Activation of acid-sensing ion channels by carbon dioxide regulates amygdala synaptic protein degradation in memory...

Reconsolidation has been considered a process in which a consolidated memory is turned into a labile stage. Within the reconsolidation window, the labile memory can be either erased or strengthened. Manipulating acid-sensing ion channels (ASICs) in the amygdala via carbon dioxide (CO₂) inhalation enhances memory retrieval and its lability within the reconsolidation window. Moreover, pairing CO₂ inhalation with retrieval bears the reactivation of the memory trace and enhances the synaptic exchange of the calcium-impermeable AMPA receptors to calcium-permeable AMPA receptors. Our patch-clamp data suggest that the exchange of the AMPA receptors depends on the ubiquitin-proteasome system (UPS), via protein degradation. Ziram (50 µM), a ubiquitination inhibitor, reduces the turnover of the AMPA receptors. CO₂ inhalation with retrieval boosts the ubiquitination without altering the proteasome activity. Several calcium-dependent kinases potentially involved in the CO₂-inhalation regulated memory liability were identified using the Kinome assay. These results suggest that the UPS plays a key role in regulating the turnover of AMPA receptors during CO₂ inhalation.