Stimulation of hippocampal adenylyl cyclase activity dissociates memory consolidation processes for response and place learning.

Full Abstract

Procedural and declarative memory systems are postulated to interact in either a synergistic or a competitive manner, and memory consolidation appears to be a highly critical stage for this process. However, the precise cellular mechanisms subserving these interactions remain unknown. To investigate this issue, 24-h retention performances were examined in mice given post-training intrahippocampal injections of forskolin (FK) aiming at stimulating hippocampal adenylyl cyclases (ACs). The injection was given at different time points over a period of 9 h following acquisition in either an appetitive bar-pressing task or water-maze tasks challenging respectively "response memory" and "place memory." Retention testing (24 h) showed that FK injection altered memory formation only when given within a 3- to 6-h time window after acquisition but yielded opposite memory effects as a function of task demands. Retention of the spatial task was impaired, whereas retention of both the cued-response in the water maze and the rewarded bar-press response were improved. Intrahippocampal injections of FK produced an increase in pCREB immunoreactivity, which was strictly limited to the hippocampus and lasted less than 2 h, suggesting that early effects (0-2 h) of FK-induced cAMP/CREB activation can be distinguished from late effects (3-6 h). These results delineate a consolidation period during which specific cAMP levels in the hippocampus play a crucial role in enhancing memory processes mediated by other brain regions (e.g., dorsal or ventral striatum) while eliminating interference by the formation of hippocampus-dependent memory.

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Author information

Author/s: Martel, Guillaume (G); Millard, Annabelle (A); Jaffard, Robert (R); Guillou, Jean-Louis (JL);

Affiliation: Laboratoire de Neurosciences Cognitives, Université Bordeaux I, Centre Nationale de la Recherche Scientifique Unite Mixte de Recherche (CNRS UMR) 5106, 33405 Talence cedex, France.

Journal and publication information

Publication Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't

Journal: Learning & memory (Cold Spring Harbor, N.Y.) (Learn Mem), published in United States. (Language: eng)

Reference: -2006 May-Jun; vol 13 (issue 3) : pp 342-8

Dates: Created 2006/06/02; Completed 2006/08/23; Revised 2008/11/20;

PMID: 16741285, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adenylate Cyclase - metabolism
Analysis of Variance
Animals
Appetitive Behavior - drug effects; physiology
Cyclic AMP - metabolism
Cyclic AMP Response Element-Binding Protein - metabolism
Enzyme Activators - administration & dosage
Forskolin - administration & dosage
Hippocampus - drug effects; enzymology

Male
Maze Learning - drug effects; physiology
Memory - drug effects; physiology
Mice
Mice, Inbred C57BL
Microinjections
Phosphorylation
Retention (Psychology) - drug effects; physiology
Time Factors

Associated Chemicals: Cyclic AMP Response Element-Binding Protein (0) ; Enzyme Activators (0) ; Cyclic AMP (60-92-4) ; Forskolin (66428-89-5) ; Adenylate Cyclase (EC 4.6.1.1)

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