Open AccessReduced age‐related plasticity of neurotrophin receptor expression in selected sympathetic neurons of the rat
Author(s) -
Cowen T.,
Woodhoo A.,
Sullivan C. D.,
Jolly R.,
Crutcher K. A.,
Wyatt S.,
Michael G. J.,
Orike N.,
Gatzinsky K.,
Thrasivoulou C.
Publication year - 2003
Publication title -
aging cell
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.103
H-Index - 140
eISSN - 1474-9726
pISSN - 1474-9718
DOI - 10.1046/j.1474-9728.2003.00035.x
Subject(s) - biology , tropomyosin receptor kinase a , neurotrophin , in situ hybridization , nerve growth factor , endocrinology , medicine , neurotrophin 3 , receptor , neuron , gene expression , neuroscience , neurotrophic factors , brain derived neurotrophic factor , genetics , gene
Summary Selective vulnerability of particular groups of neurons is a characteristic of the aging nervous system. We have studied the role of neurotrophin (NT) signalling in this phenomenon using rat sympathetic (SCG) neurons projecting to cerebral blood vessels (CV) and iris which are, respectively, vulnerable to and protected from atrophic changes during old age. RT‐PCR was used to examine NT expression in iris and CV in 3‐ and 24‐month‐old rats. NGF and NT3 expression in iris was substantially higher compared to CV; neither target showed any alterations with age. RT‐PCR for the principal NT receptors, trkA and p75, in SCG showed increased message during early postnatal life. However, during mature adulthood and old age, trkA expression remained stable while p75 declined significantly over the same period. In situ hybridization was used to examine receptor expression in subpopulations of SCG neurons identified using retrograde tracing. Eighteen to 20 h following local treatment of iris and CV with NGF, NT3 or vehicle, expression of NT receptor protein and mRNA was higher in iris‐ compared with CV‐projecting neurons from both young and old rats. NGF and NT3 treatment had no effect on NT receptor expression in CV‐projecting neurons at either age. However, similar treatment up‐regulated p75 and trkA expression in iris‐projecting neurons from 3‐month‐old, but not 24‐month‐old, rats. We conclude that lifelong exposure to low levels of NTs combined with impaired plasticity of NT receptor expression are predictors of neuronal vulnerability to age‐related atrophy.