Effects of corticosterone treatment and rehabilitation on the hippocampal formation of neonatal and adult rats. An unbiased stereological study

• Type: Article in International Scientific Journal
• Date: 1998

Authors

Sousa, N (Author) Other; Madeira, MD (Author) FMUP; Paula Barbosa, MM (Author) Other

Journal

Title: Brain Research

Vol. 794

Pages: 199-210

ISSN: 0006-8993

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 106 Citations

Scopus - 114 Citations

Scientific classification

FOS: Medical and Health sciences > Basic medicine

Other information

Authenticus ID: P-001-7R5

DOI: 10.1016/s0006-8993(98)00218-2

Abstract (EN): Elevations in the plasma levels of glucocorticoids are associated with cognitive impairments that have been ascribed to loss of neurons in the hippocampal formation. However, recent studies have strongly challenged this view. In order to clarify this issue, we have employed for the first time the optical fractionator and the Cavalieri principle, two unbiased stereological tools, to estimate respectively the total number of neurons and the volumes of the main subdivisions of the hippocampal formation of rats submitted to corticosterone treatment for different periods, either neonatally or in adulthood. A significant reduction in the number of neurons and in the volumes of the layers of the dentate gyrus and CA3 hippocampal field was found in rats exposed to glucocorticoids in the neonatal period; furthermore, animals treated with corticosterone from birth until 180 days of age had also a reduction in the volume of the stratum radiatum of the CA1 hippocampal field. Conversely, when the exposure occurred only during adulthood, no significant neuronal loss was observed, but there were significant reductions in the volume of layers in the dentate gyrus and CA3 hippocampal field. To search for signs of structural recovery, we incorporated a group of rats submitted to corticosterone treatment during the neonatal period in which the hormonal conditions were restored thenceforth. In this group we found a significant increase in the volume of the molecular layer of the dentate gyrus when compared with rats that were kept under corticosteroid treatment. In conclusion, these data provide a sound structural basis for the cognitive deficits observed during, and following, exposure to increased levels of glucocorticoids.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12