Leeches studied for reproductive behaviors

PASADENA, Calif., March 18 (UPI) -- U.S. biologists say they have discovered the leech is a good model for studying reproductive behavior.

Researchers from the California Institute of Technology and the University of California-San Diego say they've discovered injecting a simple hormone into leeches creates a novel way to study how hormones and the nervous system work together to produce species-specific reproductive behavior.

Caltech researcher Daniel Wagenaar said he discovered injecting a particular hormone into a medicinal leech (Hirudo verbana) induced a series of movements that closely mimic natural reproductive behavior, including a stereotypical 180-degree twisting of the body.

The twisting, which takes about five minutes, is one of the slowest behavioral rhythms ever discovered and serves to align the reproductive pores on the ventral (under) side of one leech with the complementary pores on the ventral side of a partner.

Wagenaar and his colleagues said the studies establish the leech as a new model system for studying how hormones act on the nervous system to produce mating behavior.

"The knowledge gained from these studies," added study co-author 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."

The study is detailed in the March 11 early online edition of the journal Current Biology.