TRANSCRIPTION FACTOR NF-κB AND THE NEURAL MORPHOLOGIC CHANGES ASSOCIATED TO LEARNING AND MEMORY

DE LA FUENTE V; CALFA G; ROMANO A; POZZO-MILLER L

Ciudad Autónoma de Buenos Aires

Conferencia; 5th Special Conference of the International Society of Neurochemistry; 2012

International Society for Neurochemistry

Despite that the idea of storing of memories involves morphological modifications in synapses was proposed more than 100 years ago independently by Cajal and Tanzi, it was only recently that solid experimental evidence has confirmed that learning is associated with changes in dendritic spine density. Several studies have addressed this issue using different learning paradigms that involve different brain areas, yielding heterogeneous results. Despite these varied observations likely due to the brain region-specific behavioural tasks used, the common denominator of all these studies is that learning indeed produces changes in spine density. However, little is known about the molecular mechanisms involved in the morphological changes at dendritic spines caused by behavioural learning. Besides, the transcription factor NF-kappaB has been involved in memory consolidation and reconsolidation in different paradigm, both in invertebrates and vertebrates, and it is also known to trigger the transcription of many genes with varied functions, including those potentially involved in morphological plasticity like BDNF and MMP3/9. Thus, we tested if NF-κB participates in changes of spine density induced by fear conditioning in hippocampal CA1 pyramidal neurons. We stained mouse hippocampal slices by ballistic delivery of DiI for subsequent confocal imaging of dendritic spines. Our results show that (1) consolidation induces an increase in spine density in both apical and basal dendrites of CA1 pyramidal neurons;(2) the increase in spine density associated to fear conditioning is prevented by intra-hippocampal infusions of NF-kappaB inhibitors; (3) the increase in spine density caused by fear conditioning persists after a reconsolidation protocol; whether the enduring spine increase after reconsolidation also requires NF-kappaB signalling is still under investigation.