Giesler G J, Nahin R L, Madsen A M
J Neurophysiol. 1984 Feb;51(2):260-75. doi: 10.1152/jn.1984.51.2.260.
As one of a series of studies of the ascending spinal cord pathways that might be involved in nociception in the rat, we have examined the projection to the dorsal column nuclei that originates in the spinal cord dorsal horn using the retrograde transport of horseradish peroxidase (HRP). This projection in other animals has been called the postsynaptic dorsal column (PSDC) pathway. Small iontophoretic injections of HRP into the cuneate nucleus (CN) labeled more than 350 neurons in alternate sections within the ipsilateral gray matter of segments C6-8. Fewer than 25 neurons were labeled in L4-6 by injections into CN. Injections of HRP confined to the gracile nucleus (GN) labeled more than 200 neurons within a narrow band extending across the ipsilateral dorsal horn subjacent to substantia gelatinosa of L4-6. Fewer than 10 cells were labeled in C6-8 by such injections. Labeling in lumbar neurons following injections into GN was prevented by transection of the dorsal columns at T10, T8, or C2. Thus, neurons labeled by such injections ascend entirely within the dorsal columns. Lesions of the dorsal columns in C2 reduced the number of labeled neurons in the cervical cord following CN injections by approximately 90%. Combined lesions of the dorsal columns and ipsilateral dorsal lateral funiculus (DLF) reduced the number of cells labeled in C6-8 by approximately 98%. Thus, the majority of labeled neurons in the cervical enlargement project to CN via the dorsal columns; a small secondary component of the cervical projection to CN appears to ascend within the DLF. To compare the relative sizes of the projections to the dorsal column nuclei from PSDC neurons and dorsal root ganglion cells (DRG), labeled neurons were counted in the gray matter of the cervical and lumbar enlargements and the corresponding DRG. In the four animals so examined, PSDC neurons constituted over 38% of the neurons that projected to CN and approximately 30% of the cells that projected to GN. These findings indicate that the PSDC projection of the rat is capable of providing a large somatotopically organized input to the dorsal column nuclei.
作为对大鼠中可能参与伤害感受的脊髓上行通路进行的一系列研究之一，我们利用辣根过氧化物酶（HRP）的逆行运输，研究了起源于脊髓背角并投射到薄束核的通路。在其他动物中，这条投射通路被称为突触后背柱（PSDC）通路。向楔束核（CN）进行微量离子导入注射HRP，在同侧C6 - 8节段灰质的交替切片中标记了超过350个神经元。向CN注射后，L4 - 6节段标记的神经元少于25个。将HRP注射局限于薄束核（GN），在L4 - 6节段胶状质下方同侧背角的一个窄带内标记了超过200个神经元。此类注射在C6 - 8节段标记的细胞少于10个。在T10、T8或C2水平横断背柱可阻止向GN注射后腰段神经元的标记。因此，此类注射标记的神经元完全在背柱内上行。C2节段背柱损伤使CN注射后颈髓中标记神经元的数量减少了约90%。背柱和同侧背外侧索（DLF）联合损伤使C6 - 8节段标记的细胞数量减少了约98%。因此，颈膨大处的大多数标记神经元通过背柱投射到CN；颈段向CN投射的一小部分次要成分似乎在DLF内上行。为了比较PSDC神经元和背根神经节细胞（DRG）向薄束核投射的相对大小，对颈膨大、腰膨大的灰质以及相应的DRG中的标记神经元进行了计数。在接受检查的四只动物中，PSDC神经元占投射到CN的神经元的比例超过38%，占投射到GN的细胞的比例约为30%。这些发现表明，大鼠的PSDC投射能够为薄束核提供大量按躯体定位组织的输入。
