Decreased cerebral opioid receptors availability related to hormonal and psychometric profile in restrictive-type anorexia nervosa

Endogenous opioid receptors and the feast or famine of maladaptive feeding

Maladaptive feeding comprises unhealthy eating patterns that jeopardize survival, including over- and underconsumption. These behaviors are often coordinated by endogenous opioid receptors (EORs). Here, we explore the involvement of EORs in obesity and anorexia nervosa (AN), two disorders associated with dysregulated feeding behavior and relevant animal models. While seemingly opposing metabo-psychiatric states, our goal is to highlight common circuit and synaptic mechanisms underlying obesity and AN with a focus on EOR functionality. We examine the neural substrates underlying maladaptive feeding and comorbid conditions including pain, suggesting a role for EOR-driven plasticity in the pathogenesis of both obesity and AN.

Circadian copeptin and oxytocin profiles in anorexia nervosa: Exploring the interplay with neurohypophysis opioid tone

CONTEXT

Neurohypophysis (NH) function in eating disorders (ED) remains poorly elucidated. Studies on vasopressin and oxytocin display inconclusive findings regarding their levels and associations with psychological complications in ED. The profile of opioid tone, a crucial NH activity regulator, is also unknown.

OBJECTIVE

To characterise the circadian profile of NH hormones and NH opioid tone using positron emission tomography/MRI (PET/MRI) imaging in patients with ED compared to healthy controls.

METHODS

Twelve-point plasma circadian profiles of copeptin and oxytocin, alongside nutritional and psychological scores, were assessed in age-matched female participants: 13 patients with anorexia nervosa restrictive-type (ANR), 12 patients recovered from AN (ANrec), 14 patients with bulimia nervosa and 12 controls. Neurohypophysis PET/MRI [11C] diprenorphin binding potential (BPND) was evaluated in AN, ANrec and controls.

RESULTS

Results revealed lower copeptin circadian levels in both ANR and ANrec compared to controls, with no oxytocin differences. Bulimia nervosa exhibited elevated copeptin and low oxytocin levels. [11C] diprenorphin pituitary binding was fully localised in NH. Anorexia nervosa restrictive-type displayed lower NH [11C] diprenorphin BPND (indicating higher opioid tone) and volume than controls. In ANR, copeptin inversely correlated with osmolarity. Neurohypophysis [11C] diprenorphin BPND did not correlated with copeptin or oxytocin.

CONCLUSION

Copeptin demonstrated significant group differences, highlighting its potential diagnostic and prognostic value. Oxytocin levels exhibited conflicting results, questioning the reliability of peripheral blood assessment. Increased NH opioid tone in anorexia nervosa may influence the vasopressin or oxytocin release, suggesting potential therapeutic applications.

Association of OPRD1 Gene Variants with Changes in Body Weight and Psychometric Indicators in Patients with Eating Disorders

Objectives: This study aimed to investigate whether genetic variations in the OPRD1 gene affect psychopathological symptoms and personality dimensions in eating disorders (ED) patients and/or contribute to ED risk. Methods: The study involved 221 female patients with anorexia nervosa (AN), 88 with bulimia nervosa (BN), and 396 controls. Sixteen tag-single nucleotide polymorphisms (SNPs) in OPRD1 were identified. Psychometric evaluations were conducted using the Symptom Checklist 90 Revised (SCL-90R) and the Eating Disorders Inventory Test-2 (EDI-2). p-values obtained by regression models were corrected for multiple testing by the False Discovery Rate (FDR) method. Results: In AN patients, genotypes rs204077TT and rs169450TT were linked to lower body-mass index (BMI) values (FDR-q = 0.035 and 0.017, respectively), as was rs2234918 in a log-additive model (BMI: 18.0 ± 0.28, 17.22 ± 0.18 and 16.59 ± 0.39 for TT, TC and CC carriers, FDR-q = 0.012). Additionally, AN patients carrying the rs72665504AA genotype had higher scores in interpersonal distrust (FDR-q = 0.030), whilst BN carriers of rs513269TT and rs2873795TT showed lower scores in ineffectiveness (FDR-q = 0.041 and FDR-q = 0.021). In the AN group, BMI correlated with variability in a distal haplotype (rs508448/rs204077/rs223491, FDR-q = 0.028), which was also associated with the global positive symptom total (PST) index of SCL-90R (FDR-q = 0.048). Associations were more noticeable in BN patients; again, the distal region of the gene was linked to EDI-2 total scores (FDR-q = 0.004-0.048 for the four last haplotypes) and two global SCL-90R indices (GSI: FDR-q = 0.011 and positive symptom distress index (PSDI): FDR-q = 0.003 for the last s204077/rs2234918/rs169450 combination). No associations with ED risk were observed. Conclusions: Genetic variation in the OPRD1 gene, particularly in its distal region, is associated with BMI and psychopathological comorbidities in ED patients.

