Prior stress promotes the generalization of contextual fear memories: Involvement of the gabaergic signaling whithin the basolateral amygdala complex

BENDER CRHISTIAN L

Mar del Plata

Conferencia; XXXII CONGRESO ANUAL SAN 2017; 2017

Sociedad Argentina de Neurociencias

Fear generalization occurs when a response previously acquired with a threatening stimulus is transferred to a similar one. However, it could be maladaptive when stimuli that do not represent a real threat are appraised as dangerous, which is a hallmark of several anxiety disorders. Stress exposure is a major risk factor for the occurrence of anxiety disorders and it is well established that influences different phases of fear memory, but its impact on the generalization of contextual fear memories has been less studied. Here, we characterized the impact of acute restraint stress prior to contextual fear conditioning on the generalization of this fear memory and the role of the GABAergic signaling within the basolateral amygdala complex (BLA) on the stress modulatory effects. We found that a single stress exposure promoted the generalization of this memory trace to a different context that was well discriminated in unstressed conditioned animals. Moreover, this effect was dependent on the associative properties and on the order of presentation of the testing chambers (i.e., conditioning vs generalization chamber). Furthermore, we observed that increasing GABA-A signaling by intra-BLA midazolam administration prior to the stressful session exposure prevented the generalization of fear memory, whereas intra-BLA administration of the GABA-A antagonist (Bicuculline) prior to fear conditioning induced the generalization of fear memory in unstressed rats. We conclude that stress exposure prior to contextual fear conditioning promotes the generalization of fear memory and that GABAergic transmission within the BLA has a critical role in this phenomenon.