Axonal arborization of dopaminergic neurons of the rat midbrain:mechanism of Parkinson's disease

点击翻译按钮获取中文摘要

The axonal arbors of nigrostriatal dopaminergicneurons were visualized with a viral vector expressing membrane-targeted green fluorescent protein in rat brain. As results, all eight reconstructed tyrosine hydoroxylase-positive dopaminergic neurons possessed widely spread and highly dense axonal arborizations in the neostriatum. The striatal axonal bush of each reconstructed dopaminergic neurons covered 0.45 - 5.7% (mean ± S.D. = 2.7 ± 1.5%) of the total volume of the neostriatum. Furthermore, all the dopaminergic neurons innervated both striosome and matrix compartments of the neostriatum, although each neuron's arborization tended to favor one of these compartments. Detail morphological images of DA neurons derived from this new approach are used to elucidate the role of DA neurons in PD. Firstly, we point out how the new images reveal how DA neurons have a massive axonal arborization in the striatum. This arborization is on a scale not previously known, and of a form that implies both a particular vulnerability and a redundancy in DA neurons. Secondly, we describe how the imaging results indicate that DA neurons innervate both the striosome and the matrix compartments of the striatum. This dual innervation has implications for reinforcement learning in the basal ganglia,with further implications for how normal behavior is driven and how it may be disrupted by Levodopa PD therapies. In conclusion, these results would also contribute to understanding the clinicopathology of Parkinson's disease and related syndromes