Genome-wide association study identifies eight risk loci and implicates metabo-psychiatric origins for anorexia nervosa

Characterized primarily by a low body-mass index, anorexia nervosa is a complex and serious illness(1), affecting 0.9-4% of women and 0.3% of men(2-4), with twin-based heritability estimates of 50-60%(5). Mortality rates are higher than those in other psychiatric disorders(6), and outcomes are unacceptably poor(7). Here we combine data from the Anorexia Nervosa Genetics Initiative (ANGI)(8,9) and the Eating Disorders Working Group of the Psychiatric Genomics Consortium (PGC-ED) and conduct a genome-wide association study of 16,992 cases of anorexia nervosa and 55,525 controls, identifying eight significant loci. The genetic architecture of anorexia nervosa mirrors its clinical presentation, showing significant genetic correlations with psychiatric disorders, physical activity, and metabolic (including glycemic), lipid and anthropometric traits, independent of the effects of common variants associated with body-mass index. These results further encourage a reconceptualization of anorexia nervosa as a metabo-psychiatric disorder. Elucidating the metabolic component is a critical direction for future research, and paying attention to both psychiatric and metabolic components may be key to improving outcomes.</p

Multisensory cortical processing and dysfunction across the neuropsychiatric spectrum

Sensory processing is affected in multiple neuropsychiatric disorders like schizophrenia and autism spectrum disorders. Genetic and environmental factors guide the formation and fine-tuning of brain circuitry necessary to receive, organize, and respond to sensory input in order to behave in a meaningful and consistent manner. During certain developmental stages the brain is sensitive to intrinsic and external factors. For example, disturbed expression levels of certain risk genes during critical neurodevelopmental periods may lead to exaggerated brain plasticity processes within the sensory circuits, and sensory stimulation immediately after birth contributes to fine-tuning of these circuits. Here, the neurodevelopmental trajectory of sensory circuit development will be described and related to some example risk gene mutations that are found in neuropsychiatric disorders. Subsequently, the flow of sensory information through these circuits and the relationship to synaptic plasticity will be described. Research focusing on the combined analyses of neural circuit development and functioning are necessary to expand our understanding of sensory processing and behavioral deficits that are relevant across the neuropsychiatric spectrum

Histamine H3 receptor antagonism modulates autism-like hyperactivity but not repetitive behaviors in BTBR T+Itpr3tf/J inbred mice

Background: Autism spectrum disorders (ASDs) are a group of neurodevelopmental conditions defined by behavioral deficits in social communication and interactions, mental inflexibility and repetitive behaviors. Converging evidence from observational and preclinical studies suggest that excessive repetitive behaviors in people with ASD may be due to elevated histaminergic H3 receptor signaling in the striatum. We hypothesized that systemic administration of pharmacological histamine H3 receptor antagonists would attenuate the expression of repetitive behaviors in the BTBR T+Itpr3tf/J (BTBR) mouse inbred strain, an established mouse model presenting autism-like repetitive behaviors and novelty-induced hyperactivity. We further aimed to investigate whether agonism of the histamine H3 receptor would be sufficient to induce repetitive behaviors in the C57BL/6J control mouse strain. Methods: Different doses of H3 receptor agonists (i.e., (R)-α-methylhistamine and immethridine) and H3 receptor antagonists/inverse agonists (i.e., ciproxifan and pitolisant) were administered via intraperitoneal (i.p.) injection in male mice to characterize the acute effects of these compounds on ASD-related behavioral readouts. Results: The highly selective H3 receptor agonist immethridine significantly increased the time spent in stereo-typic patterns in C57BL/6J mice, but this effect appeared to be driven by general sedative properties of the compound. High doses of pitolisant significantly decreased locomotor hyperactivity in novel environments in BTBR mice, without significant effects on repetitive behaviors. Conclusions: Based on our findings, we conclude that acute H3 receptor manipulation mainly affected general motor activity levels in novel environments. Small changes in stereotyped behaviors were observed but appeared to be driven by altered general activity levels

Heterogeneity of cell surface glutamate and GABA receptor expression in Shank and CNTN4 autism mouse models

