Beyond Aggression: Characterizing the Phenotype of the BALB/cJ Mouse
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Background: Children with conduct disorder (CD) show high levels of aggression, cognitive impairments and changes in baseline heart rate. Common comorbidities of CD are attentiondeficit- hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). Here, we further characterized the behavioural and physiological phenotype of BALB/cJ mice, known for their increased levels of aggression. We investigated if they show symptoms of ASD (social withdrawal) and ADHD (hyperactivity and low temperature) as well as symptoms of CD (cognitive impairments and changes in heart rate). Method: In experiment 1, social withdrawal was investigated with a modified version of the three-chamber social interaction test. In experiment 2, telemetric devices were implanted to measure locomotion and body temperature for a period of 86 hours. Experiment 3 was an extension of experiment 2 and also involved the investigation of the heart rate. In experiment 4, a virtual environment task was used to test for deficits in learning, attention and cognitive flexibility. Results: In the social interaction test, BALB/cJ mice showed less interest in an unfamiliar mouse compared to BALB/cByJ mice. Experiment 2 showed that BALB/cJ mice had increased locomotor activity during the active period and a lower body temperature in the non-active period compared to control mice. In experiment 3, it was demonstrated that BALB/cJ mice have a low heart rate given their increased locomotor activity. Experiment 4 indicated deficits in learning, attention and cognitive flexibility. Discussion: We have further characterized the behavioural and physiological phenotype of BALB/cJ mice, demonstrating that these mice show symptoms of CD, and its associated comorbidities, ASD and ADHD. The model can be used to study brain structures that might give rise to the linked symptoms of CD, ADHD and ASD.
Faculteit der Sociale Wetenschappen