title: Associative fear conditioning of enkephalin mRNA levels in central amygdalar neurons.
abstract: The central nucleus of the amygdala (CEA) is required for the expression of learned fear responses. This study used in situ hybridization to show that mRNA levels of the neuropeptide enkephalin are increased in CEA neurons after rats are placed in an environment that they associate with an unpleasant experience. In contrast, mRNA levels of another neuropeptide, corticotropin releasing hormone, do not change under the same conditions in the CEA of the same rats. Conditioned neuropeptide levels in amygdalar circuits may act as a reversible "gain control" for long-term modulation of subsequent fear responses.
authors.affiliation: Program in Neural Informational and Behavioral Sciences, University of Southern California, Los Angeles 90089-2520, USA.
authors.forename: G D
authors.initials: GD
authors.lastname: Petrovich
authors.forename: A P
authors.initials: AP
authors.lastname: Scicli
authors.forename: R F
authors.initials: RF
authors.lastname: Thompson
authors.forename: L W
authors.initials: LW
authors.lastname: Swanson
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D001245:Association Learning / Q000502:physiology*; D001931:Brain Mapping; D003214:Conditioning, Classical / Q000502:physiology*; D004745:Enkephalins / Q000235:genetics*; D005239:Fear / Q000502:physiology*; D015870:Gene Expression / Q000502:physiology; D008297:Male; D009415:Nerve Net / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004745:Enkephalins; D012333:RNA, Messenger