Shank2 Mutant Mice Display Hyperactivity Insensitive to Methylphenidate and Reduced Flexibility in Social Motivation, but Normal Social Recognition

Mouse models of autism can be used to study evolutionarily conserved mechanisms underlying behavioral abnormalities in social communication and repetitive behaviors. SHANK genes code for synaptic scaffolding proteins at excitatory synapses and mutations in all SHANK genes have been associated with autism. Here, we present three behavioral aspects of the mutant mice deleted for exon 16 in Shank2. First, we treated Shank2 mutant mice with methylphenidate to rescue the hyperactivity. Our failure to do so suggests that the hyperactivity displayed by Shank2 mutant mice is not related to the one displayed by the typical mouse models of hyperactivity, and might be more closely related to manic-like behaviors. Second, by testing the effect of group housing and social isolation on social interest, we highlighted that Shank2 mutant mice lack the typical flexibility to modulate social interest, in comparison with wild-type littermates. Finally, we established a new protocol to test for social recognition in a social context. We used this protocol to show that Shank2 mutant mice were able to discriminate familiar and unknown conspecifics in free interactions. Altogether, these studies shed some light on specific aspects of the behavioral defects displayed by the Shank2 mouse model. Such information could be used to orient therapeutic strategies and to design more specific tests to characterize the complex behavior of mouse models of autism

Étude des bases neurobiologiques des troubles du spectre autistique : caractérisation comportementale et moléculaire de souris invalidées pour Shank3

Autism spectrum disorders (ASD) are neurodevelopmental psychiatric disorders characterized by alterations in social interactions and communications as well as stereotyped behaviours and restricted interests. Mutations in genes coding synaptic proteins are strongly associated with ASD and more specifically SHANK3, encoding for a scaffolding protein in the post-synaptic density of glutamatergic synapses. The aim of the present PhD thesis is to characterise a mouse model deleted for exon 11 in Shank3 and to better understand the brain regions affected by this mutation. We characterised the mice at the behavioural level (a longitudinal study between three and twelve months of age) and at the molecular level (transcriptome analysis using mRNA sequencing). At three months of age, we observed a decreased locomotor activity, increased stereotyped behaviour and increased social motivation during free interaction in Shank3-/- mice compared to Shank3+/+ mice. When testing animals at 3, 8, and 12 months of age, we noticed a worsening of the phenotype in Shank3-/- mice while ageing, especially in self-grooming behaviour. When exploring the transcriptomic, we revealed an impairment of gene expression of striatal neurons sensitive to dopamine, the medium spiny neurons, as well as post-synaptic signalling in striatum. Altogether, this project provides a comprehensive characterisation of a mouse model of ASD. It sheds some light on the molecular mechanisms possibly involved in patients with ASD mutated in SHANK3. This insight could reveal new therapeutic approaches targeting the imbalance in dopaminosensitive neurons.Les troubles du spectre autistique (TSA) sont des troubles psychiatriques neurodéveloppementaux caractérisés par des altérations de l’interaction et de la communication sociales ainsi que des comportements stéréotypés et des intérêts restreints. Les TSA sont fortement associés à des composantes génétiques et en particulier avec le gène SHANK3, codant pour une protéine d'échafaudage dans la densité post-synaptique des synapses glutamatergiques. L’objectif de ce doctorat est de caractériser un modèle de souris Shank3 et de mieux comprendre les régions du cerveau affectées par la délétion de Shank3. Nous avons caractérisé les souris au niveau comportemental (une étude longitudinale entre trois et douze mois) et au niveau moléculaire (analyse du transcriptome en utilisant le séquençage de l'ARNm). À l'âge de trois mois, nous avons observé une diminution de l'activité locomotrice, une augmentation des comportements stéréotypés et une motivation sociale accrue au cours d'interaction libre chez les souris Shank3-/- en comparant aux souris Shank3+/+. Lorsque nous avons testé les animaux à l'âge de 8 et 12 mois, nous avons observé une détérioration du phénotype chez les souris Shank3- / - en vieillissant, en particulier pour les comportements stéréotypés. Lors de l’analyse du transcriptome, nous avons révélé, au niveau du striatum, une altération de l'expression génique des neurones sensibles à la dopamine, les neurones épineux moyens, ainsi que des problèmes de la signalisation post-synaptique. Ainsi, ce projet fournit une caractérisation complète d'un modèle murin de l’autisme. Il met en lumière les mécanismes moléculaires éventuellement impliqués chez les patients atteints de TSA et portant une mutation dans SHANK3. Cette idée pourrait révéler une nouvelle approche thérapeutique pour les patients ciblant le déséquilibre dans les neurones du striatum

Behavioural Phenotypes and Neural Circuit Dysfunctions in Mouse Models of Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition primarily characterised by alterations in social interaction and communication combined with the presence of restricted interests and stereotyped behaviours. Mutations in several genes have been associated with ASD resulting in the generation of corresponding mouse models. Here, we focus on the behavioural (social and stereotyped behaviours), functional and structural traits of mice with mutations in genes encoding defined synaptic proteins including adhesion proteins, scaffolding proteins and subunits of channels and receptors. A meta-analysis on ASD mouse models shows that they can be divided into two subgroups. Cluster I gathered models highly impaired in social interest, stereotyped behaviours, synaptic physiology and protein composition, while Cluster II regrouped much less impaired models, with typical social interactions. This distribution was not related to gene families. Even within the large panel of mouse models carrying mutations in Shank3, the number of mutated isoforms was not related to the severity of the phenotype. Our study points that the majority of structural or functional analyses were performed in the hippocampus. However, to robustly link the structural and functional impairments with the behavioural deficits observed, brain structures forming relevant nodes in networks involved in social and stereotyped behaviours should be targeted in the future. In addition, the characterisation of core ASD-like behaviours needs to be more detailed using new approaches quantifying the variations in social motivation, recognition and stereotyped behaviours

Social communication in mice - Are there optimal cage conditions?

Video and audio recordings of social interactions in adult male C57BL/6J mice under different conditions (habituation time to the test cage and cage shape and size

Behavioural phenotypes and neural circuit dysfunctions in mouse models of autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition primarily characterised by alterations in social interaction and communication combined with the presence of restricted interests and stereotyped behaviours. Mutations in several genes have been associated with ASD resulting in the generation of corresponding mouse models. Here, we focus on the behavioural (social and stereotyped behaviours), functional and structural traits of mice with mutations in genes encoding defined synaptic proteins including adhesion proteins, scaffolding proteins and subunits of channels and receptors. A meta-analysis on ASD mouse models shows that they can be divided into two subgroups. Cluster I gathered models highly impaired in social interest, stereotyped behaviours, synaptic physiology and protein composition, while Cluster II regrouped much less impaired models, with typical social interactions. This distribution was not related to gene families. Even within the large panel of mouse models carrying mutations in Shank3, the number of mutated isoforms was not related to the severity of the phenotype. Our study points that the majority of structural or functional analyses were performed in the hippocampus. However, to robustly link the structural and functional impairments with the behavioural deficits observed, brain structures forming relevant nodes in networks involved in social and stereotyped behaviours should be targeted in the future. In addition, the characterisation of core ASD-like behaviours needs to be more detailed using new approaches quantifying the variations in social motivation, recognition and stereotyped behaviours

Recording Mouse Ultrasonic Vocalizations to Evaluate Social Communication.

International audienceMice emit ultrasonic vocalizations in different contexts throughout development and in adulthood. These vocal signals are now currently used as proxies for modeling the genetic bases of vocal communication deficits. Characterizing the vocal behavior of mouse models carrying mutations in genes associated with neuropsychiatric disorders such as autism spectrum disorders will help to understand the mechanisms leading to social communication deficits. We provide here protocols to reliably elicit ultrasonic vocalizations in pups and in adult mice. This standardization will help reduce inter-study variability due to the experimental settings. Pup isolation calls are recorded throughout development from individual pups isolated from dam and littermates. In adulthood, vocalizations are recorded during same-sex interactions (without a sexual component) by exposing socially motivated males or females to an unknown same-sex conspecific. We also provide a protocol to record vocalizations from adult males exposed to an estrus female. In this context, there is a sexual component in the interaction. These protocols are established to elicit a large amount of ultrasonic vocalizations in laboratory mice. However, we point out the important inter-individual variability in the vocal behavior of mice, which should be taken into account by recording a minimal number of individuals (at least 12 in each condition). These recordings of ultrasonic vocalizations are used to evaluate the call rate, the vocal repertoire and the acoustic structure of the calls. Data are combined with the analysis of synchronous video recordings to provide a more complete view on social communication in mice. These protocols are used to characterize the vocal communication deficits in mice lacking ProSAP1/Shank2, a gene associated with autism spectrum disorders. More ultrasonic vocalizations recordings can also be found on the mouseTube database, developed to favor the exchange of such data

Contexts of ultrasonic vocalization emission during social interactions.

<p>Proportion of ultrasonic vocalizations emitted during social events during the first 4 min of interactions (A) after 20 min habituation in the rectangular cage, (B) after 20 min habituation in the round cage, (C) after 20 min habituation in the square cage, (D) after 30 min habituation in the rectangular cage, (E) after 30 min habituation in the round cage, (F) after 30 min habituation in the square cage. Social events are presented in the following order: contact < 1 cm, nose-to-nose contact, <i>occupant</i> sniffing ano-genital region of <i>new-comer</i>, <i>occupant</i> sniffing ano-genital region of <i>new-comer</i>, <i>occupant</i> behind <i>new-comer</i>, <i>new-comer</i> behind <i>occupant</i>, <i>occupant</i> not moving, <i>new-comer</i> not moving, <i>occupant</i> approaches <i>new-comer</i> & <i>new-comer</i> escapes, <i>new-comer</i> approaches <i>occupant</i> and <i>occupant</i> escapes, <i>occupant</i> approaches <i>new-comer</i> & <i>occupant</i> escapes, <i>new-comer</i> approaches <i>occupant</i> & <i>new-comer</i> escapes, <i>occupant</i> following <i>new-comer</i>, <i>new-comer</i> in the vision field of <i>occupant</i>, <i>occupant</i> in the vision field of <i>new-comer</i> (n = 8 pairs of mice per condition; data are presented as mean +/- sem).</p

No significant effect of habituation time and cage shape/size on the vocal behavior of the pairs of interacting mice.

<p>Measures were taken during the first 4 min of interaction after 20 min (left panel) or 30 min (right panel) habituation time in three cage types. (A) Latency for the first ultrasonic vocalization. (B) Number of ultrasonic vocalizations emitted by minute. (C) Mean duration of ultrasonic vocalizations. (Wilcoxon-Mann-Whitney U-tests: n = 8 pairs of mice per condition; data are presented as mean +/- sem).</p

Limited influence of habituation time and cage shape/size on the time spent in contact.

<p>Time in contact (< 1 cm) was measured during the first 4 min of interaction after 20 min (left panel) or 30 min (right panel) habituation time in three cage types. (Wilcoxon-Mann-Whitney U-tests: n = 8 pairs of mice per condition; *: p<0.05; data are presented as mean +/- sem).</p