Implementation of the EQIPD Quality System

The EQIPD Quality System (QS) was conceptualized and established by an international consortium consisting of academic and industrial partners to ensure that non-regulated biomedical research will be conducted according to Good Research Practice expectations. The QS supports researchers to reflect on and improve internal practices by providing a systematic framework and guidance for implementing the EQIPD QS in a time and cost effective manner. This report describes the content of the EQIPD QS with its key features and 18 Core Requirements (CR) in more detail. It gives a short background on each CR and hands on examples on how they were addressed by two different research labs in their respective laboratory environments. Thereby, this article provides examples and direction for other research labs who aim to implement the QS as well. The final paragraphs discuss the potential benefits of the QS in respect to different user groups and stakeholders within the scientific community and summarize the overall governance structure of the EQIPD framework.

Suppression of Cofilin function in the somatosensory cortex alters social contact behavior in the BTBR mouse inbred line

Sensory differences are a core feature of autism spectrum disorders (ASD) and are predictive of other ASD core symptoms such as social difficulties. However, the neurobiological substrate underlying the functional relationship between sensory and social functioning is poorly understood. Here, we examined whether misregulation of structural plasticity in the somatosensory cortex modulates aberrant social functioning in BTBR mice, a mouse model for autism spectrum disorder-like phenotypes. By locally expressing a dominant-negative form of Cofilin (CofilinS3D; a key regulator of synaptic structure) in the somatosensory cortex, we tested whether somatosensory suppression of Cofilin activity alters social functioning in BTBR mice. Somatosensory Cofilin suppression altered social contact and nest-hide behavior of BTBR mice in a social colony, assessed for seven consecutive days. Subsequent behavioral testing revealed that altered social functioning is related to altered tactile sensory perception; CofilinS3D-treated BTBR mice showed a time-dependent difference in the sensory bedding preference task. These findings show that Cofilin suppression in the somatosensory cortex alters social functioning in BTBR mice and that this is associated with tactile sensory processing, a critical indicator of somatosensory functioning.

A New Intervention for Implementation of Pharmacogenetics in Psychiatry: A Description of the PSY-PGx Clinical Study

(1) Background Pharmacological treatment for psychiatric disorders has shown to only be effective in about one-third of patients, as it is associated with frequent treatment failure, often because of side effects, and a long process of trial-and-error pharmacotherapy until an effective and tolerable treatment is found. This notion emphasizes the urgency for a personalized medicine approach in psychiatry. (2) Methods This prospective patient- and rater-blinded, randomized, controlled study will investigate the effect of dose-adjustment of antidepressants escitalopram and sertraline or antipsychotics risperidone and aripiprazole according to the latest state-of-the-art international dosing recommendations for CYP2C19 and CYP2D6 metabolizer status in patients with mood, anxiety, and psychotic disorders. A total sample of N = 2500 will be recruited at nine sites in seven countries (expected drop-out rate of 30%). Patients will be randomized to a pharmacogenetic group or a dosing-as-usual group and treated over a 24-week period with four study visits. The primary outcome is personal recovery using the Recovery Assessment Scale as assessed by the patient (RAS-DS), with secondary outcomes including clinical effects (response or symptomatic remission), side effects, general well-being, digital phenotyping, and psychosocial functioning. (3) Conclusions This is, to our knowledge, the first international, multi-center, non-industry-sponsored randomized controlled trial (RCT) that may provide insights into the effectiveness and utility of implementing pharmacogenetic-guided treatment of psychiatric disorders, and as such, results will be incorporated in already available dosing guidelines.

Digital behavioural signatures reveal trans-diagnostic clusters of Schizophrenia and Alzheimer's disease patients

The current neuropsychiatric nosological categories underlie pragmatic treatment choice, regulation and clinical research but does not encompass biological rationale. However, subgroups of patients suffering from schizophrenia or Alzheimer's disease have more in common than the neuropsychiatric nature of their condition, such as the expression of social dysfunction. The PRISM project presents here initial quantitative biological insights allowing the first steps toward a novel trans-diagnostic classification of psychiatric and neurological symptomatology intended to reinvigorate drug discovery in this area. In this study, we applied spectral clustering on digital behavioural endpoints derived from passive smartphone monitoring data in a subgroup of Schizophrenia and Alzheimer's disease patients, as well as age matched healthy controls, as part of the PRISM clinical study. This analysis provided an objective social functioning characterization with three differential clusters that transcended initial diagnostic classification and was shown to be linked to quantitative neurobiological parameters assessed. This emerging quantitative framework will both offer new ways to classify individuals in biologically homogenous clusters irrespective of their initial diagnosis, and also offer insights into the pathophysiological mechanisms underlying these clusters.

The human neuropsychiatric risk gene Drd2 is necessary for social functioning across evolutionary distant species

The Drd2 gene, encoding the dopamine D2 receptor (D2R), was recently indicated as a potential target in the etiology of lowered sociability (i.e., social withdrawal), a symptom of several neuropsychiatric disorders such as Schizophrenia and Major Depression. Many animal species show social withdrawal in response to stimuli, including the vinegar fly Drosophila melanogaster and mice, which also share most human disease-related genes. Here we will test for causality between Drd2 and sociability and for its evolutionary conserved function in these two distant species, as well as assess its mechanism as a potential therapeutic target. During behavioral observations in groups of freely interacting D. melanogaster, Drd2 homologue mutant showed decreased social interactions and locomotor activity. After confirming Drd2's social effects in flies, conditional transgenic mice lacking Drd2 in dopaminergic cells (autoreceptor KO) or in serotonergic cells (heteroreceptor KO) were studied in semi-natural environments, where they could freely interact. Autoreceptor KOs showed increased sociability, but reduced activity, while no overall effect of Drd2 deletion was observed in heteroreceptor KOs. To determine acute effects of D2R signaling on sociability, we also showed that a direct intervention with the D2R agonist Sumanirole decreased sociability in wild type mice, while the antagonist showed no effects. Using a computational ethological approach, this study demonstrates that Drd2 regulates sociability across evolutionary distant species, and that activation of the mammalian D2R autoreceptor, in particular, is necessary for social functioning.

Personal preferences for treatment and care during and after a First Episode Psychosis: A qualitative study

AIM

A first episode of psychosis (FEP) is a stressful, often life-changing experience. Scarce information is available about personal preferences regarding their care needs during and after a FEP. Whereas a more thorough understanding of these preferences is essential to aid shared decision-making during treatment and improve treatment satisfaction.

METHODS

Face-to-face interviews with participants in remission of a FEP were set up, addressing personal preferences and needs for care during and after a FEP. The interviews were conducted by a female and a male researcher, the latter being an expert with lived experience.

RESULTS

Twenty individuals in remission of a FEP were interviewed, of which 16 had been hospitalized. The distinguished themes based on personal preferences were tranquillity, peace and quietness, information, being understood, support from significant others, and practical guidance in rebuilding one's life. Our findings revealed that the need for information and the need to be heard were often not sufficiently met. For 16/20 participants, the tranquillity of inpatient treatment of the FEP was predominantly perceived as a welcome safe haven. The presence and support of family and close friends were mentioned as an important factor in the process of achieving remission.

