Advances in behavioral genetics: mouse models of autism

Maternal behaviours disrupted by Gprasp2 deletion modulate neurodevelopmental trajectory in progeny

Autism spectrum disorders (ASDs) are known to present sex-specific differences. At the same time, understanding how maternal behaviours are affected by pathogenic mutations is crucial to translate research efforts since rearing may recursively modulate neurodevelopment phenotype of the progeny. In this work, we focused on the effects of Gprasp2 deletion in females and its impact in progeny care and development. Female mice, wild-type (WT), Gprasp2+/- (HET) or Gprasp2-/- (KO) mutants and their progeny were used and behavioural paradigms targeting anxiety, memory, maternal care, and other social behaviours were performed. Analysis of communication was carried out through daily recordings of ultrasonic vocalizations in isolated pups and cross-fostering experiments were performed to understand the effect of maternal genotype in pup development. We found that Gprasp2-/- females presented striking impairments in social and working memory. Females also showed disruptions in maternal care, as well as physiological and molecular alterations in the reproductive system and hypothalamus, such as the structure of the mammary gland and the expression levels of oxytocin receptor (OxtR) in nulliparous versus primiparous females. We observed alterations in pup communication, particularly a reduced number of calls in Gprasp2 KO pups, which resulted from an interaction effect of the dam and pup genotype. Cross-fostering mutant pups with wild-type dams rescued some of the early defects shown in vocalizations, however, this effect was not bidirectional, as rearing WT pups with Gprasp2-/- dams was not sufficient to induce significant phenotypical alterations. Our results suggest Gprasp2 mutations perturb social and working memory in a sex-independent manner, but impact female-specific behaviours towards progeny care, female physiology, and gene expression. These changes in mutant dams contribute to a disruption in early stages of progeny development. More generally, our results highlight the need to better understand GxE interactions in the context of ASDs, when female behaviour may present a contributing factor in postnatal neurodevelopmental trajectory.

Autistic-like behaviour and changes in thalamic cell numbers a rat model of valproic acid-induced autism; A behavioural and stereological study

The contribution of the thalamus to the development and behavioural changes in autism spectrum disorders (ASD), a neurodevelopmental syndrome, remains unclear. The aim of this study was to determine the changes in thalamic volume and cell number in the valproic acid (VPA)-induced ASD model using stereological methods and to clarify the relationship between thalamus and ASD-like behaviour. Ten pregnant rats were administered a single dose (600 mg/kg) of VPA intraperitoneally on G12.5 (VPA group), while five pregnant rats were injected with 5 ml saline (control group). Behavioural tests were performed to determine appropriate subjects and ASD-like behaviours. At P55, the brains of the subjects were removed. The sagittal sections were stained with cresyl violet and toluidine blue. The thalamic and hemispheric volumes with their ratios, the total number of thalamic cells, neurons and non-neuronal cells were calculated using stereological methods. Data were compared using a t-test and a Pearson correlation analysis was performed to examine the relationship between behaviour and stereological outcomes. VPA-treated rats had lower sociability and sociability indexes. There was no difference in social novelty preference and anxiety. The VPA group had larger hemispheric volume, lower thalamic volume, and fewer neurons. The highest percentage decrease was in non-neuronal cells. There was a moderate positive correlation between the number of non-neuronal cells and sociability, thalamic volume and the number of neurons as well as the time spent in the light box. The correlation between behaviour and stereological data suggests that the thalamus is associated with ASD-like behaviour.

Sex-specific modulation of early life vocalization and cognition by Fmr1 gene dosage in a mouse model of Fragile X Syndrome

BACKGROUND

Pup-dam ultrasonic vocalizations (USVs) are essential to cognitive and socio-emotional development. In autism and Fragile X Syndrome (FXS), disruptions in pup-dam USV communication hint at a possible connection between abnormal early developmental USV communication and the later emergence of communication and social deficits.

METHODS

Here, we gathered USVs from PND 10 FXS pups during a short period of separation from their mothers, encompassing animals of all possible genotypes and both sexes (i.e., Fmr1-/y vs. Fmr1+/y males and Fmr1+/+, +/-, and -/- females). This allowed comparing the influence of sex and gene dosage on pups' communication capabilities. Leveraging DeepSqueak and analyzing vocal patterns, intricate vocal behaviors such as call structure, duration, frequency modulation, and temporal patterns were examined. Furthermore, homing behavior was assessed as a sensitive indicator of early cognitive development and social discrimination. This behavior relies on the use of olfactory and thermal cues to navigate and search for the maternal or nest odor in the surrounding space.

RESULTS

The results show that FMRP-deficient pups of both sexes display an increased inclination to vocalize when separated from their mothers, and this behavior is accompanied by significant sex-specific changes in the main features of their USVs as well as in body weight. Analysis of the vocal repertoire and syntactic usage revealed that Fmr1 gene silencing primarily alters the USVs' qualitative composition in males. Moreover, sex-specific effects of Fmr1 silencing on locomotor activity and homing behavior were observed. FMRP deficiency in females increased activity, reduced nest-reaching time, and extended nest time. In males, it prolonged nest-reaching time and reduced nest time without affecting locomotion.

CONCLUSIONS

These findings highlight the interplay between Fmr1 gene dosage and sex in influencing communicative and cognitive skills during infancy.

Trans Species RNA Activity: Sperm RNA of the Father of an Autistic Child Programs Glial Cells and Behavioral Disorders in Mice

Recently, we described the alteration of six miRNAs in the serum of autistic children, their fathers, mothers, siblings, and in the sperm of autistic mouse models. Studies in model organisms suggest that noncoding RNAs participate in transcriptional modulation pathways. Using mice, approaches to alter the amount of RNA in fertilized eggs enable in vivo intervention at an early stage of development. Noncoding RNAs are very numerous in spermatozoa. Our study addresses a fundamental question: can the transfer of RNA content from sperm to eggs result in changes in phenotypic traits, such as autism? To explore this, we used sperm RNA from a normal father but with autistic children to create mouse models for autism. Here, we induced, in a single step by microinjecting sperm RNA into fertilized mouse eggs, a transcriptional alteration with the transformation in adults of glial cells into cells affected by astrogliosis and microgliosis developing deficiency disorders of the 'autism-like' type in mice born following these manipulations. Human sperm RNA alters gene expression in mice, and validates the possibility of non-Mendelian inheritance in autism.

Challenges and advanced concepts for the assessment of learning and memory function in mice

The mechanisms underlying the formation and retrieval of memories are still an active area of research and discussion. Manifold models have been proposed and refined over the years, with most assuming a dichotomy between memory processes involving non-conscious and conscious mechanisms. Despite our incomplete understanding of the underlying mechanisms, tests of memory and learning count among the most performed behavioral experiments. Here, we will discuss available protocols for testing learning and memory using the example of the most prevalent animal species in research, the laboratory mouse. A wide range of protocols has been developed in mice to test, e.g., object recognition, spatial learning, procedural memory, sequential problem solving, operant- and fear conditioning, and social recognition. Those assays are carried out with individual subjects in apparatuses such as arenas and mazes, which allow for a high degree of standardization across laboratories and straightforward data interpretation but are not without caveats and limitations. In animal research, there is growing concern about the translatability of study results and animal welfare, leading to novel approaches beyond established protocols. Here, we present some of the more recent developments and more advanced concepts in learning and memory testing, such as multi-step sequential lockboxes, assays involving groups of animals, as well as home cage-based assays supported by automated tracking solutions; and weight their potential and limitations against those of established paradigms. Shifting the focus of learning tests from the classical experimental chamber to settings which are more natural for rodents comes with a new set of challenges for behavioral researchers, but also offers the opportunity to understand memory formation and retrieval in a more conclusive way than has been attainable with conventional test protocols. We predict and embrace an increase in studies relying on methods involving a higher degree of automatization, more naturalistic- and home cage-based experimental setting as well as more integrated learning tasks in the future. We are confident these trends are suited to alleviate the burden on animal subjects and improve study designs in memory research.

