Age-related declines in nigral neuronal function correlate with motor impairments in rhesus monkeys.
Although the role of dopamine dysfunction is well established in Parkinson's disease, the effect of nigrostriatal degeneration on motor performance during normal aging is less well understood. In this study, aged rhesus monkeys (25-27 years old) displayed significant impairments relative to young (3-5 years old) cohorts in motor function as assessed on a fine motor task and home cage activity. Additionally, the clinical motor function of aged monkeys was impaired relative to young monkeys as assessed on a clinical rating scale. Unbiased stereologic measurements of the substantia nigra revealed a significant age-related loss of tyrosine hydroxylase-immunoreactive (TH-ir; 50.3%) and dopamine transporter-immunoreactive (DAT-ir; 33.2%) nigral neurons. The monkeys performance on the fine motor task and on the clinical rating scale was correlated with TH-ir neuronal counts. The number of DAT-ir nigral neurons was correlated with activity and clinical rating scale scores. Our results suggest that age-related motor impairments in nonhuman primates are associated with spontaneous decreases in TH-ir and DAT-ir nigral cells. The correlation of motor deficits with the loss of TH-ir and DAT-ir nigral neurons suggests that aged nonhuman primates may provide a useful model for mimicking changes seen in human aging and early Parkinson's disease.
Emborg
M E
ME
Research Center for Brain Repair and Department of Neurological Sciences, Rush Presbyterian Medical Center, Chicago, Illinois 60612, USA.
Ma
S Y
SY
Mufson
E J
EJ
Levey
A I
AI
Taylor
M D
MD
Brown
W D
WD
Holden
J E
JE
Kordower
J H
JH
D000375:Aging / Q000502:physiology*; D000818:Animals; D002352:Carrier Proteins / Q000032:analysis; D002452:Cell Count; D003213:Conditioning, Psychological / Q000502:physiology; D004298:Dopamine / Q000502:physiology; D050483:Dopamine Plasma Membrane Transport Proteins; D005260:Female; D008253:Macaca mulatta / Q000502:physiology*; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009043:Motor Activity / Q000502:physiology*; D009046:Motor Neurons / Q000737:chemistry / Q000166:cytology* / Q000201:enzymology; D009419:Nerve Tissue Proteins / Q000032:analysis; D013378:Substantia Nigra / Q000166:cytology*; D014446:Tyrosine 3-Monooxygenase / Q000032:analysis
D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine