Spatial memory performances of aged rats in the water maze predict levels of hippocampal neurogenesis.
Proceedings of the National Academy of Sciences. 2003-11-12; 100(24): 14385-14390
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1. Proc Natl Acad Sci U S A. 2003 Nov 25;100(24):14385-90. Epub 2003 Nov 12.
Spatial memory performances of aged rats in the water maze predict levels of
Drapeau E(1), Mayo W, Aurousseau C, Le Moal M, Piazza PV, Abrous DN.
(1)Institut National de la Santá et de la Recherche Médicale Unité 588, Domaine
de Carreire, Rue Camille Saint Saëns, University of Bordeaux II, 33077 Bordeaux
Neurogenesis occurs within the adult dentate gyrus of the hippocampal formation
and it has been proposed that the newly born neurons, recruited into the
preexistent neuronal circuits, might be involved in hippocampal-dependent
learning processes. Age-dependent spatial memory impairments have been related to
an alteration in hippocampal plasticity. The aim of the current study was to
examine whether cognitive functions in aged rats are quantitatively correlated
with hippocampal neurogenesis. To this end, we took advantage of the existence of
spontaneous individual differences observed in aged subjects in a
hippocampal-dependent task, the water maze. We expected that the spatial memory
capabilities of aged rats would be related to the levels of hippocampal
neurogenesis. Old rats were trained in the water maze, and, 3 weeks after
training, rats were injected with 5-bromo-2′-deoxyuridine (BrdUrd, 50 or 150
mg/kg) to label dividing cells. Cell proliferation was examined one day after the
last BrdUrd injection, whereas cell survival and differentiation were determined
3 weeks later. It is shown that a quantitative relationship exists between
learning and the number of newly generated neurons. Animals with preserved
spatial memory, i.e., the aged-unimpaired rats, exhibited a higher level of cell
proliferation and a higher number of new neurons in comparison with rats with
spatial memory impairments, i.e., the aged-impaired rats. In conclusion, the
extent of memory dysfunction in aged rats is quantitatively related to the
hippocampal neurogenesis. These data reinforce the assumption that neurogenesis
is involved in memory processes and aged-related cognitive alterations.
PMID: 14614143 [Indexed for MEDLINE]