title: Emotional stress evoked by classical fear conditioning induces yawning behavior in rats.
abstract: Yawning is often observed not only in a state of boredom or drowsiness but also in stressful emotional situations, suggesting that yawning is an emotional behavior. However, the neural mechanisms for yawning during stressful emotional situations have not been fully determined, though previous studies have suggested that both parvocellular oxytocin (OT) and corticotropin-releasing factor (CRF) neurons in the hypothalamic paraventricular nucleus (PVN) are responsible for induction of yawning. Thus, using ethological observations and c-Fos immunohistochemistry, we examined whether emotional stress evoked by classical fear conditioning is involved in induction of yawning behavior in freely moving rats. Emotional stress induced yawning behavior that was accompanied by anxiety-related behavior, and caused neuronal activation of the central nucleus of the amygdala (CeA), as well as increases in activity of both OT and CRF neurons in the PVN. These results suggest that emotional stress may induce yawning behavior, in which the neuronal activation of the CeA may have a key role.
authors.affiliation: Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Kubota
authors.affiliation: Department of Human Health Science, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan.
authors.forename: Seiichiro
authors.initials: S
authors.lastname: Amemiya
authors.affiliation: Research Institute for Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Yanagita
authors.affiliation: Department of Human Health Science, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nishijima
authors.affiliation: Department of Human Health Science, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan. Electronic address: kita-ichiro@tmu.ac.jp.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kita
mesh_terms: D000679:Amygdala / Q000378:metabolism; D000818:Animals; D001007:Anxiety / Q000378:metabolism / Q000523:psychology; D003214:Conditioning, Classical; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D005239:Fear; D008297:Male; D009474:Neurons / Q000378:metabolism; D010121:Oxytocin / Q000378:metabolism; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000378:metabolism / Q000523:psychology*; D015000:Yawning
chemical_list: D010121:Oxytocin; D003346:Corticotropin-Releasing Hormone
keywords: Amygdala; Emotional stress; Fear conditioning; Immunohistochemistry; PVN; Yawning