Immp2l knockdown in male mice increases stimulus-driven instrumental behaviour but does not alter goal-directed learning or neuron density in cortico-striatal circuits in a model of Tourette syndrome and autism spectrum disorder

Cortico-striatal neurocircuits mediate goal-directed and habitual actions which are necessary for adaptive behaviour. It has recently been proposed that some of the core symptoms of autism spectrum disorder (ASD) and Gilles de la Tourette syndrome (GTS), such as tics and other repetitive behaviours, may emerge because of imbalances in these neurocircuits. We have recently developed a model of ASD and GTS by knocking down Immp2l, a mitochondrial gene frequently associated with these disorders. The current study sought to determine whether Immp2l knockdown (KD) in male mice alters flexible, goal- or cue- driven behaviour using procedures specifically designed to examine response-outcome and stimulus-response associations, which underlie goal-directed and habitual behaviour, respectively. Whether Immp2l KD alters neuron density in cortico-striatal neurocircuits known to regulate these behaviours was also examined. Immp2l KD mice and wild type-like mice (WT) were trained on Pavlovian and instrumental learning procedures where auditory cues predicted food delivery and lever-press responses earned a food outcome. It was demonstrated that goal-directed learning was not changed for Immp2l KD mice compared to WT mice, as lever-press responses were sensitive to changes in the value of the food outcome, and to contingency reversal and degradation. There was also no difference in the capacity of KD mice to form habitual behaviours compared to WT mice following extending training of the instrumental action. However, Immp2l KD mice were more responsive to auditory stimuli paired with food as indicated by a non-specific increase in lever response rates during Pavlovian-to-instrumental transfer. Finally, there were no alterations to neuron density in striatum or any prefrontal cortex or limbic brain structures examined. Thus, the current study suggests that Immp2l is not necessary for learned maladaptive goal or stimulus driven behaviours in ASD or GTS, but that it may contribute to increased capacity for external stimuli to drive behaviour. Alterations to stimulus-driven behaviour could potentially influence the expression of tics and repetitive behaviours, suggesting that genetic alterations to Immp2l may contribute to these core symptoms in ASD and GTS. Given that this is the first application of this battery of instrumental learning procedures to a mouse model of ASD or GTS, it is an important initial step in determining the contribution of known risk-genes to goal-directed versus habitual behaviours, which should be more broadly applied to other rodent models of ASD and GTS in the future.

Shank3 deletion in PV neurons is associated with abnormal behaviors and neuronal functions that are rescued by increasing GABAergic signaling

BACKGROUND

Phelan-McDermid syndrome (PMS) is a neurodevelopmental disorder characterized by developmental delay, intellectual disability, and autistic-like behaviors and is primarily caused by haploinsufficiency of SHANK3 gene. Currently, there is no specific treatment for PMS, highlighting the need for a better understanding of SHANK3 functions and the underlying pathophysiological mechanisms in the brain. We hypothesize that SHANK3 haploinsufficiency may lead to alterations in the inhibitory system, which could be linked to the excitatory/inhibitory imbalance observed in models of autism spectrum disorder (ASD). Investigation of these neuropathological features may shed light on the pathogenesis of PMS and potential therapeutic interventions.

METHODS

We recorded local field potentials and visual evoked responses in the visual cortex of Shank3∆11-/- mice. Then, to understand the impact of Shank3 in inhibitory neurons, we generated Pv-cre+/- Shank3Fl/Wt conditional mice, in which Shank3 was deleted in parvalbumin-positive neurons. We characterized the phenotype of this murine model and we compared this phenotype before and after ganaxolone administration.

RESULTS

We found, in the primary visual cortex, an alteration of the gain control of Shank3 KO compared with Wt mice, indicating a deficit of inhibition on pyramidal neurons. This alteration was rescued after the potentiation of GABAA receptor activity by Midazolam. Behavioral analysis showed an impairment in grooming, memory, and motor coordination of Pv-cre+/- Shank3Fl/Wt compared with Pv-cre+/- Shank3Wt/Wt mice. These deficits were rescued with ganaxolone, a positive modulator of GABAA receptors. Furthermore, we demonstrated that treatment with ganaxolone also ameliorated evocative memory deficits and repetitive behavior of Shank3 KO mice.

LIMITATIONS

Despite the significant findings of our study, some limitations remain. Firstly, the neurobiological mechanisms underlying the link between Shank3 deletion in PV neurons and behavioral alterations need further investigation. Additionally, the impact of Shank3 on other classes of inhibitory neurons requires further exploration. Finally, the pharmacological activity of ganaxolone needs further characterization to improve our understanding of its potential therapeutic effects.

CONCLUSIONS

Our study provides evidence that Shank3 deletion leads to an alteration in inhibitory feedback on cortical pyramidal neurons, resulting in cortical hyperexcitability and ASD-like behavioral problems. Specifically, cell type-specific deletion of Shank3 in PV neurons was associated with these behavioral deficits. Our findings suggest that ganaxolone may be a potential pharmacological approach for treating PMS, as it was able to rescue the behavioral deficits in Shank3 KO mice. Overall, our study highlights the importance of investigating the role of inhibitory neurons and potential therapeutic interventions in neurodevelopmental disorders such as PMS.

Ultrasonic vocalizations in laboratory mice: strain, age, and sex differences

Mice produce ultrasonic vocalizations (USVs) in different social contexts across lifespan. There is ethological evidence that pup USVs elicit maternal retrieval and adult USVs facilitate social interaction with a conspecific. Analysis of mouse vocal and social repertoire across strains, sex and contexts remains not well explored. To address these issues, in inbred (C57BL/6, FVB) and outbred (CD-1) mouse strains, we recorded and evaluated USVs as neonates and during adult social encounters (male-female and female-female social interaction). We showed significant strain differences in the quantitative (call rate and duration of USVs) and qualitative vocal analysis (spectrographic characterization) from early stage to adulthood, in line with specific patterns of social behaviors. Inbred C57BL/6 mice produced a lower number of calls with less internal changes and shorter duration; inbred FVB mice displayed more social behaviors and produced more syllables with repeated internal changes; outbred CD-1 mice had an intermediate profile. Our results suggest specific vocal signatures in each mouse strain, thus helping to better define socio-communicative profiles of mouse strains and to guide the choice of an appropriate strain according to the experimental settings.

Postweaning social isolation and autism-like phenotype: a biochemical and behavioral comparative analysis

Adolescence is a critical period for brain development. In most mammalian species, disturbances experienced during adolescence constitute a risk factor for several neuropsychiatric disorders. In this study, we compared the biochemical and behavioral profile induced by postweaning social isolation (PWSI) in inbred C57BL/6N mice with that of BTBR mice, a rodent model of autism spectrum disorders. Male C57BL/6N mice were either housed in groups of four or isolated from weaning (postnatal day 21) for four weeks before experimental analyses. After weaning, male BTBR mice were housed four per cage and analyzed at 48 days of age. PWSI reduced hippocampal levels of type 2 metabotropic glutamate (mGlu2) receptors, and glucocorticoid and mineralocorticoid receptors. A similar reduction was seen in group-housed BTBR mice. Plasma corticosterone levels in basal conditions were not influenced by PWSI, but were increased in BTBR mice. Social investigation (total and head sniffing) and the number of ultrasonic vocalizations were reduced in both PWSI mice and age-matched group-housed BTBR mice, indicating a lower social responsiveness in both groups of mice. These results suggest that absence of social stimuli during adolescence induces an endophenotype with social deficit features, which mimics the phenotype of a mouse model of autism spectrum disorders.

Reconsidering animal models used to study autism spectrum disorder: Current state and optimizing future

Neurodevelopmental disorders (NDDs), including autism spectrum disorder (ASD) and intellectual disability (ID), are pervasive, often lifelong disorders, lacking evidence-based interventions for core symptoms. With no established biological markers, diagnoses are defined by behavioral criteria. Thus, preclinical in vivo animal models of NDDs must be optimally utilized. For this reason, experts in the field of behavioral neuroscience convened a workshop with the goals of reviewing current behavioral studies, reports, and assessments in rodent models. Goals included: (a) identifying the maximal utility and limitations of behavior in animal models with construct validity; (b) providing recommendations for phenotyping animal models; and (c) guidelines on how in vivo models should be used and reported reliably and rigorously while acknowledging their limitations. We concluded by recommending minimal criteria for reporting in manuscripts going forward. The workshop elucidated a consensus of potential solutions to several problems, including revisiting claims made about animal model links to ASD (and related conditions). Specific conclusions included: mice (or other rodent or preclinical models) are models of the neurodevelopmental insult, not specifically any disorder (e.g., ASD); a model that perfectly recapitulates a disorder such as ASD is untenable; and greater attention needs be given to validation of behavioral testing methods, data analysis, and critical interpretation.

