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Press release
Discovery of a rabbit mammary pheromone that guides newborn rabbit pups to their mother's milk | |||
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Paris, July 3, 2003 |
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| For the very first time, research conducted by the ethology team of the Centre des Sciences du Goût (Taste Sciences Center) of the CNRS, in partnership with INRA and the Etablissement National d’Enseignement Supérieur Agricole (ENESA) in Dijon, France, has revealed the existence of a pheromone – a specialized smell signal – used by newborn rabbit pups to find their mother's nipple. All mammalian females have evolved signaling mechanisms for the purpose of guiding their newborns to their mammae. Newborns also possess adapted means for detecting these signals. Odors have been frequently shown to be involved in the initial mother-newborn reaction, but the chemical identity and role of pheromones had not been definitively characterized. The rabbit is a unique model since the behavior of newborn rabbit pups is almost entirely based on olfactory signals in that they are "deaf" and "blind" during the first days of their life. Moreover, the pups need a reliable sensory tether for the rapid location of their mother's nipples since she only nurses her litter once a day for an extremely short time, on the order of 3 to 5 minutes. The newborn rabbit pups do succeed, however, as the result of a typical head-searching pattern within the mother's abdominal fur in which they locate a nipple, grasp it and, finally, ingest milk. This characteristic behavior is set off by the odor of the abdomen and the milk of females at the beginning of lactation. Using methods that combined behavior and chemical analysis, the team of Benoist Schaal and Gérard Coureaud was able to identify an effective molecule from the complex mixture of volatile substances given off by rabbit milk. Using gas chromatography techniques designed for the study of food aromas in humans and a series of behavior tests, the researchers were able to find and isolate this molecule, as effective in attracting newborn rabbit pups as the milk itself. In over 90% of the newborns tested, it set off searching and oral grasping responses normally expressed when in contact with their mother's abdomen. This pheromone, known as the "mammary pheromone" as a result of its origin, is the only one of the volatile substances identified in the milk capable of provoking this typical reaction. These researchers were also able to show that this olfactory signal has a particular biological status. Made up of a unique molecule, it corresponds to a precise set of criteria. It sets off the same response in a majority of rabbits and its action is highly selective. It is confined to this animal alone, to the exclusion of other mammals such as unweaned mice and rats, kittens and even baby hares that are closely related to rabbit pups. Another important discovery: the relationship between this signal and these behaviors does not appear to result from any prior learning process, either before or after birth, which would therefore be "innate". The discovery of this substance has several broader implications concerning the way in which it is released, its regulation, its perception and the way that the brain processes information that it passes on. It should also lead to research into signals that have comparable functions in other mammal species, including human beings. Reference: Nature, Vol. 424, July 3, 2003, pages 68-72: "Chemical and behavioural characterization of the rabbit mammary pheromone". Benoist Schaal, Gérard Coureaud, Dominique Langlois, Christian Giniès, Etienne Sémon, Guy Perrier. Researcher
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: Life Sciences
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