Oxidative stress and inflammatory pathways in female eating disorders and borderline personality disorders with emotional dysregulation as linking factors with impulsivity and trauma

BACKGROUND

Borderline personality disorder (BPD) and eating disorders (ED) are both disorders with emotional dysregulation that may share some similar biological underpinnings, leading to oxidative/inflammatory alterations. Unfortunately, to date, no studies have assessed the relationship between clinical features, inflammatory alterations and childhood trauma across these disorders. Our aim was to identify the potential common and disorder-specific inflammatory pathways and examine possible associations between these dysregulated pathways and the clinical features.

METHODS

We studied a sample of 108 women (m = 27.17 years; sd = 7.64), divided into four groups: 23 patients with a restrictive ED (ED-R), 23 patients with a bingeeating/ purging ED (ED-P) and 26 patients with BPD; whereas the control group included 23 healthy subjects. Several inflammatory/oxidative parameters: tumor necrosis factor alpha (TNFα), Thiobarbituric Acid Reactive Substances (TBARS), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX2), p38 mitogenactivated protein kinases, ERK mitogen-activated protein kinases and c-Jun NH2- terminal kinase (JNK), and some antiinflammatory antioxidant elements: glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), Kelch-like ECHassociated protein (Keap1) were determined in plasma or peripheral blood mononuclear cells. Furthermore, clinical, impulsivity, trauma and eating behavior questionnaires were administered.

RESULTS

Three main inflammatory/oxidative components were extracted using principal component analysis (59.19 % of biomarker variance explained). Disorder-specific dysfunction in the inflammatory and oxidative pathways in patients with BPD and ED were revealed by means of relationships with specific principal components (p < .01). BPD patients showed higher levels of a component featured by elevated levels of JNK and lower of GPx and SOD. ED-R and impulsivity were associated with a component featured by the activation of ERK and negative influence of Keap1. The component featured by the suppression of catalase and COX2 was associated with both ED subtypes and trauma exposure.

CONCLUSION

Several risk factors such as trauma, impulsivity and eating disorder symptoms were transdiagnostically associated with some inflammatory alterations regardless of diagnosis. These findings suggest that the clinical profile comprising trauma exposure and an emotional dysregulation disorder might constitute a specific endophenotype highly linked with inflammatory alterations.

Mechanisms and predictors of menses resumption once normal weight is reached in anorexia nervosa

BACKGROUND

In cases of Anorexia Nervosa (AN), achieving weight gain recovery beyond the lower limits set by the World Health Organization and normalizing classical nutritional markers appears to be essential for most patients. However, this is not always adequate to restore menstrual cycles. This discrepancy can cause concern for both patients and healthcare providers, and can impact the medical management of these individuals. Thus, the purpose of this study was to assess the ability of anthropometric and hormonal factors to predict the resumption of menstrual cycles in individuals with anorexia nervosa upon reaching a normal body weight.

METHOD

Patients with AN who had achieved a normal Body Mass Index but had not yet resumed their menstrual cycles (referred to as ANRec) were evaluated on two occasions: first at visit 1 and then again 6 months later, provided their body weight remained stable over this period (visit 2). Among the 46 ANRec patients who reached visit 2, they were categorized into two groups: 20 with persistent amenorrhea (PA-ANRec) and 26 who had regained their menstrual cycles (RM-ANRec). Anthropometric measurements, several hormone levels, Luteinizing Hormone (LH) pulsatility over a 4-h period, and LH response to gonadotropin-releasing hormone injection (LH/GnRH) were then compared between the two groups at visit 1.

RESULTS

Patients in the RM-ANRec group exhibited higher levels of follicular stimulating hormone, estradiol, inhibin B, LH/GnRH, and lower levels of ghrelin compared to those in the PA-ANRec group. Analysis of Receiver Operating Characteristic curves indicated that having ≥ 2 LH pulses over a 4-h period, LH/GnRH levels ≥ 33 IU/l, and inhibin B levels > 63 pg/ml predicted the resumption of menstrual cycles with a high degree of specificity (87%, 100%, and 100%, respectively) and sensitivity (82%, 80%, and 79%, respectively).

CONCLUSIONS

These three hormonal tests, of which two are straightforward to perform, demonstrated a high predictive accuracy for the resumption of menstrual cycles. They could offer valuable support for the management of individuals with AN upon achieving normalized weight. Negative results from these tests could assist clinicians and patients in maintaining their efforts to attain individualized metabolic targets.

TRIAL REGISTRATION

IORG0004981.

The historical progression of positron emission tomography research in neuroendocrinology

The rapid and continual development of a number of radiopharmaceuticals targeting different receptor, enzyme and small molecule systems has fostered Positron Emission Tomography (PET) imaging of endocrine system actions in vivo in the human brain for several decades. PET radioligands have been developed to measure changes that are regulated by hormone action (e.g., glucose metabolism, cerebral blood flow, dopamine receptors) and actions within endocrine organs or glands such as steroids (e.g., glucocorticoids receptors), hormones (e.g., estrogen, insulin), and enzymes (e.g., aromatase). This systematic review is targeted to the neuroendocrinology community that may be interested in learning about positron emission tomography (PET) imaging for use in their research. Covering neuroendocrine PET research over the past half century, researchers and clinicians will be able to answer the question of where future research may benefit from the strengths of PET imaging.

