Sensory Characteristics of the Facial Region in Autism Model Mice

Objectives: People with autism spectrum disorder (ASD) are known to have communication difficulties, poor social skills, and sensory abnormalities. These features make their dental treatment difficult. Previous studies have reported unique somatosensory responses in ASD model mice, but no studies have focused on the facial region. Therefore, we assessed it in ASD models using behavioral testing.
Methods: We used two adult male ASD mouse models; 15q paternal duplication transgenic model (15q) and prenatal valproic acid exposure model (VPA). Behavioral testing included the hot plate test, operant orofacial pain assessment device (OPAD) test, and Von Frey test. In the hot plate test, mice were placed on a hot plate (52°C), and the time it took for them to jump was measured. In the OPAD test, mice accessed a reward liquid by touching thermodes set at varying temperatures (7-50°C) with their face. The number of accesses was recorded. In the Von Frey test, the mechanical threshold was determined based on their reactions.
Results: In the hot plate test, no significant differences were found between groups. In the Von Frey test, the 15q group had a significantly lower threshold, while the VPA group showed an opposite trend. In OPAD test, the 15q group accessed the reward less often under 10-15°C, while the VPA group showed an opposite trend. In contrast, both ASD groups had fewer accesses than the control groups under 40-50°C.
Conclusions: ASD models we examined showed comparable thermal sensitivity to control mice in the spinal nerve region but different sensitivity in the trigeminal nerve region. The mechanical threshold in the trigeminal region differed between two ASD models, which may relate to different responses of ASD individuals to dental treatment.