CONCLUSIONS

The current exploratory study showed that patients were able to indicate their personal needs. Important findings are the need for information and the need to be heard. Interestingly, hospitalization was mostly seen as an opportunity to achieve tranquillity. More lived experience expertise is needed to elucidate the needs of individuals in the early phase of a FEP to aid people who are recovering from their first psychosis in rebuilding their lives again.

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 (P301LK18), while control mice received a PBS injection (P301LPBS). 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 P301LK18 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.

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.

A Study on REM Sleep Homeostasis in the Day-Active Tree Shrew (Tupaia belangeri): Cold-Induced Suppression of REM Sleep Is Not Followed by a Rebound

The function and regulation of rapid-eye-movement (REM) sleep is a topic of ongoing debate. It is often assumed that REM sleep is a homeostatically regulated process and that a need for REM sleep builds up, either during prior wakefulness or during preceding slow wave sleep. In the current study, we tested this hypothesis in six diurnal tree shrews (Tupaia belangeri), small mammals closely related to primates. All animals were individually housed and kept under a 12:12 light-dark cycle with an ambient temperature of 24 °C. We recorded sleep and temperature in the tree shrews for 3 consecutive 24 h days. During the second night, we exposed the animals to a low ambient temperature of 4 °C, a procedure that is known to suppress REM sleep. Cold exposure caused a significant drop in brain temperature and body temperature and also resulted in a strong and selective suppression of REM sleep by 64.9%. However, contrary to our expectation, the loss of REM sleep was not recovered during the subsequent day and night. These findings in a diurnal mammal confirm that the expression of REM sleep is highly sensitive to environmental temperature but do not support the view that REM sleep is homeostatically regulated in this species.

Recovering object-location memories after sleep deprivation-induced amnesia

It is well established that sleep deprivation after learning impairs hippocampal memory processes and can cause amnesia. It is unknown, however, whether sleep deprivation leads to the loss of information or merely the suboptimal storage of information that is difficult to retrieve. Here, we show that hippocampal object-location memories formed under sleep deprivation conditions can be successfully retrieved multiple days following training, using optogenetic dentate gyrus (DG) memory engram activation or treatment with the clinically approved phosphodiesterase 4 (PDE4) inhibitor roflumilast. Moreover, the combination of optogenetic DG memory engram activation and roflumilast treatment, 2 days following training and sleep deprivation, made the memory more persistently accessible for retrieval even several days later (i.e., without further optogenetic or pharmacological manipulation). Altogether, our studies in mice demonstrate that sleep deprivation does not necessarily cause memory loss but instead leads to the suboptimal storage of information that cannot be retrieved without drug treatment or optogenetic stimulation. Furthermore, our findings suggest that object-location memories, consolidated under sleep deprivation conditions and thought to be lost, can be made accessible again several days after the learning and sleep deprivation episode, using the clinically approved PDE4 inhibitor roflumilast.

Influencing cognitive performance via social interactions: a novel therapeutic approach for brain disorders based on neuroanatomical mapping?

Many psychiatric and neurological disorders present deficits in both the social and cognitive domain. In this perspectives article, we provide an overview and the potential of the existence of an extensive neurobiological substrate underlying the close relationship between these two domains. By mapping the rodent brain regions involved in the social and/or cognitive domain, we show that the vast majority of brain regions involved in the cognitive domain are also involved in the social domain. The identified neuroanatomical overlap has an evolutionary basis, as complex social behavior requires cognitive skills, and aligns with the reported functional interactions of processes underlying cognitive and social performance. Based on the neuroanatomical mapping, recent (pre-)clinical findings, and the evolutionary perspective, we emphasize that the social domain requires more focus as an important treatment target and/or biomarker, especially considering the presently limited treatment strategies for these disorders.

Variation in Group Composition Alters an Early-Stage Social Phenotype in hAPP-Transgenic J20 Mice

BACKGROUND

Altered social behavior is one of the symptoms of Alzheimer's disease (AD) that results in social withdrawal and loneliness and provides a major burden on patients and their relatives. Furthermore, loneliness is associated with an increased risk to develop AD and related dementias.

OBJECTIVE

We aimed to investigate if altered social behavior is an early indicator of amyloid-β (Aβ) pathology in J20 mice, and if co-housing with wild type (WT) mice can positively influence this social phenotype.

METHODS

The social phenotype of group-housed mice was assessed using an automated behavioral scoring system for longitudinal recordings. Female mice were housed in a same-genotype (4 J20 or WT mice per colony) or mixed-genotype (2 J20 mice + 2 WT mice) colony. At 10 weeks of age, their behavior was assessed for five consecutive days.

RESULTS

J20 mice showed increased locomotor activity and social sniffing, and reduced social contact compared to WT mice housed in same-genotype colonies. Mixed-genotype housing reduced the social sniffing duration of J20 mice, increased social contact frequency of J20 mice, and increased nest hide by WT mice.

CONCLUSION

Thus, altered social behavior can be used as an early indicator of Aβ-pathology in female J20 mice. Additionally, when co-housed with WT mice, their social sniffing phenotype is not expressed and their social contact phenotype is reduced. Our findings highlight the presence of a social phenotype in the early stages of AD and indicate a role for social environment variation in the expression of social behavior of WT and J20 mice.

Largely unaffected auditory and visual sensory processing phenotypes in the evoked potentials of Fmr1 KO2 mice

Sensory sensitivity symptoms are common in autism spectrum disorders and fragile X syndrome. Mainly in the auditory modality, disturbed processing has been found in both fragile X patients and the corresponding genetic mouse model, the Fmr1 knockout mouse. Here, we tried to replicate the auditory deficits and assess whether also visual processing is affected, using electroencephalography readouts under freely behaving conditions in the second-generation Fmr1 knockout mice. No differences between wild-type and knockout animals were found in single auditory and visual evoked potentials in response to pure sine tones and full-field light flashes. Visual sensory gating was enhanced in the early but not the late components of the evoked potentials, but no changes were found in auditory sensory gating. The higher harmonics of the synchronisation response to flickering visual stimuli seemed to be reduced with 10, but not 20 or 40 Hz, stimulation. However, this effect was not reproduced in an independent second cohort of animals. No synchronisation differences were found in response to a chirp stimulus, of which the frequency steadily increased. Taken together, this study could not reproduce earlier reported increased amplitudes in auditory responses, nor could it convincingly show that synchronisation deficits found to be present in the auditory modality also existed in the visual modality. The discrepancies within this study as well as between various studies assessing sensory processing in the Fmr1 KO raise questions about the external validity of these phenotypes and warrant careful interpretation of these phenotypes.

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.

