Distribution of neurons immunoreactive for parvalbumin and calbindin in the somatosensory thalamus of the raccoon

Abstract

The aim of this study was to assess the distribution of neurons immunoreactive for parvalbumin (PV), calbindin (CaBP), glutamic acid decarboxylase (GAD), and gamma-aminobutyric acid (GABA) in the somatosensory thalamus of the raccoon and to compare these features to those of other species, especially primates. Immunohistochemistry was used to study the location of these neurons in the ventroposterior nucleus (VP), ventroposterior inferior nucleus (VPI), posterior group of nuclei (Po), and reticular nucleus (Rt). A consistent differential pattern of PV-positive (PV+) and CaBP-positive (CaBP+) cells was found in the somatosensory thalamus. Many PV+ neurons were observed in VP and Rt, but very few were found in VPI or Po. In contrast, CaBP+ neurons were distributed throughout VP, VPI, and Po but were very sparse or absent in Rt. In the VP nucleus, PV+ cells were distributed in clusters separated by interclusteral regions with a sparse distribution of PV+ cell bodies. The distributions of PV+ and CaBP+ cells tended to be complementary to each other in VP; regions with a high density of PV+ neurons had a low density of CaBP+ cell bodies. Double-labeling experiments revealed very few neurons in which PV and CaBP immunoreactivities were colocalized. Cells immunoreactive for GAD or GABA were found in PV-dense clusters of VP; fewer GABAergic neurons were present in the CaBP-dense interclusteral regions of VP and in VPI and Po. GAD+ and GABA+ neurons were most prominently distributed in Rt. We conclude that the distributions of PV+ and CaBP+ cell bodies in the raccoon somatosensory thalamus are very similar to those in primates. The density of GABAergic neurons in the somatosensory thalamus of the raccoon is less than that in the cat and monkey, but the relative distribution of GABAergic neurons in the different somatosensory nuclei is very similar to that in the cat and monkey. These results are discussed in relation to findings in other species and are related to the functions of lemniscal and nonlemniscal somatosensory pathways.

Parvalbumin and GABA in the developing somatosensory thalamus of the rat: an immunocytochemical ultrastructural correlation

“…In particular, several lines of evidence have indicated that in thalamic nuclei these CaBPs are variously expressed in different mammalian species (Jones and Hendry 1989;Bentivoglio et al 1990;Rausell et al 1992;Arai et al 1994;De Biasi et al 1994a;Herron et al 1997) and during development (Frassoni et al 1991(Frassoni et al , 1998. In the adult rat thalamus PV is expressed only by neurons of the reticular nucleus (RT) and by axonal fibers and puncta in different nuclei of the dorsal thalamus (Celio 1990;Arai et al 1994).…”

Cyto- and chemoarchitecture of the dorsal thalamus of the monotreme Tachyglossus aculeatus, the short beaked echidna

“…On the other hand, Parv + somata have been found in other thalamic nuclei of non-rodent eutheria (e.g. macaque VP- Rausell et al, 1992; VP of the galago and Tupaia- Diamond et al, 1993;AV, LP, LGv of the guinea pig-De Biasi et al, 1994; VP of the raccoon- Herron et al, 1997). The relatively large number of Parv + somata in many thalamic nuclei of the echidna may be a consequence of the small size of the thalamic reticular nucleus in this monotreme.…”

“…Somata immunoreactive for CB have been reported in midline thalamic nuclei (Re, PV, CeM), VM, LG, LD and Po (Celio, 1990;Frassoni et al, 1991;Arai et al, 1994). In non-rodent eutherians, somata immunoreactive for CB are found in the primate VPL (Rausell et al, 1992), primate LG (Diamond et al, 1993), primate pulvinar (Gutierrez et al, 1995) and raccoon VP, VPI and Po (Herron et al, 1997). In eutheria, the distribution of CB immunoreactivity is often reported to be complementary to that of Parv (Celio, 1990).…”

“…neuropil immunoreactivity or otherwise in midline thalamic nuclei), but (as in many eutheria) many nuclei have extensive populations of neurons immunoreactive for both. Herron et al (1997) reported that within VP distributions of Parv + and CB + neurons were also complementary, with clusters of Parv + cell bodies separated by sparse intercluster regions, and low densities of CB + neurons in areas where Parv + neurons were concentrated. We did note that Parv + neurons in the VPM of the echidna were not evenly distributed, whereas CB + neurons were more smoothly distributed in the VPM and it was also of note that the density of CB + neurons was substantially lower in the VPL relative to VPM.…”

The excitatory thalamo‐“cortical” projection within the song control system of zebra finches is formed by calbindin‐expressing neurons

“…In telencephalic regions, including cortical fields in mammals and parts of the avian pallium in birds (a brain region considered homologous as a field to the cortex, claustrum, and parts of the amygdala in mammals; see Reiner et al, 2004; Jarvis et al, 2005), these cells very often constitute a subpopulation of GABAergic interneurons (Hendry and Jones, 1991; Baimbridge et al, 1992; Rogers, 1992; Jones, 1993; Parent et al, 1995; DeFelipe, 1997; Pinaud et al, 2006a). Such correspondence, however, is not universal (Mize et al, 1991; Baimbridge et al, 1992; Behan et al, 1992; Mize, 1992; Jones, 1993; Herron et al, 1997). The expression of calbindin, and a related calcium‐binding protein, parvalbumin, has also been instrumental for the classification of nuclear subdivisions within the mammalian thalamus (Jones, 1998; Jones, 2001).…”