Neurochemical architecture of the human striatum

Abstract

The striatum of the human brain has a highly differentiated neurochemical architecture visible in stains for many of the neurotransmitter-related molecules present in the striatum. The distributions for these chemical markers have never been analyzed comprehensively. We compared the distributions of multiple neurochemical markers in a serial-section analysis of the caudate nucleus, the putamen, and the ventral striatum in normal human brains. The cholinergic system was identified with choline acetyltransferase (ChAT). The organization of the cholinergic fiber system was compared with that of striatal systems expressing immunoreactivity for calbindin D28k, met-enkephalin, substance P, tyrosine hydroxylase, and parvalbumin. Each striatal region analyzed displayed a unique neurochemical organization. In the dorsal caudate nucleus, the distribution of all markers followed the classical striosome/matrix organization as previously reported. In the dorsal putamen, ChAT-staining was less intense, and striosomes were delineated primarily by unstained fiber bundles. In the ventral caudate nucleus/nucleus accumbens region, the boundaries of ChAT-stained regions were not always visible with stains for calbindin, enkephalin, and substance P. The ventral putamen displayed a similar organization, except in its lateral part, where ChAT-poor regions were often found adjacent to, rather than in register with, regions expressing low levels of the other markers (calbindin, enkephalin, substance P, and tyrosine hydroxylase). Our findings suggest that, in addition to the classical striosome-matrix organization visible in the dorsal caudate nucleus and putamen, there is further neurochemical differentiation in a large ventral part of the caudate nucleus and putamen and in the ventral striatum-nucleus accumbens proper. The more complex relationships among the different neurochemical systems in the ventral striatum may reflect the increase in size in the primate of striatal regions associated with association and limbic cortex.

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A three-dimensional, histological and deformable atlas of the human basal ganglia. I. Atlas construction based on immunohistochemical and MRI data

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α6-Containing Nicotinic Acetylcholine Receptors Dominate the Nicotine Control of Dopamine Neurotransmission in Nucleus Accumbens

“…Markers of striatal cholinergic innervation (choline acetyltransferase and AChE) show dense and patchy distributions within both dorsal and ventral striatum (Graybiel et al, 1986;Holt et al, 1997;Phelps and Vaughn, 1986;Zahm and Brog, 1992) but there is not a consensus from microdialysis reports for the comparative ACh tone (eg Ichikawa et al, 2002;Parada et al, 1997). However, ambenonium in striatum has been reported to increase single-pulse-evoked DA release at low concentrations (B10 À9 -10 À8 M) but suppress DA release at higher concentrations (410 À8 M) when ACh reaches concentrations sufficient to desensitize nAChRs .…”