Spatial and Temporal Gene Function Studies in Rodents: Towards Gene-Based Therapies for Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition that is characterized by differences in social interaction, repetitive behaviors, restricted interests, and sensory differences beginning early in life. Especially sensory symptoms are highly correlated with the severity of other behavioral differences. ASD is a highly heterogeneous condition on multiple levels, including clinical presentation, genetics, and developmental trajectories. Over a thousand genes have been implicated in ASD. This has facilitated the generation of more than two hundred genetic mouse models that are contributing to understanding the biological underpinnings of ASD. Since the first symptoms already arise during early life, it is especially important to identify both spatial and temporal gene functions in relation to the ASD phenotype. To further decompose the heterogeneity, ASD-related genes can be divided into different subgroups based on common functions, such as genes involved in synaptic function. Furthermore, finding common biological processes that are modulated by this subgroup of genes is essential for possible patient stratification and the development of personalized early treatments. Here, we review the current knowledge on behavioral rodent models of synaptic dysfunction by focusing on behavioral phenotypes, spatial and temporal gene function, and molecular targets that could lead to new targeted gene-based therapy.

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 stereotypic 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.

Assessment of Social Behavior Using a Passive Monitoring App in Cognitively Normal and Cognitive Impaired Older Adults: an Observational Study (Preprint)

Background

In people with cognitive impairment, loss of social interactions has a major impact on well-being. Therefore, patients would benefit from early detection of symptoms of social withdrawal. Current measurement techniques such as questionnaires are subjective and rely on recall, in contradiction to smartphone apps, which measure social behavior passively and objectively.

Objective

This study uses the remote monitoring smartphone app Behapp to assess social behavior, and aims to investigate (1) the association between social behavior, demographic characteristics, and neuropsychiatric symptoms in cognitively normal (CN) older adults, and (2) if social behavior is altered in cognitively impaired (CI) participants. In addition, we explored in a subset of individuals the association between Behapp outcomes and neuropsychiatric symptoms.

Methods

CN, subjective cognitive decline (SCD), and CI older adults installed the Behapp app on their own Android smartphone for 7 to 42 days. CI participants had a clinical diagnosis of mild cognitive impairment (MCI) or Alzheimer-type dementia. The app continuously measured communication events, app use and location. Neuropsychiatric Inventory (NPI) total scores were available for 20 SCD and 22 CI participants. Linear models were used to assess group differences on Behapp outcomes and to assess the association of Behapp outcomes with the NPI.

Results

We included CN (n=209), SCD (n=55) and CI (n=22) participants. Older cognitively normal participants called less frequently and made less use of apps (P<.05). No sex effects were found. Compared to the CN and SCD groups, CI individuals called less unique contacts (β=–0.7 [SE 0.29], P=.049) and contacted the same contacts relatively more often (β=0.8 [SE 0.25], P=.004). They also made less use of apps (β=–0.83 [SE 0.25], P=.004). Higher total NPI scores were associated with further traveling (β=0.042 [SE 0.015], P=.03).

Conclusions

CI individuals show reduced social activity, especially those activities that are related to repeated and unique behavior, as measured by the smartphone app Behapp. Neuropsychiatric symptoms seemed only marginally associated with social behavior as measured with Behapp. This research shows that the Behapp app is able to objectively and passively measure altered social behavior in a cognitively impaired population.

Measuring Behavior in the Home Cage: Study Design, Applications, Challenges, and Perspectives

The reproducibility crisis (or replication crisis) in biomedical research is a particularly existential and under-addressed issue in the field of behavioral neuroscience, where, in spite of efforts to standardize testing and assay protocols, several known and unknown sources of confounding environmental factors add to variance. Human interference is a major contributor to variability both within and across laboratories, as well as novelty-induced anxiety. Attempts to reduce human interference and to measure more "natural" behaviors in subjects has led to the development of automated home-cage monitoring systems. These systems enable prolonged and longitudinal recordings, and provide large continuous measures of spontaneous behavior that can be analyzed across multiple time scales. In this review, a diverse team of neuroscientists and product developers share their experiences using such an automated monitoring system that combines Noldus PhenoTyper® home-cages and the video-based tracking software, EthoVision® XT, to extract digital biomarkers of motor, emotional, social and cognitive behavior. After presenting our working definition of a "home-cage", we compare home-cage testing with more conventional out-of-cage tests (e.g., the open field) and outline the various advantages of the former, including opportunities for within-subject analyses and assessments of circadian and ultradian activity. Next, we address technical issues pertaining to the acquisition of behavioral data, such as the fine-tuning of the tracking software and the potential for integration with biotelemetry and optogenetics. Finally, we provide guidance on which behavioral measures to emphasize, how to filter, segment, and analyze behavior, and how to use analysis scripts. We summarize how the PhenoTyper has applications to study neuropharmacology as well as animal models of neurodegenerative and neuropsychiatric illness. Looking forward, we examine current challenges and the impact of new developments. Examples include the automated recognition of specific behaviors, unambiguous tracking of individuals in a social context, the development of more animal-centered measures of behavior and ways of dealing with large datasets. Together, we advocate that by embracing standardized home-cage monitoring platforms like the PhenoTyper, we are poised to directly assess issues pertaining to reproducibility, and more importantly, measure features of rodent behavior under more ethologically relevant scenarios.

Loss of Cntnap2 Causes Axonal Excitability Deficits, Developmental Delay in Cortical Myelination, and Abnormal Stereotyped Motor Behavior

Contactin-associated protein-like 2 (Caspr2) is found at the nodes of Ranvier and has been associated with physiological properties of white matter conductivity. Genetic variation in CNTNAP2, the gene encoding Caspr2, has been linked to several neurodevelopmental conditions, yet pathophysiological effects of CNTNAP2 mutations on axonal physiology and brain myelination are unknown. Here, we have investigated mouse mutants for Cntnap2 and found profound deficiencies in the clustering of Kv1-family potassium channels in the juxtaparanodes of brain myelinated axons. These deficits are associated with a change in the waveform of axonal action potentials and increases in postsynaptic excitatory responses. We also observed that the normal process of myelination is delayed in Cntnap2 mutant mice. This later phenotype is a likely modulator of the developmental expressivity of the stereotyped motor behaviors that characterize Cntnap2 mutant mice. Altogether, our results reveal a mechanism linked to white matter conductivity through which mutation of CNTNAP2 may affect neurodevelopmental outcomes.

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 illness1, affecting 0.9-4% of women and 0.3% of men2-4, with twin-based heritability estimates of 50-60%5. Mortality rates are higher than those in other psychiatric disorders6, and outcomes are unacceptably poor7. 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.

