December 15, 2014

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Fig. 1 A pheromone that transmits danger signals in rats is released from the perianal region, and increases anxiety in other rats.
© Yukari Takeuchi

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 late 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.

Paper Information

Hideaki Inagaki, Yasushi Kiyokawa, Shigeyuki Tamogami, Hidenori Watanabe, Yukari Takeuchi, Yuji Mori,
“Identification of a pheromone that increases anxiety in rats,”
Proceedings of the National Academy of Sciences of the United States of America
Online Edition: 2014/12/16 (Japan time), doi: 10.1073/pnas.1414710112.
Online URL (Abstract page, not full text):