title: Synaptophysin immunoreactivity and distributions of calcium-binding proteins highlight the functional organization of the rat's dorsal column nuclei.
abstract: The mammalian dorsal column nuclei (DCN) are principally composed of the cuneate (CN) and gracile (GN) nuclei. Data presented here support previously published anatomical and functional evidence that the longitudinal organization of the CN and GN reflect the complex role of the DCN in somatosensory processing. The CN is organized longitudinally into three parts. Within the middle portion of this nucleus, primary afferent projections and cuneothalamic cells are concentrated. Although traditional cytoarchitectonic analyses had failed to detect this tripartite organization in rats, we found evidence for it, with a functional middle region, extending approximately 0.2-0.9 mm caudal to the obex, characterized by precise somatotopy of primary afferent terminations and corresponding somatotopy of cytochrome oxidase (CO) blotches. Additional evidence is presented here consistent with a functionally distinct middle region within the rat's CN: (1) patches of dense synaptophysin (a synaptic-vesical-associated protein)-immunoreactivity (SYN-IR) are limited to the middle CN region, coincident with the dense CO blotches; (2) neurons immunoreactive for the calcium-binding proteins calbindin-D28 (CB), calretinin (CR) and parvalbumin (PV) are concentrated in the middle CN region. Furthermore, in adult rats subjected to perinatal forepaw removal, (1) the patterns of SYN-IR in the middle region of the CN are disrupted, as had previously been shown for the patterns of CO blotches; (2) in contrast, however, distributions of CN cells with PV-, CB- and CR-IR are unaffected. Evidence for a tripartite division in the GN is also presented, based on the distributions of cells with PV-, CB- and CR-IR.
authors.affiliation: Department of Neuroscience and Cell Biology, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway 08854-5635, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Crockett
authors.forename: S
authors.initials: S
authors.lastname: Maslany
authors.forename: M D
authors.initials: MD
authors.lastname: Egger
mesh_terms: D000818:Animals; D064032:Calbindin 2; D064026:Calbindins; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D008526:Medulla Oblongata / Q000033:anatomy & histology*; D010320:Parvalbumins / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism*; D051381:Rats; D064030:S100 Calcium Binding Protein G / Q000378:metabolism
chemical_list: C576512:Calb2 protein, rat; D064032:Calbindin 2; D064026:Calbindins; D002135:Calcium-Binding Proteins; D010320:Parvalbumins; D064030:S100 Calcium Binding Protein G