Dopamine Innervation in the Thalamus: Monkey versus Rat

We recently identified the thalamic dopaminergic system in the human and macaque monkey brains, and, based on earlier reports on the paucity of dopamine in the rat thalamus, hypothesized that this dopaminergic system was particularly developed in primates. Here we test this hypothesis using immunohi...

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Bibliographic Details
Published in:Cerebral cortex (New York, N.Y. 1991) N.Y. 1991), 2009-02, Vol.19 (2), p.424-434
Main Authors: García-Cabezas, Miguel Ángel, Martínez-Sánchez, Patricia, Sánchez-González, Miguel Ángel, Garzón, Miguel, Cavada, Carmen
Format: Article
Language:English
Subjects:
Animals
Axons - physiology
Axons - ultrastructure
dopamine
Dopamine - physiology
Immunohistochemistry
Interneurons - physiology
Interneurons - ultrastructure
Macaca
Macaca fascicularis
macaque
Male
Mediodorsal Thalamic Nucleus - cytology
Mediodorsal Thalamic Nucleus - physiology
Mediodorsal Thalamic Nucleus - ultrastructure
Microscopy, Electron
Primates
rat
Rats
Rats, Sprague-Dawley
species differences
Species Specificity
thalamus
Thalamus - cytology
Thalamus - physiology
Tissue Fixation
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Summary:We recently identified the thalamic dopaminergic system in the human and macaque monkey brains, and, based on earlier reports on the paucity of dopamine in the rat thalamus, hypothesized that this dopaminergic system was particularly developed in primates. Here we test this hypothesis using immunohistochemistry against the dopamine transporter (DAT) in adult macaque and rat brains. The extent and density of DAT-immunoreactive (-ir) axons were remarkably greater in the macaque dorsal thalamus, where the mediodorsal association nucleus and the ventral motor nuclei held the densest immunolabeling. In contrast, sparse DAT immunolabeling was present in the rat dorsal thalamus; it was mainly located in the mediodorsal, paraventricular, ventral medial, and ventral lateral nuclei. The reticular nucleus, zona incerta, and lateral habenular nucleus held numerous DAT-ir axons in both species. Ultrastructural analysis in the macaque mediodorsal nucleus revealed that thalamic interneurons are a main postsynaptic target of DAT-ir axons; this suggests that the marked expansion of the dopamine innervation in the primate in comparison to the rodent thalamus may be related to the presence of a sizable interneuron population in primates. We remark that it is important to be aware of brain species differences when using animal models of human brain disease.
ISSN:1047-3211
1460-2199
DOI:10.1093/cercor/bhn093