Document Detail

Reorganization of the morphology of hippocampal neurites and synapses after stress-induced damage correlates with behavioral improvement.
MedLine Citation:
PMID:  10799757     Owner:  NLM     Status:  MEDLINE    
We recently demonstrated that stress-induced cognitive deficits in rats do not correlate with hippocampal neuronal loss. Working on the premise that subtle structural changes may however be involved, we here evaluated the effects of chronic stress on hippocampal dendrite morphology, the volume of the mossy fiber system, and number and morphology of synapses between mossy fibers and CA3 dendritic excrescences. To better understand the mechanisms by which stress exerts its structural effects, we also studied these parameters in rats given exogenous corticosterone. Further, to search for signs of structural reorganization following the termination of the stress and corticosterone treatments, we analysed groups of rats returned to treatment-free conditions. All animals were assessed for spatial learning and memory performance in the Morris water maze. Consistent with previous findings, dendritic atrophy was observed in the CA3 hippocampal region of chronically stressed and corticosterone-treated rats; in addition, we observed atrophy in granule and CA1 pyramidal cells following these treatments. Additionally, profound changes in the morphology of the mossy fiber terminals and significant loss of synapses were detected in both conditions. These alterations were partially reversible following rehabilitation from stress or corticosterone treatments. The fine structural changes, which resulted from prolonged hypercortisolism, were accompanied by impairments in spatial learning and memory; the latter were undetectable following rehabilitation. We conclude that there is an intimate relationship between corticosteroid levels, hippocampal neuritic structure and hippocampal-dependent learning and memory.
N Sousa; N V Lukoyanov; M D Madeira; O F Almeida; M M Paula-Barbosa
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Neuroscience     Volume:  97     ISSN:  0306-4522     ISO Abbreviation:  Neuroscience     Publication Date:  2000  
Date Detail:
Created Date:  2000-07-27     Completed Date:  2000-07-27     Revised Date:  2009-11-03    
Medline Journal Info:
Nlm Unique ID:  7605074     Medline TA:  Neuroscience     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  253-66     Citation Subset:  IM; S    
Department of Anatomy, Porto Medical School, Alameda Prof. Hernâni Monteiro, 4200-319, Porto, Portugal.
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MeSH Terms
Corticosterone / pharmacology
Dendrites / pathology
Hippocampus / drug effects,  pathology*
Maze Learning / physiology*
Nerve Fibers / pathology
Neurites / pathology*
Neurons / pathology*
Pyramidal Cells / pathology
Rats, Wistar
Restraint, Physical
Social Behavior
Stress, Psychological / pathology*,  physiopathology*
Synapses / pathology*
Reg. No./Substance:

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