title: A BDNF sensitive mechanism is involved in the fear memory resulting from the interaction between stress and the retrieval of an established trace.
abstract: The present study investigates the fear memory resulting from the interaction of a stressful experience and the retrieval of an established fear memory trace. Such a combination enhanced both fear expression and fear retention in adult Wistar rats. Likewise, midazolam intra-basolateral amygdala (BLA) infusion prior to stress attenuated the enhancement of fear memory thus suggesting the involvement of a stress-induced reduction of the GABAergic transmission in BLA in the stress-induced enhancing effect. It has been suggested that, unlike the immediate-early gene Zif268 which is related to the reconsolidation process, the expression of hippocampal brain-derived neurotrophic factor (BDNF) is highly correlated with consolidation. We therefore evaluate the relative contribution of these two neurobiological processes to the fear memory resulting from the above-mentioned interaction. Intra-dorsal hippocampus (DH) infusions of either the antisense Zif268 or the inhibitor of the protein degradation (Clasto-Lactacystin β-Lactone), suggested to be involved in the retrieval-dependent destabilization process, did not affect the resulting contextual memory. In contrast, the knockdown of hippocampal BDNF mitigated the stress-induced facilitating influence on fear retention. In addition, the retrieval experience elevated BDNF level in DH at 60 min after recall exclusively in stressed animals. These findings suggest the involvement of a hippocampal BDNF sensitive mechanism in the stress-promoting influence on the fear memory following retrieval.
authors.affiliation: IFEC-CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de Torre y Medina Allende, Ciudad Universitaria, (5000) Córdoba, Argentina.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Giachero
authors.forename: Silvia G
authors.initials: SG
authors.lastname: Bustos
authors.forename: Gaston
authors.initials: G
authors.lastname: Calfa
authors.forename: Victor A
authors.initials: VA
authors.lastname: Molina
mesh_terms: D000679:Amygdala / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D051766:Early Growth Response Protein 1 / Q000037:antagonists & inhibitors; D005239:Fear / Q000187:drug effects / Q000502:physiology*; D018757:GABA Modulators / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D007783:Lactones / Q000494:pharmacology; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D008874:Midazolam / Q000494:pharmacology; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000378:metabolism*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D018757:GABA Modulators; D007783:Lactones; D020319:Oligodeoxyribonucleotides, Antisense; C098869:clasto-lactacystin beta-lactone; D008874:Midazolam