The neuropeptide Drosulfakinin regulates social isolation-induced aggression in <i>Drosophila</i>

Abstract

Social isolation strongly modulates behavior across the animal kingdom. We utilized the fruit fly <i>Drosophila melanogaster</i> to study social isolation-driven changes in animal behavior and gene expression in the brain. RNA-seq identified several head-expressed genes strongly responding to social isolation or enrichment. Of particular interest, social isolation downregulated expression of the gene encoding the neuropeptide Drosulfakinin (Dsk), the homologue of vertebrate cholecystokinin (CCK), which is critical for many mammalian social behaviors. <i>Dsk</i> knockdown significantly increased social isolation-induced aggression. Genetic activation or silencing of <i>Dsk</i> neurons each similarly increased isolation-driven aggression. Our results suggest a U-shaped dependence of social isolation-induced aggressive behavior on <i>Dsk</i> signaling, similar to the actions of many neuromodulators in other contexts.