BOSTON--August 18, 1997--Researchers are identifying multiple paths for the powerful neural signals from pheromones, the subconscious odorous chemicals released by mammals that elicit mating and other innate behaviors in members of the same species. Their findings are paving the way for the identification of mammalian pheromone molecules, which for the most part have eluded scientists.
Although researchers have identified as many as 1,000 different types of odor receptors in the nose, until recently they knew very little about how mammals detect pheromones. They did suspect, however, that in mice pheromones are processed by two segregated groups of sensory neurons lining the vomeronasal organ (VNO), a specialized structure at the base of the nasal septum. Several years ago, Howard Hughes investigators at Columbia identified a family of candidate pheromone receptors that seem to be expressed exclusively in one group of sensory neurons in the VNO.
Now Linda B. Buck, Howard Hughes investigator at Harvard Medical School, and research fellow Hiroaki Matsunami have identified a multigene family that codes for about 140 candidate pheromone receptors expressed by the other group of sensory neurons in the VNO. Although these receptors belong to the same G-protein-coupled receptor super family as the first family of candidate pheromone receptors and the odor receptors, they have an unusual structure which suggests that they may be responsible for recognizing a different class of pheromones.
"It appears that sensory input from the two groups of sensory neurons remains segregated in the brain and could be targeted to different regions of the amygdala and hypothalamus that mediate different effects, such as mating versus aggressive behaviors, in mice," says Buck.
A curious feature of the new receptor gene family is that many of its members give rise to variant mRNA forms that do not encode complete receptors. These proteins might have an important, yet-to-be understood function, such as binding to and blocking certain pheromones. Alternately, they could be nonfunctional "fossil" proteins, indicating that the gene family is rapidly evolving. "We have evidence for related gene families in other species, including human, but are not yet sure whether they encode functional receptors," says Buck.
Their findings are published in the August 22 Cell along with another related paper.
Editors, please note: Linda Buck will be available for interviews on Wednesday, August 20 from 1:00 p.m. to 5:00 p.m. EDT.