Chronic dietary changes in n-6/n-3 polyunsaturated fatty acid ratios cause developmental delay and reduce social interest in mice

Polyunsaturated fatty acids (PUFAs) are one of the main cellular building blocks, and dietary changes in PUFA composition are proposed as a potential route to influence brain development. For example, initial studies indicated that there is a relation between blood omega-6(n-6)/omega-3(n-3) PUFA ratios and neurodevelopmental disease diagnosis. To study the consequences of dietary n-6/n-3 PUFA ratio changes, we investigated the impact of a n-3 supplemented and n-3 deficient diet in developing BTBR T + Itpr3tf/J (BTBR) - a mouse inbred strain displaying Autism Spectrum Disorder (ASD)-like symptomatology - and control C57BL/6J mice. This study showed that pre- and postnatal changed dietary n-6/n-3 ratio intake has a major impact on blood and brain PUFA composition, and led to delayed physical development and puberty onset in both strains. The PUFA induced developmental delay did not impact adult cognitive performance, but resulted in reduced social interest, a main ASD behavioral feature. Thus, both chronic dietary n-3 PUFA supplementation and depletion may not be beneficial.

Modeling the quantitative nature of neurodevelopmental disorders using Collaborative Cross mice

Background

Animal models for neurodevelopmental disorders (NDD) generally rely on a single genetic mutation on a fixed genetic background. Recent human genetic studies however indicate that a clinical diagnosis with ASDAutism Spectrum Disorder (ASD) is almost always associated with multiple genetic fore- and background changes. The translational value of animal model studies would be greatly enhanced if genetic insults could be studied in a more quantitative framework across genetic backgrounds.

Methods

We used the Collaborative Cross (CC), a novel mouse genetic reference population, to investigate the quantitative genetic architecture of mouse behavioral phenotypes commonly used in animal models for NDD.

Results

Classical tests of social recognition and grooming phenotypes appeared insufficient for quantitative studies due to genetic dilution and limited heritability. In contrast, digging, locomotor activity, and stereotyped exploratory patterns were characterized by continuous distribution across our CC sample and also mapped to quantitative trait loci containing genes associated with corresponding phenotypes in human populations.

Conclusions

These findings show that the CC can move animal model studies beyond comparative single gene-single background designs, and point out which type of behavioral phenotypes are most suitable to quantify the effect of developmental etiologies across multiple genetic backgrounds.

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 several ionotropic glutamate and GABA receptor subunits: GluA1, GluA2, and GluN1 were analyzed for excitatory synaptic transmission, and the α1 subunit of the GABA_A 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 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.

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.

Structural abnormalities in the primary somatosensory cortex and a normal behavioral profile in Contactin-5 deficient mice

Contactin-5 (Cntn5) is an immunoglobulin cell adhesion molecule that is exclusively expressed in the central nervous system. In view of its association with neurodevelopmental disorders, particularly autism spectrum disorder (ASD), this study focused on Cntn5-positive areas in the forebrain and aimed to explore the morphological and behavioral phenotypes of the Cntn5 null mutant (Cntn5^−/−) mouse in relation to these areas and ASD symptomatology. A newly generated antibody enabled us to elaborately describe the spatial expression pattern of Cntn5 in P7 wild type (Cntn5^+/+) mice. The Cntn5 expression pattern included strong expression in the cerebral cortex, hippocampus and mammillary bodies in addition to described previously brain nuclei of the auditory pathway and the dorsal thalamus. Thinning of the primary somatosensory (S1) cortex was found in Cntn5^−/− mice and ascribed to a misplacement of Cntn5-ablated cells. This phenotype was accompanied by a reduction in the barrel/septa ratio of the S1 barrel field. The structure and morphology of the hippocampus was intact in Cntn5^−/− mice. A set of behavioral experiments including social, exploratory and repetitive behaviors showed that these were unaffected in Cntn5^−/− mice. Taken together, these data demonstrate a selective role of Cntn5 in development of the cerebral cortex without overt behavioral phenotypes.

Limited impact of Cntn4 mutation on autism-related traits in developing and adult C57BL/6J mice

Background

Mouse models offer an essential tool to unravel the impact of genetic mutations on autism-related phenotypes. The behavioral impact of some important candidate gene models for autism spectrum disorder (ASD) has not yet been studied, and existing characterizations mostly describe behavioral phenotypes at adult ages, disregarding the developmental nature of the disorder. In this context, the behavioral influence of CNTN4, one of the strongest suggested ASD candidate genes, is unknown. Here, we used our recently established developmental test battery to characterize the consequences of disruption of contactin 4 (Cntn4) on neurological, sensory, cognitive, and behavioral phenotypes across different developmental stages.

Methods

C57BL/6J mice with heterozygous and homozygous disruption of Cntn4 were studied through an extensive, partially longitudinal, test battery at various developmental stages, including various paradigms testing social and restricted repetitive behaviors.

Results

Developmental neurological and cognitive screenings revealed no significant differences between genotypes, and ASD-related behavioral domains were also unchanged in Cntn4-deficient versus wild-type mice. The impact of Cntn4-deficiency was found to be limited to increased startle responsiveness following auditory stimuli of different high amplitudes in heterozygous and homozygous Cntn4-deficient mice and enhanced acquisition in a spatial learning task in homozygous mice.

Conclusions

Disruption of Cntn4 in the C57BL/6J background does not affect specific autism-related phenotypes in developing or adult mice but causes subtle non-disorder specific changes in sensory behavioral responses and cognitive performance.

Electronic supplementary material

The online version of this article (doi:10.1186/s11689-016-9140-2) contains supplementary material, which is available to authorized users.

mTOR plays an important role in cow's milk allergy-associated behavioral and immunological deficits

Autism spectrum disorder (ASD) is multifactorial, with both genetic as well as environmental factors working in concert to develop the autistic phenotype. Immunological disturbances in autistic individuals have been reported and a role for food allergy has been suggested in ASD. Single gene mutations in mammalian target of rapamycin (mTOR) signaling pathway are associated with the development of ASD and enhanced mTOR signaling plays a central role in directing immune responses towards allergy as well. Therefore, the mTOR pathway may be a pivotal link between the immune disturbances and behavioral deficits observed in ASD. In this study it was investigated whether the mTOR pathway plays a role in food allergy-induced behavioral and immunological deficits. Mice were orally sensitized and challenged with whey protein. Meanwhile, cow's milk allergic (CMA) mice received daily treatment of rapamycin. The validity of the CMA model was confirmed by showing increased allergic immune responses. CMA mice showed reduced social interaction and increased repetitive self-grooming behavior. Enhanced mTORC1 activity was found in the brain and ileum of CMA mice. Inhibition of mTORC1 activity by rapamycin improved the behavioral and immunological deficits of CMA mice. This effect was associated with increase of Treg associated transcription factors in the ileum of CMA mice. These findings indicate that mTOR activation may be central to both the intestinal, immunological, and psychiatric ASD-like symptoms seen in CMA mice. It remains to be investigated whether mTOR can be seen as a therapeutic target in cow's milk allergic children suffering from ASD-like symptoms.

