title: Retrieval of conditioned fear activates the basolateral and intercalated nucleus of amygdala.
abstract: The amygdala is one of the crucial brain structures for conditioned fear, in which conditioned stimuli are received by the basolateral nucleus of the amygdala (BLA), inducing a fear reaction via the central nucleus of the amygdala (CeA). Whereas BLA sends glutamatergic projections into CeA, the intercalated nucleus of the amygdala (ITC) sends GABAergic projections into CeA, which is doubly regulated by BLA and ITC. In the present study, we investigated the characteristics of the neural cells activated by retrieval of conditioned fear in BLA and ITC using immunohistochemistry, in situ hybridization, and Western blot analysis of transcription factors and neural cell markers. Because most conditioned fear-induced c-Fos-positive cells in BLA were glutaminase positive and 67-kDa isomer of glutamic acid decarboxylase (GAD67) negative, these cells are speculated to be glutamatergic. Seventy-eight percent of the phosphorylated CREB (pCREB)-positive cells were glutaminase double positive and 13% of the pCREB-positive cells were GAD67 double positive, indicating that many of the conditioned fear-induced pCREB-positive cells in BLA were glutamatergic, but at least some of the pCREB-positive cells were GABAergic. These results suggested that CREB phosphorylation was increased both in glutamatergic and in GABAergic neurons, but c-Fos expression was increased mainly in glutamatergic neurons in BLA. CREB phosphorylation but not c-Fos expression in ITC was specifically increased by retrieval of conditioned fear. It is therefore speculated that ITC GABAergic neurons were activated by retrieval of conditioned fear and that transcription factors other than c-Fos were relevant to the activation.
authors.affiliation: Department of Neuropharmacology, Hokkaido University Graduate School of Medicine, Sapporo, Japan. psyizumi@med.hokudai.ac.jp
authors.forename: Takeshi
authors.initials: T
authors.lastname: Izumi
authors.forename: Shuken
authors.initials: S
authors.lastname: Boku
authors.forename: Weng
authors.initials: W
authors.lastname: Shinmin
authors.forename: Takeshi
authors.initials: T
authors.lastname: Inoue
authors.forename: Kotaro
authors.initials: K
authors.lastname: Konno
authors.forename: Taku
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Yoshida
authors.forename: Machiko
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Masahiko
authors.initials: M
authors.lastname: Watanabe
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Koyama
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yoshioka
mesh_terms: D000679:Amygdala / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D001923:Brain Chemistry / Q000502:physiology*; D003213:Conditioning, Psychological / Q000502:physiology*; D004195:Disease Models, Animal; D005239:Fear / Q000502:physiology*; D008297:Male; D008568:Memory / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
chemical_list: D005680:gamma-Aminobutyric Acid