Mitochondrial function influences expression of methamphetamine-induced behavioral sensitization

Repeated methamphetamine use leads to long lasting brain and behavioral changes in humans and laboratory rats. These changes have high energy requirements, implicating a role for mitochondria. We explored whether mitochondrial function underpins behaviors that occur in rats months after stopping methamphetamine self-administration. Accordingly, rats self-administered intravenous methamphetamine for 3 h/day for 14 days. The mitochondrial toxin rotenone was administered as (1 mg/kg/day for 6 days) via an osmotic minipump starting at 0, 14 or 28 days of abstinence abstinence. On abstinence day 61, expression of methamphetamine-induced behavioral sensitization was obtained with an acute methamphetamine challenge in rotenone-free rats. Rotenone impeded the expression of sensitization, with the most robust effects obtained with later abstinence exposure. These findings verified that self-titration of moderate methamphetamine doses results in behavioral (and thus brain) changes that can be revealed months after exposure termination, and that the meth-initiated processes progressed during abstinence so that longer abstinence periods were more susceptible to the consequences of exposure to a mitochondrial toxin.

Auditory hypersensitivity and processing deficits in a rat model of fragile X syndrome

Fragile X (FX) syndrome is one of the leading inherited causes of autism spectrum disorder (ASD). A majority of FX and ASD patients exhibit sensory hypersensitivity, including auditory hypersensitivity or hyperacusis, a condition in which everyday sounds are perceived as much louder than normal. Auditory processing deficits in FX and ASD also afford the opportunity to develop objective and quantifiable outcome measures that are likely to translate between humans and animal models due to the well-conserved nature of the auditory system and well-developed behavioral read-outs of sound perception. Therefore, in this study we characterized auditory hypersensitivity in a Fmr1 knockout (KO) transgenic rat model of FX using an operant conditioning task to assess sound detection thresholds and suprathreshold auditory reaction time-intensity (RT-I) functions, a reliable psychoacoustic measure of loudness growth, at a variety of stimulus frequencies, bandwidths, and durations. Male Fmr1 KO and littermate WT rats both learned the task at the same rate and exhibited normal hearing thresholds. However, Fmr1 KO rats had faster auditory RTs over a broad range of intensities and steeper RT-I slopes than WT controls, perceptual evidence of excessive loudness growth in Fmr1 KO rats. Furthermore, we found that Fmr1 KO animals exhibited abnormal perceptual integration of sound duration and bandwidth, with diminished temporal but enhanced spectral integration of sound intensity. Because temporal and spectral integration of sound stimuli were altered in opposite directions in Fmr1 KO rats, this suggests that abnormal RTs in these animals are evidence of aberrant auditory processing rather than generalized hyperactivity or altered motor responses. Together, these results are indicative of fundamental changes to low-level auditory processing in Fmr1 KO animals. Finally, we demonstrated that antagonism of metabotropic glutamate receptor 5 (mGlu5) selectively and dose-dependently restored normal loudness growth in Fmr1 KO rats, suggesting a pharmacologic approach for alleviating sensory hypersensitivity associated with FX. This study leverages the tractable nature of the auditory system and the unique behavioral advantages of rats to provide important insights into the nature of a centrally important yet understudied aspect of FX and ASD.

The Mouse Action Recognition System (MARS) software pipeline for automated analysis of social behaviors in mice

The study of naturalistic social behavior requires quantification of animals' interactions. This is generally done through manual annotation-a highly time-consuming and tedious process. Recent advances in computer vision enable tracking the pose (posture) of freely behaving animals. However, automatically and accurately classifying complex social behaviors remains technically challenging. We introduce the Mouse Action Recognition System (MARS), an automated pipeline for pose estimation and behavior quantification in pairs of freely interacting mice. We compare MARS's annotations to human annotations and find that MARS's pose estimation and behavior classification achieve human-level performance. We also release the pose and annotation datasets used to train MARS to serve as community benchmarks and resources. Finally, we introduce the Behavior Ensemble and Neural Trajectory Observatory (BENTO), a graphical user interface for analysis of multimodal neuroscience datasets. Together, MARS and BENTO provide an end-to-end pipeline for behavior data extraction and analysis in a package that is user-friendly and easily modifiable.

Ultrasonic vocalizations in mice: relevance for ethologic and neurodevelopmental disorders studies

Mice use ultrasonic vocalizations (USVs) to communicate each other and to convey their emotional state. USVs have been greatly characterized in specific life phases and contexts, such as mother isolation-induced USVs for pups or female-induced USVs for male mice during courtship. USVs can be acquired by means of specific tools and later analyzed on the base of both quantitative and qualitative parameters. Indeed, different ultrasonic call categories exist and have already been defined. The understanding of different calls meaning is still missing, and it will represent an essential step forward in the field of USVs. They have long been studied in the ethological context, but recently they emerged as a precious instrument to study pathologies characterized by deficits in communication, in particular neurodevelopmental disorders (NDDs), such as autism spectrum disorders. This review covers the topics of USVs characteristics in mice, contexts for USVs emission and factors that modulate their expression. A particular focus will be devoted to mouse USVs in the context of NDDs. Indeed, several NDDs murine models exist and an intense study of USVs is currently in progress, with the aim of both performing an early diagnosis and to find a pharmacological/behavioral intervention to improve patients' quality of life.

Maternal anesthesia with sevoflurane during the mid-gestation induces social interaction deficits in offspring C57BL/6 mice

Sevoflurane anesthesia in pregnant mice could induce neurotoxicity in the developing brain and disturb learning and memory in the offspring mice. Whether it could impair social behaviors in the offspring mice is uncertain. Therefore, we assessed the neurobehavioral effect of in-utero exposure to sevoflurane on social interaction behaviors in C57BL/6 mice. The pregnant mice were anesthetized with 2.5% sevoflurane in 100% oxygen for 2 h, and their offspring mice were tested in three-chambered social paradigm, which includes three 10-min sessions of habituation, sociability, and preference for social novelty. At the juvenile age, the offspring mice showed abnormal sociability, as proved by not taking more time sniffing at the stranger 1 mouse compared with the empty enclosure (108.5 ± 25.4 vs. 108.2 ± 44.0 s, P = 0.9876). Meanwhile, these mice showed impaired preference for social novelty, as evidenced by not taking more time sniffing at the stranger 2 compared with the stranger 1 mouse (92.1 ± 52.2 vs. 126.7 ± 50.8 s, P = 0.1502). At the early adulthood, the offspring mice retrieved the normal sociability (145.6 ± 33.2 vs. 76.0 ± 31.8 s, P = 0.0001), but remained the impaired preference for social novelty (100.6 ± 29.3 vs. 118.0 ± 47.9 s, P = 0.3269). Collectively, these results suggested maternal anesthesia with sevoflurane could induce social interaction deficits in their offspring mice. Although the disturbance of sociability could be recoverable, the impairment of preference for social novelty could be long-lasting.

Neural Mechanisms Underlying Repetitive Behaviors in Rodent Models of Autism Spectrum Disorders

Autism spectrum disorder (ASD) is comprised of several conditions characterized by alterations in social interaction, communication, and repetitive behaviors. Genetic and environmental factors contribute to the heterogeneous development of ASD behaviors. Several rodent models display ASD-like phenotypes, including repetitive behaviors. In this review article, we discuss the potential neural mechanisms involved in repetitive behaviors in rodent models of ASD and related neuropsychiatric disorders. We review signaling pathways, neural circuits, and anatomical alterations in rodent models that display robust stereotypic behaviors. Understanding the mechanisms and circuit alterations underlying repetitive behaviors in rodent models of ASD will inform translational research and provide useful insight into therapeutic strategies for the treatment of repetitive behaviors in ASD and other neuropsychiatric disorders.

