No detectable effect of P2 neurons on female post-mating changes in sleep and feeding in Drosophila melanogaster

In many insects, females exhibit behavioral changes after mating. This plasticity can be mediated by interactions between male-derived seminal fluid proteins (SFPs) and the female nervous system. The Drosophila melanogaster seminal fluid protein Sex Peptide (SP) causes mated females to sleep less during the day and consume more food than unmated females, among other behavioral changes. Although the SP-sensing neural circuits that convey information to the female's brain are known, the downstream neurons that affect post-mating behaviors remain unknown. P2 neurons in the fly's central brain are good candidates for regulating post-mating changes in sleep and food consumption, as they express feeding- and sleep-responsive neuropeptide F (NPF), directly innervate the fly's sleep center (the dorsal fan-shaped body, dFB), and are responsible for social-isolation-induced changes in sleep and food consumption. Using the GAL4/UAS system, we activated or silenced P2 neurons in mated and unmated females. We measured sleep duration using Drosophila Activity Monitors (DAM) and food consumption using Capillary Feeder (CAFE) and blue-dye assays. We found that P2-neurons are not responsible for post-mating changes in sleep and food consumption: mated females slept less during the day and ate more compared to unmated females irrespective of P2 neuron perturbation. Together, these results indicate that P2 neurons are unlikely to be primary downstream neurons through which male-transferred SP regulates post-mating sleep and food consumption. Future studies could determine whether P2 neurons regulate other post-mating behaviors or modulate sleep and feeding behaviors in a context-dependent manner.