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Title: PDE5 Inhibition Improves Object Memory in Standard Housed Rats but Not in Rats Housed in an Enriched Environment: Implications for Memory Models?
Authors: Akkerman, Sven
Prickaerts, Jos
Bruder, Ann K.
Wolfs, Kevin H. M.
DE VRY, Jochen 
Blokland, Arjan
Issue Date: 2014
Source: PLOS ONE, 9 (11)
Abstract: Drug effects are usually evaluated in animals housed under maximally standardized conditions. However, it is assumed that an enriched environment (EE) more closely resembles human conditions as compared to maximally standardized laboratory conditions. In the present study, we examined the acute cognition enhancing effects of vardenafil, a PDE5 inhibitor, which stimulates protein kinase G/CREB signaling in cells, in three different groups of male Wistar rats tested in an object recognition task (ORT). Rats were either housed solitarily (SOL) or socially (SOC) under standard conditions, or socially in an EE. Although EE animals remembered object information longer in the vehicle condition, vardenafil only improved object memory in SOL and SOC animals. While EE animals had a heavier dorsal hippocampus, we found no differences between experimental groups in total cell numbers in the dentate gyrus, CA2-3 or CA1. Neither were there any differences in markers for pre-and postsynaptic density. No changes in PDE5 mRNA-and protein expression levels were observed. Basal pCREB levels were increased in EE rats only, whereas beta-catenin was not affected, suggesting specific activation of the MAP kinase signaling pathway and not the AKT pathway. A possible explanation for the inefficacy of vardenafil could be that CREB signaling is already optimally stimulated in the hippocampus of EE rats. Since previous data has shown that acute PDE5 inhibition does not improve memory performance in humans, the use of EE animals could be considered as a more valid model for testing cognition enhancing drugs.
Notes: [Akkerman, Sven; Prickaerts, Jos; Wolfs, Kevin H. M.; De Vry, Jochen] Maastricht Univ, European Sch Neurosci EURON, Fac Hlth Med & Life Sci, Dept Psychiat & Neuropsychol, Maastricht, Netherlands. [Blokland, Arjan] Maastricht Univ, European Sch Neurosci EURON, Fac Psychol & Neurosci, Dept Neuropsychol & Psychopharmacol, Maastricht, Netherlands. [Vanmierlo, Tim] Hasselt Univ, Biomed Res Inst, Dept Immunol & Biochem, Hasselt, Belgium. [Bruder, Ann K.] Univ Bonn, Univ Hosp Bonn, Inst Clin Chem & Clin Pharmacol, Bonn, Germany.
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ISSN: 1932-6203
e-ISSN: 1932-6203
DOI: 10.1371/journal.pone.0111692
ISI #: 000344556900062
Rights: Copyright: © 2014 Akkerman et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Category: A1
Type: Journal Contribution
Validations: ecoom 2015
Appears in Collections:Research publications

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