CD103 Deficiency Promotes Autism (ASD) and Attention-Deficit Hyperactivity Disorder (ADHD) Behavioral Spectra and Reduces Age-Related Cognitive Decline

The incidence of autism spectrum disorders (ASD) and attention deficit hyperactivity disorder (ADHD), which frequently co-occur, are both rising. The causes of ASD and ADHD remain elusive, even as both appear to involve perturbation of the gut-brain-immune axis. CD103 is an integrin and E-cadherin receptor most prominently expressed on CD8 T cells that reside in gut, brain, and other tissues. CD103 deficiency is well-known to impair gut immunity and resident T cell function, but it's impact on neurodevelopmental disorders has not been examined. We show here that CD8 T cells influence neural progenitor cell function, and that CD103 modulates this impact both directly and potentially by controlling CD8 levels in brain. CD103 knockout (CD103KO) mice exhibited a variety of behavioral abnormalities, including superior cognitive performance coupled with repetitive behavior, aversion to novelty and social impairment in females, with hyperactivity with delayed learning in males. Brain protein markers in female and male CD103KOs coincided with known aspects of ASD and ADHD in humans, respectively. Surprisingly, CD103 deficiency also decreased age-related cognitive decline in both sexes, albeit by distinct means. Together, our findings reveal a novel role for CD103 in brain developmental function, and identify it as a unique factor linking ASD and ADHD etiology. Our data also introduce a new animal model of combined ASD and ADHD with associated cognitive benefits, and reveal potential therapeutic targets for these disorders and age-related cognitive decline.

Hippocampal Lnx1-NMDAR multiprotein complex mediates initial social memory

Social interaction and communication are evolutionary conserved behaviours that are developed in mammals to establish partner cognition. Deficit in sociability has been represented in human patients and animal models of neurodevelopmental disorders, which are connected with genetic variants of synaptic glutamate receptors and associated PDZ-binding proteins. However, it remains elusive how these key proteins are specialized in the cellular level for the initial social behaviour during postnatal developmental stage. Here we identify a hippocampal CA3 specifically expressed PDZ scaffold protein Lnx1 required for initial social behaviour. Through gene targeting we find that Lnx1 deficiency led to a hippocampal subregional disorder in neuronal activity and social memory impairments for partner discrimination observed in juvenile mice which also show cognitive defects in adult stage. We further demonstrate that Lnx1 deletion causes NMDA receptor (NMDAR) hypofunction and this is attributable to decreased GluN2B expression in PSD compartment and disruption of the Lnx1-NMDAR-EphB2 complex. Specific restoration of Lnx1 or EphB2 protein in the CA3 area of Lnx1^-/- mice rescues the defective synaptic function and social memory. These findings thus reveal crucial roles of postsynaptic NMDAR multiprotein complex that regulates the formation of initial social memory during the adolescent period.

Mouse model systems of autism spectrum disorder: Replicability and informatics signature

Phenotyping mouse model systems of human disease has proven to be a difficult task, with frequent poor inter- and intra-laboratory replicability, particularly in behavioral domains such as social and cognitive function. However, establishing robust animal model systems with strong construct validity is of fundamental importance as they are central tools for understanding disease pathophysiology and developing therapeutics. To complete our studies of mouse model systems relevant to autism spectrum disorder (ASD), we present a replication of the main findings from our two published studies of five genetic mouse model systems of ASD. To assess the intra-laboratory robustness of previous results, we chose the two model systems that showed the greatest phenotypic differences, the Shank3/F and Cntnap2, and repeated assessments of general health, activity and social behavior. We additionally explored all five model systems in the same framework, comparing all results obtained in this three-yearlong effort using informatics techniques to assess commonalities and differences. Our results showed high intra-laboratory replicability of results, even for those with effect sizes that were not particularly large, suggesting that discrepancies in the literature may be dependent on subtle but pivotal differences in testing conditions, housing enrichment, or background strains and less so on the variability of the behavioral phenotypes. The overall informatics analysis suggests that in our behavioral assays we can separate the set of tested mouse model system into two main classes that in some aspects lie on opposite ends of the behavioral spectrum, supporting the view that autism is not a unitary concept.

A heritable profile of six miRNAs in autistic patients and mouse models

Autism spectrum disorder (ASD) is a group of developmental pathologies that impair social communication and cause repetitive behaviors. The suggested roles of noncoding RNAs in pathology led us to perform a comparative analysis of the microRNAs expressed in the serum of human ASD patients. The analysis of a cohort of 45 children with ASD revealed that six microRNAs (miR-19a-3p, miR-361-5p, miR-3613-3p, miR-150-5p, miR-126-3p, and miR-499a-5p) were expressed at low to very low levels compared to those in healthy controls. A similar but less pronounced decrease was registered in the clinically unaffected parents of the sick children and in their siblings but never in any genetically unrelated control. Results consistent with these observations were obtained in the blood, hypothalamus and sperm of two of the established mouse models of ASD: valproic acid-treated animals and Cc2d1a^+/- heterozygotes. In both instances, the same characteristic miRNA profile was evidenced in the affected individuals and inherited together with disease symptoms in the progeny of crosses with healthy animals. The consistent association of these genetic regulatory changes with the disease provides a starting point for evaluating the changes in the activity of the target genes and, thus, the underlying mechanism(s). From the applied societal and medical perspectives, once properly confirmed in large cohorts, these observations provide tools for the very early identification of affected children and progenitors.

Gene Expressions, Hippocampal Volume Loss, and MMSE Scores in Computation of Progression and Pharmacologic Therapy Effects for Alzheimer's Disease

We build personalized relevance parameterization method (prep-ad) based on artificial intelligence (ai) techniques to compute Alzheimer's disease (ad) progression for patients at the mild cognitive impairment (mci) stage. Expressions of ad related genes, mini mental state examination (mmse) scores, and hippocampal volume measurements of mci patients are obtained from the Alzheimer's Disease Neuroimaging Initiative (adni) database. In evaluation of cognitive changes under pharmacological therapies, patients are grouped based on available clinical measurements and the type of therapy administered, namely donepezil monotherapy and polytherapy of donepezil with memantine. Average leave one out cross validation (loocv) error rates are calculated for prep-ad results as less than 8 percent when mmse scores are used to compute disease progression for a 60 month period, and 3 percent with hippocampal volume measurements for 12 months. Statistical significance is calculated as p = 0.003 for using ad related genes in disease progression and as for the results computed by prep-ad. These relatively small average loocv errors and p-values suggest that our prep-ad methods employing gene expressions, mmse scores and hippocampal volume loss measurements can be useful in supporting pharmacologic therapy decisions during early stages of ad.

Resveratrol in Autism Spectrum Disorders: Behavioral and Molecular Effects

Resveratrol (RSV) is a polyphenolic stillbenoid with significant anti-oxidative and anti-inflammatory properties recently tested in animal models of several neurological diseases. Altered immune alteration and oxidative stress have also been found in patients with autism spectrum disorders (ASD), and these alterations could add to the pathophysiology associated with ASD. We reviewed the current evidence about the effects of RSV administration in animal models and in patients with ASD. RSV administration improves the core-symptoms (social impairment and stereotyped activity) in animal models and it also displays beneficial effects in other behavioral abnormalities such as hyperactivity, anxiety and cognitive function. The molecular mechanisms by which RSV restores or improves behavioral abnormalities in animal models encompass both normalization of central and peripheral immune alteration and oxidative stress markers and new molecular mechanisms such as expression of cortical gamma-amino butyric acid neurons, certain type of miRNAs that regulate spine growth. One randomized, placebo-controlled clinical trial (RCT) suggested that RSV add-on risperidone therapy improves comorbid hyperactivity/non-compliance, whereas no effects where seen in core symptoms of ASD No RCTs about the effect of RSV as monotherapy have been performed and the results from preclinical studies encourage its feasibility. Further clinical trials should also identify those ASD patients with immune alterations and/or with increased oxidative stress markers that would likely benefit from RSV administration.