A genome-wide association study of anorexia nervosa

Anorexia nervosa (AN) is a complex and heritable eating disorder characterized by dangerously low body weight. Neither candidate gene studies nor an initial genome-wide association study (GWAS) have yielded significant and replicated results. We performed a GWAS in 2907 cases with AN from 14 countries (15 sites) and 14 860 ancestrally matched controls as part of the Genetic Consortium for AN (GCAN) and the Wellcome Trust Case Control Consortium 3 (WTCCC3). Individual association analyses were conducted in each stratum and meta-analyzed across all 15 discovery data sets. Seventy-six (72 independent) single nucleotide polymorphisms were taken forward for in silico (two data sets) or de novo (13 data sets) replication genotyping in 2677 independent AN cases and 8629 European ancestry controls along with 458 AN cases and 421 controls from Japan. The final global meta-analysis across discovery and replication data sets comprised 5551 AN cases and 21 080 controls. AN subtype analyses (1606 AN restricting; 1445 AN binge-purge) were performed. No findings reached genome-wide significance. Two intronic variants were suggestively associated: rs9839776 (P=3.01 × 10(-7)) in SOX2OT and rs17030795 (P=5.84 × 10(-6)) in PPP3CA. Two additional signals were specific to Europeans: rs1523921 (P=5.76 × 10(-)(6)) between CUL3 and FAM124B and rs1886797 (P=8.05 × 10(-)(6)) near SPATA13. Comparing discovery with replication results, 76% of the effects were in the same direction, an observation highly unlikely to be due to chance (P=4 × 10(-6)), strongly suggesting that true findings exist but our sample, the largest yet reported, was underpowered for their detection. The accrual of large genotyped AN case-control samples should be an immediate priority for the field.

Identification of Srp9 as a febrile seizure susceptibility gene

OBJECTIVE

Febrile seizures (FS) are the most common seizure type in young children. Complex FS are a risk factor for mesial temporal lobe epilepsy (mTLE). To identify new FS susceptibility genes we used a forward genetic strategy in mice and subsequently analyzed candidate genes in humans.

METHODS

We mapped a quantitative trait locus (QTL1) for hyperthermia-induced FS on mouse chromosome 1, containing the signal recognition particle 9 (Srp9) gene. Effects of differential Srp9 expression were assessed in vivo and in vitro. Hippocampal SRP9 expression and genetic association were analyzed in FS and mTLE patients.

RESULTS

Srp9 was differentially expressed between parental strains C57BL/6J and A/J. Chromosome substitution strain 1 (CSS1) mice exhibited lower FS susceptibility and Srp9 expression than C57BL/6J mice. In vivo knockdown of brain Srp9 reduced FS susceptibility. Mice with reduced Srp9 expression and FS susceptibility, exhibited reduced hippocampal AMPA and NMDA currents. Downregulation of neuronal Srp9 reduced surface expression of AMPA receptor subunit GluA1. mTLE patients with antecedent FS had higher SRP9 expression than patients without. SRP9 promoter SNP rs12403575(G/A) was genetically associated with FS and mTLE.

INTERPRETATION

Our findings identify SRP9 as a novel FS susceptibility gene and indicate that SRP9 conveys its effects through endoplasmic reticulum (ER)-dependent synthesis and trafficking of membrane proteins, such as glutamate receptors. Discovery of this new FS gene and mechanism may provide new leads for early diagnosis and treatment of children with complex FS at risk for mTLE.

Social isolation stress reduces hippocampal long-term potentiation: effect of animal strain and involvement of glucocorticoid receptors

BACKGROUND

Depressive patients show cognitive impairments that are strongly associated with cortisol levels and hippocampus functioning that interact via unknown mechanisms. In addition, a relation between depression and hippocampal synaptic plasticity was described.

METHODS

In the first experiment, strain-dependent effects of 72-h social isolation on long-term potentiation (LTP) in the CA1 area of the in vitro hippocampus, was determined. Extracellular field excitatory postsynaptic potentials were recorded and a brief high-frequency stimulation (100 Hz, 1s) was applied and recording resumed after the high frequency stimulation (HFS) for 30 min to determine the effect of HFS. In the second experiment we investigated the effect of 72 h of corticosterone treatment and the involvement of glucocorticoid receptors (GRs) in the effect of 72 h of social isolation on LTP in the CA1 area of hippocampus, in vitro.

RESULTS

Genetic background has a major effect on the level of hippocampal LTP impairment in mice following social isolation. Data showed that the potentiation levels in socially housed (SH) A/J mice were significantly higher than the SH C57BL/6J mice (224.88 ± 16.65, 131.56 ± 6.25% of the baseline values, t(9)=2.648, p=0.026). However, both strains showed depressed induction of potentiation when reared in an isolated environment for 72 h, and no significant difference was recorded between the two (112.88 ± 16.65%, and 117.91 ± 3.23% of the baseline values, respectively, t(10)=0.618, p=0.551). Social isolation increased corticosterone levels significantly and chronic corticosterone infusion in SH phenocopied the LTP impairments observed in socially isolated mice. Infusion of the GR antagonist RU38486 rescued the LTP-impairments following social isolation.

CONCLUSIONS

These findings support the notion that increased levels of stress hormone act via the GR on hippocampal functioning and that, in this way, the cognitive deficits in mood disorders may be restored.

Longitudinal changes in the physical activity of adolescents with anorexia nervosa and their influence on body composition and leptin serum levels after recovery

Objective

Patients with anorexia nervosa (AN) are often observed to have high levels of physical activity, which do not necessarily diminish after a successful therapy. Previous studies have shown that body fat tissue recovery in these patients is associated with a disproportional restoration of the adipocyte hormone, leptin. Therefore, we wondered whether the individual variation in physical activity in AN patients prior to treatment may be related to body fat percentage and plasma leptin level outcome.

Method

Body fat percentage, leptin serum, and physical activity levels (accelerometer) were measured in adolescents with an (n=37, age 13 to 17.5 years) at initial assessment, at the end of study participation (median 12 months), and at one-year follow-up.

Results

Accelerometer data were used to split the patients in two groups: those with low (n=26) and those with high levels of physical activity (HLPA, n=11). These groups did not differ in terms of age, IQ, presence of menses, BMI and season of admission. The HLPA group was characterized by a longer total duration of illness. Physical activity levels during therapy decreased for the group with initially HLPA and increased for the group with low levels of physical activity (to comparable levels). Physical activity remained stable after one year. The increase in body fat percentage and leptin levels were dependent on the recovery status; however, recovered patients with initially HLPA had significantly higher fat mass during the follow-up.

Discussion

HLPA, an important modulator of AN progression in adolescents, can be successfully diminished by therapeutic intervention. Among recovered patients, those with initially HLPA had higher fat mass levels than those with low levels of physical activity. This finding suggests that HLPA are an important modulator of the body composition recovery mechanism.

The Val66Met polymorphism of the BDNF gene in anorexia nervosa: new data and a meta-analysis

OBJECTIVES

The Val66Met polymorphism (rs6265) of the BDNF gene is a non-synonymous polymorphism, previously associated with anorexia nervosa (AN).

METHODS

We genotyped rs6265 in 235 patients with AN and 643 controls. Furthermore, we performed a systematic review of all case-control and family-based studies testing this SNP in AN, and combined the results in a meta-analysis.

