Domain-specific and sex-dependent behavioral alterations in the BTBR mouse model of autism

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by social communication deficits and restricted, repetitive behaviors, often accompanied by motor, cognitive, and anxiety-related alterations. Although ASD is diagnosed more frequently in males than females, females remain underrepresented in preclinical studies, limiting understanding of sex-dependent phenotypes. The BTBR T + Itpr3 tf /J (BTBR) mouse strain is a widely used animal model of ASD, yet its sex-specific behavioral profiles across functional domains remain incompletely characterized. Here, we conducted a systematic, multi-domain behavioral assessment in male and female BTBR mice and wild-type (WT) controls, examining action control, motor learning, social behavior, and anxiety-related exploration. Despite normal acquisition of instrumental responding, BTBR mice exhibited altered action control characterized by reduced habitual responding and persistent sensitivity to action-outcome contingencies following extended habit training, with effects being more pronounced in females. In the accelerating rotarod task, BTBR mice displayed impaired motor learning that was more prominent in males, whereas performance under constant-speed conditions indicated largely preserved baseline motor coordination. Social impairments were dimension-specific: BTBR males showed delayed initiation of social investigation, whereas BTBR females exhibited reduced social engagement. In the elevated plus maze (EPM), overall genotype effects were modest; However, sex-dependent differences emerged within BTBR strain, suggesting altered exploratory behavior and risk-assessment strategies rather than generalized anxiety-like behavior. Together, these findings identify domain- and sex-specific alterations in action selection, motor learning, social behavior and anxiety-related exploration in BTBR mice. These results highlight the importance of sex-stratified analyses in preclinical ASD research and provide a behavioral framework for investigating the mechanisms underlying ASD-relevant phenotypes.