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Environmental enrichment reverses learning impairment in the Morris water maze after focal cerebral ischemia in rats
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine.
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2004 (English)In: European Journal of Neuroscience, ISSN 0953-816X, E-ISSN 1460-9568, Vol. 19, no 8, 2288-2298 p.Article in journal (Refereed) Published
Abstract [en]

Cognitive impairment is common after ischemic stroke. In rodent stroke models using occlusion of the middle cerebral artery (MCA) this is reflected by impaired spatial memory associated with the size of the ischemic lesion. Housing in an enriched environment enhances brain plasticity and improves recovery of sensorimotor functions after experimental stroke in rats. In this study we report that postischemic housing in an enriched environment also attenuates the long-term spatial memory impairment after MCA occlusion and extinguishes the association between spatial memory and infarct volume. An enriched environment did not significantly alter the expression of selected neuronal plasticity-associated genes 1 month after MCA occlusion, indicating that most of the adaptive changes induced by an enriched environment have already occurred at this time point. We conclude that the attenuated memory impairment induced by environmental enrichment after MCA occlusion provides a useful model for further studies on the neurobiological mechanisms of recovery of cognitive functions after ischemic stroke.

Place, publisher, year, edition, pages
2004. Vol. 19, no 8, 2288-2298 p.
Keyword [en]
animals, brain ischemia/metabolism/*psychology, cognition/physiology, environment, male, maze learning/*physiology, memory disorders/metabolism/prevention & control/*psychology, rats, sprague-dawley, synapsins/biosynthesis
National Category
Clinical Medicine
URN: urn:nbn:se:umu:diva-3997DOI: 10.1111/j.0953-816X.2004.03248.xPubMedID: 15090055OAI: diva2:142928
Available from: 2004-05-12 Created: 2004-05-12 Last updated: 2010-08-19Bibliographically approved
In thesis
1. The effect of enriched environment on gene expression and stroke recovery
Open this publication in new window or tab >>The effect of enriched environment on gene expression and stroke recovery
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Stroke is the third leading cause of death and the major course of long-term disabilities in industrialized countries. Most surviving stroke patients show some degree of spontaneous recovery, but persistent symptoms in sensorimotor and cognitive functions are common. The symptoms can be reproduced in experimental stroke models in rats by occlusion of the middle cerebral artery. Housing rats in an enriched environment (EE), i.e. group housing in a large cage with toys that are changed daily, increases neuronal plasticity in healthy rats and can also improve functional recovery after experimental stroke.

The present thesis investigates the effect of EE on the recovery of sensorimotor and cognitive functions one month after focal cerebral ischemia in rats, with emphasis on the underlying molecular mechanisms. Furthermore, EE-induced effect on gene expression in healthy rats was investigated after different periods of EE-housing and at different time points of the day.

We show an improved recovery of both sensorimotor and cognitive functions in rats housed in EE for one month after focal cerebral ischemia. The recovery of sensorimotor function correlated significantly to mRNA expression of the plasticity associated transcription factors NGFI-A and NGFI-B in hippocampus and cortical regions outside the infarct. Social interaction seems to be an important component for the beneficial effects of EE after focal cerebral ischemia. Microarray analysis of hippocampal gene expression after one month of postischemic environmental enrichment revealed no confirmable EE-induced changes that could explain the improved recovery in spatial memory. Interestingly, healthy rats housed in EE showed increased mRNA expression of NGFI-A and Krox-20 exclusively during the dark period of the day compared to rats housed in isolation. In addition, EE housed rats had a substantial diurnal variation in NGFI-A, Krox-20 and NGFI-B mRNA expression; this was absent in single-housed rats. EE-induced changes in gene expression are more evident during the dark period of the day, when rats are more active and can benefit from the stimulating environment. This is important to consider in future investigation of putative mediators of the EE-induced neuronal plasticity.

In summary, these findings may contribute to an increased understanding of the underlying molecular mechanisms behind improved functional recovery in rats housed in enriched environment after focal cerebral ischemia.

115 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 883
Medicine, experimental stroke, recovery, memory, inducible transcription factors, Medicin
National Category
Dermatology and Venereal Diseases
urn:nbn:se:umu:diva-278 (URN)91-7305-626-X (ISBN)
Public defence
2004-06-04, Sal B, plan 9, By 1D, Tandläkarhögskolan, Norrlands universitetssjukhus, Umeå, 13:00
Available from: 2004-05-12 Created: 2004-05-12Bibliographically approved

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Dahlqvist, PerRönnbäck, AnnicaBergström, Sven-AndersSöderström, IngegerdOlsson, Tommy
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