Evidence that sympathetic preganglionic neurones are arranged in target-specific columns in the thoracic spinal cord of the rat.

It is recognised that selective activation of different target-specific sympathetic preganglionic neurones forms the basis of many autonomic responses. The anatomical basis for this could be the spatial arrangement of these neurones in the spinal cord nuclei. The present study tested this possibility in the rat by determining the location in single animals of three distinct groups of sympathetic preganglionic neurones, one group projecting to the superior cervical ganglion, another to the stellate ganglion and one to the adrenal medulla. Sympathetic preganglionic neurones to each of these targets were simultaneously labeled with fluorescent dyes, either Fluorogold, Fast Blue, or Diamidino Yellow. The numbers and general morphology of the neurones were similar to previous descriptions, and they were distributed in four subnuclei, the nucleus intermediolateralis pars principalis, the nucleus intermediolateralis pars funiculus, the nucleus intercalatus spinalis, and the nucleus intercalatus spinalis pars paraependymalis. It was shown that all three groups of neurones were represented in the more medial sympathetic nuclei, but in the nuclei at the lateral border of the intermediate grey matter each one of the three groups of neurones occupied a discrete location. Adrenal medullary sympathetic preganglionic neurones occupied a lateral aspect, the superior cervical ganglion sympathetic preganglionic neurones a medial aspect, and the stellate ganglion sympathetic preganglionic neurones a space between. Some sympathetic preganglionic neurones were double labeled after dye injections into the superior cervical and stellate ganglion thus indicating that they projected to both ganglia.(ABSTRACT TRUNCATED AT 250 WORDS)