Premium
Activation of septal 5‐HT 1A receptors alters spatial memory encoding, interferes with consolidation, but does not affect retrieval in rats subjected to a water‐maze task
Author(s) -
Koenig Julie,
Cosquer Brigitte,
Cassel JeanChristophe
Publication year - 2008
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.20368
Subject(s) - memory consolidation , memory retention , psychology , antagonist , receptor , neuroscience , water maze , chemistry , anesthesia , pharmacology , medicine , hippocampus
Using Long‐Evans rats tested in a water maze, this study assessed the role of 5‐HT 1A /5‐HT 7 receptors of the medial septum in encoding, consolidation, and retrieval of spatial information. The testing protocol ( acquisition: daily four‐trial sessions over three consecutive days; retention: probe trial on day 4) was first validated by showing that intraseptal infusions of lidocaine (LIDO; 40 μg/0.5 μL) disrupted acquisition and retrieval of the task. 8‐OH‐DPAT (4 μg/0.5 μL) infused before each acquisition session prevented learning/retention of the platform location, an effect attenuated by pretreatment with the 5‐HT 1A receptor antagonist WAY 100635. With the 5‐HT 7 antagonist SB 269970, the 8‐OH‐DPAT‐induced acquisition deficit seemed attenuated, but there was no subsequent retention. When infused immediately, 1, 4, or 6 h after each acquisition session, 8‐OH‐DPAT did not hinder consolidation. When the infusions were performed 2 h postacquisition, however, consolidation was disrupted. Finally, when infused before a probe trial after drug‐free acquisition, 8‐OH‐DPAT had no effect, suggesting no interference with retrieval processes. We also established that 8‐OH‐DPAT had no effects when the platform was visible, and altered neither home‐cage activity nor anxiety‐related behavior (elevated plus‐maze). Altogether, these results show that 5‐HT 1A receptors in the septal region contribute both to declarative‐like information encoding and subsequently, within a given postacquisition time window, to its consolidation. They do not participate in the retrieval of recently learned declarative‐like information. These observations suggest that 5‐HT 1A receptors of the medial septum contribute to a serotonin‐mediated mechanism involved in the encoding and consolidation, not the retrieval of spatial hippocampal‐ dependent knowledge. These results might have some relevance to approaches aimed at modifying serotonergic functions in the brain for the treatment of disorders such as depression, anxiety, post‐traumatic stress, and amnesia. © 2007 Wiley‐Liss, Inc.