Genetic backgrounds have unique seizure response profiles and behavioral outcomes following convulsant administration

Three highly utilized strains of mice, common for preclinical genetic studies, were evaluated for seizure susceptibility and behavioral outcomes common to the clinical phenotypes of numerous psychiatric disorders following repeated low-dose treatment with either a gamma-aminobutyric acid (GABA) receptor antagonist (pentylenetetrazole (PTZ)) or a glutamate agonist (kainic acid (KA)). Effects of strain and treatment were evaluated with classic seizure scoring and a tailored behavior battery focused on behavioral domains common in neuropsychiatric research: learning and memory, social behavior, and motor abilities, as well as seizure susceptibility and/or resistance. Seizure response was induced by a single daily treatment of either PTZ (30 mg/kg, intraperitoneally (i.p.)) or KA (5 mg/kg, i.p.) for 10 days. Pentylenetetrazole-treated FVB/NJ and C57BL/6NJ strains of mice showed strong, clear seizure responses. This also resulted in cognitive and social deficits, and increased susceptibility to a high dose of PTZ. Kainic acid-treated FVB/NJ and C57BL/6NJ strains of mice had a robust seizure response, which resulted in hyperactivity. Pentylenetetrazole-treated C57BL/6J mice demonstrated mild hyperactivity, while KA-treated C57BL/6J displayed cognitive deficits and resistance to a high dose of KA but no social deficits. Overall, a uniquely different seizure response profile was detected in the C57BL/6J strain with few observable instances of seizure response despite repeated convulsant administration by two mechanisms. This work illustrated that differing background genetic strains have unique seizure susceptibility profiles and distinct social and cognitive behavior following PTZ and/or KA treatment and that it is, therefore, necessary to consider strain differences before attributing behavioral phenotypes to gene(s) of interest during preclinical evaluations of genetic mouse models, especially when outcome measures are focused on cognitive and/or social behaviors common to the clinical features of numerous neurological disorders.

Bridging the species gap in translational research for neurodevelopmental disorders

The prevalence and societal impact of neurodevelopmental disorders (NDDs) continue to increase despite years of research in both patient populations and animal models. There remains an urgent need for translational efforts between clinical and preclinical research to (i) identify and evaluate putative causes of NDD, (ii) determine their underlying neurobiological mechanisms, (iii) develop and test novel therapeutic approaches, and (iv) translate basic research into safe and effective clinical practices. Given the complexity behind potential causes and behaviors affected by NDDs, modeling these uniquely human brain disorders in animals will require that we capitalize on unique advantages of a diverse array of species. While much NDD research has been conducted in more traditional animal models such as the mouse, ultimately, we may benefit from creating animal models with species that have a more sophisticated social behavior repertoire such as the rat (Rattus norvegicus) or species that more closely related to humans, such as the rhesus macaque (Macaca mulatta). Here, we highlight the rat and rhesus macaque models for their role in previous psychological research discoveries, current efforts to understand the neurobiology of NDDs, and focus on the convergence of behavior outcome measures that parallel features of human NDDs.

Increased oxidative stress in the cerebellum and peripheral immune cells leads to exaggerated autism-like repetitive behavior due to deficiency of antioxidant response in BTBR T + tf/J mice

Autism is a neurodevelopmental disorder that affects social cognitive abilities resulting in communication or sensory deficits, and stereotyped behaviors in millions of people worldwide. Oxidant-antioxidant imbalance contributes significantly to the neurobehavioral dysregulations and severity of symptoms in patients with autism, however it has not been explored earlier whether it affects autism-like behavior directly. Therefore, we investigated oxidant-antioxidant balance in peripheral immune cells (neutrophils and CD3+ T cells) and cerebellum of BTBR T + tf/J (BTBR) mice which show autism-like behavior and the social C57BL/6 J (C57) mice. Further, we utilized buthionine sulfoximine (BSO), a glutathione depleting agent to assess the impact of oxidant-antioxidant dysregulation on autism-like behavior. Our study shows that BTBR mice have increased lipid/protein oxidation products in cerebellum and neutrophils/CD3+ T cells along with increased NADPH oxidase (NOX2) and inducible nitric oxide synthase (iNOS) expression. This was concurrent with lower levels of glutathione and enzymatic antioxidants such as superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the cerebellum and peripheral immune cells. BSO administration led to further lowering of glutathione with a concurrent upregulation of iNOS, and NOX2 in cerebellum and peripheral immune cells. However, there was deficiency of an adaptive antioxidant response which was associated with exaggerated repetitive behaviors in BTBR mice. On the other hand, C57 mice also had increased oxidative stress after BSO treatment, however there was an enzymatic antioxidant response both in cerebellum and periphery. Overall, this study suggests that BTBR mice have increased oxidative stress with a deficient enzymatic antioxidant response that is associated with autism-like repetitive behaviors.

Evidence for Brainstem Contributions to Autism Spectrum Disorders

Autism spectrum disorder (ASD) is a neurodevelopmental condition that affects one in 59 children in the United States. Although there is a mounting body of knowledge of cortical and cerebellar contributions to ASD, our knowledge about the early developing brainstem in ASD is only beginning to accumulate. Understanding how brainstem neurotransmission is implicated in ASD is important because many of this condition’s sensory and motor symptoms are consistent with brainstem pathology. Therefore, the purpose of this review was to integrate epidemiological, behavioral, histological, neuroimaging, and animal evidence of brainstem contributions to ASD. Because ASD is a neurodevelopmental condition, we examined the available data through a lens of hierarchical brain development. The review of the literature suggests that developmental alterations of the brainstem could have potential cascading effects on cortical and cerebellar formation, ultimately leading to ASD symptoms. This view is supported by human epidemiology findings and data from animal models of ASD, showing that perturbed development of the brainstem substructures, particularly during the peak formation of the brainstem’s monoaminergic centers, may relate to ASD or ASD-like behaviors. Furthermore, we review evidence from human histology, psychophysiology, and neuroimaging suggesting that brainstem development and maturation may be atypical in ASD and may be related to key ASD symptoms, such as atypical sensorimotor features and social responsiveness. From this review there emerges the need of future research to validate early detection of the brainstem-based somatosensory and psychophysiological behaviors that emerge in infancy, and to examine the brainstem across the life span, while accounting for age. In all, there is preliminary evidence for brainstem involvement in ASD, but a better understanding of the brainstem’s role would likely pave the way for earlier diagnosis and treatment of ASD.

Sociability in Fruit Flies: Genetic Variation, Heritability and Plasticity

Sociability, defined as individuals' propensity to participate in non-aggressive activities with conspecifics, is a fundamental feature of behavior in many animals including humans. However, we still have a limited knowledge of the mechanisms and evolutionary biology of sociability. To enhance our understanding, we developed a new protocol to quantify sociability in fruit flies (Drosophila melanogaster). In a series of experiments with 59 F1 hybrids derived from inbred lines, we documented, first, significant genetic variation in sociability in both males and females, with broad-sense heritabilities of 0.24 and 0.21 respectively. Second, we observed little genetic correlation in sociability between the sexes. Third, we found genetic variation in social plasticity among the hybrids, with a broad-sense heritability of ~0.24. That is, genotypes differed in the degree of sociability after experiencing the same relevant social experience. Our data pave the way for further research on the mechanisms that underlie sociability as well as its ecological and evolutionary consequences.

Maternal immune activation in neurodevelopmental disorders

Converging lines of evidence from basic science and clinical studies suggest a relationship between maternal immune activation (MIA) and neurodevelopmental disorders such as autism spectrum disorder (ASD) and schizophrenia. The mechanisms through which MIA increases the risk of neurodevelopmental disorders have become a subject of intensive research. This review aims to describe how dysregulation of microglial function and immune mechanisms may link MIA and neurodevelopmental pathologies. We also summarize the current evidence in animal models of MIA. Developmental Dynamics 247:588-619, 2018. © 2017 Wiley Periodicals, Inc.

A novel system for tracking social preference dynamics in mice reveals sex- and strain-specific characteristics

Background

Deciphering the biological mechanisms underlying social behavior in animal models requires standard behavioral paradigms that can be unbiasedly employed in an observer- and laboratory-independent manner. During the past decade, the three-chamber test has become such a standard paradigm used to evaluate social preference (sociability) and social novelty preference in mice. This test suffers from several caveats, including its reliance on spatial navigation skills and negligence of behavioral dynamics.

Methods

Here, we present a novel experimental apparatus and an automated analysis system which offer an alternative to the three-chamber test while solving the aforementioned caveats. The custom-made apparatus is simple for production, and the analysis system is publically available as an open-source software, enabling its free use. We used this system to compare the dynamics of social behavior during the social preference and social novelty preference tests between male and female C57BL/6J mice.

Results

We found that in both tests, male mice keep their preference towards one of the stimuli for longer periods than females. We then employed our system to define several new parameters of social behavioral dynamics in mice and revealed that social preference behavior is segregated in time into two distinct phases. An early exploration phase, characterized by high rate of transitions between stimuli and short bouts of stimulus investigation, is followed by an interaction phase with low transition rate and prolonged interactions, mainly with the preferred stimulus. Finally, we compared the dynamics of social behavior between C57BL/6J and BTBR male mice, the latter of which are considered as asocial strain serving as a model for autism spectrum disorder. We found that BTBR mice (n = 8) showed a specific deficit in transition from the exploration phase to the interaction phase in the social preference test, suggesting a reduced tendency towards social interaction.