Autism spectrum disorder (ASD) refers to a large set of neurodevelopmental disorders, which have in common both repetitive behavior and abnormalities in social interactions and communication. Interestingly, most forms of ASD have a strong genetic contribution. However, the molecular underpinnings of this disorder remain elusive. The SHANK3 gene (and to a lesser degree SHANK2) which encode for the postsynaptic density (PSD) proteins SHANK3/SHANK2 and the CONTACTIN 4 gene which encodes for the neuronal glycoprotein CONTACTIN4 (CNTN4) exhibit mutated variants which are associated with ASD. Like many of the other genes associated with ASD, both SHANKs and CNTN4 affect synapse formation and function and are therefore related to the proper development and signaling capability of excitatory and inhibitory neuronal networks in the adult mammal brain. In this study we used mutant/knock-out mice of Shank2 (Shank2-/-), Shank3 (Shank3αβ-/-), and Cntn4 (Cntn4-/-) as ASD-models to explore whether these mice share a molecular signature in glutamatergic and GABAergic synaptic transmission in ASD-related brain regions. Using a biotinylation assay and subsequent western blotting we focused our analysis on cell surface expression of classical several ionotropic glutamate and GABA receptor subunits: GluA1, GluA2, and NR1GluN1 were analyzed for excitatory synaptic transmission, and the α1 subunit of the GABAA receptor was analyzed for inhibitory synaptic transmission. We found that both Shank2-/- and Shank3αβ-/- mice exhibit reduced levels of several cell surface glutamate receptors in most of the analyzed brain regions – especially in the striatum and thalamus – when compared to wildtype controls. Interestingly, even though Cntn4-/- mice also show reduced levels of some cell surface glutamate receptors in the cortex and hippocampus, increased levels of cell surface glutamate receptors were found in the striatum. Moreover, Cntn4-/- mice do not only show brain region-specific alterations in cell surface glutamate receptors but also a downregulation of cell surface GABA receptors in several of the analyzed brain regions. The results of this study suggest that even though mutations in defined genes can be associated with ASD this does not necessarily result in a common molecular phenotype in surface expression of glutamatergic and GABAergic receptor subunits in defined brain regions

Behavioral, physiological, and molecular differences in response to dietary restriction in three inbred mouse strains

, physiological, and molecular differences in response to dietary restriction in three inbred mouse strains. Am J Physiol Endocrinol Metab 291: E574 -E581, 2006. First published May 2, 2006; doi:10.1152/ajpendo.00068.2006.-Food restriction paradigms are widely used in animal studies to investigate systems involved in energy regulation. We have observed behavioral, physiological, and molecular differences in response to food restriction in three inbred mouse strains, C57BL/6J, A/J, and DBA/2J. These are the progenitors of chromosome substitution and recombinant inbred mouse strains used for mapping complex traits. DBA/2J and A/J mice increased their locomotor activity during food restriction, and both displayed a decrease in body temperature, but the decrease was significantly larger in DBA/2J compared with A/J mice. C57BL/6J mice did not increase their locomotor activity and displayed a large decrease in their body temperature. The large decline in body temperature during food restriction in DBA/2J and C57BL/6J strains was associated with a robust reduction in plasma leptin levels. DBA/2J mice showed a marked decrease in white and brown adipose tissue masses and an upregulation of the antithermogenic hypothalamic neuropeptide Y Y1 receptor. In contrast, A/J mice showed a reduction in body temperature to a lesser extent that may be explained by downregulation of the thermogenic melanocortin 3 receptor and by behavioral thermoregulation as a consequence of their increased locomotor activity. These data indicate that genetic background is an important parameter in controlling an animal&apos;s adaptation strategy in response to food restriction. Therefore, mouse genetic mapping populations based on these progenitor lines are highly valuable for investigating mechanisms underlying strain-dependent differences in behavioral physiology that are seen during reduced food availability. locomotor activity; body temperature; food intake; neuropeptide Y; melanocortin ENERGY BALANCE is regulated by processes that influence food intake and energy expenditure. The main components of energy expenditure are metabolism and thermogenesis induced by exercise, cold, and diet, and these are regulated by the interaction of behavioral, physiological, and molecular mechanisms. Imbalances in energy state can result in health problems, such as malnutrition, eating disorders, or obesity Food restriction paradigms are widely used in animal studies to investigate mechanisms involved in the regulation of energy balance Behavioral thermoregulation is one of the mechanisms by which endothermic animals achieve and maintain a stable body temperature during times of food shortage In addition to behavioral thermogenesis, endothermic animals use autonomic mechanisms to regulate their core temperature (47). For example, brown adipose tissue (BAT)-mediated nonshivering thermogenesis is involved in heat production when animals are exposed to cold. Mitochondrial uncoupling proteins (UCPs) in the BAT generate heat by uncoupling oxidative phosphorylation, and, in mice, targeted inactivation of the gene coding for UCP1 leads to cold sensitivity (13). Leptin increases the thermogenesis in BAT by increasing UCP1 expression (48); therefore, decreased heat production resulting from hypoleptinemia could be associated with the increased locomotor activity seen in some inbred mice strains and rats in response to restricted feeding. Leptin&apos;s effects on the hypothalamic neuropeptide Y (NPY) and melanocortin systems have been implicated in the regulation of energy balance (56, 59). For example, selective NPY Y 1 and Y 5 receptor agonists increase food consumption and decrease circulating levels of thyroid hormones, showing that both receptors mediate the stimulatory effects of NPY on foo

