Prior stress exposure facilitates the behavioural and molecular changes induced by a weak fear conditioning procedure

MALDONADO NOELIA MARTINA; IRENE DELIA MARTIJENA; VICTOR ALEJANDRO MOLINA

Congreso; IIRCN, Second Joint Meeting of the Society for Neurosciences (SAN) and the Argentine Workshop in Neurosciences (TAN); 2010

Exposure to threatening stimuli results in exaggerated fear and anxiety in response to novel environmental stimulus, a process defined as Emotional Sensitization. The Basolateral Complex of the amygdale (BLA) plays a key role in the processing of aversive information. Previous reports suggested that MAPKinasas pathway play a rol in the consolidation of auditory and contextual fear memories. The purpose of this study was to determine neurochemical changes involved in the facilitation of fear responses induced by stress. Male Wistar rats (280-300g) were used to perform the experiments, 10 minutes before the restraint session (30 min), animals were injected either with MDZ 1.5mg/Kg,i.p or 1ug/0,25ul/side intra BLA prior to a weak contextual fear conditioning protocol (0,3mAX1 shock, CFC). The behavioural test was conduced 24 hs after CFC. We observed high freezing levels in stressed animals who received VEH intra BLA or i.p. Using western blot ,the ERK2 activity in BLA was quantifiyed, after the CFC at different times points. An increase in perk2 was observed in the CFC in animals previously stressed, in comparisson with there respective controls. The administration of MDZ 1,5mg/kg, before the restraint session, impaired the emotional sensitization process in CFC. We observed that ERK2 phosphorylation would be necessary to install the negative emotional state induced by stress. On the other hand, MDZ impaired the perk2 increase in BLA 30 after CFC.