Conclusions

We successfully employed our new experimental system to unravel previously unidentified sex- and strain-specific differences in the dynamics of social behavior in mice. Thus, the system presented here facilitates a more thorough and detailed analysis of social behavior in small rodent models, enabling a better comparison between strains and treatments.

Electronic supplementary material

The online version of this article (10.1186/s13229-017-0169-1) contains supplementary material, which is available to authorized users.

Epigenetics of Autism Spectrum Disorder

Autism spectrum disorder (ASD), one of the most common childhood neurodevelopmental disorders (NDDs), is diagnosed in 1 of every 68 children. ASD is incredibly heterogeneous both clinically and aetiologically. The etiopathogenesis of ASD is known to be complex, including genetic, environmental and epigenetic factors. Normal epigenetic marks modifiable by both genetics and environmental exposures can result in epigenetic alterations that disrupt the regulation of gene expression, negatively impacting biological pathways important for brain development. In this chapter we aim to summarize some of the important literature that supports a role for epigenetics in the underlying molecular mechanism of ASD. We provide evidence from work in genetics, from environmental exposures and finally from more recent studies aimed at directly determining ASD-specific epigenetic patterns, focusing mainly on DNA methylation (DNAm). Finally, we briefly discuss some of the implications of current research on potential epigenetic targets for therapeutics and novel avenues for future work.

Social propinquity in rodents as measured by tube cooccupancy differs between inbred and outbred genotypes

Existing assays of social interaction are suboptimal, and none measures propinquity, the tendency of rodents to maintain close physical proximity. These assays are ubiquitously performed using inbred mouse strains and mutations placed on inbred genetic backgrounds. We developed the automatable tube cooccupancy test (TCOT) based on propinquity, the tendency of freely mobile rodents to maintain close physical proximity, and assessed TCOT behavior on a variety of genotypes and social and environmental conditions. In outbred mice and rats, familiarity determined willingness to cooccupy the tube, with siblings and/or cagemates of both sexes exhibiting higher cooccupancy behavior than strangers. Subsequent testing using multiple genotypes revealed that inbred strain siblings do not cooccupy at higher rates than strangers, in marked contrast to both outbred and rederived wild mice. Mutant mouse strains with "autistic-like" phenotypes (Fmr1^-/y and Eif4e Ser209Ala) displayed significantly decreased cooccupancy.

RELN Mutations in Autism Spectrum Disorder

RELN encodes a large, secreted glycoprotein integral to proper neuronal positioning during development and regulation of synaptic function postnatally. Rare, homozygous, null mutations lead to lissencephaly with cerebellar hypoplasia (LCH), accompanied by developmental delay and epilepsy. Until recently, little was known about the frequency or consequences of heterozygous mutations. Several lines of evidence from multiple studies now implicate heterozygous mutations in RELN in autism spectrum disorders (ASD). RELN maps to the AUTS1 locus on 7q22, and at this time over 40 distinct mutations have been identified that would alter the protein sequence, four of which are de novo. The RELN mutations that are most clearly consequential are those that are predicted to inactivate the signaling function of the encoded protein and those that fall in a highly conserved RXR motif found at the core of the 16 Reelin subrepeats. Despite the growing evidence of RELN dysfunction in ASD, it appears that these mutations in isolation are insufficient and that secondary genetic or environmental factors are likely required for a diagnosis.

Glutamatergic medication in the treatment of obsessive compulsive disorder (OCD) and autism spectrum disorder (ASD) - study protocol for a randomised controlled trial

BACKGROUND

Compulsivity is a cross-disorder trait underlying phenotypically distinct psychiatric disorders that emerge in childhood or adolescence. Despite the effectiveness of serotonergic compounds in the treatment of obsessive-compulsive disorder, treatment-resistant symptoms remaining in 40 to 60 % of patients present a pressing clinical problem. There are currently no medications that effectively treat the core impairments of autism spectrum disorder. There is an urgent need for the development of conceptually novel pharmacological strategies. Agents targeting glutamate neurotransmission, such as memantine, represent promising candidates. This proof-of-concept clinical study will allow pilot-testing of memantine for both clinical effectiveness and tolerability/safety. Memantine is an N-methyl-D-aspartate receptor antagonist, approved for the treatment of Alzheimer's dementia in a number of countries.

METHODS/DESIGN

This 12-week study has an add-on, randomised, double-blind, placebo-controlled design of treatment with memantine, including an up-titration phase (forced flexible dose design, 5-15 mg/day), in patients aged 6-17 years and 9 months with obsessive-compulsive disorder or autism spectrum disorder. It is planned to include patients with obsessive-compulsive disorder (N = 50) or autism spectrum disorder (N = 50) across four centres in three European countries. Patients will be randomly assigned to memantine or placebo in a 1:1 ratio. Primary objectives are the investigation of the effectiveness of memantine in paediatric patients for improving symptoms of compulsivity (primary outcome measure: total score on the Children's Yale-Brown Obsessive-Compulsive Scale) and to explore its tolerability and safety. Secondary objectives are to explore the effects of memantine at the level of structure, function and biochemistry of the fronto-striatal circuits, and to collect blood for genetic analyses and biomarkers. Tertiary objectives are to explore the role of new candidate genes and pathways for compulsivity by linking genes to clinical phenotypes, response to treatment, neurocognitive test performance, and key structural and functional neuroimaging measures of the fronto-striatal circuits and to explore biomarkers/proteomics for compulsivity traits.

DISCUSSION

This study is part of the large, translational project TACTICS ( http://www.tactics-project.eu/ ) that is funded by the European Union and investigates the neural, genetic and molecular factors involved in the pathogenesis of compulsivity. Its results will provide clinically relevant solid information on potential new mechanisms and medication treatment in obsessive-compulsive and autism spectrum disorders.

TRIAL REGISTRATION

EudraCT Number: 2014-003080-38 , date of registration: 14 July 2014.

Functional Deficiencies in Fragile X Neurons Derived from Human Embryonic Stem Cells

Fragile X syndrome (FXS), the most common form of inherited mental retardation, is a neurodevelopmental disorder caused by silencing of the FMR1 gene, which in FXS becomes inactivated during human embryonic development. We have shown recently that this process is recapitulated by in vitro neural differentiation of FX human embryonic stem cells (FX-hESCs), derived from FXS blastocysts. In the present study, we analyzed morphological and functional properties of neurons generated from FX-hESCs. Human FX neurons can fire single action potentials (APs) to depolarizing current commands, but are unable to discharge trains of APs. Their APs are of a reduced amplitudes and longer durations than controls. These are reflected in reduced inward Na(+) and outward K(+) currents. In addition, human FX neurons contain fewer synaptic vesicles and lack spontaneous synaptic activity. Notably, synaptic activity in these neurons can be restored by coculturing them with normal rat hippocampal neurons, demonstrating a critical role for synaptic mechanisms in FXS pathology. This is the first extensive functional analysis of human FX neurons derived in vitro from hESCs that provides a convenient tool for studying molecular mechanisms underlying the impaired neuronal functions in FXS.

SIGNIFICANCE STATEMENT

Fragile X syndrome (FXS), the most common form of inherited mental retardation, is caused by silencing of the FMR1 gene. In this study, we describe for the first time the properties of neurons developed from human embryonic stem cells (hESCs) that carry the FMR1 mutation and are grown in culture for extended periods. These neurons are retarded compared with controls in several morphological and functional properties. In vitro neural differentiation of FX hESCs can thus serve as a most relevant system for the analysis of molecular mechanisms underlying the impaired neuronal functions in FXS.

Clinical chorioamnionitis at term V: umbilical cord plasma cytokine profile in the context of a systemic maternal inflammatory response

OBJECTIVE

Microbial invasion of the fetus due to intra-amniotic infection can lead to a systemic inflammatory response characterized by elevated concentrations of cytokines in the umbilical cord plasma/serum. Clinical chorioamnionitis represents the maternal syndrome often associated with intra-amniotic infection, although other causes of this syndrome have been recently described. The objective of this study was to characterize the umbilical cord plasma cytokine profile in neonates born to mothers with clinical chorioamnionitis at term, according to the presence or absence of bacteria and/or intra-amniotic inflammation.

