NPY-containing nerve terminals and fibers in close association with peptidergic sympathetic preganglionic neurons.

The anatomical relationship between neuropeptide Y (NPY)-containing nerve terminals and fibers and peptidergic sympathetic preganglionic neurons (SPN) was studied immunohistochemically in cat spinal cord after colchicine administration. Terminals and fibers with NPY were found in apparent close apposition to SPN containing enkephalin-, neurotensin-, somatostatin- and substance P-like immunoreactivities along the entire thoracolumbar cord and to varying degrees. The results argue against involvement of NPY in peptide-specific pathways to peripheral organs and suggest, instead, that NPY and its association with peptidergic SPN play a more general role in the regulation of the autonomic nervous system.