RESULTS

The results of the case-control study were non-significant. For the meta-analysis, nine studies were identified (ncases = 2,767; ncontrols = 3,322, ntrios = 53) and included. Primarily, the analyses indicated an association with OR of 1.11 (P = 0.024) in the allelic contrast, and OR of 1.14 (P = 0.025) for the dominant effect of the Met allele. However, additional analyses revealed that the first published study (from those included in the meta-analysis) overly influenced the pooled effect size (possibly due to a phenomenon known as a winner's curse). When this case-control study was replaced by a trio study (ntrios = 293) performed on a largely overlapping sample, the effect size became smaller and non-significant, both for the allelic contrast (OR = 1.07, P = 0.156) and the dominant effect (OR = 1.07, P = 0.319). The quality of included studies was good and there was no significant heterogeneity across the effect sizes.

CONCLUSIONS

Our analyses indicate that the BDNF Val66Met variant is not associated with AN at detectable levels.

Contactins in the neurobiology of autism

Autism is a disease of brain plasticity. Inspiring work of Willem Hendrik Gispen on neuronal plasticity has stimulated us to investigate gene defects in autism and the consequences for brain development. The central process in the pathogenesis of autism is local dendritic mRNA translation which is dependent on axodendritic communication. Hence, most autism-related gene products (i) are part of the protein synthesis machinery itself, (ii) are components of the mTOR signal transduction pathway, or (iii) shape synaptic activity and plasticity. Accordingly, prototype drugs have been recognized that interfere with these pathways. The contactin (CNTN) family of Ig cell adhesion molecules (IgCAMs) harbours at least three members that have genetically been implicated in autism: CNTN4, CNTN5, and CNTN6. In this chapter we review the genetic and neurobiological data underpinning their role in normal and abnormal development of brain systems, and the consequences for behavior. Although data on each of these CNTNs are far from complete, we tentatively conclude that these three contactins play roles in brain development in a critical phase of establishing brain systems and their plasticity. They modulate neuronal activities, such as neurite outgrowth, synaptogenesis, survival, guidance of projections and terminal branching of axons in forming neural circuits. Current research on these CNTNs concentrate on the neurobiological mechanism of their developmental functions. A future task will be to establish if proposed pharmacological strategies to counteract ASD-related symptomes can also be applied to reversal of phenotypes caused by genetic defects in these CNTN genes.

Fibroblast growth factors in neurodevelopment and psychopathology

In psychiatric disorders, the effect of genetic and environmental factors may converge on molecular pathways and brain circuits related to growth factor functioning. In this review, we describe how disturbances in fibroblast growth factors (FGFs) and their receptors influence behavior by affecting brain development. Recently, several studies reported associations of members of the FGF family with psychiatric disorders. FGFs are key candidates to modulate the impact of environmental factors, such as stress. Mutant mice for FGF receptor 1 show schizophrenia-like behaviors that are related to general loss of neurons and postnatal glia dysfunction. Mice lacking FGF2, a FGFR1 ligand, show similar reductions in brain volume and hyperactivity, as well as increased anxiety behaviors. FGFR2 and FGF17 are involved in the development of frontal brain regions and impairments in cognitive and social behaviors, respectively. Moreover, treatment with FGF2 was beneficial for depressive and cognitive measures in several animal studies and one human study. These findings indicate the importance of the FGF system with respect to developing novel etiology-directed treatments for psychopathology.

Intranasal mesenchymal stem cell treatment for neonatal brain damage: long-term cognitive and sensorimotor improvement

Mesenchymal stem cell (MSC) administration via the intranasal route could become an effective therapy to treat neonatal hypoxic-ischemic (HI) brain damage. We analyzed long-term effects of intranasal MSC treatment on lesion size, sensorimotor and cognitive behavior, and determined the therapeutic window and dose response relationships. Furthermore, the appearance of MSCs at the lesion site in relation to the therapeutic window was examined. Nine-day-old mice were subjected to unilateral carotid artery occlusion and hypoxia. MSCs were administered intranasally at 3, 10 or 17 days after hypoxia-ischemia (HI). Motor, cognitive and histological outcome was investigated. PKH-26 labeled cells were used to localize MSCs in the brain. We identified 0.5×10⁶ MSCs as the minimal effective dose with a therapeutic window of at least 10 days but less than 17 days post-HI. A single dose was sufficient for a marked beneficial effect. MSCs reach the lesion site within 24 h when given 3 or 10 days after injury. However, no MSCs were detected in the lesion when administered 17 days following HI. We also show for the first time that intranasal MSC treatment after HI improves cognitive function. Improvement of sensorimotor function and histological outcome was maintained until at least 9 weeks post-HI. The capacity of MSCs to reach the lesion site within 24 h after intranasal administration at 10 days but not at 17 days post-HI indicates a therapeutic window of at least 10 days. Our data strongly indicate that intranasal MSC treatment may become a promising non-invasive therapeutic tool to effectively reduce neonatal encephalopathy.

Marked inbred mouse strain difference in the expression of quinpirole induced compulsive like behavior based on behavioral pattern analysis

Obsessive-compulsive disorder (OCD) is a chronic and complex psychiatric disorder with a lifetime prevalence of 2-3%. Recent work has shown that OCD rituals were not only characterized by a high rate of repetition but also by an increased behavioral repertoire due to additional non-functional unique acts. These two behavioral characteristics may provide an ethological basis for studying compulsive behavior in an animal model of OCD. Here, quinpirole induced behavior (so far only investigated in rats) has been studied in A/J and C57BL/6J mice by using behavioral pattern analysis. The aim of this study is to investigate whether genetic background is mediating this behavior. Results showed that open field motor activity levels of saline treated C57BL/6J mice was significantly higher compared to A/J treated saline mice. Long-term quinpirole treatment increased open field motor activity levels in A/J, but not in C57BL/6J. Quinpirole treatment induced a strain dependent difference in behavioral repertoire. There was a dose dependent increase in the number of different behavioral patterns in A/J, whereas, in C57BL/6J there was a dose dependent decrease. This data suggest that genetic background is important in expressing quinpirole induced compulsive like behavior. Following quinpirole treatment, A/J mice express a greater behavioral repertoire with a high rate of repetition. This phenotype resembles that of OCD rituals in patients and indicates that this strain is very interesting to further validate for studying neurobiological mechanisms of compulsive behavior.

Hyperactivity in anorexia nervosa: warming up not just burning-off calories

Excessive physical activity is a common feature in Anorexia Nervosa (AN) that interferes with the recovery process. Animal models have demonstrated that ambient temperature modulates physical activity in semi-starved animals. The aim of the present study was to assess the effect of ambient temperature on physical activity in AN patients in the acute phase of the illness. Thirty-seven patients with AN wore an accelerometer to measure physical activity within the first week of contacting a specialized eating disorder center. Standardized measures of anxiety, depression and eating disorder psychopathology were assessed. Corresponding daily values for ambient temperature were obtained from local meteorological stations. Ambient temperature was negatively correlated with physical activity (p = −.405) and was the only variable that accounted for a significant portion of the variance in physical activity (p = .034). Consistent with recent research with an analogous animal model of the disorder, our findings suggest that ambient temperature is a critical factor contributing to the expression of excessive physical activity levels in AN. Keeping patients warm may prove to be a beneficial treatment option for this symptom.

