Ultrasound Communications Reveal Social Aversion in Rats With Contact Motivation Deficits but not Anhedonia.

Objectives: Animal models of human diseases are commonly used in experimental research. Autism Spectrum Disorder (ASD) is characterized by reduced social motivation and often co-occurs with epilepsy, representing a distinct clinical subgroup. This study investigated social deficits in Krushinsky-Molodkina (KM) rats, which present with latent epilepsy and an autistic-like phenotype, by measuring ultrasonic communications during social interaction.

Methods: The three-chamber test for social preference/novelty, accompanied by registration of ultrasonic vocalizations (USVs), was conducted in 12 KM and 12 control Wistar rats. For analysis, each individual vocalization trajectory was mapped and the results were derived from aggregating the individual data. To assess potential anhedonia, sucrose preference was tested in a separate group (10 KM and 20 Wistar rats) by measuring the consumption of 1% sucrose and water in individual rats over a 24-h period. All animals used were seizure-naive males, aged 4-6 months.

Results: A longer duration of aversive USV calls was registered during the sociability tests in KM rats (p < 0.05, compared with controls). The majority (p < 0.05) of aversive USVs occurred when KM rats distanced themselves from the social stimuli, and the duration of these calls showed a positive correlation with freezing behavior (Spearman coefficient Rs = 0.68, p < 0.05). Reduced sucrose preference was not observed in KM rats; instead, an increase in daytime sucrose consumption was noted.

Conclusions: KM rats exhibit negative emotional states in sociability tests, as evidenced by enhanced aversive vocalizations and distancing behavior. The social aversion observed in KM rats is not associated with anhedonia.