"We started out studying the behavior of whole animals that we simply injected with the hormone. Then we cut leeches in thirds and injected each part with hormone, and found that the hormone acted only in the central part, which contains the reproductive organs. We then cut open that central part and stretched out the skin so we could study in more detail the muscle contractions underlying the behavior of the whole animal."
"Finally," he says, "we removed the body entirely, keeping just the nervous system, and found that even the disembodied central nervous system"in particular, the ganglia (clusters of nerve cell bodies) located in the reproductive segments of the leech"produced the appropriate nerve signals to generate the pattern of muscle activity we had observed."
"Our next project will be to use voltage-sensitive dyes to record signals from a large fraction of all the neurons in the reproductive ganglia, to find which ones contribute to generating and maintaining the behavior," he adds.
Wagenaar and his colleagues believe these studies establish the leech as a new model system for studying how hormones act on the nervous system to produce mating behavior, and for deciphering the specific neural circuits that control the behavior.
"The knowledge gained from these studies," adds study coauthor Kathleen French of UCSD, "is expected to shed new light on the interactions of hormones and neurons in controlling courtship and reproductive behavior in a wide variety of sexually reproducing species, from the lowly leech to humans in a singles bar."
|Contact: Kathy Svitil|
California Institute of Technology