MATERIALS AND METHODS

A cross-sectional study was conducted, including patients with clinical chorioamnionitis at term (n=38; cases) and those with spontaneous term labor without clinical chorioamnionitis (n=77; controls). Women with clinical chorioamnionitis were classified according to the results of amniotic fluid culture, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry (PCR/ESI-MS) and amniotic fluid interleukin (IL)-6 concentration into three groups: 1) no intra-amniotic inflammation; 2) intra-amniotic inflammation without detectable microorganisms; or 3) microbial-associated intra-amniotic inflammation. A fetal inflammatory response syndrome (FIRS) was defined as an umbilical cord plasma IL-6 concentration >11 pg/mL. The umbilical cord plasma concentrations of 29 cytokines were determined with sensitive and specific V-PLEX immunoassays. Nonparametric statistical methods were used for analysis, adjusting for a false discovery rate of 5%.

RESULTS

1) Neonates born to mothers with clinical chorioamnionitis at term (considered in toto) had significantly higher median umbilical cord plasma concentrations of IL-6, IL-12p70, IL-16, IL-13, IL-4, IL-10 and IL-8, but significantly lower interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF)-α concentrations than neonates born to mothers with spontaneous term labor without clinical chorioamnionitis; 2) neonates born to mothers with clinical chorioamnionitis at term but without intra-amniotic inflammation had higher concentrations of IL-6, IL-12p70, IL-13, IL-4, IL-5, and IL-8, but lower IFN-γ, than neonates not exposed to clinical chorioamnionitis, suggesting that maternal fever in the absence of intra-amniotic inflammation leads to a change in the fetal cytokine network; 3) there were significant, positive correlations between maternal and umbilical cord plasma IL-6 and IL-8 concentrations (IL-6: Spearman correlation=0.53; P<0.001; IL-8: Spearman correlation=0.42; P<0.001), consistent with placental transfer of cytokines; 4) an elevated fetal plasma IL-6 (>11 pg/mL), the diagnostic criterion for FIRS, was present in 21% of cases (8/38), and all these neonates were born to mothers with proven intra-amniotic infection; and 5) FIRS was associated with a high concentration of umbilical cord plasma IL-8, IL-10 and monocyte chemoattractant protein (MCP)-1.

CONCLUSIONS

Neonates born to mothers with clinical chorioamnionitis at term had higher concentrations of umbilical cord plasma cytokines than those born to mothers without clinical chorioamnionitis. Even neonates exposed to clinical chorioamnionitis but not to intra-amniotic inflammation had elevated concentrations of multiple cytokines, suggesting that intrapartum fever alters the fetal immune response.

Translational Mouse Models of Autism: Advancing Toward Pharmacological Therapeutics

Animal models provide preclinical tools to investigate the causal role of genetic mutations and environmental factors in the etiology of autism spectrum disorder (ASD). Knockout and humanized knock-in mice, and more recently knockout rats, have been generated for many of the de novo single gene mutations and copy number variants (CNVs) detected in ASD and comorbid neurodevelopmental disorders. Mouse models incorporating genetic and environmental manipulations have been employed for preclinical testing of hypothesis-driven pharmacological targets, to begin to develop treatments for the diagnostic and associated symptoms of autism. In this review, we summarize rodent behavioral assays relevant to the core features of autism, preclinical and clinical evaluations of pharmacological interventions, and strategies to improve the translational value of rodent models of autism.

Development and function of the midbrain dopamine system: what we know and what we need to

The past two decades have seen an explosion in our understanding of the origin and development of the midbrain dopamine system. Much of this work has been focused on the aspects of dopamine neuron development related to the onset of movement disorders such as Parkinson's disease, with the intent of hopefully delaying, preventing or fixing symptoms. While midbrain dopamine degeneration is a major focus for treatment and research, many other human disorders are impacted by abnormal dopamine, including drug addiction, autism and schizophrenia. Understanding dopamine neuron ontogeny and how dopamine connections and circuitry develops may provide us with key insights into potentially important avenues of research for other dopamine-related disorders. This review will provide a brief overview of the major molecular and genetic players throughout the development of midbrain dopamine neurons and what we know about the behavioral- and disease-related implications associated with perturbations to midbrain dopamine neuron development. We intend to combine the knowledge of two broad fields of neuroscience, both developmental and behavioral, with the intent on fostering greater discussion between branches of neuroscience in the service of addressing complex cognitive questions from a developmental perspective and identifying important gaps in our knowledge for future study.

Understanding the molecular basis of autism in a dish using hiPSCs-derived neurons from ASD patients

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by deficits in social cognition, language development, and repetitive/restricted behaviors. Due to the complexity and heterogeneity of ASD and lack of a proper human cellular model system, the pathophysiological mechanism of ASD during the developmental process is largely unknown. However, recent progress in induced pluripotent stem cell (iPSC) technology as well as in vitro neural differentiation techniques have allowed us to functionally characterize neurons and analyze cortical development during neural differentiation. These technical advances will increase our understanding of the pathogenic mechanisms of heterogeneous ASD and help identify molecular biomarkers for patient stratification as well as personalized medicine. In this review, we summarize our current knowledge of iPSC generation, differentiation of specific neuronal subtypes from iPSCs, and phenotypic characterizations of human ASD patient-derived iPSC models. Finally, we discuss the current limitations of iPSC technology and future directions of ASD pathophysiology studies using iPSCs.

Molecular underpinnings of prefrontal cortex development in rodents provide insights into the etiology of neurodevelopmental disorders

The prefrontal cortex (PFC), seat of the highest-order cognitive functions, constitutes a conglomerate of highly specialized brain areas and has been implicated to have a role in the onset and installation of various neurodevelopmental disorders. The development of a properly functioning PFC is directed by transcription factors, guidance cues and other regulatory molecules and requires the intricate and temporal orchestration of a number of developmental processes. Disturbance or failure of any of these processes causing neurodevelopmental abnormalities within the PFC may contribute to several of the cognitive deficits seen in patients with neurodevelopmental disorders. In this review, we elaborate on the specific processes underlying prefrontal development, such as induction and patterning of the prefrontal area, proliferation, migration and axonal guidance of medial prefrontal progenitors, and their eventual efferent and afferent connections. We furthermore integrate for the first time the available knowledge from genome-wide studies that have revealed genes linked to neurodevelopmental disorders with experimental molecular evidence in rodents. The integrated data suggest that the pathogenic variants in the neurodevelopmental disorder-associated genes induce prefrontal cytoarchitectonical impairments. This enhances our understanding of the molecular mechanisms of prefrontal (mis)development underlying the four major neurodevelopmental disorders in humans, that is, intellectual disability, autism spectrum disorders, attention deficit hyperactivity disorder and schizophrenia, and may thus provide clues for the development of novel therapies.

Enhancement of Short-Term Memory by Methyl-6-(Phenylethynyl)-Pyridine in the BTBR T+tf/J Mouse Model of Autism Spectrum Disorder

BACKGROUND

Autism spectrum disorder (ASD) encompasses a range of disorders that are characterized by social and communication deficits and repetitive behaviors. This study evaluated the effect of methyl-6-(phenylethynyl)-pyridine (MPEP), an antagonist of the mGluR5 metabotropic glutamate receptor, on memory enhancement in the BTBR T+tf/J (BTBR) mouse strain, which has been recognized as a model of ASD.

METHODS

The pharmacological effects of MPEP on memory and motor coordination were assessed using the Morris water maze and rotarod tests in BTBR and C57BL/6J (B6) mice. Furthermore, we performed morphological analyses of cerebellar foliation in BTBR and B6 mice using hematoxylin and eosin staining.

RESULTS

MPEP-treated BTBR mice exhibited improved learning and memory in the Morris water maze test. MPEP administration also improved motor coordination in the rotarod test. However, no significant difference was observed regarding the numbers of Purkinje cells in the cerebella of BTBR versus normal B6 mice.

CONCLUSION

This study suggests that the mGluR5 antagonist MPEP has the potential to ameliorate learning and memory dysfunction and impaired motor coordination in BTBR mice. These results further suggest that the BTBR mouse model may be useful in pharmacological studies investigating drugs that could potentially alleviate cognitive dysfunction in ASD.

