The Scent Of Anxiety

The combination of two chemicals that are simultaneously sensed by different olfactory systems makes rats respond with anxiety.

AsianScientist (Jan. 13, 2015) – Scientists have identified what might be the first mammalian pheromone, a form of chemical communication common in lower animals. Their results, published in the Proceedings of the National Academy of Science, show that a combination of two chemicals—4-methylpentanal and hexanal—secreted by one rat triggers anxiety in other rats.

Animals release specific odors into the air when they are stressed, and these odors increase anxiety in conspecifics. These alarm odors or alarm pheromones appear to be important signals that are evolutionarily conserved because they are released by a variety of mammalian species, including rats, deer, cattle, swine and humans.

A research team led by the Professor Yuji Mori, Associate Professor Yukari Takeuchi and Assistant Professor Yasushi Kiyokawa in the Graduate School of Agricultural and Life Sciences at the University of Tokyo has identified a mixture of 4-methylpentanal and hexanal in the rat alarm odor and demonstrated that this mixture is a pheromone increases anxiety in other rats. These compounds were isolated from the many substances released from the rat perianal region, and while they had no effect individually, in combination they increased anxiety in rats.

The results of this study identifying this pheromone could aid further research on rat pheromones, and enhance our understanding of chemical communication in mammals. In addition, these findings could help us develop new technologies using pheromones to control mammal pests.

The article can be found at: Inagaki et al. (2015) Identification of a Pheromone that Increases Anxiety in Rats.


Source: University of Tokyo.
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