The Effect of the [mu]-Opioid Receptor Antagonist Naloxone on Extinction of Conditioned Fear in the Developing Rat

Autor/inn/en	Kim, Jee Hyun; Richardson, Rick
Titel	The Effect of the [mu]-Opioid Receptor Antagonist Naloxone on Extinction of Conditioned Fear in the Developing Rat
Quelle	In: Learning & Memory, 16 (2009) 3, S.161-166 (6 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	1072-0502
DOI	10.1101/lm.1282309
Schlagwörter	Animals; Fear; Pretests Posttests; Experiments; Classical Conditioning; Stimuli; Associative Learning + Suchen Sie Ihr Suchwort? Animal; Tier; Tiere; Furcht; Erprobung; Anreizsystem
Abstract	Several recent studies report that neurotransmitters that are critically involved in extinction in adult rats are not important for extinction in young rats. Specifically, pretest injection of the [gamma]-aminobutryic acid (GABA) receptor inverse agonist FG7142 has no effect on extinction in postnatal day (P)17 rats, although it reverses extinction in P24 rats as reported by Kim and Richardson in an earlier paper. Further, pre-extinction injection of the N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 has no effect on extinction in P17 rats, whereas it impairs long-term extinction in P24 rats as per Langton and colleagues in an earlier work. These findings indicate that extinction in P17 rats is qualitatively different from extinction in older rats. The present study examines the involvement of the endogenous opioid system in extinction in the developing rat using systemic injections of the [mu]-opioid receptor antagonist naloxone. Experiment 1 showed that injection of naloxone before extinction training disrupted the acquisition of extinction in both P17 and P24 rats. This effect was dependent on central rather than peripheral [mu]-opioid receptors (Experiment 2), and neither pre-test nor post-extinction injection of naloxone had effects on extinction (Experiments 3 and 4). Taken together, these findings indicate that opioid neurotransmission, in contrast to GABA and NMDA activity, is critical for extinction acquisition across development. (Contains 4 figures and 1 table.) (As Provided).
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Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10