title: Blockade of amygdala metabotropic glutamate receptor subtype 1 impairs fear extinction.
abstract: The metabotropic glutamate receptor subtype 1 (mGluR1) is thought to be crucial for several forms of memory, but its role in memory extinction has not been determined. Here, we examined a role of mGluR1 in the extinction of conditioned fear using microinjection of an mGluR1 antagonist, CPCCOEt, into the lateral amygdala (LA), a critical structure for fear conditioning and extinction. Intra-LA injection of 3 microg CPCCOEt impaired extinction that was initiated 48 h after the conditioning, but not that initiated 2h after the conditioning, indicating that the effectiveness of CPCCOEt depends upon the length of time since fear conditioning. The CPCCOEt injection failed to alter an mGluR1-like receptor (mGluR5)-dependent acquisition of fear memory, further supporting the specificity of the injected CPCCOEt on mGluR1. Together, our results suggest that amygdala mGluR1 plays a critical role in the extinction of learned fear, but not in the acquisition of fear memory.
authors.affiliation: School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Jeongyeon
authors.initials: J
authors.lastname: Kim
authors.forename: Sukwon
authors.initials: S
authors.lastname: Lee
authors.forename: Heewoo
authors.initials: H
authors.lastname: Park
authors.forename: Beomjong
authors.initials: B
authors.lastname: Song
authors.forename: Ingie
authors.initials: I
authors.lastname: Hong
authors.forename: Dongho
authors.initials: D
authors.lastname: Geum
authors.forename: Kisoon
authors.initials: K
authors.lastname: Shin
authors.forename: Sukwoo
authors.initials: S
authors.lastname: Choi
mesh_terms: D000679:Amygdala / Q000502:physiology*; D000818:Animals; D002867:Chromones / Q000494:pharmacology*; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology; D004597:Electroshock; D005108:Extinction, Psychological / Q000187:drug effects / Q000502:physiology*; D005239:Fear / Q000502:physiology*; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors*
chemical_list: C117789:7-(hydroxyimino)cyclopropan(b)chromen-1a-carbxoylic acid ethyl ester; D002867:Chromones; D018094:Receptors, Metabotropic Glutamate; C104077:metabotropic glutamate receptor type 1