Enkephalin-δ Opioid Receptor Signaling Mediates Glucoprivic Suppression of LH Pulse and Gluconeogenesis in Female Rats

Energy availability is an important regulator of reproductive function at various reproductive phases in mammals. Glucoprivation induced by 2-deoxy-D-glucose (2DG), an inhibitor of glucose utilization, as an experimental model of malnutrition suppresses the pulsatile release of GnRH/LH and induces gluconeogenesis. The present study was performed with the aim of examining whether enkephalin-δ-opioid receptor (DOR) signaling mediates the suppression of pulsatile GnRH/LH release and gluconeogenesis during malnutrition. The administration of naltrindole hydrochloride (NTI), a selective DOR antagonist, into the third ventricle blocked the suppression of LH pulses and part of gluconeogenesis induced by IV 2DG administration in ovariectomized rats treated with a negative feedback level of estradiol-17 β (OVX + low E2). The IV 2DG administration significantly increased the number of Penk (enkephalin gene)-positive cells coexpressing fos (neuronal activation marker gene) in the paraventricular nucleus (PVN), but not in the arcuate nucleus (ARC) in OVX + low E2 rats. Furthermore, double in situ hybridization for Penk/Pdyn (dynorphin gene) in the PVN revealed that approximately 35% of the PVN Penk-expressing cells coexpressed Pdyn. Double in situ hybridization for Penk/Crh (corticotropin-releasing hormone gene) in the PVN and Penk/Kiss1 (kisspeptin gene) in the ARC revealed that few Penk-expressing cells coexpressed Crh and Kiss1. Taken together, these results suggest that central enkephalin-DOR signaling mediates the suppression of pulsatile LH release during malnutrition. Moreover, the current study suggests that central enkephalin-DOR signaling is also involved in gluconeogenesis during malnutrition in female rats.

Anhedonia in Eating Disorders

Anhedonia is frequently observed among individuals with eating disorders (ED), though its relevance to ED pathology and clinical outcomes remain poorly understood. This chapter will present the latest findings regarding anhedonia in ED, with the majority of data available for anorexia nervosa (AN) and bulimia nervosa (BN). We consider anhedonia from the mechanistic lens of altered reward processing, with attention given to subjective experience, neurotransmitter function, neural correlates, and cognitive performance corresponding to distinct components of reward (i.e., liking, wanting, and learning). Findings from animal models are also highlighted. The chapter concludes with a discussion of implications for treatment and future directions aimed at better understanding anhedonia in ED.

Evaluation of Specific Binding of [11C]RTI-97 to Kappa Opioid Receptor by Autoradiography and PET Imaging in Rat

Kappa opioid receptor (KOR) PET imaging remains attractive to understand the role of KOR in health and diseases and to help the development of drugs especially for psychiatric disorders such as depression, anxiety, and addiction. The potent and selective KOR antagonist RTI-97 labeled with carbon-11 was previously demonstrated to display specific KOR binding in mouse brain by ex vivo autoradiography studies. Herein, we evaluated [¹¹C]RTI-97 in rat by in vitro autoradiography and by in vivo PET imaging. The radiosynthesis of [¹¹C]RTI-97 was optimized to obtain high molar activities. Despite a low cerebral uptake, the overall results showed a heterogeneous repartition and specific KOR binding of [¹¹C]RTI-97 in brain and a high and specific accumulation of [¹¹C]RTI-97 in pituitary in accordance with KOR expression.

A highly reproducible method for the measurement of [6-O-methyl-11 C]diprenorphine and its radio-metabolites based on solid-phase extraction and radio-high-pressure liquid chromatography

Described here is a method for the measurement of the radio-metabolites of the positron emission tomography radiotracer [6-O-methyl-11 C]diprenorphine ([11 C]diprenorphine) using in-line solid-phase extraction (SPE) combined with radio-high-pressure liquid chromatography analysis. We believe that this method offers a reliable and reproducible approach to [11 C]diprenorphine metabolite analysis. In addition, different SPE stationary phases are assessed for their efficiency for loading, retention and elution of the parent molecule and its metabolites. Having assessed C4, phenyl and C18 stationary phase, we concluded that a C18 SPE was optimal for our method. Finally, in silico predictions of diprenorphine metabolism were compared with in vivo metabolism of [11 C]diprenorphine induced by hepatic microsomal digestion and analysed by matrix-assisted laser desorption/ionisation mass spectrometry. It was found that there was a high degree of agreement between the two methods and in particular the formation of the diprenorphine-3-glucuronide metabolite.