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摘要
The pace of nigrostriatal degeneration, both with regards to striatal denervation and loss of melanin and tyrosine hydroxylase-positive neurons, is poorly understood especially early in the Parkinson%26apos;s disease process. This study investigated the extent of nigrostriatal degeneration in patients with Parkinson%26apos;s disease at different disease durations from time of diagnosis. Brains of patients with Parkinson%26apos;s disease (n = 28) with post-diagnostic intervals of 1-27 years and normal elderly control subjects (n = 9) were examined. Sections of the post-commissural putamen and substantia nigra pars compacta were processed for tyrosine hydroxylase and dopamine transporter immunohistochemistry. The post-commissural putamen was selected due to tissue availability and the fact that dopamine loss in this region is associated with motor disability in Parkinson%26apos;s disease. Quantitative assessments of putaminal dopaminergic fibre density and stereological estimates of the number of melanin-containing and tyrosine hydroxylase-immunoreactive neurons in the substantia nigra pars compacta (both in total and in subregions) were performed by blinded investigators in cases where suitable material was available (n = 17). Dopaminergic markers in the dorsal putamen showed a modest loss at 1 year after diagnosis in the single case available for study. There was variable (moderate to marked) loss, at 3 years. At 4 years post-diagnosis and thereafter, there was virtually complete loss of staining in the dorsal putamen with only an occasional abnormal dopaminergic fibre detected. In the substantia nigra pars compacta, there was a 50-90% loss of tyrosine hydroxylase-positive neurons from the earliest time points studied with only marginal additional loss thereafter. There was only a similar to 10% loss of melanized neurons in the one case evaluated 1 year post-diagnosis, and variable (30 to 60%) loss during the first several years post-diagnosis with more gradual and subtle loss in the second decade. At all time points, there were more melanin-containing than tyrosine hydroxylase-positive cells. Loss of dopaminergic markers in the dorsal putamen occurs rapidly and is virtually complete by 4 years post-diagnosis. Loss of melanized nigral neurons lags behind the loss of dopamine markers. These findings have important implications for understanding the nature of Parkinson%26apos;s disease neurodegeneration and for studies of putative neuroprotective/restorative therapies.
- 出版日期2013-8
