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Ageing of substantia nigra in humans:
cell loss may be compensated by hypertrophy
Author(s) -
Cabello C. R.,
Thune J. J.,
Pakkenberg H.,
Pakkenberg B.
Publication year - 2002
Publication title -
neuropathology and applied neurobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.538
H-Index - 95
eISSN - 1365-2990
pISSN - 0305-1846
DOI - 10.1046/j.1365-2990.2002.00393.x
Subject(s) - substantia nigra , melanin , muscle hypertrophy , ageing , dopamine , medicine , degeneration (medical) , endocrinology , biology , cell , neuromelanin , anatomy , pathology , dopaminergic , biochemistry
In a stereological study of the human substantia nigra (SN), the total number of melanin‐positive and melanin‐negative neurones from 28 male subjects aged 19–92 years was estimated using a uniform sampling design and optical disectors. There was a significant decrease in the total number of melanin‐positive neurones as a function of age ( r 2 =0.18, residual‐CV=0.35, 2 P =0.032). Using the rotator method, the size distribution of the melanin‐positive neurones was estimated and showed a significant difference in mean cell volume of melanin‐positive neurones between the seven youngest (21 077 µm 3 ) and the seven oldest individuals (32 011 µm 3 ), 2 P =0.022. Using a combination of the total number of melanin‐positive neurones and their size distribution, the total perikaryon volume of melanin‐positive neurones could be estimated and showed no decrease with increasing age ( r 2 =0.01, residual‐CV=0.41, 2 P =0.62). Age‐related decline in dopamine‐transporter neurones within the SN might explain the occurrence of extrapyramidal symptoms in many elderly individuals. Although age‐related cell hypertrophy is usually considered to be an indication of cell degeneration or necrosis, this might not always be the case. The fact that motor symptoms, although present in many of the elderly, are of a limited nature despite the high percentage of lost neurones could be due to a compensatory increase in the cell body of dopamine‐producing SN neurones. Thus, the total amount of cell substance capable of producing the essential transmitters might not be reduced to a critically low level as a result of ageing.