By short-circuiting the sensory organ that detects the chemical cues mice use to attract mates, a team of Howard Hughes Medical Institute (HHMI) researchers has prompted female mice to behave like male mice in the throes of courtship.
The finding, reported August 5, 2007, in the journal Nature, suggests that the neural circuits that govern gender-specific behaviors, such as aggression and courtship, are similar in the male and female brain. According to the new study, the sexual behaviors of female mice, at least, are ruled by a pheromone-detecting organ that engages a neural circuit that determines whether a mouse shows its feminine side or acts like a male.
Biologists have long searched for the root causes of sexually dimorphic behaviors -- those that differ between the sexes. The new findings promise to redirect that quest.
"From a developmental standpoint, the finding is very satisfactory," said Catherine Dulac, an HHMI investigator at Harvard University professor of molecular and cellular biology who led the new study. "It means you only have to build one brain in a species and that the one brain is built, more or less, the same in the male and the female."
Dulac's team, composed of first author Tali Kimchi, a postdoctoral fellow, and collaborator Jennings Xu, a Harvard undergraduate student, plumbed the neural depths of sexually dimorphic mouse behavior by engineering females to have functionally deficient vomeronasal organs. Also known as Jacobson's organ, the vomeronasal organ is a pocket in the nasal cavity of many animals that is packed with receptor cells. It is the key detector of pheromones, chemical signals that elicit specific behavioral responses in certain animals, including mice.
The researchers found that female mice whose vomeronasal organs were genetically disabled behaved like males in the throes of courtship, exhibiting behaviors such as mounting, pelvic thrusts, solicitation and the complex ultraso
Contact: Jennifer Michalowski
Howard Hughes Medical Institute