Autism spectrum disorders: from genes to neurobiology

Advances in genome-wide technology, coupled with the availability of large cohorts, are finally yielding a steady stream of autism spectrum disorder (ASD) genes carrying mutations of large effect. These findings represent important molecular clues, but at the same time present notable challenges to traditional strategies for moving from genes to neurobiology. A remarkable degree of genetic heterogeneity, the biological pleiotropy of ASD genes, and the tremendous complexity of the human brain are prompting the development of new strategies for translating genetic discoveries into therapeutic targets. Recent developments in systems biology approaches that 'contextualize' these genetic findings along spatial, temporal, and cellular axes of human brain development are beginning to bridge the gap between high-throughput gene discovery and testable pathophysiological hypotheses.

Deficits in tactile learning in a mouse model of fragile X syndrome

The fragile X mental retardation 1 mutant mouse (Fmr1 KO) recapitulates several of the neurologic deficits associated with Fragile X syndrome (FXS). As tactile hypersensitivity is a hallmark of FXS, we examined the sensory representation of individual whiskers in somatosensory barrel cortex of Fmr1 KO and wild-type (WT) mice and compared their performance in a whisker-dependent learning paradigm, the gap cross assay. Fmr1 KO mice exhibited elevated responses to stimulation of individual whiskers as measured by optical imaging of intrinsic signals. In the gap cross task, initial performance of Fmr1 KO mice was indistinguishable from WT controls. However, while WT mice improved significantly with experience at all gap distances, Fmr1 KO mice displayed significant and specific deficits in improvement at longer distances which rely solely on tactile information from whiskers. Thus, Fmr1 KO mice possess altered cortical responses to sensory input that correlates with a deficit in tactile learning.

Overview of mouse models of autism spectrum disorders

This overview describes many well characterized mouse models of autism spectrum disorders (ASDs). Mouse models considered here were selected because they are examples of genetically engineered models where human genetic evidence supports a causative relationship between the targeted mutation and the behavioral phenotype. As the ASD diagnosis is based primarily on behavioral evaluations in humans in the domains of social interaction, communication, and restricted interests, the murine phenotypes analogous to human autistic behaviors are highlighted for the different models and behaviors. Although genetically engineered mouse models with good construct and face validity are valuable for identifying and defining underlying pathophysiological mechanisms and for developing potential therapeutic interventions for the human condition, the translational value of various rodent behavioral assays remains a subject of debate. Significant challenges associated with modeling ASDs in rodents because of the clinical and molecular heterogeneity that characterize this disorder are also considered.

The effects of aging on the BTBR mouse model of autism spectrum disorder

Autism spectrum disorder (ASD) is a complex heterogeneous neurodevelopmental disorder characterized by alterations in social functioning, communicative abilities, and engagement in repetitive or restrictive behaviors. The process of aging in individuals with autism and related neurodevelopmental disorders is not well understood, despite the fact that the number of individuals with ASD aged 65 and older is projected to increase by over half a million individuals in the next 20 years. To elucidate the effects of aging in the context of a modified central nervous system, we investigated the effects of age on the BTBR T + tf/j mouse, a well characterized and widely used mouse model that displays an ASD-like phenotype. We found that a reduction in social behavior persists into old age in male BTBR T + tf/j mice. We employed quantitative proteomics to discover potential alterations in signaling systems that could regulate aging in the BTBR mice. Unbiased proteomic analysis of hippocampal and cortical tissue of BTBR mice compared to age-matched wild-type controls revealed a significant decrease in brain derived neurotrophic factor and significant increases in multiple synaptic markers (spinophilin, Synapsin I, PSD 95, NeuN), as well as distinct changes in functional pathways related to these proteins, including “Neural synaptic plasticity regulation” and “Neurotransmitter secretion regulation.” Taken together, these results contribute to our understanding of the effects of aging on an ASD-like mouse model in regards to both behavior and protein alterations, though additional studies are needed to fully understand the complex interplay underlying aging in mouse models displaying an ASD-like phenotype.

Sociosexual and communication deficits after traumatic injury to the developing murine brain

Despite the life-long implications of social and communication dysfunction after pediatric traumatic brain injury, there is a poor understanding of these deficits in terms of their developmental trajectory and underlying mechanisms. In a well-characterized murine model of pediatric brain injury, we recently demonstrated that pronounced deficits in social interactions emerge across maturation to adulthood after injury at postnatal day (p) 21, approximating a toddler-aged child. Extending these findings, we here hypothesized that these social deficits are dependent upon brain maturation at the time of injury, and coincide with abnormal sociosexual behaviors and communication. Age-dependent vulnerability of the developing brain to social deficits was addressed by comparing behavioral and neuroanatomical outcomes in mice injured at either a pediatric age (p21) or during adolescence (p35). Sociosexual behaviors including social investigation and mounting were evaluated in a resident-intruder paradigm at adulthood. These outcomes were complemented by assays of urine scent marking and ultrasonic vocalizations as indices of social communication. We provide evidence of sociosexual deficits after brain injury at p21, which manifest as reduced mounting behavior and scent marking towards an unfamiliar female at adulthood. In contrast, with the exception of the loss of social recognition in a three-chamber social approach task, mice that received TBI at adolescence were remarkably resilient to social deficits at adulthood. Increased emission of ultrasonic vocalizations (USVs) as well as preferential emission of high frequency USVs after injury was dependent upon both the stimulus and prior social experience. Contrary to the hypothesis that changes in white matter volume may underlie social dysfunction, injury at both p21 and p35 resulted in a similar degree of atrophy of the corpus callosum by adulthood. However, loss of hippocampal tissue was greater after p21 compared to p35 injury, suggesting that a longer period of lesion progression or differences in the kinetics of secondary pathogenesis after p21 injury may contribute to observed behavioral differences. Together, these findings indicate vulnerability of the developing brain to social dysfunction, and suggest that a younger age-at-insult results in poorer social and sociosexual outcomes.

Social interaction and social withdrawal in rodents as readouts for investigating the negative symptoms of schizophrenia

Negative symptoms (e.g., asociality and anhedonia) are a distinct symptomatic domain that has been found to significantly affect the quality of life in patients diagnosed with schizophrenia. Additionally, the primary negative symptom of asociality (i.e., withdrawal from social contact that derives from indifference or lack of desire to have social contact) is a major contributor to poor psychosocial functioning and has been found to play an important role in the course of the disorder. Nonetheless, the pathophysiology underlying these symptoms is unknown and currently available treatment options (e.g., antipsychotics and cognitive-behavioral therapy) fail to reliably produce efficacious benefits. Utilizing rodent paradigms that measure social behaviors (e.g., social withdrawal) to elucidate the neurobiological substrates that underlie social dysfunction and to identify novel therapeutic targets may be highly informative and useful to understand more about the negative symptoms of schizophrenia. Accordingly, the purpose of this review is to provide an overview of the behavioral tasks for assessing social functioning that may be translationally relevant for investigating negative symptoms associated with schizophrenia.

Autism-related behavioral phenotypes in an inbred rat substrain

Behavioral and genetic differences among Wistar-Kyoto (WKY) rats from different vendors and different breeders have long been observed, but generally overlooked. In our prior work, we found that two closely related WKY substrains, the WKY/NCrl and WKY/NHsd rats, differ in a small percentage of their genome which appeared to be highly enriched for autism risk genes. Although both substrains have been used widely in studies of hypertension, attention deficit/hyperactivity disorder (ADHD) and depression, they have not been tested for any autism-related behavioral phenotypes. Furthermore, these two substrains have often been used interchangeably in previous studies; no study has systematically examined the phenotypic differences that could be attributed by their small yet potentially meaningful genetic differences. In this paper we compared these two substrains on a battery of neurobehavioral tests. Although two substrains were similar in locomotor activity, WKY/NCrl rats were significantly different from WKY/NHsd rats in the elevated plus maze test, as well as measures of social interaction and ultrasonic vocalization. These strains were also compared with Sprague Dawley (SD) rats, a common outbred strain, and spontaneous hypertensive rats (SHR), an inbred rat model for ADHD and hypertension, which were derived from the same ancestor strain as the WKY strains. Our behavioral findings suggest that WKY/NCrl rats may be useful as a model autism spectrum disorders due to their lower social interest, lower ultrasonic vocalization and higher anxiety levels when WKY/NHsd rats are used as the control strain. Given the small genetic difference between the two inbred substrains, future studies to identify the exact gene and sequence variants that differ between the two may be useful for identifying the genetic mechanisms underlying these behaviors.