psychiatric research and clinic to the possibility of more syndrome- and symptom-specific treatment approaches.

Association of multiple DRD2 polymorphisms with anorexia nervosa

To investigate whether the dopaminergic system plays a role in the etiology of anorexia nervosa (AN) via the dopamine D2 receptor, we investigated association and transmission disequilibrium at seven single-nucleotide polymorphisms (SNPs) spanning about 75 kbp of the gene DRD2. We studied 191 probands with a DSM-IV diagnosis of AN, 457 parents and affected relatives with a DSM-IV eating disorder diagnosis, and 98 unrelated, female, normal weight controls. The -141 C/- insertion/deletion (-141 Indel), previously shown to affect DRD2 transcription efficiency, and multiple exon seven polymorphisms, one of which has previously been shown to affect DRD2 transcript stability, exhibited statistically significant association with diagnosis in haplotype transmission disequilibrium and in haplotype case : control analyses. Significant linkage disequilibrium between the -141 Indel and two exon seven SNPs (939Y and 957Y) was observed over a distance of >50 kbp in the AN probands but not in the controls. Genetically transmitted variation in D2 dopamine receptor expression mediated by functional polymorphisms affecting transcription and translation efficiency may play a role in vulnerability to AN.