Identification of a pheromone that increases anxiety in rats

Chemical communication plays an important role in the social lives of various mammalian species. Some of these chemicals are called pheromones. Rats release a specific odor into the air when stressed. This stress-related odor increases the anxiety levels of other rats; therefore, it is possible that...

Ausführliche Beschreibung

Gespeichert in:
Bibliographische Detailangaben
Veröffentlicht in:Proceedings of the National Academy of Sciences - PNAS 2014-12, Vol.111 (52), p.18751-18756
Hauptverfasser: Inagaki, Hideaki, Kiyokawa, Yasushi, Tamogami, Shigeyuki, Watanabe, Hidenori, Takeuchi, Yukari, Mori, Yuji
Format: Artikel
Sprache:eng
Schlagworte:
Online-Zugang:Volltext
Tags: Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
Beschreibung
Zusammenfassung:Chemical communication plays an important role in the social lives of various mammalian species. Some of these chemicals are called pheromones. Rats release a specific odor into the air when stressed. This stress-related odor increases the anxiety levels of other rats; therefore, it is possible that the anxiety-causing molecules are present in the stress-related odorants. Here, we have tried to identify the responsible molecules by using the acoustic startle reflex as a bioassay system to detect anxiogenic activity. After successive fractionation of the stress-related odor, we detected 4-methylpentanal and hexanal in the final fraction that still possessed anxiogenic properties. Using synthetic molecules, we found that minute amounts of the binary mixture, but not either molecule separately, increased anxiety in rats. Furthermore, we determined that the mixture increased a specific type of anxiety and evoked anxiety-related behavioral responses in an experimental model that was different from the acoustic startle reflex. Analyses of neural mechanisms proposed that the neural circuit related to anxiety was only activated when the two molecules were simultaneously perceived by two olfactory systems. We concluded that the mixture is a pheromone that increases anxiety in rats. To our knowledge, this is the first study identifying a rat pheromone. Our results could aid further research on rat pheromones, which would enhance our understanding of chemical communication in mammals. Significance Animals communicate with other members of the same species by using pheromones. Rats release a specific odor into the air when they are stressed. Because this stress-related odor increases anxiety in the other rats, it is likely that there are some anxiogenic molecules in this odor. In this study, we have tried to identify these molecules. We discovered that a combination of two molecules, 4-methylpentanal and hexanal, increased anxiety in rats. We concluded that the mixture is a pheromone in rats that can increase anxiety in conspecifics. Furthermore, we proposed that the neural circuit relating to anxiety was only activated when the two molecules were simultaneously perceived by two separate olfactory systems.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1414710112