title: Neurosteroids infusion into the CA1 hippocampal region on exploration, anxiety-like behaviour and aversive learning.
abstract: Neurosteroids (NS) are substances synthesised de novo in the brain that have rapid modulatory effects on ionotropic receptors. Specifically, NS can act as positive allosteric modulators of GABAA receptors as pregnanolone or allopregnanolone (Allop), or GABAA negative modulators and NMDA positive modulators as pregnenolone (PREG) or dehydroepiandrosterone (DHEA) and their sulphate esters (PREGS and DHEAS). Given this, their role in anxiety and emotional disturbances has been suggested. In addition, NS such as PREGS or DHEAS have demonstrated a promnesic role in several learning tests. The aim of the present work is to highlight the role that the dorsal (CA1) hippocampus plays in the behavioural profile of NS such as Allop and PREGS in tests assessing exploration, anxiety and aversive learning in rats. For this purpose, animals were administered intrahippocampally with Allop (0.2μg/0.5μl), PREGS (5ng/0.5μl) or vehicle in each hippocampus, and tested in the Boissier and elevated plus maze (EPM) tests. For learning test we have chosen the passive avoidance paradigm. Results indicate that intrahippocampal administration of Allop enhances exploration, reflected in an increase in the total and the inner number of head-dips. Allop-injected animals also showed an increase in the percentage of entries into the open arms of the EPM, suggesting an anxiolytic-like profile. In addition, post-acquisition PREGS administration enhanced passive avoidance retention, while post-acquisition Allop administration had no effects on aversive learning retention. These results point out the important role of the dorsal (CA1) hippocampus in several NS behavioural effects, such as exploration, anxiety, learning and memory.
authors.affiliation: Departament de Psicobiologia i Metodologia en Ciències de la Salut, Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Mòdol
authors.forename: Sònia
authors.initials: S
authors.lastname: Darbra
authors.forename: Marc
authors.initials: M
authors.lastname: Pallarès
mesh_terms: D000818:Animals; D001007:Anxiety / Q000188:drug therapy* / Q000503:physiopathology; D001362:Avoidance Learning / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D056547:CA1 Region, Hippocampal / Q000187:drug effects* / Q000502:physiology; D004195:Disease Models, Animal; D005106:Exploratory Behavior / Q000187:drug effects*; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D011280:Pregnanolone / Q000008:administration & dosage*; D011284:Pregnenolone / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D018709:Statistics, Nonparametric
chemical_list: C018370:pregnenolone sulfate; D011284:Pregnenolone; D011280:Pregnanolone