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Role for calbindin‐D28 K in in vitro classical conditioning of abducens nerve responses in turtles
Author(s) -
Keifer Joyce,
Brewer Boone T.,
Meehan Phillip E.,
Brue Richard J.,
Clark Timothy G.
Publication year - 2003
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.10219
Subject(s) - calbindin , parvalbumin , neuroscience , medicine , calcium binding protein , endocrinology , nmda receptor , biology , calmodulin , receptor , microbiology and biotechnology , calcium , chemistry
Intracellular calcium has a pivotal role in synaptic modifications that may underlie learning and memory. The present study examined whether there were changes in immunoreactivity levels of the AMPA receptor subunits GluR2/3 and calcium binding proteins during classical conditioning recorded in the abducens nerve of in vitro brain stem preparations from turtles. The results showed that abducens motor neurons in unconditioned turtle brain stems were immunopositive for GluR2/3, calbindin‐D28 K , and calmodulin, but were immunonegative for parvalbumin. After classical conditioning, immunoreactivity for calbindin‐D28 K in the abducens motor nuclei was significantly reduced, whereas there were no significant changes in GluR2/3, calmodulin, or parvalbumin. This reduction in calbindin‐D28 K immunoreactivity was not observed following conditioning in the NMDA receptor antagonist AP‐5, which blocked conditioned responses, suggesting that these changes are NMDA receptor‐dependent. Moreover, the degree of the decrease in calbindin‐D28 K immunoreactivity was negatively correlated with the level of conditioning. Consistent with the immunocytochemical findings, Western blot analysis showed that calbindin‐D28 K protein levels were reduced after classical conditioning. The results support the hypothesis that in vitro classical conditioning of abducens nerve responses utilizes intracellular calcium‐dependent signaling pathways that require NMDA receptor function and suggest a specific role for the calcium binding protein calbindin‐D28 K . Synapse 49:106–115, 2003. © 2003 Wiley‐Liss, Inc.