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

Carlos Paz

Congreso; Reunión Anual de la Sociedad Argentina de Investigación en Neurociencias; 2019

Sociedad Argentina de Investigación en Neurociencias

A consolidated memory may enter a transient labile state when presented with a reminder, necessitating a protein synthesis-dependant re-stabilization termed reconsolidation. The labilization/reconsolidation process has been rendered a potential therapeutical target for the treatment of anxiety disorders such as phobias and post-traumatic stress disorder (PTSD) due to the possibility of altering or interfering a memory during the temporal window in which said process occur. It is known the key role of the basolateral amygdala (BLA) and the Dorsal Hippocampus (DH) 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. In order to do so, we used Ifenprodil (IFEN), a selective NR2B subunit of the NMDA receptor antagonist, infused intra-BLA in male wistar rats, to prevent the labilization of a contextual fear memory. The Rats were sacrificed 60 minutes and 24 hours after the retrieval session to measure dendritic spine density in the CA1 region of DH. Our preliminary results show that animals infused with IFEN present a high number of spines at both 60 minutes and 24 hours post retrieval, while animals infused with saline solution (SAL) show a decrease in dendritic spines 60 minutes after retrieval, consistent with the dynamic changes in 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 and reconsolidated.