Actin cytoskeleton: the backbone of memory trace?

MEDINA, CANDELA; ROMANO, ARTURO; DE LA FUENTE, VERÓNICA

Mar del Plata, Pcia de Buenos Aires

Congreso; XXXII Congress of the Argentine Society for Research in Neuroscience; 2017

SAN

Long-term memory has been associated with morphological changes in the brain, in strictcorrelation with changes in synaptic efficacy. Such plasticity is proposed to rely on dendriticspines as a sort of neuronal canvas on which these changes can take place. Given its key roleon spine morphology, actin cytoskeleton dynamics and its major regulating factors (such asADF/Cofilin) become an attractive target to study processes underlying dendritic plasticity.Using a contextual fear conditioning paradigm in mice, we found that pharmacologicalinduction of depolymerization of actin filaments through an intra-hippocampal injection ofBMS-5 ?a potent inhibitor of LIM kinase, which is in turn an inhibitor of ADF/Cofilin activity?causes an impairment in memory consolidation and reconsolidation. On the other hand,when favoring stabilization of actin filaments by intra-hippocampal injection of Jasplakinolideimmediately before a short reminder session that usually elicits memory reconsolidation, theformation of an extinction memory was facilitated. On top of that, we found an increase in PCofilin/Cofilinratio in synaptoneurosome-enriched hippocampal extracts obtained after areconsolidation eliciting reminder, implying a diminished depolymerization activity by thisfactor, therefore favoring stabilization of actin filaments when this phase of memory is takingplace. Our results support the importance of actin cytoskeleton dynamics underlying thememory trace.