title: A specific area of olfactory cortex involved in stress hormone responses to predator odours.
abstract: Instinctive reactions to danger are critical to the perpetuation of species and are observed throughout the animal kingdom. The scent of predators induces an instinctive fear response in mice that includes behavioural changes, as well as a surge in blood stress hormones that mobilizes multiple body systems to escape impending danger. How the olfactory system routes predator signals detected in the nose to achieve these effects is unknown. Here we identify a specific area of the olfactory cortex in mice that induces stress hormone responses to volatile predator odours. Using monosynaptic and polysynaptic viral tracers, we found that multiple olfactory cortical areas transmit signals to hypothalamic corticotropin-releasing hormone (CRH) neurons, which control stress hormone levels. However, only one minor cortical area, the amygdalo-piriform transition area (AmPir), contained neurons upstream of CRH neurons that were activated by volatile predator odours. Chemogenetic stimulation of AmPir activated CRH neurons and induced an increase in blood stress hormones, mimicking an instinctive fear response. Moreover, chemogenetic silencing of AmPir markedly reduced the stress hormone response to predator odours without affecting a fear behaviour. These findings suggest that AmPir, a small area comprising <5% of the olfactory cortex, plays a key part in the hormonal component of the instinctive fear response to volatile predator scents.
authors.affiliation: Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109, USA.
authors.forename: Kunio
authors.initials: K
authors.lastname: Kondoh
authors.affiliation: Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109, USA.
authors.forename: Zhonghua
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109, USA.
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Ye
authors.affiliation: Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: David P
authors.initials: DP
authors.lastname: Olson
authors.affiliation: Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Bradford B
authors.initials: BB
authors.lastname: Lowell
authors.affiliation: Howard Hughes Medical Institute, Basic Sciences Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, Washington 98109, USA.
authors.forename: Linda B
authors.initials: LB
authors.lastname: Buck
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000097:blood / Q000378:metabolism; D004924:Escape Reaction; D005239:Fear; D005260:Female; D006624:Hippocampus / Q000166:cytology / Q000502:physiology; D006728:Hormones / Q000097:blood / Q000378:metabolism*; D007323:Instinct; D008297:Male; D051379:Mice; D009474:Neurons / Q000378:metabolism; D009812:Odorants / Q000032:analysis*; D066194:Olfactory Cortex / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D009833:Olfactory Pathways; D055696:Olfactory Perception / Q000502:physiology; D011235:Predatory Behavior; D012903:Smell / Q000502:physiology*; D013315:Stress, Psychological; D013687:Telencephalon / Q000033:anatomy & histology / Q000166:cytology / Q000502:physiology
chemical_list: D006728:Hormones; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D003345:Corticosterone