Sexual dimorphisms are widespread in the animal kingdom. At the behavioral level, there is evidence for sex differences in social play behavior. In rats, males typically engage more in rough-and-tumble play than females. One prominent component of the rough-and-tumble play repertoire in rats is the emission of 50-kHz ultrasonic vocalizations (USV). Such 50-kHz USV reflect the rewarding nature of play and serve as socioaffective signals. Here, we provide evidence for sexual dimorphisms within rough-and-tumble play-induced 50-kHz USV in juvenile rats. Specifically, females displayed reduced 50-kHz USV emission during playful interactions. This reduction was associated with changes in 50-kHz USV emission rates and subtype profiles during specific rough-and-tumble components, i.e., pinning, wrestling, and chasing, as well as differences in acoustic parameters. Interestingly, sex differences were modulated by Cacna1c, a gene strongly implicated in major neuropsychiatric disorders, often characterized by prominent sex biases, most notably autism. Specifically, Cacna1c haploinsufficiency affected the emission of 50-kHz USV during rough-and-tumble play in female rats and we provide evidence supporting the notion that such effects of Cacna1c haploinsufficiency are driven by male-typical features of 50-kHz USV emission. This is in line with the hypermasculinized social play repertoire previously observed in juvenile Cacna1c haploinsufficient females.
Keywords: Cav1.2; calcium; rats; rough-and-tumble play; sex differences; social behavior; ultrasonic vocalizations.
© 2020 The Authors. Developmental Psychobiology published by Wiley Periodicals LLC.