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Elucidating the mechanisms of fear extinction in developing animals: a special case of NMDA receptor-independent extinction in adolescent rats
被引:6
作者:
Bisby, Madelyne A.
[1
]
Baker, Kathryn D.
[1
]
Richardson, Rick
[1
]
机构:
[1] UNSW Sydney, Sch Psychol, Sydney, NSW 2052, Australia
基金:
澳大利亚国家健康与医学研究理事会;
澳大利亚研究理事会;
英国医学研究理事会;
关键词:
NICOTINIC ACETYLCHOLINE-RECEPTOR;
VENTROMEDIAL PREFRONTAL CORTEX;
ENDOCANNABINOID SYSTEM;
POTENTIATED STARTLE;
LEARNED FEAR;
AMYGDALA;
MK-801;
MEMORY;
EXPRESSION;
TERM;
D O I:
10.1101/lm.047209.117
中图分类号:
Q189 [神经科学];
学科分类号:
071006 ;
摘要:
NMDA receptors (NMDARs) are considered critical for the consolidation of extinction but recent work challenges this assumption. Namely, NMDARs are not required for extinction retention in infant rats as well as when extinction training occurs for a second time (i.e., reextinction) in adult rats. In this study, a possible third instance of NMDAR-independent extinction was tested. Although adolescents typically exhibit impaired extinction retention, rats that are conditioned as juveniles and then given extinction training as adolescents (JuvCond-AdolesExt) have good extinction retention. Unexpectedly, this good extinction retention is not associated with an up-regulation of a synaptic plasticity marker in the medial prefrontal cortex, a region implicated in extinction consolidation. In the current study, rats received either the noncompetitive NMDAR antagonist MK801 (0.1 mg/kg, s.c.) or saline before extinction training. In several experiments, rats conditioned and extinguished as juveniles, adolescents, or adults exhibited impaired extinction retention after MK801 compared to saline, but this effect was not observed in JuvCond-AdolesExt rats. Further experiments ruled out several alternative explanations for why NMDAR antagonism did not affect extinction retention in adolescents extinguishing fear learned as a juvenile. These results illustrate yet another circumstance in which NMDARs are not required for successful extinction retention and highlight the complexity of fear inhibition across development.
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页码:158 / 164
页数:7
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