Cat odor, but not trimethylthiazoline (fox odor), activates accessory olfactory and defense-related brain regions in rats

doi:10.1016/j.neuroscience.2007.11.039

Neuroscience

Volume 151, Issue 4, 19 February 2008, Pages 937-947

https://doi.org/10.1016/j.neuroscience.2007.11.039 Get rights and content

Abstract

Cat odor and trimethylthiazoline (TMT, a component of fox feces) are two stimuli widely used in rodent models of fear and anxiety. Recent studies suggest that these odorants have distinct behavioral effects, raising questions as to whether TMT is a true “predator odor.” Here we used c-Fos immunohistochemistry to compare patterns of neural activation produced by cat odor and TMT. Rats were exposed to either (1) three pieces of a collar that had been worn by a domestic cat, (2) three collar pieces impregnated with TMT (30 μl/piece), (3) three collar pieces impregnated with 4% formaldehyde (200 μl/piece, an acrid but non-predatory odor), or (4) three control (no odor) collar pieces. Odors were presented in a small well-ventilated plastic box. All odorants (cat odor, TMT and formaldehyde) produced increased defecation in rats compared with the control group, and formaldehyde exposure also decreased rearing. Cat odor increased contact with the stimulus relative to all other groups, while TMT increased contact compared with the formaldehyde and clean air groups. Only cat odor decreased grooming and elicited escape attempts. In addition, only cat odor caused pronounced activation of Fos in the accessory olfactory bulb and its projection areas, anterior olfactory nucleus, medial prefrontal cortex, striatum, and a medial hypothalamic circuit associated with defensive behavior. In contrast, the only areas activated by TMT were the internal granular layer of the main olfactory bulb and central amygdala, while both cat odor and TMT activated the glomeruli of the main olfactory bulb, piriform cortex, ventral orbital cortex and anterior cortical amygdala. Results indicate that the effects of cat odor and TMT are easily distinguished both behaviorally and at a neural level, and suggest that TMT lacks the “pheromone-like” quality of cat odor that engages key hypothalamic sites involved in defensive behavior.

Section snippets

Subjects

The subjects (n=24) were male Australian Albino Wistar rats, weighing 321±7 g at the time of testing. They were housed in groups of six with free access to food and water in a temperature-controlled colony room (21±2 °C) on a reverse light/dark cycle (lights on from 20:00 to 08:00 h). Behavioral testing occurred during the dark cycle. All efforts were made to minimize both the suffering and the number of rats used. All experimentation was approved by the University of Sydney Animal Ethics

Behavior

ANOVA revealed significant overall group effects on all of the behaviors measured (Table 1). Rats exposed to any of the three odors (cat odor, formaldehyde or TMT) showed more defecation than the CONTROL group (F_3,20=7.73, P<0.001). In addition, rats in the group exposed to formaldehyde showed lower rearing scores compared with the CONTROL group (F_3,20=3.20, P<0.05). However only rats in the group exposed to cat odor made attempts to escape the test box via jumping (F_3,20=5.46, P<0.01). In

Discussion

The results of the current experiment show that cat odor and TMT are easily distinguishable at both the behavioral and neural level. Behaviorally, only cat odor induced repeated escape attempts and an inhibition of adaptive behavior (grooming), while at the neural level, only cat odor produced a typical pattern of Fos activation in accessory olfactory regions, and brain regions previously associated with defensive behavior (Canteras et al 1997, Dielenberg et al 2001, McGregor et al 2004,

Conclusions

The results from the current research suggest that TMT and cat odor are not comparable predator odors. This may be because the ethological relevance of such chemosignals in mammals relies on a complexity (Brennan and Kendrick, 2006) that is retained by naturally occurring fur/skin odors, but lost from synthetic components such as TMT. Alternatively, odors derived from feces may be less predictive of a predatory threat than those derived from sources such fur or skin (Blanchard et al., 2003).

Acknowledgments

This work was supported by an Australian Research Council grant to Iain S. McGregor.

