Got milk? A pheromonal message for newborn rabbits.

A substance in rabbit milk, 2-methylbut-2-enal (2MB2), has been identified as a pheromone that triggers stereotypical searching behavior from rabbit pups. Pups respond to the odor of 2MB2 solutions in concentration-dependent manner, but fail to respond to 20 other volatile components in rabbit milk and 20 additional odorants. The effectiveness of 2MB2 generalizes across strains and breeds of rabbits, but is ineffective in closely related species. Finally, pup responsiveness to 2MB2 is innate and does not require learning. This study, for the first time, identifies a mammary pheromone that provides sufficient sensory cue for nipple attachment by newborns. In addition to contributing to our understanding of pheromonal communication, it provides an advantageous model system for neurobiologists. Copyright 2003 Wiley Periodicals, Inc.