open access

Vol 65, No 4 (2006)
ORIGINAL ARTICLES
Published online: 2006-09-18
Submitted: 2012-02-06
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The influence of acute and chronic open-field exposure on the hippocampal formation: an immunohistochemical study

Badowska-Szalewska E, Klejbor I, Dziwiątkowski J, Spodnik JH, Moryś J
Folia Morphol 2006;65(4):343-351.

open access

Vol 65, No 4 (2006)
ORIGINAL ARTICLES
Published online: 2006-09-18
Submitted: 2012-02-06

Abstract

The hippocampus plays a role in new learning, memory and emotion and is a component of the neuroanatomical stress circuit. The structure is involved in terminating hypothalamic-pituitary-adrenocortical (HPA) axis responses to stress and attenuates stress responses by shutting off this axis.
The immunoreactivity (-ir) of c-Fos, NGF and its receptor TrkA following acute and chronic open-field stress were studied in CA1-CA3 and the DG of the hippocampus.
The material consisted of 21 male adult rats divided into three groups: nonstressed (control) animals and rats exposed to acute (15 min once) and chronic (15 min daily for 21 days) aversive stimulation (open-field exposure). The brains were stained with use of immunohistochemical methods for c-Fos, NGF or TrkA. In the animals exposed to acute open-field stress the number of c-Fos-, TrkAand NGF-ir cells was higher in all the structures studied than in the control animals. However they were differentiated only in c-Fos immunoreactivity. In the rats exposed to chronic open-field stress the number of c-Fos-ir cells in the structures of the hippocampal formation studied was smaller than in rats exposed to acute stress and was comparable to that in the control group. No differences were observed between the groups exposed to acute and chronic stress in the number of TrkA-ir cells in the structures under investigation. The number of NGF-ir neurons in CA1 and CA2 was lower after exposure to chronic than after exposure to acute stress but was still higher than that in the control group. Our findings indicate that neurons of CA1-CA3 and the DG are engaged in the stress response after acute as well as chronic open-field exposure. This is probably related to the important role of the hippocampus in processing new spatial information as well as in the habituation processes, although these appear to have different mechanisms.

Abstract

The hippocampus plays a role in new learning, memory and emotion and is a component of the neuroanatomical stress circuit. The structure is involved in terminating hypothalamic-pituitary-adrenocortical (HPA) axis responses to stress and attenuates stress responses by shutting off this axis.
The immunoreactivity (-ir) of c-Fos, NGF and its receptor TrkA following acute and chronic open-field stress were studied in CA1-CA3 and the DG of the hippocampus.
The material consisted of 21 male adult rats divided into three groups: nonstressed (control) animals and rats exposed to acute (15 min once) and chronic (15 min daily for 21 days) aversive stimulation (open-field exposure). The brains were stained with use of immunohistochemical methods for c-Fos, NGF or TrkA. In the animals exposed to acute open-field stress the number of c-Fos-, TrkAand NGF-ir cells was higher in all the structures studied than in the control animals. However they were differentiated only in c-Fos immunoreactivity. In the rats exposed to chronic open-field stress the number of c-Fos-ir cells in the structures of the hippocampal formation studied was smaller than in rats exposed to acute stress and was comparable to that in the control group. No differences were observed between the groups exposed to acute and chronic stress in the number of TrkA-ir cells in the structures under investigation. The number of NGF-ir neurons in CA1 and CA2 was lower after exposure to chronic than after exposure to acute stress but was still higher than that in the control group. Our findings indicate that neurons of CA1-CA3 and the DG are engaged in the stress response after acute as well as chronic open-field exposure. This is probably related to the important role of the hippocampus in processing new spatial information as well as in the habituation processes, although these appear to have different mechanisms.
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Keywords

NGF; TrkA; hippocampus; open field test; stress; c-Fos; neurotrophins

About this article
Title

The influence of acute and chronic open-field exposure on the hippocampal formation: an immunohistochemical study

Journal

Folia Morphologica

Issue

Vol 65, No 4 (2006)

Pages

343-351

Published online

2006-09-18

Bibliographic record

Folia Morphol 2006;65(4):343-351.

Keywords

NGF
TrkA
hippocampus
open field test
stress
c-Fos
neurotrophins

Authors

Badowska-Szalewska E
Klejbor I
Dziwiątkowski J
Spodnik JH
Moryś J

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