title: Egr-1 mRNA expression patterns in the prefrontal cortex, hippocampus, and amygdala during variants of contextual fear conditioning in adolescent rats.
abstract: We report activation of the immediate-early gene Egr-1 in the lateral amygdala (LA), hippocampus (CA1), and medial prefrontal cortex (mPFC) 30-min following the training phase in the context pre-exposure facilitation effect (CPFE) and standard context fear conditioning (180 s context exposure→shock). On day one of the CPFE paradigm, postnatal day (PD) 31 rats (±1) were pre-exposed to Context A (Pre) or Context B (Alt-Pre) for 5 min followed by five additional 1-min exposures. A day later, Pre and Alt-Pre rats received a 2-s, 1.5 mA footshock immediately upon placement in Context A. Animals included in in situ hybridization were then sacrificed 30 (±3) min later. On day three, the behaviorally-tested Pre rats showed significantly more fear-conditioned freezing in Context A than Alt-Pre rats. Standard context fear conditioning groups showed much greater freezing than the Pre group, as well as no shock and immediate-shock controls. Thirty minutes after immediate shock training, Pre rats showed increased Egr-1 mRNA in the prelimbic mPFC relative to Alt-Pre rats. Standard context conditioning selectively increased Egr-1 in CA1. In the LA and mPFC, Egr-1 increased to a similar extent in no shock, immediate shock, and standard context conditioning relative to homecage controls. The present study demonstrates that Egr-1 mRNA expression has a complex relationship to fear learning in different brain regions and variants of context conditioning.
authors: Department of Psychological & Brain Sciences, University of Delaware, Newark, DE 19716, USA.
authors: W B
authors: WB
authors: Schreiber
authors: Department of Psychological & Brain Sciences, University of Delaware, Newark, DE 19716, USA.
authors: A
authors: A
authors: Asok
authors: Department of Psychological & Brain Sciences, University of Delaware, Newark, DE 19716, USA.
authors: S A
authors: SA
authors: Jablonski
authors: Department of Psychological & Brain Sciences, University of Delaware, Newark, DE 19716, USA.
authors: J B
authors: JB
authors: Rosen
authors: Department of Psychological & Brain Sciences, University of Delaware, Newark, DE 19716, USA. Electronic address: stanton@udel.edu.
authors: M E
authors: ME
authors: Stanton
mesh_terms: D000367:Age Factors; D000679:Amygdala / Q000378:metabolism* / Q000502:physiology; D000818:Animals; D003214:Conditioning, Classical / Q000502:physiology*; D051766:Early Growth Response Protein 1 / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D004597:Electroshock; D005239:Fear / Q000502:physiology*; D005260:Female; D046352:Freezing Reaction, Cataleptic / Q000502:physiology*; D017781:Genes, Immediate-Early; D006234:Handling, Psychological; D006624:Hippocampus / Q000378:metabolism* / Q000502:physiology; D008297:Male; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D009473:Neuronal Plasticity; D017397:Prefrontal Cortex / Q000378:metabolism* / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D020318:Rats, Long-Evans; D013997:Time Factors
chemical_list: D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger
keywords: Amygdala; CPFE; Context fear conditioning; Egr-1; Hippocampus; Prefrontal cortex