Substance P, enkephalins, somatostatin, cholecystokinin, oxytocin, and vasopressin in human spinal cord.

Several neuropeptides were immunohistologically studied in normal human spinal cords. Substance P, methionine-enkephalin, leucine-enkephalin, and cholecystokinin positive fibers were found in all cytoarchitectonic layers, with a specific distribution pattern for each peptide. Somatostatin, oxytocin, and vasopressin immunoreactivities were restricted to particular spinal layers. Perikarya and proximal dendrites were visualized and classified by comparison with previous Golgi analyses. Substance P was contained in "radiate cells" of layer III, methionine-enkephalin in marginal neurons as well as in layer II "stellate cells," and somatostatin in layer II "islet cells." Several results differed from those reported in other species. Chemical neuroanatomy may provide new insights into the neuronal organization of the human spinal cord.