Cheirando o perigo: ratos instintivamente evitam se misturar em urina de carnívoros

terça-feira, julho 05, 2011

The Smell of Danger: Rats Instinctively Avoid Compound in Carnivore Urine

ScienceDaily (July 3, 2011) — The mechanics of instinctive behavior are mysterious. Even something as simple as the question of how a mouse can use its powerful sense of smell to detect and evade predators, including species it has never met before, has been almost totally unknown at the molecular level until now.

Researchers have discovered a single compound found in high concentrations in the urine of carnivores that triggers an instinctual avoidance response in mice and rats. (Credit: © Oleg Kozlov / Fotolia)

David Ferrero and Stephen Liberles, neuroscientists at Harvard Medical School, have discovered a single compound found in high concentrations in the urine of carnivores that triggers an instinctual avoidance response in mice and rats. This is the first time that scientists have identified a chemical tag that would let rodents sense carnivores in general from a safe distance. The authors write that understanding the molecular basis of predator odor recognition by rodents will provide crucial tools to study the neural circuitry associated with innate behavior.
Their findings were published online in the Proceedings of the National Academy of Science on June 20, 2011.

The search began in 2006, when Stephen Liberles, now Assistant Professor of Cell Biology at Harvard Medical School, was working as a post-doc in the lab of Linda Buck. Buck was part of the team that won the Nobel Prize for identifying the receptors that allow olfactory neurons to detect odors. While in her lab, Liberles identified a new type of olfactory receptor, the trace amine-associated receptors (TAARs).

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Detection and avoidance of a carnivore odor by prey

David M. Ferrero a, Jamie K. Lemon a, Daniela Fluegge b, Stan L. Pashkovski c, Wayne J. Korzan a, Sandeep Robert Datta c, Marc Spehr d, Markus Fendt d, and  Stephen D. Liberles a,1

Author Affiliations

aDepartments of Cell Biology and
bDepartment of Chemosensation, Institute for Biology II, Rheinisch-Westfälische Technische Hochschule Aachen University, 52074 Aachen, Germany;
cNeurobiology, Harvard Medical School, Boston, MA 02115;  and 
dNovartis Institutes for BioMedical Research, Neuroscience DA, 4056 Basel, Switzerland

Edited* by David E. Clapham, Children's Hospital Boston, Howard Hughes Medical Institute, Boston, MA, and approved May 23, 2011 (received for review February 28, 2011)


Predator–prey relationships provide a classic paradigm for the study of innate animal behavior. Odors from carnivores elicit stereotyped fear and avoidance responses in rodents, although sensory mechanisms involved are largely unknown. Here, we identified a chemical produced by predators that activates a mouse olfactory receptor and produces an innate behavioral response. We purified this predator cue from bobcat urine and identified it to be a biogenic amine, 2-phenylethylamine. Quantitative HPLC analysis across 38 mammalian species indicates enriched 2-phenylethylamine production by numerous carnivores, with some producing >3,000-fold more than herbivores examined. Calcium imaging of neuronal responses in mouse olfactory tissue slices identified dispersed carnivore odor-selective sensory neurons that also responded to 2-phenylethylamine. Two prey species, rat and mouse, avoid a 2-phenylethylamine odor source, and loss-of-function studies involving enzymatic depletion of 2-phenylethylamine from a carnivore odor indicate it to be required for full avoidance behavior. Thus, rodent olfactory sensory neurons and chemosensory receptors have the capacity for recognizing interspecies odors. One such cue, carnivore-derived 2-phenylethylamine, is a key component of a predator odor blend that triggers hard-wired aversion circuits in the rodent brain. These data show how a single, volatile chemical detected in the environment can drive an elaborate danger-associated behavioral response in mammals.

kairomone, olfaction, pheromone, trace amine-associated receptors, G protein-coupled receptor


1To whom correspondence should be addressed. 

Author contributions: D.M.F., J.K.L., D.F., S.L.P., W.J.K., S.R.D., M.S., M.F., and S.D.L. designed research; D.M.F., J.K.L., D.F., S.L.P., W.J.K., M.F., and S.D.L. performed research; D.M.F., W.J.K., S.R.D., and S.D.L. contributed new reagents/analytic tools; D.M.F., D.F., S.L.P., S.R.D., M.S., M.F., and S.D.L. analyzed data; and D.M.F., M.S., M.F., and S.D.L. wrote the paper.

The authors declare no conflict of interest.

*This Direct Submission article had a prearranged editor.

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