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Gerontology. 2005 Jul-Aug;51(4):215-24.

Age influences the expression of GAP-43 in the rat hippocampus following seizure.

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1
Department of Neurology, Ernst Moritz Arndt University, Greifswald, Germany.

Abstract

BACKGROUND:

Normal aging is associated with impairments in learning and memory and motor function. One viable hypothesis is that these changes reflect an age-related decrease in brain plasticity.

OBJECTIVE:

The aim of the present study was to identify age-related changes in the time course of expression of the axonal growth associated protein 43 (GAP-43) in a rat model of brain plasticity.

METHODS:

We examined by Northern blotting, in situ hybridization, and immunohistochemistry the effects of age on the time course of the expression GAP-43 following pentylenetetrazole-induced seizure in the hippocampus of 3-, 18-, and 28-month-old rats.

RESULTS:

In this model of brain plasticity, young rats displayed a decrease in GAP-43 mRNA levels in CA1, CA3, and polymorphic regions, lasting from 10 h to 3 days after seizure. This was followed by recovery, with peak expression between days 10 and 20. The baseline levels of GAP-43 mRNA decreased with age, especially in the CA3 region. Despite lower baseline levels, middle-aged rats showed the same pattern of upregulation of GAP-43 mRNA expression as the young animals. Old rats showed only minimal upregulation, however, and this occurred only in the polymorphic layer. The level GAP-43 protein itself was higher in old control rats than in the other two control groups, a condition that was transiently reversed by seizure activity.

CONCLUSIONS:

Middle-aged rats are still capable of a sustained, though diminished, response to seizure activity, while old rats lose this ability. Disruption of the temporal and anatomical coordination of expression of GAP-43 may contribute to the general decline in brain plasticity with age.

PMID:
15980649
DOI:
10.1159/000085117
[Indexed for MEDLINE]
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