PDF-1 neuropeptide signaling modulates a neural circuit for mate-searching behavior in C. elegans

Appetitive behaviors require complex decision-making, involving the integration of environmental stimuli and physiological needs. C. elegans mate searching is a male-specific exploratory behavior regulated by two competing needs: food versus reproductive appetite. Here we show that the Pigment Dispersing Factor Receptor (PDFR-1) modulates the circuit that encodes the male reproductive drive promoting male exploration upon mate-deprivation. PDFR-1 and its ligand PDF-1 stimulate mate searching in the male but not in the hermaphrodite. pdf-1 is required in the gender-shared interneuron AIM and the receptor acts in internal and external environment-sensing neurons of the shared nervous system (URY, PQR and PHA) to produce mate-searching behavior. Thus, the pdf-1/pdfr-1 pathway functions in non sex-specific neurons to produce a male-specific, goal-oriented exploratory behavior. Our results indicate that secretin neuropeptidergic signaling plays an ancient role in regulating motivational internal states.