Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 50, Issue 4 B193-B200, Copyright © 1995 by The Gerontological Society of America
Reduced expression of the molecular markers of dopaminergic neuronal atrophy in the aging rat brain
T Himi, M Cao and N Mori
Division of Neurogerontology, Andrus Gerontology Center, University of Southern California, Los Angeles, USA.
Expression of mRNAs encoding the dopamine transporter (DAT) and tyrosine
hydroxylase (TH) in dopaminergic neurons of the substantia nigra (SN) was
examined in young and aged Fischer 344 rats by in situ hybridization.
Quantitative analysis revealed a statistically significant decline in both
DAT and TH mRNA expression in 24-month-old rats in comparison to
6-month-old rats. In addition, it was noted that DAT mRNA expression tended
to decrease by 18 months, while TH mRNA reduction did not occur until 24
months. The age-related loss of DAT and TH mRNA expressions was accompanied
by diminished expression of mRNA for a neuronal growth-associated protein
GAP-43, but not for SCG10 or alpha 1-tubulin. The loss of GAP-43 mRNA
became evident when both DAT and TH gene expression declined with advanced
age. Our findings indicate that DAT may be a marker of atrophy in dopamine
neurons during normal aging.
