Locomotor, Anxiety, and Risk Assessment Related Phenotyping and Striatal Transcriptome Analysis in Four Autism Mouse Models

Background: In recent years, multiple mouse models have been produced to study autism.  In order to gain high-impact information from these mice models, we propose that the parallel behavioral and molecular phenotyping of several mouse will help to identify behaviors and molecular mechanisms that are in common in multiple models, and are therefore more likely to be directly involved in autistic behavior.  

Objectives: In our current study, we looked at locomotor function, anxiety, and risk assessment behaviors in four autism mouse models.  In order to discover common molecular pathways that are dysregulated in all mouse models, we did whole transcriptome sequencing in the striatum of these mice models.  By comparing the behavior of these multiple models and the transcriptome dysregulation in the striatum, a brain area highly involved in these behaviors, we can determine specific molecular mechanisms that are directly responsible for the relevant behavioral dysfunctions.

Methods:  We performed motor-related and risk- assessment related behavioral and molecular experimentation on four mouse models of ASD: Shank3 KO, CNTNAP2 KO, Chr16p11.2del, and BTBR mice.  We performed Open Field (OF), Dark Light (DL), and Elevated Plus Maze (EPM) on all mouse models at basal conditions, and also at one hour, and 24 hours, after restraint stress.  Rotorod test was also performed on all animals to test motor function.  We extracted RNA from the striatum of all four mouse models, and their controls, and performed whole throughput RNA sequencing (RNA-seq) on all samples.  This has produced data about the whole genome transcriptome in the striatum of all four mouse models.

Results: In the OF test, the CNTNAP2 and BTBR mice displayed hyperactivity at all conditions, the Chr16p11.2del displayed hyperactivity after stress, and Shank3 KO displayed hypoactivity.  However, Shank3 KO also displayed motor deficits in the rotorod test.  In DL, both the Shank3 KO and CNTNAP2 KO mice spent more time in the light area, suggesting less anxiety-like behavior, as well as less risk-assessment.  In addition, in the EPM test, the Shank3KO, CNTNAPKO, and Chr16p11.2del models all spent significantly more time in the open arms, suggesting less anxiety-like behavior as well.  Close analysis of the behavior of the CNTNAP2KO model in both the EPM and DL tests shows that their behavior can be explained by less time doing risk assessment.  RNA-seq data collection has already been performed and the data is currently being analyzed to be presented in the conference.

Conclusions:  All four mouse models displayed a dysregulation in locomotor activity, highlighting the importance of locomotion and motor function in autistic behavior.  In addition, all genetic mouse models displayed a similar behavioral profile in the EPM and DL mazes, demonstrating that there is a shared behavioral outcome to several genetic mutations involved in autism.  The profile suggests less anxiety-like behavior, which may be explained by less assessment of potential risks.  By comparing these behaviors to whole transcriptome analysis in the striatum, we will be able to identify shared molecular dysregulation that is directly involved in these behavioral phenotypes.