Mapping an X-linked locus that influences heat-induced febrile seizures in mice

PURPOSE

Febrile seizures (FS) are the most common seizure type in children between the age of 6 months and 5 years. Although FS are largely benign, recurrent FS are a major risk factor for developing temporal lobe epilepsy (TLE) later in life. The mechanisms underlying FS are largely unknown; however, family and twin studies indicate that FS susceptibility is under complex genetic control. We have recently developed a phenotypic screen to study the genetics of FS susceptibility in mice. Using this screen in a phenotype-driven genetic strategy we analyzed the C57BL/6J-Chr #(A)/NaJ chromosome substitution strain (CSS) panel. In each CSS line one chromosome of the A/J strain is substituted in a genetically homogeneous C57BL/6J background. The analysis of the CSS panel revealed that A/J chromosomes 1, 2, 6, 10, 13, and X carry at least one quantitative trait locus (QTL) for heat-induced FS susceptibility. The fact that many X-linked genes are highly expressed in the brain and have been implicated in human developmental disorders often presenting with seizures (like fragile X mental retardation) prompted us to map the chromosome X QTL.

METHODS

C57BL/6J mice were mated with C57BL/6J-Chr X(A) /NaJ (CSSX) to generate F(2)-generations-CXBL6 and BL6CX-originating from CSSX or C57BL/6J mothers, respectively. Heat-induced FS were elicited on postnatal day 14 by exposure to a controlled warm airstream of 50°C. The latency to heat-induced FS is our phenotype. This phenotype has previously been validated by video-electroencephalography (EEG) monitoring. After phenotyping and genotyping the F(2)-population, QTL analysis was performed using R/QTL software.

KEY FINDINGS

QTL analysis revealed a significant peak with an LOD-score of 3.25. The 1-LOD confidence interval (149,886,866-158,836,462 bp) comprises 52 protein coding genes, of which 34 are known to be brain expressed. Two of these brain-expressed genes have previously been linked to X-linked epilepsies, namely Cdkl5 and Pdha1.

SIGNIFICANCE

Our results show that the mouse genetics of X-linked FS susceptibility is complex, and that our heat-induced FS-driven genetic approach is a powerful tool for use in unraveling the complexities of this trait in mice. Fine-mapping and functional studies will be required to further identify the X-linked FS susceptibility genes.

Neurobiology driving hyperactivity in activity-based anorexia

Hyperactivity in anorexia nervosa is difficult to control and negatively impacts outcome. Hyperactivity is a key driving force to starvation in an animal model named activity-based anorexia (ABA). Recent research has started unraveling what mechanisms underlie this hyperactivity. Besides a general increase in locomotor activity that may be an expression of foraging behavior and involves frontal brain regions, the increased locomotor activity expressed before food is presented (food anticipatory behavior or FAA) involves hypothalamic neural circuits. Ghrelin plays a role in FAA, whereas decreased leptin signaling is involved in both aspects of increased locomotor activity. We hypothesize that increased ghrelin and decreased leptin signaling drive the activity of dopamine neurons in the ventral tegmental area. In anorexia nervosa patients, this altered activity of the dopamine system may be involved not only in hyperactivity but also in aberrant cognitive processing related to food.

Mandometer treatment not superior to treatment as usual for anorexia nervosa

OBJECTIVE

A comparison of the efficacy of a novel treatment method for anorexia nervosa (AN), the Mandometer treatment (MT), with treatment as usual (TAU).

METHOD

During treatment data were collected to determine weight recovery and outcome as assessed by the Morgan Russell Outcome Assessment Schedule (MROAS).

RESULTS

After treatment 63% of the MT group and 85% of the TAU group had reached a normal weight level and both MT and TAU showed a good outcome on the MROAS (75 and 71%, respectively). After two years more MT than TAU patients were still in treatment and more MT patients had relapsed.

DISCUSSION

The outcome for both treatments in our study were similar and comparable with, if not better than outcome data of other AN studies. MT is not superior to TAU in outcome results and in relapse rate during the first two years following admission for AN treatment.

Sex-dependent novelty response in neurexin-1α mutant mice

Neurexin-1 alpha (NRXN1α) belongs to the family of cell adhesion molecules (CAMs), which are involved in the formation of neuronal networks and synapses. NRXN1α gene mutations have been identified in neuropsychiatric diseases including Schizophrenia (SCZ) and Autism Spectrum Disorder (ASD). In order to get a better understanding of the pleiotropic behavioral manifestations caused by NRXN1α gene mutations, we performed a behavioral study of Nrxn1α heterozygous knock-out (+/−) mice and observed increased responsiveness to novelty and accelerated habituation to novel environments compared to wild type (+/+) litter-mates. However, this effect was mainly observed in male mice, strongly suggesting that gender-specific mechanisms play an important role in Nrxn1α-induced phenotypes.

Current status and future prospects for epigenetic psychopharmacology

Mounting evidence suggest that epigenetic regulation of brain functions is important in the etiology of psychiatric disorders. These epigenetic regulatory mechanisms, such as DNA methylation and histone acetylation, are influenced by many pharmaceutical compounds including psychiatric drugs. It is therefore of interest to investigate how psychiatric drugs are of influence and what the potential is of new epigenetic drugs for psychiatric disorders. With this targeted review we summarize the current state of knowledge in order to provide insight in this developing field. Several traditional psychiatric drugs have been found to alter the epigenome and in a variety of animal studies, experimental compounds with epigenetic targets have been investigated as potential psychiatric drugs. After discussion of the most relevant epigenetic mechanisms we present the evidence for epigenetic effects for the most relevant classes of drugs.

Behavioral pattern analysis and dopamine release in quinpirole-induced repetitive behavior in rats

Obsessive-compulsive disorder (OCD) is a chronic and disabling psychiatric disease with a lifetime prevalence of 2-3%. People with OCD suffer from intrusive, unwanted and recurrent thoughts (obsessions) and/or repetitive ritualistic behaviors (compulsions). The aim of this study is to quantify the dimensions of ritualistic 'compulsive-like' behavior in quinpirole-induced behavior in rats by using T-pattern behavioral analysis. In addition, we investigated whether the behavioral effects elicited by quinpirole sensitization remained after 2 weeks of cessation of treatment. Finally, to study the neurobiological underpinnings of this 'compulsive-like' behavior, we investigated the effect of quinpirole treatment on the extracellular dopamine levels in the nucleus accumbens. Once established, 'compulsive-like' behavior is dependent upon quinpirole administration, as this behavior rapidly normalized after cessation of treatment. After a single dose of quinpirole the dopamine level decreased more in saline pre-treated animals as compared with animals given quinpirole treatment continuously. Furthermore, T-pattern analysis revealed that quinpirole-induced behavior consists, unlike OCD rituals, of a smaller behavioral repertoire. As seen in patients with OCD, quinpirole-treated animals performed these behaviors with a high rate of repetition. These findings suggest that quinpirole-induced behavior mimics only part of the compulsive behavior as shown in OCD patients.

