Open AccessFear learning-induced changes in AMPAR and NMDAR expression in the fear circuit
Author(s) -
Brianna Shultz,
Abigail Farkash,
Bailey Collins,
Negin Mohammadmirzaei,
Dayan Knox
Publication year - 2022
Publication title -
learning and memory
Language(s) - English
Resource type - Journals
eISSN - 1549-5485
pISSN - 1072-0502
DOI - 10.1101/lm.053525.121
Subject(s) - fear conditioning , ampa receptor , neuroscience , fear processing in the brain , amygdala , nmda receptor , hippocampus , psychology , basolateral amygdala , anterior cingulate cortex , glutamate receptor , infralimbic cortex , prefrontal cortex , receptor , medicine , cognition
NMDA receptors (NMDARs) and AMPA receptors (AMPARs) in amygdala nuclei and the dorsal hippocampus (dHipp) are critical for fear conditioning. Enhancements in synaptic AMPAR expression in amygdala nuclei and the dHipp are critical for fear conditioning, with some studies observing changes in AMPAR expression across many neurons in these brain regions. Whether similar changes occur in other nodes of the fear circuit (e.g., ventral hippocampus [vHipp]) or changes in NMDAR expression in the fear circuit occur with fear conditioning have not been sufficiently examined. To address this we used near-infrared immunohistochemistry (IHC) to measure AMPAR and NMDAR subunit expression in several nodes of the fear circuit. Long-term changes in GluR1 and GluR2 expression in the ventral hippocampus (vHipp) and anterior cingulate cortex (ACC), enhanced NR2A expression in amygdala nuclei, and changes in the ratio of GluR1/NR2A and GluR2/NR2A in the dHipp was observed with fear conditioning. Most of these changes were dependent on protein synthesis during fear conditioning and were not observed immediately after fear conditioning. The results of the study suggest that global changes in AMPARs and NMDARs occur in multiple nodes within the fear circuit and raise the possibility that these changes contribute to fear memory. Further research examining how global changes in AMPAR, NMDAR, and AMPAR/NMDAR ratios within nodes of the fear circuit contribute to fear memory is needed.