References (40)

R.J. Blanchard et al.
The effects of ethanol and diazepam on reactions to predatory odors
Pharmacol Biochem Behav
(1990)
R.J. Blanchard et al.
Cue and context conditioning of defensive behaviors to cat odor stimuli
Neurosci Biobehav Rev
(2001)
P.C. Brunjes et al.
A field guide to the anterior olfactory nucleus (cortex)
Brain Res Rev
(2005)
N.S. Canteras et al.
Severe reduction of rat defensive behavior to a predator by discrete hypothalamic chemical lesions
Brain Res Bull
(1997)
H.M. Cooper et al.
Neuroanatomical pathways linking vision and olfaction in mammals
Psychoneuroendocrinology
(1994)
H.E.W. Day et al.
The pattern of brain c-fos mRNA induced by a component of fox odor, 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), in rats, suggests both systemic and processive stress characteristics
Brain Res
(2004)
R.A. Dielenberg et al.
Low-dose midazolam attenuates predatory odor avoidance in rats
Pharmacol Biochem Behav
(1999)
R.A. Dielenberg et al.
“When a rat smells a cat”: the distribution of Fos immunoreactivity in rat brain following exposure to a predatory odor
Neuroscience
(2001)
M. Fendt et al.
TMT-induced autonomic and behavioral changes and the neural basis of its processing
Neurosci Biobehav Rev
(2005)
D.T. Hubbard et al.
Development of defensive behavior and conditioning to cat odor in the rat
Physiol Behav
(2004)

C. Linster et al.

Neural activity in the horizontal limb of the diagonal band of Broca can be modulated by electrical stimulation of the olfactory bulb and cortex in rats

Neurosci Lett

(2000)

I.S. McGregor et al.

Not all “predator odours” are equal: cat odour but not 2,4,5 trimethylthiazoline (TMT; fox odour) elicits specific defensive behaviours in rats

Behav Brain Res

(2002)

T.A. Schoenfeld et al.

The anatomical logic of smell

Trends Neurosci

(2005)

L.G. Staples et al.

Neural activation during cat odor-induced conditioned fear and “trial 2” fear in rats

Neurosci Biobehav Rev

(2005)

L.G. Staples et al.

Defensive responses of Wistar and Sprague-Dawley rats to cat odour and TMT

Behav Brain Res

(2006)

L.K. Takahashi et al.

The smell of danger: A behavioral and neural analysis of predator odor-induced fear

Neurosci Biobehav Rev

(2005)

D.C. Blanchard et al.

Failure to produce conditioning with low-dose trimethylthiazoline or cat feces as unconditioned stimuli

Behav Neurosci

(2003)

Y. Boucher et al.

Activation of brain stem neurons by irritant chemical stimulation of the throat assessed by c-fos immunohistochemistry

Exp Brain Res

(2003)

P. Brennan et al.

Mammalian social odours: attraction and individual recognition

Philos Trans R Soc B

(2006)

Y.-M. Chang et al.

Maternal odours induce Fos in the main but not the accessory olfactory bulbs of neonatal male and female ferrets

J Neuroendocrinol

(2001)

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Behavioural neuroscienceCat odor, but not trimethylthiazoline (fox odor), activates accessory olfactory and defense-related brain regions in rats

Abstract

Section snippets

Subjects

Behavior

Discussion

Conclusions

Acknowledgments

Pharmacol Biochem Behav

Neurosci Biobehav Rev

Brain Res Rev

Brain Res Bull

Psychoneuroendocrinology

Brain Res

Pharmacol Biochem Behav

Neuroscience

Neurosci Biobehav Rev

Physiol Behav

Neurosci Lett

Behav Brain Res

Trends Neurosci

Neurosci Biobehav Rev

Behav Brain Res

Neurosci Biobehav Rev

Failure to produce conditioning with low-dose trimethylthiazoline or cat feces as unconditioned stimuli

Behav Neurosci

Activation of brain stem neurons by irritant chemical stimulation of the throat assessed by c-fos immunohistochemistry

Exp Brain Res

Mammalian social odours: attraction and individual recognition

Philos Trans R Soc B

Maternal odours induce Fos in the main but not the accessory olfactory bulbs of neonatal male and female ferrets

J Neuroendocrinol

Behavioural neuroscience
Cat odor, but not trimethylthiazoline (fox odor), activates accessory olfactory and defense-related brain regions in rats