The structure of the caudate nucleus of the cat: light and electron microscopy

220

218

Section: Resultsmentioning

confidence: 99%

Drd1a-tdTomato BAC Transgenic Mice for Simultaneous Visualization of Medium Spiny Neurons in the Direct and Indirect Pathways of the Basal Ganglia

Shuen¹,

Chen²,

Gloss³

et al. 2008

220

218

“…For example, the medium spiny cells of the neostriatum were thought to be local circuit neurons because of their locally arborizing axons (Fox et al, 1971;Kemp and Powell, 1971), but recent studies exploiting the intracellular injection of HRP have revealed that these neurons do have local axonal branches within the neostriatum, but they also have axonal branches to the globus pallidus and substantia nigra (Preston et al, 1980). Closer to the subject of our study is the Golgi analysis of the ventral posterior nucleus showing cells that have local axonal branches (Tbmbol, 1967).…”

Section: Discussionmentioning

confidence: 99%

Glutamic acid decarboxylase-immunoreactive neurons and horseradish peroxidase-labeled projection neurons in the ventral posterior nucleus of the cat and Galago senegalensis

Penny¹,

Fitzpatrick²,

Schmechel³

et al. 1983

116

Immunocytochemical methods were used to identify neurons in the ventral posterior nucleus of the cat and Galago senegalensis that contain glutamic acid decarboxylase (GAD), the synthetic enzyme for the inhibitory neurotransmitter, GABA. In both species GAD-immunoreactive neurons make up about 30% of the total neurons in the ventral posterior nucleus and form a distinct class of small cells. After cortical injections of horseradish peroxidase (HRP), GAD-immunoreactive cells are not labeled with HRP and may, therefore, be GABAergic local circuit neurons. Comparison of the dendritic morphology of GAD-immunoreactive neurons with that of HRP-filled projection neurons reveals that the morphology of the GAD-containing neurons is distinct and, in particular, that the GAD-immunoreactive neurons display fewer primary dendrites. The relay neurons, in turn, can be divided into classes based on dendritic morphology and cell body size.The idea that thalamic neurons could be divided into classes based on morphological criteria has a long history. According to Rambn y Cajal (1909, the most fundamental distinction was between the neurons with long axons that project to the cerebral cortex and neurons with short axons that were thought to be local circuit neurons. Cajal found the neurons with short axons or "cellules 6 cylindre-axe court" to be distributed widely in the nervous system and to be especially numerous in the thalamus and neocortex of higher mammals. The neurons with long axons (or projection neurons) could be further subdivided into classes based on their appearance in Golgi material. T6mb61 recently (1967) identified at least two classes in the case of the somatosensory ventral posterior nucleus of the cat.

“…It is the target of inputs from the entire cortex and certain thalamic nuclei (parafascicular and centromedian nucleus) and provides output to other nuclei of the basal ganglia. The striatum is composed primarily of spiny projection neurons (DiFiglia et al, 1976;Bishop et al, 1982;Gerfen and Wilson, 1996), which constitute ϳ95% of the striatal neuronal population (Kemp and Powell, 1971). These projection neurons are also the major target of afferents to the striatum.…”

Section: Abstract: Striatum; Dopaminergic Cells; Parkinson's Diseasementioning

confidence: 99%

Dopaminergic Neurons Intrinsic to the Primate Striatum

Betarbet¹,

Turner²,

Chockkan³

et al. 1997

241

198

Intrinsic, striatal tyrosine hydroxylase-immunoreactive (TH-i) cells have received little consideration. In this study we have characterized these neurons and their regulatory response to nigrostriatal dopaminergic deafferentation. TH-i cells were observed in the striatum of both control and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys; TH-i cell counts, however, were 3.5-fold higher in the striatum of MPTPlesioned monkeys. To establish the dopaminergic nature of the TH-i cells, sections were double-labeled with antibodies to dopamine transporter (DAT). Immunofluorescence studies demonstrated that nearly all TH-i cells were double-labeled with DAT, suggesting that they contain the machinery to be functional dopaminergic neurons. Two types of TH-i cells were identified in the striatum: small, aspiny, bipolar cells with varicose dendrites and larger spiny, multipolar cells. The aspiny cells, which were more prevalent, corresponded morphologically to the GABAergic interneurons of the striatum. Doublelabel immunofluorescence studies using antibodies to TH and glutamate decarboxylase (GAD 67 ), the synthetic enzyme for GABA, showed that 99% of the TH-i cells were GAD 67 -positive. Very few (Ͻ1%) of the TH-i cells, however, were immunoreactive for the calcium-binding proteins calbindin and parvalbumin. In summary, these results demonstrate that the dopaminergic cell population of the striatum responds to dopamine denervation by increasing in number, apparently to compensate for loss of extrinsic dopaminergic innervation. Moreover, this population of cells corresponds largely with the intrinsic GABAergic cells of the striatum. This study also suggests that the adult primate striatum does retain some intrinsic capacity to compensate for dopaminergic cell loss.