A meta-analysis of circulating BDNF concentrations in anorexia nervosa

OBJECTIVES

Brain derived neurotrophic factor (BDNF) is involved in neuroplasticity, and in the homeostatic regulation of food intake and energy expenditure. It also has a role in stress responsivity and reward processing. On the basis of its involvement in these various processes, BDNF can be hypothesized to be an important factor in the development and maintenance of anorexia nervosa (AN). This study meta-analytically summarizes investigations of serum BDNF concentrations in people currently ill with AN, in comparison to healthy controls.

METHODS

Seven studies measuring BDNF in serum of individuals with AN (n=155) and healthy controls (n=174) were identified and included in the meta-analysis of the mean differences between case and control groups.

RESULTS

This study confirms that AN is associated with decreased serum BDNF concentrations, in comparison to healthy controls. The combined effect size (standardized mean difference, SMD) was large (SMD=-0.96; 95% CI -1.33 to -0.59; P<0.001). Significant heterogeneity of effect sizes was identified (I(2)=58.3%; P<0.001), which emerged as being primarily attributable to the first published study on the investigated association.

CONCLUSIONS

The present meta-analytical summary of studies measuring circulating BDNF concentrations in women with AN and healthy controls confirms that it is significantly reduced in this patient group. Difficulties associated with the measurement of BDNF have been identified and potential confounding factors have been discussed. Current data do not allow inferences to be made about causal links between levels of circulating BDNF and AN. However, possible explanations for the relationship between BDNF and AN have been presented.

Cross-species behavioural genetics: A starting point for unravelling the neurobiology of human psychiatric disorders

Identifying the genetic and neurobiological mechanisms underlying certain behavioural traits is an important strategy to understand the aetiology of various psychiatric disorders and to find potential new treatment possibilities. It has proven a great challenge to develop paradigms that allow translational research for behavioural phenotypes that are relevant for disorders across the psychiatric spectrum. Recently, there has been increasing attention for studies that implement rodent behavioural paradigms in the home cage to assess the association between genetic backgrounds and behavioural traits. The application of interspecies genetics to unravel these traits has revealed novel insights in the genetic mechanisms that are encoding phenotypes relevant to biological processes underlying psychiatric disorders. By means of two examples, namely the stress-induced hyperthermia paradigm and the home cage environment, this review aims to show that by using individual genetic variations with phenotypes obtained from mice and across categories of neuropsychiatric disorders, novel insights in the neurobiological trajectory of psychiatric disorders can be obtained.

Advances in multidisciplinary and cross-species approaches to examine the neurobiology of psychiatric disorders

Current approaches to dissect the molecular neurobiology of complex neuropsychiatric disorders such as schizophrenia and major depression have been rightly criticized for failing to provide benefits to patients. Improving the translational potential of our efforts will require the development and refinement of better disease models that consider a wide variety of contributing factors, such as genetic variation, gene-by-environment interactions, endophenotype or intermediate phenotype assessment, cross species analysis, sex differences, and developmental stages. During a targeted expert meeting of the European College of Neuropsychopharmacology (ECNP) in Istanbul, we addressed the opportunities and pitfalls of current translational animal models of psychiatric disorders and agreed on a series of core guidelines and recommendations that we believe will help guiding further research in this area.

Hippocampal gene expression analysis highlights Ly6a/Sca-1 as candidate gene for previously mapped novelty induced behaviors in mice

In this study, we show that the covariance between behavior and gene expression in the brain can help further unravel the determinants of neurobehavioral traits. Previously, a QTL for novelty induced motor activity levels was identified on murine chromosome 15 using consomic strains. With the goal of narrowing down the linked region and possibly identifying the gene underlying the quantitative trait, gene expression data from this F₂-population was collected and used for expression QTL analysis. While genetic variation in these mice was limited to chromosome 15, eQTL analysis of gene expression showed strong cis-effects as well as trans-effects elsewhere in the genome. Using weighted gene co-expression network analysis, we were able to identify modules of co-expressed genes related to novelty induced motor activity levels. In eQTL analyses, the expression of Ly6a (a.k.a. Sca-1) was found to be cis-regulated by chromosome 15. Ly6a also surfaced in a group of genes resulting from the network analysis that was correlated with behavior. Behavioral analysis of Ly6a knock-out mice revealed reduced novelty induced motor activity levels when compared to wild type controls, confirming functional importance of Ly6a in this behavior, possibly through regulating other genes in a pathway. This study shows that gene expression profiling can be used to narrow down a previously identified behavioral QTL in mice, providing support for Ly6a as a candidate gene for functional involvement in novelty responsiveness.

Animal models of eating disorder traits

Eating disorders, such as anorexia and bulimia nervosa, are psychiatric disorders that are likely determined by a complex interaction between genetic variations, developmental processes, and certain life events. Cross-species analysis of traits related to eating disorders may provide a way to functionally and systematically study neurobiological mechanisms underlying these disorders. Interspecies trait genetics may offer opportunities to identify common neurobiological mechanisms underlying eating disorder characteristics relevant to the initiation, progression, and/or maintenance of the disease, such as cognitive rigidity, increased anxiety levels, and behavioral hyperactivity. These can subsequently be tested directly by studying allelic variation in mice and human subjects and by applying methods that can modify gene expression levels in rodent models. Increasing our knowledge about these traits and their underlying neurobiological mechanisms will be relevant to develop new therapies for patients within the heterogeneous eating disorder populations. Novel mouse genetic and phenotyping tools offer a way to study these neurobehavioral traits under controlled environmental and genetic background conditions.

Chromosomal mapping of excessive physical activity in mice in response to a restricted feeding schedule

Excessive physical activity plays an important role in the progression of anorexia nervosa (AN) by accelerating weight loss during dietary restriction. To search for mechanisms underlying this trait, a panel of mouse chromosome substitution strains derived from C57BL/6J and A/J strains was exposed to a scheduled feeding paradigm and to voluntary running wheel (RW) access. Here, we showed that A/J chromosomes 4, 12 and 13 contribute to the development of a disrupted RW activity in response to daily restricted feeding. This pattern is characterized by intense RW activity during the habitual rest phase and leads to accelerated body weight loss. Regions on mouse chromosomes 4, 12 and 13 display homology with regions on human chromosomes linked with anxiety and obsessionality in AN cohorts. Therefore, our data open new roads for interspecies genetic studies of AN and for unraveling novel mechanisms and potential effective treatment strategies for these neurobehavioral traits.