Reorganization of the morphology of hippocampal neurites and synapses after stress-induced damage correlates with behavioral improvement

• Type: Article in International Scientific Journal
• Date: 2000

Authors

Sousa, N (Author) Other; Lukoyanov, NV (Author) Other; Madeira, MD (Author) FMUP; Almeida, OFX (Author) Other; Paula Barbosa, MM (Author) Other

Journal

Title: Neuroscience

Vol. 97

Pages: 253-266

ISSN: 0306-4522

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 576 Citations

Scopus - 627 Citations

Scientific classification

FOS: Medical and Health sciences > Basic medicine

Other information

Authenticus ID: P-001-1Y5

DOI: 10.1016/s0306-4522(00)00050-6

Abstract (EN): 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. (C) 2000 IBRO. Published by Elsevier Science Ltd.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 14