Abstract
Among the basal ganglia-thalamocortical circuits, the putamen plays a critical role in the “motor” circuits that control voluntary movements and motor learning. The human neostriatum comprises two functional subdivisions known as the striosome (patch) and matrix compartments. Accumulating evidence suggests that compartment-specific dysregulations of dopamine activity might be involved in the disease-specific pathology and symptoms of human striatal diseases including movement disorders. This study was undertaken to examine whether or how striatal dopaminergic innervations are organized into the compartmentalized architecture found in the putamen of adult human brains. For this purpose, we used a highly sensitive immunohistochemistry (IHC) technique to identify tyrosine hydroxylase (TH; EC 1.14.16.2), a marker for striatal dopaminergic axons and terminals, in formalin-fixed paraffin-embedded (FFPE) tissues obtained from autopsied human brains. Herein, we report that discrete compartmentalization of TH-labeled innervations occurs in the putamen, as in the caudate nucleus (CN), with a higher density of TH labeling in the matrix compared to the striosomes. Our results provide anatomical evidence to support the hypothesis that compartment-specific dysfunction of the striosome-matrix dopaminergic systems might contribute to the genesis of movement disorders.
Highlights
The human neostriatum comprising the caudate nucleus (CN) and putamen is the primary input region of the basal ganglia, a group of subcortical nuclei that control a wide range of sensorimotor, cognitive and emotional functions
We showed an immunohistochemical evidence that tyrosine hydroxylase (TH) is compartmentally distributed in both the CN and putamen in formalin-fixed paraffin-embedded (FFPE) human autopsy brains
By means of the serial section analysis and the double fluorescent labeling technique, the present study indicates that TH is enriched in the matrix compartment relative to the striosomes at the striatal levels from the rostral to the caudal throughout
Summary
The human neostriatum comprising the caudate nucleus (CN) and putamen is the primary input region of the basal ganglia, a group of subcortical nuclei that control a wide range of sensorimotor, cognitive and emotional functions (for review see, Graybiel, 2008; Amemori et al, 2011). It has so far been known that the basal ganglia are organized into several structurally and functionally distinct neural circuits that link the cortex, basal ganglia, and thalamus, with each circuit focused on a different frontal cortex territory (Alexander et al, 1986, 1990). Among these basal gangliathalamocortical circuits, the putamen participates in the ‘‘motor’’ circuits and is thereby important to basal ganglia motor control and movement disorders (Albin et al, 1989; DeLong, 1990). Kish et al (1988) showed that the depletion of dopamine in patients with PD was most remarkable in the putamen, in its caudal portions. Goto et al (1989a, 1996) documented that in parkinsonian patients, a pathological lesion was found in the nigrostriatal loop that forms a link with the putamen
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