Vasopressin and oxytocin are among the most highly conserved molecules in all of biology, both in their molecular structure and in their functions. They are small peptide hormones that control reproductive behaviors (e.g., courting, copulation, infant care, pair-bonding) in a broad range of animals from snails and worms to rodents and humans. However, hormones do not by themselves produce these important behaviors. Instead, they act on the nervous system, changing its activity and as a result, changing behavior. This study will use a relatively simple model organism, the European medicinal leech, to study how a neuronal circuit is activated by the animal's version of oxytocin and produces courtship behaviors. The investigators will use modern molecular techniques (mass spectroscopy) to identify the leech version of oxytocin, and will use cutting-edge electrical and optical techniques to characterize the set of neurons that are activated by the hormone. Based upon their previous findings, they expect to find that the leech, like mammals including humans, uses the oxytocin analog both as a neurotransmitter between specific neurons and as a hormone that modifies the properties of all the neurons. They will be able to trace these effects from the molecular mechanisms to the behavior produced. This characterization of the leech system will be the first complete description of the circuitry underlying any reproductive behavior, and it will show how the same molecule can function both to activate behaviors and help to produce them. The results will serve as a springboard to inspire similar characterizations of neural networks for reproductive behaviors in more complicated animals, including mammals. This project will offer unique training opportunities for students who will participate in every phase of this research project.
