GABAergic signaling in the Basolateral Amygdala Complex (BLA) plays a crucial role in the modulation of stress-induced promoting influence on fear memory. Moreover, accumulating evidence suggest that the dorsal hippocampus (DH) is a downstream target of BLA neurons in contextual fear. Given that hippocampal structural plasticity is proposed to provide a substrate for the storage of long-term memories, the main aim of this study was to evaluate the modulation of GABA neurotransmission in the BLA on spine density in the DH following stress on contextual fear learning. Prior stressful experience promoted contextual fear memory and enhanced spine density in the DH. Intra-BLA infusion of Midazolam, a positive modulator of GABAa sites, prevented the facilitating influence of stress on both fear retention and hippocampal structural plasticity. Similarly to the effects induced by stress, the blockade of GABAa sites within the BLA ameliorated fear memory emergence and increased structural remodeling in the DH. These findings suggest that structural changes in DH associated to the promoting influence of stress on fear memory are under the control of GABAergic transmission in BLA.
