Hippocamppal structural plasticity associated to the f ear memory destabilization/reconsolidation process

RAMIRO GABRIEL COMAS MUTIS; IRENE DELIA MARTIJENA; VICTOR ALEJANDRO MOLINA; GASTÓN DIEGO CALFA

Congreso; XXXIV Annual Meeting of the Argentine Society for Research in Neuroscience; 2019

A con
solidated memory can enter a transient labile state when presented with a
reminder, requiring a protein synthesis dependent re stabilization process termed
reconsolidation. It is known that the basolat eral amygdala (BLA) and the Dorsal
Hippocampus (DH) pl ay a key role in processing emotional information and the
contextual representation of fear memories respectively. In the pr esent study, we
assessed the modulating role of BLA on the hippocampal structu ral plasticity
associated with the labilization/recons olidation of a contextual fear memory. We
used Ifenprodil (IFEN), a selective NR2B subunit of the NMDA receptor antagonist,
infused intra BLA in male wistar rats, in order to prevent the labilization. R ats were
sacrificed 60 minutes and 24 hours after the retrieval session to evaluate the
structural plasticity of the CA1 region of DH.
Our results show that rats infused with IF EN present a high number of spines at
both 60 minutes and 24 hours post retrie val, while rats infused with saline solution
(SAL) sho w a decrease in dendritic spines 60 minutes after retrieval, consistent
with the dynamic changes in dendritic spines observe d in our previous work.
Altogether, our findings seem to indicate that labiliz ation impairment prevents
structural changes in the CA 1 region of DH, thus supporting our hypothesis of the
modulating role of BLA on the hippocampal structural plasticity and th e idea that
changes in dendritic spines density are required for a memory to b e updated.