Temporary inactivation of the anterior part of the bed nucleus of the stria terminalis blocks alarm pheromone-induced defensive behavior in rats.

Tino Breitfeld,Johann E A Bruning,Markus Fendt,Yukari Takeuchi,Yasushi Kiyokawa,Hideaki Inagaki

doi:10.3389/fnins.2015.00321

Abstract

Rats emit an alarm pheromone in threatening situations. Exposure of rats to this alarm pheromone induces defensive behaviors, such as head out behavior, and increases c-Fos expression in brain areas involved in the mediation of defensive behaviors. One of these brain areas is the anterior bed nucleus of the stria terminalis (aBNST). The goal of the present study was to investigate if pharmacological inactivation of the aBNST by local microinjections of the GABAA receptor-agonist muscimol modulates alarm pheromone-induced defensive behaviors. We first established the behavioral paradigm of alarm pheromone-induced defensive behaviors in Sprague-Dawley rats in our laboratory. In a second experiment, we inactivated the aBNST, then exposed rats to one of four different odors (neck odor, female urine, alarm pheromone, fox urine) and tested the effects of the aBNST inactivation on the behavior in response to these odors. Our data show that temporary inactivation of the aBNST blocked head out behavior in response to the alarm pheromone. This indicates that the aBNST plays an important role in the mediation of the alarm pheromone-induced defensive behavior in rats.

Highlights

Pheromones are olfactory signals that are used for intraspecific communication (Karlson and Luscher, 1959)
Experiment 2: The Role of the anterior bed nucleus of the stria terminalis (aBNST) in the Alarm Pheromone Effects In our second experiment, we injected either saline or muscimol into the aBNST to investigate the role of the aBNST in alarm pheromone-induced defensive behavior
We assessed the hypothesis that the aBNST plays a crucial role in alarm pheromone-induced defensive behavior in rats

Summary

Introduction

Pheromones are olfactory signals that are used for intraspecific communication (Karlson and Luscher, 1959) They can transmit different information, e.g., sex, age, and reproduction status, about the releaser (Beny and Kimchi, 2014). Pheromones have different ecological functions including marking a trail or territory, attracting potential mating partners, inducing aggregation or dispersion of conspecifics or warning conspecifics to potential danger (Hauser et al, 2011). Pheromones with the latter function are called alarm pheromones (Inagaki et al, 2014). For the alarm pheromone of rats, it is known that it is emitted from the perianal region (Kiyokawa et al, 2004), consists of at least two active ingredients, 4-methylpentanal and hexanal

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