Neuronal plasticity in aging: a quantitative immunohistochemical study of GAP-43 distribution in discrete regions of the rat brain.
Age-related changes in neuroplasticity have been investigated considering the neuronal growth-associated protein GAP-43 as a marker of nerve cell structural adaptive capabilities. We carried out a quantitative immunohistochemical study on the distribution of GAP-43 in the molecular layer of the cerebellar cortex, in the inner molecular layer of the hippocampal dentate gyrus, in the stratum radiatum of the CA1 region, in layer 1 of the cingulate cortex and in the nerve fiber layer of the main olfactory bulb of 3-, 18- and 31-month-old Wistar rats. A decrease of GAP-43 immunoreactivity was observed in the old rats in comparison with the adult animals in all the 5 areas analyzed, although these variations were only statistically significant in the dentate gyrus, cingulate cortex and olfactory bulb. In these latter zones, GAP-43 immunolabeling is reduced by 54, 42 and 38%, respectively, in the old versus the adult group. Comparing these data with the age-dependent decrease of neuron density innervating the areas investigated, we support the hypothesis that the decline of GAP-43 observed in old animals documents a consistent reduction of axon plasticity in the inner molecular layer of the dentate gyrus and in layer 1 of the cingulate cortex. These results suggest an important role of GAP-43 as a marker of age-dependent deterioration of synaptic plasticity, especially in those areas of the brain involved in memory and emotional behavior.
Casoli
T
T
Neurobiology of Aging Laboratory, 'N. Masera' I.N.R.C.A. Research Department, Ancona, Italy.
Spagna
C
C
Fattoretti
P
P
Gesuita
R
R
Bertoni-Freddari
C
C
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002540:Cerebral Cortex / Q000378:metabolism; D005260:Female; D019922:GAP-43 Protein; D007150:Immunohistochemistry; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D019922:GAP-43 Protein; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins