Previous stress diminishes the interfering effect of midazolam on fear memory reconsolidation. Effect of intra basolateral amygdala D-cycloserine administration

Congreso; XXIX Congreso anual de la Sociedad Argentina de Investigación en Neurociencia; 2014

A fully consolidated memory can enter into a new labile state when is retrieved, requiring an additional restabilization process defined as reconsolidation. However, there are conditions in which this phenomenon is constrained. For instance, the recall of memories induced by robust training, among others, are known as boundary conditions. Previous studies in our laboratory have shown that a stressful event prior to a contextual fear conditioning generates a memory that is resistant to the disruptive effect of Midazolam (MDZ) on reconsolidation, and this resistance can be reverted by D-cycloserine (DCS). The goal of this study was to evaluate the anatomical locus of the effect of DCS in the reversal of such resistance. As expected, stressed rats were resistant to the disruptive effect of MDZ, additionally, DCS infusion intra-basolateral amygdala (BLA) before reactivation restored MDZ interference, with no effect per se in DCS/SAL group. By the other hand, in the non stressed groups, all animals administered with MDZ despite of the pretreatment with DCS or SAL exhibit memory interference at Test. This result suggests that BLA is, at least, one of the brain structures involved in memory resistance due to the stressful experience and that activation of NMDA receptors is crucial for memory labilization. Finally, we propose that the occurrence of a negative emotional state at the moment of learning limits the subsequent emergence of the labilization/reconsolidation process.