The influence of stress on fear memory extinction is not associated with dendritic spines remodeling in the ventral hippocampus.

RUIZ SD; BENDER CL; MOLINA VA; CALFA GD

Mar del Plata

Congreso; XXXII CONGRESO ANUAL SAN 2017; 2017

Sociedad Argentina de Neurociencias

Fear extinction results in the suppression of the fear response once the conditioned stimulus does not predict the threatening event anymore. Different anxiety disorders have typical deficits in both extinction memory formation and expression.Ventral Hippocampus (VH) is critically involved in the processing of the aversive information as well as in the expression fear extinction memory. The aim of the present work was to evaluate whether the structural plasticity of CA1 VH accompanied the characteristic extinction memory formation and the influence of stress on the extinction memory.Stressed animals were fear conditioned to context and later trained in an extinction paradigm (repeated context re-exposures without foot-shock). Animals were sacrificed for preparation 1 day after conditioning (before extinction) or 1 day after extinction.Prior stress exposure induced a deficit in the formation of the extinction fear memory. With respect to structural plasticity, and on the contrary to the higher density of dendritic spines observed in CA1 Dorsal Hippocampus after fear conditioning, returning to basal levels after extinction training, CA1 VH presented no changes in the number or the morphology of dendritic spines, regardless of the fear conditioning, extinction training or stress condition.Thus, changes in the dynamic of the extinction fear memory might not be supported by synaptic structural remodeling in VH.