The spino-latero-reticular system of the rat: Projections from the superficial dorsal horn and structural characterization of marginal neurons involved

Quantitative and neurogenic analysis of neurons with supraspinal projections in the superficial dorsal horn of the rat lumbar spinal cord

“…Propriospinal neurons in each of the three regions of lamina I have also been found to be distributed in proportion to the total number of neurons in each region (Bice and Beal, 1997). The fact that regional variations in distribution were not found in the present study may be due to the fact that projection targets injected with retrograde tracers in the present study were larger and overlapped several of the injection sites described in the studies by Lima and Coimbra (1988, 1990, 1991a.…”

“…Differences in the sensitivity and efficacy of various retrograde tracers may be responsible for much of the variability. By using the retrograde tracer cholera toxin subunit B, for example, it has been shown that, in lamina I, there are 28.5 spinothalamic neurons in spinal segments L1 plus L2 (Lima and Coimbra, 1988), 224 spinomesencephalic neurons in spinal segments T13 through L6 (Lima and Coimbra, 1989), and 95.3 spinomedullary neurons (projecting to the lateral reticular nucleus only) in spinal segments T13 through L6 (Lima and Coimbra, 1991a). If it is assumed that each spinal segment is approximately 2,000 µm in length, then the extrapolated number of neurons in each of the above cases would be as follows: 0.07 spinothalamic, 0.16 spinomesencephalic, and 0.07 spinomedullary neurons per each 10-µm section of tissue.…”

“…in lamina I, the majority of spinothalamic neurons are located in the middle one-third of the lamina (Lima and Coimbra, 1988), most spinomedullary neurons that project to the dorsal reticular nucleus are in the medial one-third (Lima and Coimbra, 1990), spinomedullary neurons that project to the lateral reticular nucleus are mainly in the lateral one-third of the lamina (Lima and Coimbra, 1991a), and spinomesencephalic neurons are distributed throughout all three regions (Lima and Coimbra, 1989). In the present study, however, all three groups of supraspinal projection neurons in lamina I (FG-labeled, FG-plus TB-labeled, and TB-labeled cells) were distributed in each of the three regions in proportion to the total number of neurons within each region.…”

Effect of lesions of A5 or A7 noradrenergic cell group or surgical transection of brainstem catecholamine pathways on plasma catecholamine levels in rats injected subcutaneously by formalin

“…Nociceptive signals from the spinal cord and the brainstem reach neurons in the lower brainstem catecholaminergic cell groups (Menetrey and Basbaum 1987;Lima et al 1991;Tavares et al 1996;Palkovits et al 1997;Palkovits 2002). Here, we investigated the effect of lesioning of selected catecholamine neurons or pathways in the lower brain stem on the activity of the sympatho-adrenal system in response to acute painful stimuli.…”

Structural characterization of marginal (lamina I) spinal cord neurons in the cat: A golgi study

“…In the rat, fusiform cells were found to be immunoreactive for GABA and DYN, multipolar cells for GABA, flattened cells for SP and DYN, and pyramidal cells for ENK and, in smaller amounts, for DYN . Studies based on spinal retrograde labeling from several brain sites showed that fusiform cells project to the caudal ventrolateral medullary reticular formation (VLMlat; Lima et al, 1991), NTS (Esteves et al, 1993), and caudal mesencephalon (Lima and Coimbra, 1989); multipolar cells project to the DRt (Lima and Coimbra, 1990); flattened cells to the VLM, NTS, DRt, and ventrobasal complex of the thalamus Coimbra, 1988, 1990;Lima et al, 1991;Esteves et al, 1993); and pyramidal cells to all the above-mentioned targets (Lima and Coimbra, 1988,1990Lima et al, 1991;Esteves et al, 1993).…”