α7 nicotinic acetylcholine receptors in the retrosplenial cortex modulate neuronal activity in the retrosplenial cortex and hippocampus during aversive memory acquisition

α7 nicotinic acetylcholine receptors (α7 nAChRs) in the retrosplenial cortex (RSC), located predominantly on GABAergic interneurons in superficial cortical layers, modulate the acquisition of aversive memory. To investigate the RSC–dorsal hippocampal circuit, this study analyzed the expression profile of the immediate early gene c-Fos in the RSC and hippocampal regions 90 minutes after pharmacological blockade of RSC α7 nAChRs with methyllycaconitine (MLA) during acquisition of an inhibitory avoidance (IA) task. Blocking α7 nAChRs produced a significant increase in c-Fos expression in the anterior RSC (aRSC), particularly in layers 2 and 2/3, as well as in CA1 and CA3. These findings indicate that RSC α7 nAChRs modulate neuronal activity across the RSC–hippocampal circuit during aversive learning. Given the predominant localization of RSC a7nAChRs on GABAergic interneurons, their blockade may alter local excitation–inhibition dynamics and consequently affect the integration of contextual information within the aRSC.