The effects of social environment on AD-related pathology in hAPP-J20 mice and tau-P301L mice

In humans, social factors (e.g., loneliness) have been linked to the risk of developing Alzheimer's Disease (AD). To date, AD pathology is primarily characterized by amyloid-β plaques and tau tangles. We aimed to assess the effect of single- and group-housing on AD-related pathology in a mouse model for amyloid pathology (J20, and WT controls) and a mouse model for tau pathology (P301L) with and without seeding of synthetic human tau fragments (K18). Female mice were either single housed (SH) or group housed (GH) from the age of 6-7 weeks onwards. In 12-week-old P301L mice, tau pathology was induced through seeding by injecting K18 into the dorsal hippocampus (P301L K18), while control mice received a PBS injection (P301L PBS). P301L mice were sacrificed at 4 months of age and J20 mice at 10 months of age. In all mice brain pathology was histologically assessed by examining microglia, the CA1 pyramidal cell layer and specific AD pathology: analysis of plaques in J20 mice and tau hyperphosphorylation in P301L mice. Contrary to our expectation, SH-J20 mice interestingly displayed fewer plaques in the hippocampus compared to GH-J20 mice. However, housing did not affect tau hyperphosphorylation at Ser202/Thr205 of P301L mice, nor neuronal cell death in the CA1 region in any of the mice. The number of microglia was increased by the J20 genotype, and their activation (based on cell body to cell size ratio) in the CA1 was affected by genotype and housing condition (interaction effect). Single housing of P301L mice was linked to the development of stereotypic behavior (i.e. somersaulting and circling behavior). In P301L K18 mice, an increased number of microglia were observed, among which were rod microglia. Taken together, our findings point to a significant effect of social housing conditions on amyloid plaques and microglia in J20 mice and on the development of stereotypic behavior in P301L mice, indicating that the social environment can modulate AD-related pathology. </p

Models and methods: a perspective of the impact of six IMI translational data-centric initiatives for Alzheimer’s disease and other neuropsychiatric disorders

The Innovative Medicines Initiative (IMI), was a European public–private partnership (PPP) undertaking intended to improve the drug development process, facilitate biomarker development, accelerate clinical trial timelines, improve success rates, and generally increase the competitiveness of European pharmaceutical sector research. Through the IMI, pharmaceutical research interests and the research agenda of the EU are supported by academic partnership and financed by both the pharmaceutical companies and public funds. Since its inception, the IMI has funded dozens of research partnerships focused on solving the core problems that have consistently obstructed the translation of research into clinical success. In this post-mortem review paper, we focus on six research initiatives that tackled foundational challenges of this nature: Aetionomy, EMIF, EPAD, EQIPD, eTRIKS, and PRISM. Several of these initiatives focused on neurodegenerative diseases; we therefore discuss the state of neurodegenerative research both at the start of the IMI and now, and the contributions that IMI partnerships made to progress in the field. Many of the initiatives we review had goals including, but not limited to, the establishment of translational, data-centric initiatives and the implementation of trans-diagnostic approaches that move beyond the candidate disease approach to assess symptom etiology without bias, challenging the construct of disease diagnosis. We discuss the successes of these initiatives, the challenges faced, and the merits and shortcomings of the IMI approach with participating senior scientists for each. Here, we distill their perspectives on the lessons learned, with an aim to positively impact funding policy and approaches in the future

