Hippocamppal structural plasticity associated to the fear memory destabilization/reconsolidation process

Cordoba

Congreso; XXXIV Congreso anual de la Sociedad Argentina de Investigación en Neurociencias; 2019

Sociedad Argentina en Investigacion en Neurociencias

A consolidated 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 basolateral amygdala (BLA) and the Dorsal Hippocampus (DH) play a key role in processing emotional information and the contextual representation of fear memories respectively. In the present study, we assessed the modulating role of BLA on the hippocampal structural plasticity associated with the labilization/reconsolidation 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. Rats 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 IFEN present a high number of spines at both 60 minutes and 24 hours post retrieval, while rats infused with saline solution (SAL) show a decrease in dendritic spines 60 minutes after retrieval, consistent with the dynamic changes in dendritic spines observed in our previous work. Altogether, our findings seem to indicate that labilization impairment prevents structural changes in the CA1 region of DH, thus supporting our hypothesis of the modulating role of BLA on the hippocampal structural plasticity and the idea that changes in dendritic spines density are required for a memory to be updated.