Effects of Cacna1c haploinsufficiency on social interaction behavior and 50-kHz ultrasonic vocalizations in adult female rats.

The risk gene CACNA1C is strongly implicated in the etiology of all major psychiatric disorders, such as depressive disorder, bipolar disorder, autism spectrum disorder, and schizophrenia. These disorders feature high levels of comorbidity and share an overlap of symptoms; in particular, deficits in social functioning are common. Intriguingly, sex-dependent effects of CACNA1C single nucleotide polymorphisms on prevalence, health outcomes, and psychological traits have been reported, typically suggesting that women are more affected by CACNA1C mutations than men. In rodents, genetic modifications specifically targeting Cacna1c have repeatedly been linked to deficits in social behavior in male mice and rats but many studies neglect the sex-dependent effects observed in humans. Our study focused on the role of Cacna1c in regulating social behavior and communication in adult female rats. We compared social and non-social behavior together with concomitant emission of pro-social 50-kHz ultrasonic vocalizations (USV) associated with positive affect in constitutive heterozygous (Cacna1c^+/-) rats to wildtype (Cacna1c^+/+) littermate controls. Our results indicate that partial Cacna1c depletion leads to strongly reduced emission of 50-kHz USV and mild social deficits during female direct reciprocal social interaction. Detailed temporal analyses revealed most prominent reductions of 50-kHz USV during non-social behavior, suggesting that reduced positive affect occurs in a social context in Cacna1c^+/- rats but is not specifically linked to social behavior. Finally, we observed increased self-grooming behavior in Cacna1c^+/- rats, consistent with an autism-like phenotype. Our findings in rats thus support a role of Cacna1c in regulating behavioral phenotypes with relevance for several neuropsychiatric disorders.

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