TitleExtinction of contextual cocaine memories requires Cav1.2 within D1R-expressing cells and recruits hippocampal Cav1.2-dependent signaling mechanisms
Publication TypeJournal Article
Year of Publication2017
AuthorsBurgdorf CE, Schierberl KC, Lee AS, Fischer DK, Van Kempen TA, Mudragel V, Huganir RL, Milner TA, Glass MJ, Rajadhyaksha AM
JournalJournal Of Neuroscience

Exposure to cocaine-associated contextual cues significantly contributes to relapse. Extinction of these contextual associations, which involves a new form of learning, reduces cocaine-seeking behavior, however the molecular mechanisms underlying this process remain largely unknown. We report that extinction, but not acquisition of cocaine conditioned place preference (CPP) in male mice increased Cav1.2 L-type Ca2+ channel mRNA and protein in postsynaptic density (PSD) fractions of the hippocampus, a brain region involved in drug-context associations. Moreover, viral-mediated deletion of Cav1.2 in the dorsal hippocampus attenuated extinction of cocaine CPP. Molecular studies examining downstream Cav1.2 targets revealed that extinction recruited CaMKII to the hippocampal PSD. This occurred in parallel with an increase in phosphorylation of the AMPA GluA1 receptor subunit at serine 831 (S831), a CaMKII site, along with an increase in total PSD GluA1. The necessity of S831 GluA1 was further demonstrated by the lack of extinction in S831A GluA1 phospho-mutant mice. Surprisingly, hippocampal GluA1 levels remained unaltered at the PSD but were reduced near the PSD and at perisynaptic sites of dendritic spines in extinction-resistant S831A mutant mice. Finally, conditional knockout of Cav1.2 in dopamine D1R-expressing cells resulted in attenuation of cocaine CPP extinction and lack of extinction-dependent changes in hippocampal PSD CaMKII expression and S831 GluA1 phosphorylation. In summary, we demonstrate an essential role for the hippocampal Cav1.2/CaMKII/S831 GluA1 pathway in cocaine CPP extinction, with data supporting contribution of hippocampal D1R-expressing cells in this process. These findings demonstrate a novel role for Cav1.2 channels in extinction of contextual cocaine-associated memories.