Picrotoxin enhances latent extinction of conditioned fear.
Male CD1 mice received 20 pairings of tone and footshock (FS) or tone alone in an arm of a Y-maze on Day 1. On Day 2 either extinction (tone alone) or no extinction was followed immediately by saline or picrotoxin (0.5 or 1.0 mg/kg ip). Nonextinguished groups received only saline or picrotoxin (1.0 mg/kg ip) on Day 2. Other groups received saline or picrotoxin (1.0 mg/kg) 2 hr after extinction. On Day 3 all mice were placed in the Y-maze (with doors to all 3 alleys open), and total alley entries during a 2-min test session were recorded. Day 1 FS training resulted in reduced alley entries during the test session. Day 2 extinction session significantly attenuated the effects of the FS training. Day 3 performance of mice given picrotoxin (1.0 but not 0.5 mg/kg) immediately postextinction was comparable to that of mice not given FS on Day 1. The findings suggest that picrotoxin enhanced extinction of conditioned fear.
McGaugh
J L
JL
Center for the Neurobiology of Learning and Memory, University of California, Irvine 92717.
Castellano
C
C
Brioni
J
J
D000818:Animals; D001143:Arousal / Q000187:drug effects; D003214:Conditioning, Classical / Q000187:drug effects*; D004193:Discrimination Learning / Q000187:drug effects*; D004597:Electroshock; D005108:Extinction, Psychological / Q000187:drug effects*; D005239:Fear / Q000187:drug effects*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009949:Orientation / Q000187:drug effects*; D010852:Picrotoxin / Q000494:pharmacology*; D012153:Retention, Psychology / Q000187:drug effects
D010852:Picrotoxin