Cross-site reproducibility of social deficits in group-housed BTBR mice using automated longitudinal behavioural monitoring

Social withdrawal is associated with a variety of neuropsychiatric disorders, including neurodevelopmental disorders. Rodent studies provide the opportunity to study neurobiological mechanisms underlying social withdrawal, however, homologous paradigms to increase translatability of social behaviour between human and animal observation are needed. Standard behavioural rodent assays have limited ethological validity in terms of number of interaction partners, type of behaviour, duration of observation and environmental conditions. In addition, reproducibility of behavioural findings in rodents is further limited by manual and subjective behavioural scoring. Using a newly developed automated tracking tool for longitudinal monitoring of freely moving mice, we assessed social behaviours (approach, sniff, follow and leave) over seven consecutive days in colonies of BTBR and of C57BL/6J mice in two independent laboratories. Results from both laboratories confirmed previous findings of reduced social interaction in BTBR mice revealing a high level of reproducibility for this mouse phenotype using longitudinal colony assessments. In addition, we showed that detector settings contribute to laboratory specific findings as part of the behavioural data analysis procedure. Our cross-site study demonstrates reproducibility and robustness of reduced social interaction in BTBR mice using automated analysis in an ethologically relevant context

Translational validity and methodological underreporting in animal research:A systematic review and meta-analysis of the Fragile X syndrome (Fmr1 KO) rodent model

Predictive models are essential for advancing knowledge of brain disorders. High variation in study outcomes hampers progress. To address the validity of predictive models, we performed a systematic review and meta-analysis on behavioural phenotypes of the knock-out rodent model for Fragile X syndrome according to the PRISMA reporting guidelines. In addition, factors accountable for the heterogeneity between findings were analyzed. The knock-out model showed good translational validity and replicability for hyperactivity, cognitive and seizure phenotypes. Despite low replicability, translational validity was also found for social behaviour and sensory sensitivity, but not for attention, aggression and cognitive flexibility. Anxiety, acoustic startle and prepulse inhibition phenotypes, despite low replicability, were opposite to patient symptomatology. Subgroup analyses for experimental factors moderately explain the low replicability, these analyses were hindered by under-reporting of methodologies and environmental conditions. Together, the model has translational validity for most clinical phenotypes, but caution must be taken due to low effect sizes and high inter-study variability. These findings should be considered in view of other rodent models in preclinical research

<i>Cntn4</i>, a risk gene for neuropsychiatric disorders, modulates hippocampal synaptic plasticity and behavior

Neurodevelopmental and neuropsychiatric disorders, such as autism spectrum disorders (ASD), anorexia nervosa (AN), Alzheimer’s disease (AD), and schizophrenia (SZ), are heterogeneous brain disorders with unknown etiology. Genome wide studies have revealed a wide variety of risk genes for these disorders, indicating a biological link between genetic signaling pathways and brain pathology. A unique risk gene is Contactin 4 (Cntn4), an Ig cell adhesion molecule (IgCAM) gene, which has been associated with several neuropsychiatric disorders including ASD, AN, AD, and SZ. Here, we investigated the Cntn4 gene knockout (KO) mouse model to determine whether memory dysfunction and altered brain plasticity, common neuropsychiatric symptoms, are affected by Cntn4 genetic disruption. For that purpose, we tested if Cntn4 genetic disruption affects CA1 synaptic transmission and the ability to induce LTP in hippocampal slices. Stimulation in CA1 striatum radiatum significantly decreased synaptic potentiation in slices of Cntn4 KO mice. Neuroanatomical analyses showed abnormal dendritic arborization and spines of hippocampal CA1 neurons. Short- and long-term recognition memory, spatial memory, and fear conditioning responses were also assessed. These behavioral studies showed increased contextual fear conditioning in heterozygous and homozygous KO mice, quantified by a gene-dose dependent increase in freezing response. In comparison to wild-type mice, Cntn4-deficient animals froze significantly longer and groomed more, indicative of increased stress responsiveness under these test conditions. Our electrophysiological, neuro-anatomical, and behavioral results in Cntn4 KO mice suggest that Cntn4 has important functions related to fear memory possibly in association with the neuronal morphological and synaptic plasticity changes in hippocampus CA1 neurons